International journal of food microbiology最新文献_第4页

Comparative analyses of bacterial contamination and microbiome of broiler carcasses in wet market and industrial processing environments 湿市场和工业加工环境中肉鸡屠体细菌污染和微生物组的比较分析

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-12 DOI: 10.1016/j.ijfoodmicro.2024.110937

Yuanyuan Zhou , Nan-lin Wang , Jin-qi Cen , Jia-tong Han , Yu-xuan Tang , Zi-qi Xu , Hang Zeng , Kurt Houf , Zhongjia Yu

The slaughtering environment is crucial for the food hygiene and safety of poultry products. Despite the global dominance of industrial processing, live bird slaughtering in wet markets persists due to cultural, religious, and economic reasons. This study aims to reveal the correlation between hygiene scales in wet markets and bacterial contamination levels on broiler carcasses, with a particular focus on pathobiont transmission risks and microbiome characteristics. Wet markets were categorized based on home-made ratings and the Hygiene and Biosecurity Assessment Tool (HABT). The study assessed total aerobic bacterial (TAB) levels, food spoilage and hygiene indicators (Pseudomonas and E. coli), foodborne pathogen Salmonella, and the microbiome of broiler carcasses, intestinal contents, and slaughtering facilities. Comparative analyses were conducted between market and industrial processing environments. TAB levels on broiler carcasses showed a significant negative correlation with hygiene scores, indicating that both HABT and home-made rating tools effectively assess and improve processing hygiene. Industrial processing consistently reduced bacterial contamination compared to wet markets. Although Salmonella spp. prevalence was lower in market-processed carcasses, the study identified significant cross-transmission of pathobionts and variations in bacterial composition with hygiene improvements. Notably, the microbiome analysis revealed overlaps in amplicon sequence variants (ASVs) between carcasses and contamination vectors, highlighting pathobiont transmission risks. The present study confirmed the scales of hygiene standards among wet markets reflect bacterial contamination on broiler carcasses. Enhancing slaughter practices to meet industrial hygiene standards is essential for reducing the transmission of foodborne pathogens and pathobionts, and improving food safety.

屠宰环境对家禽产品的食品卫生和安全至关重要。尽管工业化加工在全球占主导地位，但由于文化、宗教和经济原因，在湿市场屠宰活禽的现象依然存在。本研究旨在揭示湿市场卫生等级与肉鸡胴体细菌污染水平之间的相关性，尤其关注病原体传播风险和微生物组特征。湿货市场根据自制评级和卫生与生物安全评估工具（HABT）进行分类。研究评估了需氧细菌总数（TAB）水平、食品腐败和卫生指标（假单胞菌和大肠杆菌）、食源性致病菌沙门氏菌以及肉鸡屠体、肠道内容物和屠宰设施的微生物组。对市场和工业加工环境进行了比较分析。肉鸡胴体上的 TAB 含量与卫生评分呈显著负相关，表明 HABT 和自制评级工具都能有效评估和改善加工卫生。与湿货市场相比，工业加工可持续减少细菌污染。虽然沙门氏菌属在市场加工胴体中的流行率较低，但研究发现，随着卫生条件的改善，病原菌的交叉传播和细菌组成的变化非常明显。值得注意的是，微生物组分析揭示了胴体和污染载体之间的扩增子序列变异（ASVs）重叠，突显了病原菌传播的风险。本研究证实，湿法市场的卫生标准规模反映了肉鸡胴体的细菌污染情况。加强屠宰操作以达到工业卫生标准对于减少食源性病原体和致病菌的传播以及提高食品安全至关重要。

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引用次数: 0

Community dynamics and assembly is driven by environmental microbiota mediated by spatiotemporal distribution: The case of Daqu fermentation 群落的动态和组合是由环境微生物群的时空分布驱动的：大曲发酵案例

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-09 DOI: 10.1016/j.ijfoodmicro.2024.110933

Shibo Ban , Yi Shen , Wei Cheng , Bo Chen , Yadong Zhang , Hongfang Nie , Shilei Wang , Yan Xu , Qun Wu

