Food microbiology最新文献

Synergistic regulation of microbial metabolism and quality features in liver products using combined ultrasound-pulsed electric field assisted co-fermentation 联合超声脉冲电场辅助共发酵对肝脏产物微生物代谢和品质特征的协同调节

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-27 DOI: 10.1016/j.fm.2026.105046

Jinglin Xu , Xinze Li , Changyu Zhou , Anderson S. Sant'Ana , Daodong Pan , Jinxuan Cao , Hao Zhang , Qiang Xia

Bio-fermentation process is widely used to improve the quality and flavor of meat products, but the mechanisms by which co-applied physical fields synergistically regulate microbial metabolism during fermentation remain insufficiently elucidated. In this study, yeast and lactic acid bacteria were co-inoculated for lamb liver fermentation, to which ultrasound (US), pulsed electric field (PEF), and their combination (US-PEF) were applied to evaluate their effects on the physicochemical properties, sensory characteristics, and metabolome shifts. The results showed that US-PEF significantly reduced pH, total volatile basic nitrogen, and thiobarbituric acid reactive substances by 23.86 %, 73.30 %, and 53.40 %, respectively, relative to the unfermented group, while maintaining color and texture. Additionally, the perceived off-flavor intensity decreased by 52.12 %, and overall flavor improved significantly. Microstructural characterization showed that US-PEF treatment caused localized damage to the microbial cell surface structure, including cytoplasmic loosening and increased vacuolation, corresponding to enhanced membrane permeability and substrate utilization. Untargeted metabolomics revealed clear separation of metabolic profiles among treatments, with differential regulation observed in amino acid and lipid pathways. By increasing membrane permeability and potentially activating microbial enzymes, US-PEF accelerated protein degradation and increased dipeptides and taste-active amino acids, while lowering levels of unsaturated fatty acid precursors and thereby suppressing the formation of off-flavor compounds. These findings elucidate the synergistic regulation by physical fields-assisted fermentation contributed to improving the quality and flavor of livestock by-products.

生物发酵工艺被广泛用于改善肉制品的品质和风味，但在发酵过程中协同作用的物理场调控微生物代谢的机制尚不清楚。本研究采用酵母和乳酸菌共接种进行羊肝发酵，采用超声（US）、脉冲电场（PEF）及其组合（US-PEF）研究其对羊肝理化特性、感官特性和代谢组变化的影响。结果表明，与未发酵组相比，US-PEF显著降低了pH、总挥发性碱性氮和硫代巴比托酸活性物质，分别降低了23.86%、73.30%和53.40%，同时保持了颜色和质地。此外，感知的异味强度降低了52.12%，整体风味显著改善。微观结构表征表明，US-PEF处理对微生物细胞表面结构造成局部损伤，包括细胞质松动和空泡化增加，相应的膜通透性和底物利用率增加。非靶向代谢组学揭示了不同处理之间的代谢谱明显分离，在氨基酸和脂质途径中观察到不同的调节。通过增加膜通透性和潜在激活微生物酶，US-PEF加速了蛋白质降解，增加了二肽和风味活性氨基酸，同时降低了不饱和脂肪酸前体的水平，从而抑制了异味化合物的形成。这些结果阐明了物理场辅助发酵对畜产品品质和风味的协同调节作用。

{"title":"Synergistic regulation of microbial metabolism and quality features in liver products using combined ultrasound-pulsed electric field assisted co-fermentation","authors":"Jinglin Xu , Xinze Li , Changyu Zhou , Anderson S. Sant'Ana , Daodong Pan , Jinxuan Cao , Hao Zhang , Qiang Xia","doi":"10.1016/j.fm.2026.105046","DOIUrl":"10.1016/j.fm.2026.105046","url":null,"abstract":"<div><div>Bio-fermentation process is widely used to improve the quality and flavor of meat products, but the mechanisms by which co-applied physical fields synergistically regulate microbial metabolism during fermentation remain insufficiently elucidated. In this study, yeast and lactic acid bacteria were co-inoculated for lamb liver fermentation, to which ultrasound (US), pulsed electric field (PEF), and their combination (US-PEF) were applied to evaluate their effects on the physicochemical properties, sensory characteristics, and metabolome shifts. The results showed that US-PEF significantly reduced pH, total volatile basic nitrogen, and thiobarbituric acid reactive substances by 23.86 %, 73.30 %, and 53.40 %, respectively, relative to the unfermented group, while maintaining color and texture. Additionally, the perceived off-flavor intensity decreased by 52.12 %, and overall flavor improved significantly. Microstructural characterization showed that US-PEF treatment caused localized damage to the microbial cell surface structure, including cytoplasmic loosening and increased vacuolation, corresponding to enhanced membrane permeability and substrate utilization. Untargeted metabolomics revealed clear separation of metabolic profiles among treatments, with differential regulation observed in amino acid and lipid pathways. By increasing membrane permeability and potentially activating microbial enzymes, US-PEF accelerated protein degradation and increased dipeptides and taste-active amino acids, while lowering levels of unsaturated fatty acid precursors and thereby suppressing the formation of off-flavor compounds. These findings elucidate the synergistic regulation by physical fields-assisted fermentation contributed to improving the quality and flavor of livestock by-products.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105046"},"PeriodicalIF":4.6,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Polymorphism exploration of Schizosaccharomyces japonicus strains based on single nucleotide polymorphism and phenotypic analysis 基于单核苷酸多态性和表型分析的日本裂糖菌多态性研究

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-27 DOI: 10.1016/j.fm.2026.105044

Zhanyan Zhang , Chunxiao Wang , Cheng Wu , Yuxuan Zhang , Qiming Wang , Angxin Song , Yuangen Wu , Shuyi Qiu

Strain polymorphism of non-Saccharomyces has not yet been fully explored due to the limitation of genome information compared to Saccharomyces yeast. This study targeted Schizosaccharomyces japonicus (S. japonicus) for polymorphism exploration. On one hand, single nucleotide polymorphism (SNP) primers with short-amplicon target were newly designed based on genome-wide SNP variations, and could discriminate strains from different isolation sources. Primer S. japonicus-3 could classify 195 strains into 13 haplotypes, and the haplotypes TA and TCA checked by primer S. japonicus-3 only presented in S. japonicus isolates from spontaneous fermentation of the Ziqiu variety of grape. On the other hand, high polysaccharide production and high flocculence in S. japonicus correlated with specific haplotypes: GC and TTA were exclusively detected in polysaccharide high producing strains, while TC and CA were uniquely associated with high flocculence phenotypes. This study provides a new method for the strain differentiation of S. japonicus, and would be helpful for the application of S. japonicus in wine industry.

