International journal of food microbiology最新文献

Nontyphoidal Salmonella (NTS) represents a significant public health concern. However, the health risks associated with pork consumption in China have not been adequately characterized, particularly within household settings. This study aimed to develop a quantitative microbiological risk assessment (QMRA) model that integrates consumers' food handling practices and multidrug resistance (MDR) profiles of NTS to assess the health risks and disease burden, expressed as disability-adjusted life years (DALYs), associated with pork-derived NTS exposure in Chinese households. With 17.6% of pork consumption posing a foodborne risk, the QMRA models predicted a substantial annual incidence of 3.56 million (95% CI: 3.36-3.76) of pork-derived salmonellosis cases in China. Cross-contamination accounted for 77.2% of total cases, representing a 3.4-fold higher risk compared with undercooking. The total disease burden was estimated at 16,597 DALYs (95% CI: 15,627-17,567), with MDR-NTS strains accounting for 91.8% of the total burden. Scenario analysis showed that reducing initial contamination prevalence yielded the greatest marginal reduction in disease burden, while combined interventions at the production and consumption stages could reduce the burden by up to 80%. This study presents an evidence-based, bottom-up risk assessment framework for NTS associated with household pork consumption in China, highlighting the need for strengthened food safety regulations and more effective consumer-targeted interventions.

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a significant pathogen in animal-derived food production. The use of natural antimicrobial agents is becoming a promising method to reduce the risk of MRSA. Resveratrol, a natural product, may be used as an alternative green preservative for the meat industry. This study investigated the antimicrobial efficacy of resveratrol against MRSA, including its inhibitory activity on MRSA inoculated in beef under different storage conditions (4 °C for 7 days and 25 °C for 3 days). The antimicrobial mechanism was further investigated via assessments of MRSA alkaline phosphatase (AKP) activity, cell leakage, propidium iodide staining, scanning electron microscope observations, intracellular reactive oxygen species (ROS) levels, and proteomic profiles. The results demonstrated that the minimum inhibitory concentration (MIC) of resveratrol on MRSA was 200 μg/mL. Resveratrol significantly inhibited the MRSA growth in beef, in which the MIC group reduced 1.55 and 2.56 log CFU/g MRSA compared to the control group without resveratrol after 7-day storage at 4 °C and 3-day storage at 25 °C, respectively. This was mainly attributed to the disruption of the cell membrane and wall structure rather than the ROS-mediated oxidative damage. Proteomic analysis revealed that resveratrol at sub-MIC (100 μg/mL) led to interference in cell wall and membrane synthesis, causing damage to MRSA cells. Additionally, some key enzymes were upregulated in response to resveratrol stress, including glucose-6-phosphate dehydrogenase in the pentose phosphate pathway, as well as ornithine aminotransferase and pyrroline-5-carboxylate reductase in the arginine and proline metabolism pathways. Furthermore, the resveratrol treatment reduced toxin production and the invasion ability of MRSA. These results indicated that resveratrol demonstrated significant application value in controlling foodborne MRSA within the beef industry and can provide important technical support for the safety control and quality assurance of beef products.

Despite its acidic environment, kimchi has occasionally been linked with foodborne pathogen contamination, emphasizing the need to increase its microbial safety. While kimchi fermentation generally occurs at low temperatures, most previous studies on starter cultures have focused on mesophilic lactic acid bacteria (LAB). The present study investigated the potential of psychrotrophic LAB as starter cultures for kimchi fermentation, with particular focus on their antimicrobial activity and metabolic characteristics. Two psychrotrophic strains, Dellaglioa algida and Leuconostoc gelidum subsp. aenigmaticum, were individually co-inoculated with pathogens including Escherichia coli O157:H7, Staphylococcus aureus, and Listeria monocytogenes in kimchi and fermented at 4 °C for 42 days. Their performance was compared with that of a mesophilic LAB strain, Leu. mesenteroides, through microbial, physicochemical, and metabolomics analyses. The psychrotrophic starters accelerated acidification, maintained high dominance, and effectively suppressed pathogens. Moreover, E. coli O157:H7 counts were 1.8-2.4 log CFU/mL lower, and S. aureus reached the limit of detection (1.0 log CFU/mL) 7 days earlier than the mesophilic starter. Untargeted metabolomics using ultra-performance liquid chromatography-quadrupole-Orbitrap mass spectrometry revealed strain-specific inhibition of metabolic pathways in foodborne pathogens. D. algida primarily suppressed nucleotide metabolism, whereas Leu. gelidum subsp. aenigmaticum strongly inhibited energy-related and stress defense pathways, ultimately impairing pathogen growth. In contrast, Leu. mesenteroides exhibited relatively limited metabolic inhibition. In conclusion, psychrotrophic LAB exhibited broad-spectrum antimicrobial activity and strain-specific inhibition mechanisms, underscoring their potential as functional starters to enhance microbial safety and consistency in low-temperature fermented foods.

The conversion of lactate to 1,2-propanediol and 1,2-propanediol to propionate sustains viability and metabolic activity of stationaryphase cells of lactobacilli over weeks or even months. The pathway was described only in few lactobacilli, and factors regulating its expression remain poorly understood. This study investigated the metabolic pathways of 1,2-propanediol in heterofermentative lactobacilli, focusing on lentilactobacilli, levilactobacilli and furfurilactobacilli. Lentilactobacillus buchneri FUA3252 demonstrated high 1,2-propanediol production in modified MRS (mMRS) medium with lactate, while Furfurilactobacillus spp. exhibited minimal 1,2-propanediol synthesis but produced notable amounts of mannitol. In sorghum sourdough, Ff. cerealis C5 and Ff. rossiae FUA3124 showed increased 1,2-propanediol levels after prolonged fermentation, with Ff. cerealis C5 yielding 40 mmol/kg sourdough by day 7. The effect of pH and lactate on expression of aldA, which encodes lactaldehyde dehydrogenase, was inconsistent among the strains and incubation conditions. The expression of pduC, coding for propanediol utilization enzyme, was not different between mMRS and sorghum sourdoughs, and its expression was not altered by lactate concentrations. The expression of aldA was consistently increased during the stationary phase of growth, which conforms to the continuing conversion of lactate to 1,2-propanediol by stationary phase cells during extended (weeks or month) incubation. The study provides insights into the metabolic versatility of lactobacilli and their potential applications in food biotechnology.

Antimicrobial resistance in Listeria monocytogenes is an increasing concern in food processing environments, especially when biocides are applied incorrectly. In this study, the susceptibility of 19 L. monocytogenes strains to three commonly used disinfectants - benzalkonium chloride (BKC), peracetic acid (PAA), and sodium hypochlorite (SHY) - was assessed by using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) determination. Subsequently, strains were gradually exposed to increasing subinhibitory concentrations of the disinfectants to assess the impact of such exposure on their resistance profiles. All strains exhibited higher MIC and MBC values after adaptation, with increments of 0.77- to 155.93-fold, especially those from industrial environments, suggesting the selection of more tolerant phenotypes. Strain-dependent adaptation was demonstrated by principal component analysis (PCA), which revealed a clear shift in the phenotypic profiles of adapted strains, as well as increased variability. On the other hand, the susceptibility pattern of wild-type strains was maintained more homogeneous. These results confirmed that subinhibitory exposure to disinfectants induced tolerance development in L. monocytogenes, which has direct implications for hygiene protocols. Therefore, to prevent the development and persistence of cross-resistant strains in food industry, proper disinfectant control and their application are crucial.