In almost all environments, microbial interaction is shaped by differences in environmental microbial transport, resulting in synergistic or antagonistic effects among community members. Unfortunately, the current understanding of how environmental microbiota affect spontaneous fermentation is very limited. Here, we selected Daqu workshops with different usage times (named X (60 years), Y (10 years), and Z (0 year)) as research model. The microbial contribution of raw material and environments to the microbiota of Daqu fermentation among workshops was compared, raw material microbiota contributed more bacterial genera (44.70 %–73.56 %) to the fermentation, and environmental microbiota contributed more fungal genera (10.09 %–99.76 %) to the fermentation. The deterministic assembly ratio and interaction intensity of workshop X were the highest, followed by Y and Z. We analyzed the relationship between environmental microbiota, fermentation microbiota, fermentation characteristics and flavor compounds. Environmental microbiota negatively drove the microbial diversity during fermentation (path coefficient = −1, P = 0.004), and further indirectly affected the community dynamics and assembly (path coefficient = −0.990, P < 0.001). Finally, community dynamics and assembly drove flavor compound diversity (path coefficient = 0.923, P < 0.001), it indicated the positive effect of environmental microbiota on flavor compound diversity. This work will help to understand the relationship between environmental microbiota and fermentation quality, supporting quality improvement of spontaneously fermented food in new workshop.

几乎在所有环境中，微生物的相互作用都受环境微生物迁移差异的影响，导致群落成员之间产生协同或拮抗作用。遗憾的是，目前对环境微生物群如何影响自发发酵的了解非常有限。在此，我们选择了使用时间不同的大曲作坊（分别命名为 X（60 年）、Y（10 年）和 Z（0 年））作为研究模型。比较了原料和环境对大曲发酵微生物区系的贡献，原料微生物区系对大曲发酵贡献较多的是细菌属（44.70%-73.56%），环境微生物区系对大曲发酵贡献较多的是真菌属（10.09%-99.76%）。我们分析了环境微生物群、发酵微生物群、发酵特征和风味化合物之间的关系。环境微生物群对发酵过程中的微生物多样性具有负向驱动作用（路径系数=-1，P=0.004），并进一步间接影响了群落动态和集合（路径系数=-0.990，P< 0.001）。最后，群落动态和集结推动了风味化合物多样性（路径系数 = 0.923，P <0.001），这表明环境微生物群对风味化合物多样性有积极影响。这项工作将有助于理解环境微生物群与发酵质量之间的关系，为新车间自发发酵食品的质量改进提供支持。

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引用次数: 0

Caproiciproducens converts lactic acid into caproic acid during Chinese strong-flavor Baijiu brewing 己酸菌在中国浓香型白酒酿造过程中将乳酸转化为己酸

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-09 DOI: 10.1016/j.ijfoodmicro.2024.110931

Xiangyi Jin, Hua Wang, Huixue Tian, Yongmei Hu, Nan Peng, Shumiao Zhao

Strong-flavor Baijiu, a type of Chinese liquor, is produced through anaerobic solid-state fermentation in a sealed mud pit. Ethyl caproate, the characteristic flavor compound of strong-flavor Baijiu, is influenced by caproic acid-producing bacteria in the pit mud. To better understand the formation of caproic acid, this study investigated the microbial composition and physicochemical parameters of pit mud from different layers (top, middle, and bottom) in Hubei and Sichuan provinces, China. The results revealed that Caproiciproducens plays a key role in caproic acid production by using lactic acid as a substrate, with its abundance increasing with the depth of the pit mud. A strain Caproiciproducens sp. R1, isolated from the pit mud, was shown to produce caproic acid from lactic acid within an initial pH range of 5.5–9.0 and lactic acid concentrations of 1 %–5 % (m/v). In addition, inoculation of strain R1 into Huangshui (a lactic acid-rich liquid from Baijiu production) resulted in 40.72 mM caproic acid production. This study demonstrates that Caproiciproducens plays a crucial role in caproic acid production from lactic acid during the fermentation process of strong-flavor Baijiu.