与酵母菌相比，由于基因组信息的限制，非酵母菌的菌株多态性尚未得到充分的探索。本研究以日本裂糖菌（Schizosaccharomyces japonicus， S. japonicus）为研究对象进行多态性分析。一方面，基于全基因组SNP变异，设计了短扩增子目标单核苷酸多态性（SNP）引物，能够区分不同分离源的菌株；引物S. japonicus-3可将195株菌株划分为13个单倍型，且引物S. japonicus-3检测到的单倍型TA和TCA仅存在于葡萄子丘品种的自然发酵中。另一方面，稻瘟病菌的高多糖产量和高絮凝性与特定的单倍型相关：GC和TTA仅在多糖高产菌株中检测到，而TC和CA则与高絮凝表型相关联。本研究为黄参的品系鉴别提供了一种新的方法，为黄参在酒业中的应用提供了依据。

{"title":"Polymorphism exploration of Schizosaccharomyces japonicus strains based on single nucleotide polymorphism and phenotypic analysis","authors":"Zhanyan Zhang , Chunxiao Wang , Cheng Wu , Yuxuan Zhang , Qiming Wang , Angxin Song , Yuangen Wu , Shuyi Qiu","doi":"10.1016/j.fm.2026.105044","DOIUrl":"10.1016/j.fm.2026.105044","url":null,"abstract":"<div><div>Strain polymorphism of non-<em>Saccharomyces</em> has not yet been fully explored due to the limitation of genome information compared to <em>Saccharomyces</em> yeast. This study targeted <em>Schizosaccharomyces japonicus</em> (<em>S. japonicus</em>) for polymorphism exploration. On one hand, single nucleotide polymorphism (SNP) primers with short-amplicon target were newly designed based on genome-wide SNP variations, and could discriminate strains from different isolation sources. Primer <em>S. japonicus</em>-3 could classify 195 strains into 13 haplotypes, and the haplotypes TA and TCA checked by primer <em>S. japonicus</em>-3 only presented in <em>S. japonicus</em> isolates from spontaneous fermentation of the Ziqiu variety of grape. On the other hand, high polysaccharide production and high flocculence in <em>S. japonicus</em> correlated with specific haplotypes: GC and TTA were exclusively detected in polysaccharide high producing strains, while TC and CA were uniquely associated with high flocculence phenotypes. This study provides a new method for the strain differentiation of <em>S. japonicus</em>, and would be helpful for the application of <em>S. japonicus</em> in wine industry.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105044"},"PeriodicalIF":4.6,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modelling gene-dependent PEF resistance of E. coli K-12 大肠杆菌K-12基因依赖性PEF抗性的建模

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-24 DOI: 10.1016/j.fm.2026.105042

Fotios Lytras , Georgios Psakis , Ruben Gatt , Javier Raso , Vasilis Valdramidis

The current study investigated the antimicrobial mechanisms of Pulsed Electric Fields (PEF) by evaluating the resistance of 22 Escherichia coli K12 mutants. Initial screening at PEF treatment (23 kV/cm, 53.3 μs, 95.4 kJ/kg), pH 7.0, revealed increased sensitivity (p < 0.05) of ΔclpB, ΔrpoS, and ΔdnaK expressed in Log₁₀ reductions. Further inactivation kinetic analysis of 8 selected strains at pH 7.0 and 4.0 revealed a non-linear, polyphasic behaviour. This was described by a global modelling approach combining a log-linear primary model with a second-order polynomial model incorporating treatment time, total specific energy, and survival data as variables. The calculated model parameters (C₁, C₂, and C₃) significantly differed (p < 0.05) among strains at pH 7.0, but not at pH 4.0. Furthermore, the calculated inactivation rates, k_max, varied in relation to the total specific energy. At pH 7.0, k_max was higher at low (0–40 kJ/kg) and high (140–180 kJ/kg) total specific energies, while at pH 4.0, it raised at high total specific energies (120–160 kJ/kg). In conclusion, E. coli response to PEF was dependant on the stress regulator rpoS. This response also involved genes which encode molecular chaperones such as dnaK, clpB and recA, related proteins for DNA repair. In conclusion, resistance to PEF was found to be influenced by pH and total specific energy, indicating that E. coli mounts a multifaceted response to PEF treatments, informing advanced microbial inactivation strategies for food safety.

本研究通过对22株大肠杆菌K12突变体的耐药性评估，探讨了脉冲电场（PEF）的抗菌机制。在PEF处理（23 kV/cm, 53.3 μs, 95.4 kJ/kg）， pH 7.0条件下进行初步筛选，发现ΔclpB、ΔrpoS和ΔdnaK表达Log10的敏感性增加（p < 0.05）。进一步对8株菌株在pH 7.0和4.0条件下的失活动力学分析显示其失活行为为非线性多相行为。这是通过一种全局建模方法来描述的，该方法结合了对数线性初级模型和二阶多项式模型，将治疗时间、总比能和生存数据作为变量。pH 7.0时，菌株间计算的模型参数（C1、C2和C3）差异显著（p < 0.05）， pH 4.0时差异不显著。此外，计算出的失活率kmax随总比能的变化而变化。pH 7.0时，kmax在总比能较低（0 ~ 40 kJ/kg）和较高（140 ~ 180 kJ/kg）时较高，pH 4.0时，kmax在总比能较高（120 ~ 160 kJ/kg）时升高。综上所述，大肠杆菌对PEF的反应依赖于应激调节剂rpoS。这种反应还涉及编码分子伴侣的基因，如dnaK、clpB和recA，这些分子伴侣是DNA修复的相关蛋白质。总之，发现对PEF的耐药性受到pH和总比能的影响，表明大肠杆菌对PEF处理产生了多方面的反应，为食品安全提供了先进的微生物灭活策略。