浓香型白酒是中国白酒的一种，是在密封的窖泥中通过厌氧固态发酵生产出来的。己酸乙酯是浓香型白酒的特征风味化合物，它受到坑泥中产生己酸的细菌的影响。为了更好地了解己酸的形成，本研究调查了中国湖北省和四川省不同地层（上层、中层和底层）坑泥的微生物组成和理化参数。结果表明，己酸菌（Caproiciproducens）以乳酸为底物，在己酸的生产过程中起着关键作用，其丰度随坑泥深度的增加而增加。从矿坑淤泥中分离出的一株 Caproiciproducens sp.此外，将菌株 R1 接种到黄水（一种从白酒生产中提取的富含乳酸的液体）中可产生 40.72 毫摩尔的己酸。这项研究表明，在浓香型白酒的发酵过程中，己酸菌在从乳酸中产生己酸的过程中起着至关重要的作用。

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引用次数: 0

Enhancing apple postharvest protection: Efficacy of pectin coatings containing Cryptococcus laurentii against Penicillium expansum 加强苹果采后保护：含有月桂隐球菌的果胶涂层对扩张青霉的功效

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-09 DOI: 10.1016/j.ijfoodmicro.2024.110934

Julieta Quiroga , Yésica Sabrina Lambrese , María Guadalupe García , Nelio Ariel Ochoa , Viviana Edith Calvente

The aim of this work is the application of pectin coatings containing Cryptococcus laurentii as a method of biocontrol of Penicillium expansum for postharvest protection of apples. For this purpose, the yeast was incorporated into a pectin matrix, and its viability and biocontrol activity in vitro and in vivo against P. expansum was evaluated over time. In addition, the influence of the sterilization process on coating thickness was studied. Results showed that pectin coating with C. laurentii enhanced mycelial growth inhibition in vitro studies, while no significant differences were observed in disease incidence and severity reduction in vivo studies. The sterilization process reduced the viscosity of the pectin solution, resulting in coating thicknesses ranging from 0.5 to 1 μm. As a general evaluation, in vitro and in vivo, biocontrol assays were useful in demonstrating better postharvest protection of the yeast at 7 °C concerning 25 °C.

这项工作的目的是将含有月桂隐球菌的果胶涂层作为一种扩张青霉生物控制方法，用于苹果的采后保护。为此，将酵母菌加入果胶基质中，并对其体外和体内对扩张青霉的活力和生物防治活性进行了长期评估。此外，还研究了灭菌过程对涂层厚度的影响。结果表明，在体外研究中，果胶包覆月桂酵母能增强对菌丝生长的抑制作用，而在体内研究中，在降低疾病发生率和严重程度方面没有观察到显著差异。灭菌过程降低了果胶溶液的粘度，导致涂层厚度从 0.5 到 1 微米不等。作为一般评估，体外和体内生物防治试验证明，在 7 °C 和 25 °C 温度条件下对酵母的采后保护效果更好。

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引用次数: 0

The impact of fermentation length and dough composition on the stability of liquid sourdough starters 发酵时间和面团成分对液体酸面团起动剂稳定性的影响

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-08 DOI: 10.1016/j.ijfoodmicro.2024.110932

Charlotte Bauer Munch-Andersen, Davide Porcellato, Tove Gulbrandsen Devold, Hilde Marit Østlie

Sourdough breadmaking on an industrial scale requires robust, well-performing starters that bring attractive characteristics to the product. The active nature of liquid starters provides a faster fermentation process compared to their dehydrated counterparts. However, liquid sourdough starters require meticulous management in order to maintain stability and functionality during cold storage at 4 °C.

This study investigated the stability of three liquid sourdough starters during storage and also the impact of prolonged fermentation, the addition of diastatic malted wheat flour, and a neutralising agent (CaCO₃).

The sourdough starters were evaluated for their microbial viability and metabolic activity at three individual time points during 16 weeks of cold storage. The microbial composition was analysed using culture-dependent and culture-independent methods, and metabolic changes were investigated using chromatographic methods.

Two types of sourdough starter showed satisfying viability of lactic acid bacteria (> 7 log CFU/g) and metabolic stability throughout 16 weeks of cold storage. The introduction of malted wheat flour and CaCO₃ caused a decline in viability to <7 log CFU/g within 8 weeks in the third sourdough starter type and additionally revealed an ongoing metabolic activity of this sourdough starter during cold storage.