{"title":"Modelling gene-dependent PEF resistance of E. coli K-12","authors":"Fotios Lytras , Georgios Psakis , Ruben Gatt , Javier Raso , Vasilis Valdramidis","doi":"10.1016/j.fm.2026.105042","DOIUrl":"10.1016/j.fm.2026.105042","url":null,"abstract":"<div><div>The current study investigated the antimicrobial mechanisms of Pulsed Electric Fields (PEF) by evaluating the resistance of 22 <em>Escherichia coli</em> K12 mutants. Initial screening at PEF treatment (23 kV/cm, 53.3 μs, 95.4 kJ/kg), pH 7.0, revealed increased sensitivity (<em>p < 0.05</em>) of Δ<em>clpB</em>, Δ<em>rpoS</em>, and Δ<em>dnaK</em> expressed in Log<sub>10</sub> reductions. Further inactivation kinetic analysis of 8 selected strains at pH 7.0 and 4.0 revealed a non-linear, polyphasic behaviour. This was described by a global modelling approach combining a log-linear primary model with a second-order polynomial model incorporating treatment time, total specific energy, and survival data as variables. The calculated model parameters <em>(C</em><sub><em>1</em></sub>, <em>C</em><sub><em>2</em></sub>, and <em>C</em><sub><em>3</em></sub><em>)</em> significantly differed (<em>p < 0.05</em>) among strains at pH 7.0, but not at pH 4.0. Furthermore, the calculated inactivation rates, <em>k</em><sub><em>max</em></sub>, varied in relation to the total specific energy. At pH 7.0, <em>k</em><sub><em>max</em></sub> was higher at low (0–40 kJ/kg) and high (140–180 kJ/kg) total specific energies, while at pH 4.0, it raised at high total specific energies (120–160 kJ/kg). In conclusion, <em>E. coli</em> response to PEF was dependant on the stress regulator <em>rpoS</em>. This response also involved genes which encode molecular chaperones such as <em>dnaK</em>, <em>clpB</em> and <em>recA,</em> related proteins for DNA repair. In conclusion, resistance to PEF was found to be influenced by pH and total specific energy, indicating that <em>E. coli</em> mounts a multifaceted response to PEF treatments, informing advanced microbial inactivation strategies for food safety.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105042"},"PeriodicalIF":4.6,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Aroma modulation of wet Spirulina by a microbial consortium: Deciphering the role of community succession and metabolic pathways 微生物群落对湿螺旋藻香气的调节：解读群落演替和代谢途径的作用

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-24 DOI: 10.1016/j.fm.2026.105043

Kerui Su , Feihang Wang , Anqi Zhao , Beixiao Zhang , Zhihao Fan , Qi Wang , Xuejing Duan , Hanyu Dong , A.E. Solovchenko , Ayesha Shahid , Jingliang Xu

The commercialization of wet Spirulina is severely hindered by its rapid spoilage and the development of fishy off-flavors (e.g., trimethylamine, indole) by its endogenous microbiota. This study pioneered a microbial ecosystem engineering strategy using a multi-strain consortium to address this issue. Fermentation with Effective Microorganisms (EM) consortium (achieving 8.48 log CFU/mL and a final pH of 3.67) triggered a dramatic microbial succession, effectively suppressing native spoilage bacteria and protists while enriching a functional consortium dominated by B. subtilis, S. fibuligera, and D. hansenii. This ecological remodeling significantly enhanced nutritional quality, increasing total free amino acids from 420 mg/L to 1568.54 mg/L, total essential amino acids from 140 mg/L to 288.20 mg/L, and hydroxyl radical scavenging activity by 33.82 % compared to the unfermented group. Concurrently, it drove a flavor revolution, quantitatively replacing undesirable volatiles with pleasant, fruity, and floral compounds, which was corroborated by peak sensory acceptability on fourth day of fermentation. Key aroma-active contributors included phenylethyl alcohol (floral, 218.82 μg/kg), ethyl butyrate (fruity, 100.95 μg/kg), and benzeneacetaldehyde (fruity, floral, 99.16 μg/kg). Additionally, EM consortium fermentation significantly inhibits the accumulation of biogenic amines, such as putrescine, cadaverine, and spermine. Mechanistically, integrated analysis of microbial community and metabolome analysis revealed that the functional microbiota upregulated 2-oxocarboxylic acid metabolism and the shikimate pathway for aromatic amino acid biosynthesis, funneling these precursors into the Ehrlich pathway for efficient conversion into key acidic and alcoholic VOCs. This research clarified the correlation between targeted microbial succession and flavor regulation, providing a mechanistic framework for transforming wet Spirulina targeted fermentation into palatable components for novel food applications.

湿螺旋藻的商业化受到其快速变质和内源性微生物群产生腥味（如三甲胺、吲哚）的严重阻碍。这项研究开创了一种微生物生态系统工程策略，使用多菌株联盟来解决这个问题。有效微生物（EM）联合体发酵（达到8.48 log CFU/mL，最终pH为3.67）引发了戏剧性的微生物演替，有效抑制了本地腐败细菌和原生生物，同时丰富了以枯草芽孢杆菌、S. fibuligera和D. hansenii为主的功能联合体。与未发酵组相比，这种生态重塑显著提高了营养品质，游离氨基酸总量从420 mg/L增加到1568.54 mg/L，必需氨基酸总量从140 mg/L增加到288.20 mg/L，羟基自由基清除能力提高了33.82%。同时，它推动了一场风味革命，用令人愉快的、果味的和花香的化合物定量地取代了不受欢迎的挥发物，这在发酵第四天的感官接受度峰值中得到了证实。主要的香气活性贡献者包括苯乙醇（花香，218.82 μg/kg）、丁酸乙酯（果味，100.95 μg/kg）和苯乙醛（果味，花香，99.16 μg/kg）。此外，EM联合体发酵显著抑制生物胺的积累，如腐胺、尸胺和精胺。机制上，微生物群落和代谢组学综合分析表明，功能微生物群上调2-氧羧酸代谢和莽草酸途径的芳香族氨基酸生物合成，将这些前体聚集到埃利希途径中，有效转化为关键的酸性和酒精性挥发性有机化合物。本研究阐明了目标微生物演替与风味调节之间的关系，为将湿螺旋藻靶向发酵转化为可用于新型食品应用的美味成分提供了机制框架。

{"title":"Aroma modulation of wet Spirulina by a microbial consortium: Deciphering the role of community succession and metabolic pathways","authors":"Kerui Su , Feihang Wang , Anqi Zhao , Beixiao Zhang , Zhihao Fan , Qi Wang , Xuejing Duan , Hanyu Dong , A.E. Solovchenko , Ayesha Shahid , Jingliang Xu","doi":"10.1016/j.fm.2026.105043","DOIUrl":"10.1016/j.fm.2026.105043","url":null,"abstract":"<div><div>The commercialization of wet <em>Spirulina</em> is severely hindered by its rapid spoilage and the development of fishy off-flavors (e.g., trimethylamine, indole) by its endogenous microbiota. This study pioneered a microbial ecosystem engineering strategy using a multi-strain consortium to address this issue. Fermentation with Effective Microorganisms (EM) consortium (achieving 8.48 log CFU/mL and a final pH of 3.67) triggered a dramatic microbial succession, effectively suppressing native spoilage bacteria and protists while enriching a functional consortium dominated by <em>B. subtilis, S. fibuligera,</em> and <em>D. hansenii</em>. This ecological remodeling significantly enhanced nutritional quality, increasing total free amino acids from 420 mg/L to 1568.54 mg/L, total essential amino acids from 140 mg/L to 288.20 mg/L, and hydroxyl radical scavenging activity by 33.82 % compared to the unfermented group. Concurrently, it drove a flavor revolution, quantitatively replacing undesirable volatiles with pleasant, fruity, and floral compounds, which was corroborated by peak sensory acceptability on fourth day of fermentation. Key aroma-active contributors included phenylethyl alcohol (floral, 218.82 μg/kg), ethyl butyrate (fruity, 100.95 μg/kg), and benzeneacetaldehyde (fruity, floral, 99.16 μg/kg). Additionally, EM consortium fermentation significantly inhibits the accumulation of biogenic amines, such as putrescine, cadaverine, and spermine. Mechanistically, integrated analysis of microbial community and metabolome analysis revealed that the functional microbiota upregulated 2-oxocarboxylic acid metabolism and the shikimate pathway for aromatic amino acid biosynthesis, funneling these precursors into the Ehrlich pathway for efficient conversion into key acidic and alcoholic VOCs. This research clarified the correlation between targeted microbial succession and flavor regulation, providing a mechanistic framework for transforming wet <em>Spirulina</em> targeted fermentation into palatable components for novel food applications.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105043"},"PeriodicalIF":4.6,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Enhanced environmental stress tolerance in reoccurring, emerging, and persistent (REP) Escherichia coli O157:H7 strains from leafy green associated outbreaks 绿叶相关暴发中复发、新发和持续性（REP）大肠杆菌O157:H7菌株的环境应激耐受性增强

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-21 DOI: 10.1016/j.fm.2026.105041

Yishan Yang , Irene Falco , Xiangwu Nou

Escherichia coli O157:H7, historically associated with undercooked beef, has increasingly been linked to leafy green associated outbreaks in the United States. A subset of strains, termed reoccurring, emerging, and persistent (REP), represented by REPEXH01 and REPEXH02, has repeatedly caused multistate outbreaks since 2017, raising concerns about their enhanced environmental fitness and persistence in leafy green production regions. In this study, we evaluated the stress tolerance profiles of representative REPEXH01 (PNUSAE013458) and REPEXH02 (2705C and PNUSAE019890) strains, using the meat-associated strain EDL933 and the spinach outbreak strain EC4115 as references. REPEXH01 strains exhibited elevated tolerance to starvation, arsenic, gastric acid, and antibiotics, traits consistent with genomic islands encoding multiple resistance determinants. REPEXH02 strains showed increased tolerance to UV-C irradiation, potentially linked to mutations in DNA repair genes. Both REP groups showed significantly higher survival than EDL933 under desiccation and blue light exposure (major antimicrobial spectrum in sunlight), underscoring their enhanced persistence in agricultural and processing environments. These findings highlight distinct adaptation strategies between REPEXH01 and REPEXH02 that may facilitate their continued recurrence in leafy green outbreaks. Understanding these stress response mechanisms provides critical insights into REP strain ecology and informs the development of improved intervention strategies to reduce produce-associated E. coli O157:H7 contamination.

大肠杆菌O157:H7历来与未煮熟的牛肉有关，现在越来越多地与美国与绿叶蔬菜有关的疫情联系在一起。自2017年以来，以REPEXH01和REPEXH02为代表的一组菌株被称为重复性、新兴和持久性（REP），多次引起多州暴发，引发了人们对它们在绿叶蔬菜生产区增强的环境适应性和持久性的担忧。本研究以肉类相关菌株EDL933和菠菜爆发菌株EC4115为参考，对具有代表性的REPEXH01 （PNUSAE013458）和REPEXH02 （pnusae02705c和PNUSAE019890）菌株的耐受性进行了评价。REPEXH01菌株对饥饿、砷、胃酸和抗生素的耐受性提高，这些特征与编码多种抗性决定因素的基因组岛一致。REPEXH02菌株对UV-C照射的耐受性增强，可能与DNA修复基因突变有关。两个REP组在干燥和蓝光暴露（阳光中的主要抗菌光谱）下的存活率均显著高于EDL933，这表明它们在农业和加工环境中的持久性增强。这些发现突出了REPEXH01和REPEXH02之间不同的适应策略，这可能促进它们在绿叶植物暴发中持续复发。了解这些应激反应机制有助于深入了解REP菌株生态学，并为制定改进的干预策略提供信息，以减少与农产品相关的大肠杆菌O157:H7污染。

{"title":"Enhanced environmental stress tolerance in reoccurring, emerging, and persistent (REP) Escherichia coli O157:H7 strains from leafy green associated outbreaks","authors":"Yishan Yang , Irene Falco , Xiangwu Nou","doi":"10.1016/j.fm.2026.105041","DOIUrl":"10.1016/j.fm.2026.105041","url":null,"abstract":"<div><div><em>Escherichia coli</em> O157:H7, historically associated with undercooked beef, has increasingly been linked to leafy green associated outbreaks in the United States. A subset of strains, termed reoccurring, emerging, and persistent (REP), represented by REPEXH01 and REPEXH02, has repeatedly caused multistate outbreaks since 2017, raising concerns about their enhanced environmental fitness and persistence in leafy green production regions. In this study, we evaluated the stress tolerance profiles of representative REPEXH01 (PNUSAE013458) and REPEXH02 (2705C and PNUSAE019890) strains, using the meat-associated strain EDL933 and the spinach outbreak strain EC4115 as references. REPEXH01 strains exhibited elevated tolerance to starvation, arsenic, gastric acid, and antibiotics, traits consistent with genomic islands encoding multiple resistance determinants. REPEXH02 strains showed increased tolerance to UV-C irradiation, potentially linked to mutations in DNA repair genes. Both REP groups showed significantly higher survival than EDL933 under desiccation and blue light exposure (major antimicrobial spectrum in sunlight), underscoring their enhanced persistence in agricultural and processing environments. These findings highlight distinct adaptation strategies between REPEXH01 and REPEXH02 that may facilitate their continued recurrence in leafy green outbreaks. Understanding these stress response mechanisms provides critical insights into REP strain ecology and informs the development of improved intervention strategies to reduce produce-associated <em>E. coli</em> O157:H7 contamination.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105041"},"PeriodicalIF":4.6,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Assessing the use of acid-based sanitizers for enhancing the microbial safety and quality of collard greens and kale 评估使用酸基杀菌剂提高羽衣甘蓝和羽衣甘蓝的微生物安全性和质量

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-21 DOI: 10.1016/j.fm.2026.105040