Prolonged fermentation influenced the free amino acid profile, whereas adjusting the sourdough starter formula resulted in a different fungal microbiota and increased levels of fermentable substrates (maltose), organic acids (lactic acid), and aromatic compounds (alcohol and aldehydes).

These findings provide stakeholders and researchers in sourdough fermentation technology with new insights concerning the stability of cold-stored liquid sourdough starters.

工业化规模的酸包制作需要坚固耐用、性能良好的发酵剂，这样才能为产品带来诱人的特性。与脱水的发酵剂相比，液态发酵剂的活性可加快发酵过程。本研究调查了三种液体酸包粉起发酵剂在贮藏过程中的稳定性，以及延长发酵时间、添加泻盐麦芽粉和中和剂（CaCO3）的影响。在 16 周的冷藏期间，对酸包粉起发酵剂在三个时间点的微生物活力和代谢活性进行了评估。在 16 周的冷藏过程中，两种酸面团发酵剂都表现出了令人满意的乳酸菌活力（7 log CFU/g）和新陈代谢稳定性。引入麦芽粉和 CaCO3 后，第三种酸包粉起发酵剂的存活率在 8 周内下降到 7 log CFU/g，此外还显示这种酸包粉起发酵剂在冷藏期间具有持续的新陈代谢活动。延长发酵时间会影响游离氨基酸谱，而调整酸面团起动菌配方则会导致不同的真菌微生物群以及可发酵基质（麦芽糖）、有机酸（乳酸）和芳香化合物（酒精和醛）水平的增加。

{"title":"The impact of fermentation length and dough composition on the stability of liquid sourdough starters","authors":"Charlotte Bauer Munch-Andersen, Davide Porcellato, Tove Gulbrandsen Devold, Hilde Marit Østlie","doi":"10.1016/j.ijfoodmicro.2024.110932","DOIUrl":"10.1016/j.ijfoodmicro.2024.110932","url":null,"abstract":"<div><div>Sourdough breadmaking on an industrial scale requires robust, well-performing starters that bring attractive characteristics to the product. The active nature of liquid starters provides a faster fermentation process compared to their dehydrated counterparts. However, liquid sourdough starters require meticulous management in order to maintain stability and functionality during cold storage at 4 °C.</div><div>This study investigated the stability of three liquid sourdough starters during storage and also the impact of prolonged fermentation, the addition of diastatic malted wheat flour, and a neutralising agent (CaCO<sub>3</sub>).</div><div>The sourdough starters were evaluated for their microbial viability and metabolic activity at three individual time points during 16 weeks of cold storage. The microbial composition was analysed using culture-dependent and culture-independent methods, and metabolic changes were investigated using chromatographic methods.</div><div>Two types of sourdough starter showed satisfying viability of lactic acid bacteria (> 7 log CFU/g) and metabolic stability throughout 16 weeks of cold storage. The introduction of malted wheat flour and CaCO<sub>3</sub> caused a decline in viability to <7 log CFU/g within 8 weeks in the third sourdough starter type and additionally revealed an ongoing metabolic activity of this sourdough starter during cold storage.</div><div>Prolonged fermentation influenced the free amino acid profile, whereas adjusting the sourdough starter formula resulted in a different fungal microbiota and increased levels of fermentable substrates (maltose), organic acids (lactic acid), and aromatic compounds (alcohol and aldehydes).</div><div>These findings provide stakeholders and researchers in sourdough fermentation technology with new insights concerning the stability of cold-stored liquid sourdough starters.</div></div>","PeriodicalId":14095,"journal":{"name":"International journal of food microbiology","volume":"426 ","pages":"Article 110932"},"PeriodicalIF":5.0,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The role and the determination of the LuxI protein binding targets in the formation of biogenic amines in Hafnia alvei H4 在 Hafnia alvei H4 中形成生物胺过程中 LuxI 蛋白结合目标的作用和确定。

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-05 DOI: 10.1016/j.ijfoodmicro.2024.110928