Chenxi Guo, Yucen Xie, Jaqueline Oliveira de Moraes, Luxin Wang

The consumption of collard greens (CG) and kale (KA) and different formats of their products, e.g. juices, has increased significantly. However, there have been limited studies focusing on the enhancement of the microbial quality and safety of dark leafy green vegetables (DLGVs), especially large DLGVs, despite the occurrence of several outbreaks. The larger and more rough leaf surface is one major characteristically difference between CG/KA and other DLGVs (e.g. spinach). This study evaluated the antimicrobial effectiveness of acid-based washing (vinegar, lemon juice, and peracetic acid [PAA]) in controlling the populations of native microorganisms and artificially inoculated bacteria (Enterococcus faecium) on CG and KA during washing and storage. The washing procedure included a 5 min soaking (w/v ration 1:50) and a 15 s rinsing. Results showed that PAA (80 ppm, pH ∼ 4.00) ed to the greatest reductions in native fungi (∼1.2 and 1.4 log reductions) and bacteria (∼1.0 and 1.2 log reductions on CG and KA respectively) compared to 35 % vinegar (pH ∼2.75) and 13 % lemon juice wash (pH ∼2.83). PAA-washed CG and lemon juice-washed KA also exhibited the greatest additional reductions in fungal and bacterial populations during storage. E. faecium, used as a pathogen surrogate, had the largest reductions on CG and KA washed by PAA, ∼1.5 and 2.3 log reductions respectively. Lemon juice-washed CG and PAA-washed KA showed the greatest additional reductions in E. faecium during storage. Acid washing showed promising potential in protecting the microbial safety and quality of large DLGVs; the tested washing steps can be used at retail and home settings.

羽衣甘蓝（CG）和羽衣甘蓝（KA）及其不同形式的产品（例如果汁）的消费量显著增加。然而，尽管发生了几次暴发，但关于提高深叶绿色蔬菜（DLGVs），特别是大型DLGVs的微生物质量和安全性的研究仍然有限。更大更粗糙的叶片表面是CG/KA与其他dlgv（如菠菜）之间的一个主要特征区别。本研究评估了酸基洗涤（醋、柠檬汁和过乙酸[PAA]）在洗涤和储存过程中控制天然微生物和人工接种细菌（屎肠球菌）对CG和KA的抑菌效果。洗涤过程包括5分钟浸泡（w/v比1:50）和15秒冲洗。结果表明，与35%的醋（pH ~ 2.75）和13%的柠檬汁洗涤液（pH ~ 2.83）相比，PAA （80 ppm, pH ~ 4.00）对天然真菌（降低~ 1.2和1.4对数）和细菌（分别对CG和KA降低~ 1.0和1.2对数）的影响最大。聚丙烯酸洗涤的CG和柠檬汁洗涤的KA在储存期间也表现出最大的真菌和细菌数量的额外减少。作为替代病原体的粪肠杆菌经PAA洗涤后，对CG和KA的降低幅度最大，分别为1.5和2.3 log。柠檬汁洗涤的CG和paa洗涤的KA在储存期间显示出最大的额外粪便减少。酸洗在保护大型DLGVs的微生物安全和质量方面具有广阔的应用前景；测试的洗涤步骤可用于零售和家庭设置。

{"title":"Assessing the use of acid-based sanitizers for enhancing the microbial safety and quality of collard greens and kale","authors":"Chenxi Guo, Yucen Xie, Jaqueline Oliveira de Moraes, Luxin Wang","doi":"10.1016/j.fm.2026.105040","DOIUrl":"10.1016/j.fm.2026.105040","url":null,"abstract":"<div><div>The consumption of collard greens (CG) and kale (KA) and different formats of their products, e.g. juices, has increased significantly. However, there have been limited studies focusing on the enhancement of the microbial quality and safety of dark leafy green vegetables (DLGVs), especially large DLGVs, despite the occurrence of several outbreaks. The larger and more rough leaf surface is one major characteristically difference between CG/KA and other DLGVs (e.g. spinach). This study evaluated the antimicrobial effectiveness of acid-based washing (vinegar, lemon juice, and peracetic acid [PAA]) in controlling the populations of native microorganisms and artificially inoculated bacteria (<em>Enterococcus faecium)</em> on CG and KA during washing and storage. The washing procedure included a 5 min soaking (w/v ration 1:50) and a 15 s rinsing. Results showed that PAA (80 ppm, pH ∼ 4.00) ed to the greatest reductions in native fungi (∼1.2 and 1.4 log reductions) and bacteria (∼1.0 and 1.2 log reductions on CG and KA respectively) compared to 35 % vinegar (pH ∼2.75) and 13 % lemon juice wash (pH ∼2.83). PAA-washed CG and lemon juice-washed KA also exhibited the greatest additional reductions in fungal and bacterial populations during storage. <em>E. faecium</em>, used as a pathogen surrogate, had the largest reductions on CG and KA washed by PAA, ∼1.5 and 2.3 log reductions respectively. Lemon juice-washed CG and PAA-washed KA showed the greatest additional reductions in <em>E. faecium</em> during storage. Acid washing showed promising potential in protecting the microbial safety and quality of large DLGVs; the tested washing steps can be used at retail and home settings.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105040"},"PeriodicalIF":4.6,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Geographical origin authentication of whole garlic using 16S ribosomal RNA profiling of garlic microbiota and machine learning 基于大蒜微生物群16S核糖体RNA图谱和机器学习的大蒜产地鉴定

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-15 DOI: 10.1016/j.fm.2026.105039

Zhihan Xian , Shaoting Li , David A. Mann , Xiangyu Deng

Food fraud through false declarations of geographical origin poses major economic and regulatory challenges, particularly for commodities subject to trade restrictions or premium provenance labeling. Fresh garlic (Allium sativum L.), a globally traded crop, is vulnerable to origin fraud because of long-standing antidumping duties on Chinese imports to the United States. Here, we present a proof-of-concept study demonstrating that microbiota profiling provides a robust and accessible alternative to conventional chemometric approaches for garlic origin authentication. We characterized the surface bacterial communities of 153 garlic samples collected between 2021 and 2024 from China (n = 60), the United States (n = 50), and multiple other countries (n = 43) using 16S rRNA gene amplicon sequencing. Comparative analyses revealed significant differences in alpha and beta diversity across countries, with U.S. samples exhibiting the highest microbial richness and Chinese samples the lowest. Dimensionality reduction methods showed clear clustering by country of origin, supporting the presence of distinct microbial signatures. Machine-learning classifiers trained on 16S profiles achieved >0.87 accuracy across Random Forest, k-nearest neighbors, logistic regression, and support vector machine models using only five genus-level microbial features. Multi-year sampling confirmed that these microbial signals remained stable across harvest seasons. Differential abundance analyses further identified ecologically relevant taxa driving country-level separation. Together, these results establish microbiota profiling as an additional laboratory tool to help investigate garlic origin fraud.