Xue Li , Yanan Wang , Gongliang Zhang , Jingran Bi , Hongshun Hao , Hongman Hou

Hafnia alvei is a spoilage microorganism that possesses the LuxI/LuxR-type quorum sensing (QS) system. Biogenic amines (BAs) are important in food spoilage and safety, yet the role of QS in BA formation remains poorly understood. This study investigated the ability of H. alvei H4 to produce BAs in fish flesh and decarboxylase culture media. The findings showed that H. alvei H4 produced substantial amounts of putrescine and cadaverine in turbot flesh, with its enhanced amine-producing capacity potentially leading to the eventual deterioration of the fish. Furthermore, the deletion of the QS element—AHL synthase gene luxI—affected the concentrations of both BAs. Based on these observations, the present study conducted multifaceted experiments, including phenotypic assessments and analyses of gene expression, to explore the role of luxI and to identify its specific binding targets. The results indicated that putrescine formation in H. alvei H4 primarily occurred via the arginine deiminase (ADI) pathway, with luxI playing a positive role in the conversion of arginine to ornithine and subsequently to putrescine. The reduction in putrescine content observed in a luxI mutant (ΔluxI) was attributed to the direct binding of the LuxI protein to the promoters of the argF and speC genes, which code for ornithine carbamoyltransferase and ornithine decarboxylase, respectively. The findings of this study provided the basis to understand the influence of QS on BA production in H. alvei, by specifically demonstrating the involvement of the luxI gene on putrescine and cadaverine production.

Hafnia alvei 是一种具有 LuxI/LuxR 型法定量感应（QS）系统的腐败微生物。生物胺（BA）在食品腐败和安全方面具有重要作用，但人们对 QS 在生物胺形成过程中的作用仍然知之甚少。本研究调查了白喉杆菌 H4 在鱼肉和脱羧酶培养基中产生 BAs 的能力。研究结果表明，H. alvei H4 能在多宝鱼肉中产生大量腐胺和尸胺，其产胺能力的增强可能会导致多宝鱼最终变质。此外，QS元件-AHL合成酶基因luxI的缺失也会影响这两种BA的浓度。基于这些观察结果，本研究进行了多方面的实验，包括表型评估和基因表达分析，以探索luxI的作用并确定其特定的结合靶标。结果表明，H. alvei H4中的腐胺主要是通过精氨酸脱氨酶（ADI）途径形成的，而luxI在精氨酸转化为鸟氨酸进而转化为腐胺的过程中发挥了积极作用。在luxI突变体（ΔluxI）中观察到的腐胺含量减少是由于LuxI蛋白与argF和speC基因的启动子直接结合所致，这两个基因分别编码鸟氨酸氨基甲酰转移酶和鸟氨酸脱羧酶。本研究的发现为了解 QS 对 H. alvei 产生 BA 的影响提供了基础，特别是证明了 luxI 基因参与了腐胺和尸胺的产生。

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引用次数: 0

Disruption of the signal recognition particle pathway leading to impaired growth, sugar metabolism and acid resistance of Lactococcus lactis 信号识别颗粒途径中断导致乳酸乳球菌生长、糖代谢和耐酸性受损。

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-04 DOI: 10.1016/j.ijfoodmicro.2024.110929

Meng Wang, Yanying Yue, Xiaoce Zhu, Mengjie Wang, Yifei Zhang, Jian Kong, Tingting Guo

Lactococcus lactis is a well-known workhorse for dairy products, whose important industrial traits are tightly associated with numerous cytoplasmic membrane proteins. However, roles of the signal recognition particle (SRP) pathway responsible for membrane protein targeting have not been studied in L. lactis. In this work, the putative genes ffh and ftsY encoding SRP pathway components were identified in the genome of L. lactis NZ9000. Experimental evidence showed that sequence mutation in either the ffh or ftsY was not lethal, but prolonged the lag phase of the resultant mutants Δffh and ΔftsY by 2 h and lowered their biomass to 85.7 % of the wild type under static conditions, as well as deprived the mutants of improved growth capacity under aerobic respiration conditions. Besides, the speeds of glucose consumption and lactate production were significantly decreased in the mutants. Then, the impact of the SPR components on acid resistance was detected, showing that the ffh and ftsY were transcriptionally upregulated by 3.02 ± 1.21 and 8.66 ± 1.01-fold in the wild type during acid challenge at pH 3.0, and cell survival of the Δffh and ΔftsY decreased by10- and 100-fold compared with the wild type. To explore the possible mechanism about the SRP pathway involved in the above physiological traits, proteomics analysis was performed and revealed that disruption of the Ffh or FtsY led to decrease in ribosomal proteins, but increase in DnaK, GroEL and heat shock protein GrpE, indicating that the SRP pathway was closely linked to protein synthesis and folding in L. lactis. Decrease in the fructose-bisphosphate aldolase, respiratory complexes NADH dehydrogenase, as well as glutamate decarboxylase was also detected in the Δffh and ΔftsY, which is consistent with the phenomena of impaired sugar metabolism and acid resistance. Our results demonstrated the dispensable SRP pathway could contribute to the maintenance of metabolism homeostasis and acid resistance of L. lactis.

乳酸乳球菌是众所周知的乳制品生产主力军，其重要的工业特性与众多细胞质膜蛋白密切相关。然而，在乳球菌中，负责膜蛋白靶向的信号识别颗粒（SRP）通路的作用尚未得到研究。在这项工作中，在乳酸菌 NZ9000 的基因组中发现了编码 SRP 通路元件的推定基因 ffh 和 ftsY。实验证明，ffh 或 ftsY 的序列突变并不致死，但会使突变体 Δffh 和 ΔftsY 的滞后期延长 2 小时，使其在静态条件下的生物量降至野生型的 85.7%，并使突变体在有氧呼吸条件下的生长能力下降。此外，突变体的葡萄糖消耗速度和乳酸生成速度也明显下降。结果表明，在pH 3.0的酸挑战条件下，野生型的ffh和ftsY转录上调了3.02±1.21倍和8.66±1.01倍，Δffh和ΔftsY的细胞存活率比野生型分别降低了10倍和100倍。为了探索SRP通路参与上述生理特性的可能机制，研究人员进行了蛋白质组学分析，结果表明干扰Ffh或FtsY会导致核糖体蛋白减少，但DnaK、GroEL和热休克蛋白GrpE会增加，这表明SRP通路与乳酸菌蛋白质的合成和折叠密切相关。在Δffh和ΔftsY中还检测到果糖-二磷酸醛缩酶、呼吸复合体NADH脱氢酶以及谷氨酸脱羧酶的减少，这与糖代谢受损和耐酸现象一致。我们的研究结果表明，可有可无的SRP途径有助于维持乳酸菌的代谢平衡和耐酸性。

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引用次数: 0

The applicability of the SERS technique in food contamination testing – The detailed spectroscopic, chemometric, genetic, and comparative analysis of food-borne Cronobacter spp. strains SERS 技术在食品污染检测中的适用性 - 对食源性克罗诺杆菌属菌株进行详细的光谱、化学计量、遗传和比较分析。

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-03 DOI: 10.1016/j.ijfoodmicro.2024.110930

K. Niciński , E. Witkowska , D. Korsak , M. Szuplewska , A. Kamińska

Microorganisms assigned as Cronobacter are Gram-negative, facultatively anaerobic, bacteria widely distributed in nature, home environments, and hospitals. They can also be detected in foods, milk powder, and powdered infant formula (PIF). Additionally, as an opportunistic pathogen, Cronobacter may cause serious infections, sometimes leading to the death of neonates and infants. Thus, it is essential to test food products for the presence of Cronobacter spp. The currently used standard described in ISO 22964:2017 is a laborious method that could be easily replaced by surface-enhanced Raman scattering (SERS).