通过虚假地理来源声明的食品欺诈构成了重大的经济和监管挑战，特别是对于受贸易限制或优质原产地标签约束的商品。新鲜大蒜（Allium sativum L.）是一种全球贸易作物，由于长期以来对中国进口到美国的商品征收反倾销税，它很容易受到原产地欺诈的影响。在这里，我们提出了一项概念验证研究，证明微生物群分析为大蒜原产地认证提供了一种强大且可访问的替代传统化学计量方法。我们利用16S rRNA基因扩增子测序技术，对2021年至2024年间从中国（n = 60）、美国（n = 50）和其他多个国家（n = 43）采集的153份大蒜样品的表面细菌群落进行了表征。比较分析显示，不同国家的α和β多样性存在显著差异，美国样品的微生物丰富度最高，中国样品的微生物丰富度最低。降维方法显示了原产地国家的清晰聚类，支持不同微生物特征的存在。仅使用5个属级微生物特征，机器学习分类器在随机森林、k近邻、逻辑回归和支持向量机模型上训练的准确率为0.87。多年的采样证实，这些微生物信号在收获季节保持稳定。差异丰度分析进一步确定了驱动国家级分离的生态相关类群。总之，这些结果建立了微生物群分析作为帮助调查大蒜原产地欺诈的额外实验室工具。

{"title":"Geographical origin authentication of whole garlic using 16S ribosomal RNA profiling of garlic microbiota and machine learning","authors":"Zhihan Xian , Shaoting Li , David A. Mann , Xiangyu Deng","doi":"10.1016/j.fm.2026.105039","DOIUrl":"10.1016/j.fm.2026.105039","url":null,"abstract":"<div><div>Food fraud through false declarations of geographical origin poses major economic and regulatory challenges, particularly for commodities subject to trade restrictions or premium provenance labeling. Fresh garlic (<em>Allium sativum</em> L.), a globally traded crop, is vulnerable to origin fraud because of long-standing antidumping duties on Chinese imports to the United States. Here, we present a proof-of-concept study demonstrating that microbiota profiling provides a robust and accessible alternative to conventional chemometric approaches for garlic origin authentication. We characterized the surface bacterial communities of 153 garlic samples collected between 2021 and 2024 from China (n = 60), the United States (n = 50), and multiple other countries (n = 43) using 16S rRNA gene amplicon sequencing. Comparative analyses revealed significant differences in alpha and beta diversity across countries, with U.S. samples exhibiting the highest microbial richness and Chinese samples the lowest. Dimensionality reduction methods showed clear clustering by country of origin, supporting the presence of distinct microbial signatures. Machine-learning classifiers trained on 16S profiles achieved >0.87 accuracy across Random Forest, k-nearest neighbors, logistic regression, and support vector machine models using only five genus-level microbial features. Multi-year sampling confirmed that these microbial signals remained stable across harvest seasons. Differential abundance analyses further identified ecologically relevant taxa driving country-level separation. Together, these results establish microbiota profiling as an additional laboratory tool to help investigate garlic origin fraud.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105039"},"PeriodicalIF":4.6,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Why is Bacillus cereus group enriched in sufu? -A study on prevalence, characterization and traceability 为什么蜡样芽孢杆菌群在腐殖质中富集？-流行、特征和可追溯性研究

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-10 DOI: 10.1016/j.fm.2026.105038

Zekun Jin , Li Li , Yin Zheng , Peipei An , Liling Lu , Zhaohui Zhou

This study aims to investigate the characteristics and contamination sources of the Bacillus cereus group in sufu to enhance food safety control. A total of 90 commercial sufu samples were analyzed, revealing a high contamination rate of 97.8 %, with 6.7 % exceeding the safety limit of 5 log CFU/g. 43 representative isolates from white, red, and spicy sufu varieties were further characterized using PCR-based virulence gene profiling, MLST, and panC gene sequence analysis. Virulence gene profiling revealed universal presence of nheABC and entFM (100 %), with cytK and the complete hblACD cluster present in 44.8 % and 11.6 % of isolates, respectively. Isolates harboring the complete nheABC or hblACD genes were confirmed to produce the corresponding Nhe or Hbl enterotoxins in soymilk. MLST and panC sequencing revealed distinct phylogenetic profiles among the isolates, with heat-resistant strains being frequently identified. To trace contamination routes, samples from a production facility, including environmental surfaces, equipment, raw materials, and semi-finished products, were analyzed using microbial culture and RAPD. The solid-state fermentation stage was identified as the critical control point for B. cereus proliferation, with raw soybeans and air serving as primary reservoirs. B. cereus introduced via raw materials adhered to equipment, forming persistent biofilms that facilitated cross-contamination. Conventional cleaning and disinfection procedures (on-site cleaning, standard food disinfectants) demonstrated limited efficacy against these biofilms. These findings systematically clarify the hazard characteristics, genetic background, and contamination pathways of B. cereus in sufu production, providing a scientific basis for targeted intervention and sanitation optimization in industrial processing.

本研究旨在了解豆腐乳中蜡样芽孢杆菌群的特点及其污染源，以加强食品安全控制。对90份商品腐乳样品进行分析，发现污染率高达97.8%，其中6.7%超过5 log CFU/g的安全限值。采用pcr法、MLST法和panC基因序列分析对43株代表性的白、红、辣腐腐素品种分离物进行了毒力基因分析。毒力基因分析显示nheABC和entFM普遍存在（100%），cytK和完整的hblACD集群分别存在于44.8%和11.6%的分离株中。携带完整的nheABC或hblACD基因的分离株被证实在豆浆中产生相应的Nhe或Hbl肠毒素。MLST和panC测序显示了不同菌株的系统发育特征，其中耐热菌株经常被鉴定出来。为了追踪污染途径，使用微生物培养和RAPD分析了生产设施的样品，包括环境表面、设备、原材料和半成品。固体发酵阶段被确定为蜡样芽孢杆菌增殖的关键控制点，生大豆和空气是主要储存库。蜡样芽孢杆菌通过附着在设备上的原料引入，形成持久的生物膜，促进交叉污染。传统的清洁和消毒程序（现场清洁，标准食品消毒剂）对这些生物膜的效果有限。这些发现系统地阐明了腐乳生产中蜡样芽孢杆菌的危害特征、遗传背景和污染途径，为工业加工中的针对性干预和卫生优化提供了科学依据。