Here, we demonstrate that SERS allows the identification of food-borne bacteria belonging to Cronobacter spp. based on their SERS spectra. For this purpose, twenty-six Cronobacter strains from different food samples were analyzed. Additionally, it was shown that it is possible to differentiate them from other closely related pathogens such as Salmonella enterica subsp. enterica, Escherichia coli, or Enterobacter spp. The SERS results were supported by principal component analysis (PCA), as well as and sequencing of 16S rRNA, rpoB and fusA genes. Last but not least, it was demonstrated that the cells of Cronobacter sakazakii may be easily separated from PIF using an appropriate filter, microfluidic chip, and dielectrophoresis (DEP) technique.

克罗诺杆菌是一种革兰氏阴性、兼性厌氧细菌，广泛分布于自然界、家庭环境和医院中。在食品、奶粉和婴儿配方粉（PIF）中也能检测到它们。此外，作为一种机会性病原体，克罗诺杆菌可能会引起严重感染，有时会导致新生儿和婴儿死亡。ISO 22964:2017 中描述的当前使用的标准是一种费力的方法，很容易被表面增强拉曼散射（SERS）所取代。在这里，我们证明了 SERS 可以根据其 SERS 光谱来识别属于克罗诺杆菌属的食源性细菌。为此，我们分析了来自不同食品样本的 26 株克罗诺杆菌。主成分分析（PCA）以及 16S rRNA、rpoB 和 fusA 基因的测序也支持了 SERS 的结果。最后但并非最不重要的一点是，该研究证明，使用适当的过滤器、微流控芯片和介电泳（DEP）技术，可以很容易地从 PIF 中分离出阪崎肠杆菌的细胞。

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引用次数: 0

High-pressure processing and heat treatment of Murrah buffalo milk: Comparative study on microbial changes during refrigerated storage Murrah 水牛奶的高压加工和热处理：冷藏期间微生物变化的比较研究。

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-02 DOI: 10.1016/j.ijfoodmicro.2024.110926

Darren Sim Xuan Yu , Chong Kah Hui , Mohammad Rashedi Ismail-Fitry , Pankaj Koirala , Nilesh Nirmal , Mahmud Ab Rashid Nor-Khaizura

This study aims to evaluate the effect of high-pressure processing (HPP) (500 and 600 MPa for 3 min and 5 min) on the microbial changes of Murrah buffalo milk in comparison to heat treatment (72 °C for 15 s of holding time) during refrigerated storage of 28 days. The results indicated that the total plate count (TPC) of raw milk at day 0 was 5.5 ± 0.6 log₁₀ CFU/mL. At day 0, heat treatment lowered TPC to 3.9 ± 0.6, while HPP treatment was in the range of 4.1 ± 0.3 to 4.8 ± 0.6 log₁₀ CFU/mL. Similarly, lowered yeast and mold count and lactic acid bacteria were noted in heat- and HPP-treated milk samples compared to the control sample during refrigerated storage. There were no Staphylococcus aureus and Escherichia coli detected in heat and HPP-treated samples. Heat or HPP treatment at 600 MPa for 5 min significantly extended the shelf-life of Murrah buffalo milk for three weeks at the refrigerated storage. In addition, HPP treatment did not alter the pH, lightness (L* value), protein, or fat content of Murrah buffalo milk during refrigerated storage. Hence HPP at 600 MPa for 5 min could be a suitable alternative to conventional heat treatment.

本研究旨在评估在冷藏贮存 28 天期间，高压处理（HPP，500 和 600 兆帕，3 分钟和 5 分钟）与热处理（72 °C，15 秒保温时间）相比对穆拉拉水牛奶微生物变化的影响。结果表明，生牛奶在第 0 天时的菌落总数（TPC）为 5.5 ± 0.6 log10 CFU/mL。在第 0 天，热处理将 TPC 降至 3.9 ± 0.6，而 HPP 处理的范围为 4.1 ± 0.3 至 4.8 ± 0.6 log10 CFU/mL。同样，与冷藏储存期间的对照样本相比，加热和 HPP 处理过的牛奶样本中的酵母菌、霉菌和乳酸菌数量也有所减少。在加热和 HPP 处理过的样品中没有检测到金黄色葡萄球菌和大肠杆菌。在 600 兆帕的压力下加热或 HPP 处理 5 分钟可明显延长伊拉水牛奶在冷藏条件下三周的货架期。此外，在冷藏储存期间，HPP 处理不会改变伊拉水牛奶的 pH 值、亮度（L* 值）、蛋白质或脂肪含量。因此，在 600 兆帕的压力下进行 5 分钟的 HPP 可作为传统热处理的合适替代方法。