{"title":"Why is Bacillus cereus group enriched in sufu? -A study on prevalence, characterization and traceability","authors":"Zekun Jin , Li Li , Yin Zheng , Peipei An , Liling Lu , Zhaohui Zhou","doi":"10.1016/j.fm.2026.105038","DOIUrl":"10.1016/j.fm.2026.105038","url":null,"abstract":"<div><div>This study aims to investigate the characteristics and contamination sources of the <em>Bacillus cereus</em> group in sufu to enhance food safety control. A total of 90 commercial sufu samples were analyzed, revealing a high contamination rate of 97.8 %, with 6.7 % exceeding the safety limit of 5 log CFU/g. 43 representative isolates from white, red, and spicy sufu varieties were further characterized using PCR-based virulence gene profiling, MLST, and <em>panC</em> gene sequence analysis. Virulence gene profiling revealed universal presence of <em>nheABC</em> and <em>entFM</em> (100 %), with <em>cytK</em> and the complete <em>hblACD</em> cluster present in 44.8 % and 11.6 % of isolates, respectively. Isolates harboring the complete <em>nheABC</em> or <em>hblACD</em> genes were confirmed to produce the corresponding Nhe or Hbl enterotoxins in soymilk. MLST and <em>panC</em> sequencing revealed distinct phylogenetic profiles among the isolates, with heat-resistant strains being frequently identified. To trace contamination routes, samples from a production facility, including environmental surfaces, equipment, raw materials, and semi-finished products, were analyzed using microbial culture and RAPD. The solid-state fermentation stage was identified as the critical control point for <em>B. cereus</em> proliferation, with raw soybeans and air serving as primary reservoirs. <em>B. cereus</em> introduced via raw materials adhered to equipment, forming persistent biofilms that facilitated cross-contamination. Conventional cleaning and disinfection procedures (on-site cleaning, standard food disinfectants) demonstrated limited efficacy against these biofilms. These findings systematically clarify the hazard characteristics, genetic background, and contamination pathways of <em>B. cereus</em> in sufu production, providing a scientific basis for targeted intervention and sanitation optimization in industrial processing.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105038"},"PeriodicalIF":4.6,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Adaptive hydrophobicity shifts in Listeria monocytogenes under subinhibitory exposure to benzalkonium chloride, peracetic acid and sodium hypochlorite 亚抑制暴露于苯扎氯铵、过氧乙酸和次氯酸钠下单核增生李斯特菌的适应性疏水性发生变化

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-08 DOI: 10.1016/j.fm.2025.105035

Aminta Vega-Sánchez, Josep-Maria deDios-Pont, Paula Cruz-Vera, Carolina Ripolles-Avila

The phospholipid layer is central to Listeria monocytogenes tolerance to disinfectants. We profiled surface hydrophobicity by Microbial Adhesion to Solvents (MATS) in 19 strains, tested in wild type and after adaptation to ½ MIC of benzalkonium chloride (BKC), peracetic acid (PAA), or sodium hypochlorite (SHY). We first compared two hydrocarbons for MATS (i.e. xylene vs hexadecane) to optimize solvent choice. Wild strains measured with xylene clustered near zero or negative affinity, whereas hexadecane shifted distributions to positive values with lower intra-strain variability. Across three representative strains adapted to each disinfectant, hexadecane showed significantly greater affinity than xylene (P < 0.001), and overall solvent effects were significant (P < 0.05), supporting hexadecane as the analytical solvent. Using hexadecane, wild strains were weakly hydrophobic (<20 % MATS) and not different among themselves (P > 0.05). BKC adaptation produced minimal change as most strains remained <20 %; the only shift to moderate hydrophobicity was S2-1 (22.32 ± 2.57 %). Adaptation to PAA increased hydrophobicity in a subset of strains, being EDG-e, A7, and S2bac the ones that reached intermediate levels (26.87 ± 7.02 % to 49.46 ± 11.00 %) whereas 11 of the 19 strains remained below 20 %. SHY drove the largest changes with 11/19 strains transitioning to strong hydrophobicity (>50 %), with MATS means ranging from 50.58 ± 18.75 % to 73.54 ± 7.64 %. Moreover, four strains (i.e. CECT 5672, 4423, R6, S1(R)) stayed weakly hydrophobic (6.64 ± 39.49 % to 17.97 ± 23.61 %), and two (Lm4, Lm5) were moderate (20–50 %). Overall, adaptation to subinhibitory disinfectant concentrations revealed distinct, strain-dependent surface responses that may influence bacterial persistence potential. These findings contribute to understanding how routine disinfectant exposure can shape the phenotypic resilience of L. monocytogenes, providing insights relevant to food safety management and contamination control in food-processing environments.

磷脂层是单核增生李斯特菌对消毒剂耐受的核心。我们通过微生物黏附溶剂（MATS）分析了19株菌株的表面疏水性，这些菌株在野生型和适应1 / 2 MIC的苯扎氯铵（BKC）、过氧乙酸（PAA）或次氯酸钠（SHY）后进行了测试。我们首先比较了两种碳氢化合物（即二甲苯和十六烷），以优化溶剂的选择。二甲苯测量的野生菌株聚集在接近零或负亲和的地方，而十六烷将分布转移到正值，具有较低的菌株内变异性。在适应每种消毒剂的三个代表性菌株中，十六烷的亲和力显著高于二甲苯（P < 0.001），并且总体溶剂效应显著（P < 0.05），支持十六烷作为分析溶剂。使用十六烷时，野生菌株呈弱疏水性（< 20% MATS），彼此间无差异（P > 0.05）。BKC适应产生的变化很小，因为大多数菌株保持在20%；唯一向中等疏水性转变的是S2-1（22.32±2.57%）。对PAA的适应提高了部分菌株的疏水性，其中EDG-e、A7和S2bac达到了中间水平（26.87±7.02% ~ 49.46±11.00 %），而19株菌株中有11株仍低于20%。其中，有11/19的菌株向强疏水性转变（> 50%），其中SHY的变化最大，MATS平均值为50.58±18.75% ~ 73.54±7.64%。4株（CECT 5672、4423、R6、S1(R)）为弱疏水性（6.64±39.49% ~ 17.97±23.61%），2株（Lm4、Lm5）为中度疏水性（20 ~ 50%）。总的来说，对亚抑制性消毒剂浓度的适应揭示了不同的、菌株依赖的表面反应，这可能影响细菌的持久性潜力。这些发现有助于理解常规消毒剂暴露如何塑造单核增生乳杆菌的表型弹性，为食品加工环境中的食品安全管理和污染控制提供相关见解。

{"title":"Adaptive hydrophobicity shifts in Listeria monocytogenes under subinhibitory exposure to benzalkonium chloride, peracetic acid and sodium hypochlorite","authors":"Aminta Vega-Sánchez, Josep-Maria deDios-Pont, Paula Cruz-Vera, Carolina Ripolles-Avila","doi":"10.1016/j.fm.2025.105035","DOIUrl":"10.1016/j.fm.2025.105035","url":null,"abstract":"<div><div>The phospholipid layer is central to <em>Listeria monocytogenes</em> tolerance to disinfectants. We profiled surface hydrophobicity by Microbial Adhesion to Solvents (MATS) in 19 strains, tested in wild type and after adaptation to ½ MIC of benzalkonium chloride (BKC), peracetic acid (PAA), or sodium hypochlorite (SHY). We first compared two hydrocarbons for MATS (<em>i.e.</em> xylene <em>vs</em> hexadecane) to optimize solvent choice. Wild strains measured with xylene clustered near zero or negative affinity, whereas hexadecane shifted distributions to positive values with lower intra-strain variability. Across three representative strains adapted to each disinfectant, hexadecane showed significantly greater affinity than xylene (<em>P</em> < 0.001), and overall solvent effects were significant (<em>P</em> < 0.05), supporting hexadecane as the analytical solvent. Using hexadecane, wild strains were weakly hydrophobic (<20 % MATS) and not different among themselves (<em>P</em> > 0.05). BKC adaptation produced minimal change as most strains remained <20 %; the only shift to moderate hydrophobicity was S2-1 (22.32 ± 2.57 %). Adaptation to PAA increased hydrophobicity in a subset of strains, being EDG-e, A7, and S2bac the ones that reached intermediate levels (26.87 ± 7.02 % to 49.46 ± 11.00 %) whereas 11 of the 19 strains remained below 20 %. SHY drove the largest changes with 11/19 strains transitioning to strong hydrophobicity (>50 %), with MATS means ranging from 50.58 ± 18.75 % to 73.54 ± 7.64 %. Moreover, four strains (<em>i.e.</em> CECT 5672, 4423, R6, S1(R)) stayed weakly hydrophobic (6.64 ± 39.49 % to 17.97 ± 23.61 %), and two (Lm4, Lm5) were moderate (20–50 %). Overall, adaptation to subinhibitory disinfectant concentrations revealed distinct, strain-dependent surface responses that may influence bacterial persistence potential. These findings contribute to understanding how routine disinfectant exposure can shape the phenotypic resilience of <em>L. monocytogenes</em>, providing insights relevant to food safety management and contamination control in food-processing environments.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105035"},"PeriodicalIF":4.6,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Aldo/keto reductase regulates L-lactate dehydrogenase activity as a key target for yogurt post-acidification Aldo/keto还原酶调节l -乳酸脱氢酶活性，是酸奶后酸化的关键靶点

IF 4.6 1区农林科学 Q1 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Food microbiology

Pub Date : 2026-01-05 DOI: 10.1016/j.fm.2026.105037

Qingqing Mu , Sitong Jia , Dongyao Li , Whenhao Zhao , Na Zhang , Miaoshu Wang , Hongtao Tian , Chen Li

Post-acidification during refrigeration is a critical determinant of yogurt quality. Although it is known that niacin (NA) can influence this process via aldehyde-ketone reductase (AKR) in Lactobacillus bulgaricus, its precise regulatory mechanism remains unclear. By non-targeted metabolomics analysis revealed that nicotinic acid reshapes the metabolic profile during storage, significantly reducing the accumulation of organic acids such as L-lactic acid, fumaric acid, and succinic acid. This indicates that post-acidification processes are inhibited through relevant metabolic pathways. Concurrently, the yeast two-hybrid screening identified 21 proteins interacting with AKR, confirming L-lactate dehydrogenase (L-LDH) as a key interaction partner of AKR. This enzyme directly regulates L-LDH activity. Subsequent enzyme activity assays and AKR mutation confirmed that niacin acts as a potent inhibitor of L-LDH activity by promoting the formation of an AKR-L-LDH-NA ternary complex. Regulation of L-LDH activity by AKR without altering the structure and intrinsic catalytic properties of L-LDH is expected to realize the AKR-L-LDH-NA ternary complex as a key target for the future regulation of the post-acidification process. Our study establishes a technological method to accurately regulate the post-acidification of yogurt, which provides a theoretical basis for controlling acidity in lactic acid fermented foods.

冷藏过程中的后酸化是酸奶质量的关键决定因素。虽然已知烟酸（NA）可以通过保加利亚乳杆菌中的醛酮还原酶（AKR）影响这一过程，但其确切的调控机制尚不清楚。通过非靶向代谢组学分析发现，烟酸重塑了储存过程中的代谢谱，显著减少了l -乳酸、富马酸和琥珀酸等有机酸的积累。这表明后酸化过程通过相关的代谢途径受到抑制。同时，酵母双杂交筛选鉴定出21个与AKR相互作用的蛋白，证实l -乳酸脱氢酶（L-LDH）是AKR的关键相互作用伙伴。这种酶直接调节L-LDH活性。随后的酶活性测定和AKR突变证实，烟酸通过促进AKR-L-LDH- na三元络合物的形成，作为L-LDH活性的有效抑制剂。通过AKR调控L-LDH活性而不改变L-LDH的结构和固有催化性能，有望实现AKR-L-LDH- na三元配合物作为未来调控后酸化过程的关键靶点。本研究建立了准确调控酸奶后酸化的工艺方法，为控制乳酸发酵食品的酸度提供了理论依据。

{"title":"Aldo/keto reductase regulates L-lactate dehydrogenase activity as a key target for yogurt post-acidification","authors":"Qingqing Mu , Sitong Jia , Dongyao Li , Whenhao Zhao , Na Zhang , Miaoshu Wang , Hongtao Tian , Chen Li","doi":"10.1016/j.fm.2026.105037","DOIUrl":"10.1016/j.fm.2026.105037","url":null,"abstract":"<div><div>Post-acidification during refrigeration is a critical determinant of yogurt quality. Although it is known that niacin (NA) can influence this process via aldehyde-ketone reductase (AKR) in <em>Lactobacillus bulgaricus,</em> its precise regulatory mechanism remains unclear. By non-targeted metabolomics analysis revealed that nicotinic acid reshapes the metabolic profile during storage, significantly reducing the accumulation of organic acids such as L-lactic acid, fumaric acid, and succinic acid. This indicates that post-acidification processes are inhibited through relevant metabolic pathways. Concurrently, the yeast two-hybrid screening identified 21 proteins interacting with AKR, confirming L-lactate dehydrogenase (L-LDH) as a key interaction partner of AKR. This enzyme directly regulates L-LDH activity. Subsequent enzyme activity assays and AKR mutation confirmed that niacin acts as a potent inhibitor of L-LDH activity by promoting the formation of an AKR-L-LDH-NA ternary complex. Regulation of L-LDH activity by AKR without altering the structure and intrinsic catalytic properties of L-LDH is expected to realize the AKR-L-LDH-NA ternary complex as a key target for the future regulation of the post-acidification process. Our study establishes a technological method to accurately regulate the post-acidification of yogurt, which provides a theoretical basis for controlling acidity in lactic acid fermented foods.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":"137 ","pages":"Article 105037"},"PeriodicalIF":4.6,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0