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引用次数: 0

Genomic and phenotypic polymorphism of Clostridium botulinum Group II strain Beluga through laboratory domestication 通过实验室驯化白鲸肉毒梭菌 II 型菌株的基因组和表型多态性。

IF 5 1区农林科学 Q1 FOOD SCIENCE & TECHNOLOGY

International journal of food microbiology

Pub Date : 2024-10-01 DOI: 10.1016/j.ijfoodmicro.2024.110927

Katja Selby, François P. Douillard, Miia Lindström

Laboratory domestication is the result of genetic and physiological changes of organisms acquired during numerous passages in vitro. This phenomenon has been observed in bacteria as well as in higher organisms. In an effort to understand the impact of laboratory domestication on the foodborne pathogen Clostridium botulinum and related microbial food safety research, we investigated multiple spore stocks of C. botulinum Group II Beluga from our collection, as that is a widely applied model strain used in laboratories over decades. An acquired nutrient auxotrophy was confirmed as thymidine dependency using phenotypic microarrays. In parallel, whole-genome re-sequencing of all stocks revealed a mutation in thyA encoding thymidylate synthase essential for de-novo synthesis of dTMP from dUMP in the auxotrophic stocks. A thyA-deficient Beluga variant stock was successfully complemented by introducing an intact variant of thyA and thymidine prototrophy was restored, indicating that the thymidine auxotrophy was solely due to the presence of a SNP in thyA. Our data suggested that this mutation, deleterious under nutrient-poor growth conditions in a chemically defined medium, has been present and maintained in laboratory stocks for nearly 30 years. Yet, the mutation remained unidentified since receiving the strain, most likely due to routine use of culture conditions optimized for growth performance. This work pinpoints the need for careful monitoring of model strains extensively used in laboratory settings at both phenotypic and genomic level. In applications like food safety challenge tests, compromised strains could cause incorrect predictions and thereby have deleterious consequences. To mitigate the risk of acquiring mutations, we recommend keeping passage numbers of laboratory strains low and to avoid single-colony passaging. In addition, relevant strains should be subjected to regular WGS checks and physiological validation to exclude DNA mutations with potential negative impacts on research data integrity and reproducibility.

实验室驯化是生物体在体外多次传代过程中遗传和生理变化的结果。在细菌和高等生物体中都观察到了这种现象。为了了解实验室驯化对食源性致病菌肉毒梭菌和相关微生物食品安全研究的影响，我们研究了我们收集的肉毒梭菌第二类白鲸孢子种群，因为这是几十年来实验室广泛使用的模式菌株。使用表型芯片确认了一种获得性营养物质辅助营养，即胸腺嘧啶依赖性。与此同时，对所有种群进行的全基因组重测序发现，在辅助营养型种群中，编码胸苷酸合成酶的 thyA 发生了突变，而这种突变对于从 dUMP 中重新合成 dTMP 至关重要。通过引入一个完整的 thyA 变体，成功地对一个 thyA 缺陷白鲸变体种群进行了互补，胸苷原生营养得以恢复，这表明胸苷辅助营养完全是由于 thyA 中存在一个 SNP。我们的数据表明，这种突变在化学定义的培养基中营养贫乏的生长条件下是有害的，它已经在实验室种群中存在并维持了近 30 年。然而，自接收菌株以来，该突变仍未被发现，这很可能是由于常规使用了优化生长性能的培养条件。这项工作表明，有必要在表型和基因组水平上对实验室中广泛使用的模式菌株进行仔细监测。在食品安全挑战测试等应用中，受损菌株可能会导致预测错误，从而产生有害后果。为了降低获得突变的风险，我们建议保持实验室菌株较低的传代次数，避免单菌落传代。此外，应定期对相关菌株进行 WGS 检查和生理验证，以排除对研究数据完整性和可重复性有潜在负面影响的 DNA 变异。

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