Kaboudari Ata, Aliakbarlu Javad
Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran.
BMC Microbiol. 2025 May 24;25(1):321. doi: 10.1186/s12866-025-04039-8.
The survival of food-borne pathogenic bacteria in food processing environments and increasing their resistance to antimicrobials is one of the most crucial challenges in food safety. The present study aimed to investigate the effects of freezing period (0-60 days) and meat juice model (beef, mutton, and goat juices) on the survival, hydrophobicity, and acid resistance of Listeria monocytogenes and Salmonella Typhimurium.
The survival of L. monocytogenes and S. Typhimurium in different meat juice models during the freezing period (0, 1, 2, 3, 4, 7, 14, 21, 30, and 60 days) was determined by colony counting method. The cell surface hydrophobicity of the bacteria was measured by bacterial adhesion to hydrocarbon assay. Changes in the bacterial resistance to acetic acid and lactic acid were evaluated by determining minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC).
The survival of both bacteria was significantly higher in mutton juice than in other juices (p < 0.05). The survival rate of L. monocytogenes in freezing conditions was higher than that of S. Typhimurium. The amount of hydrophobicity was increased during the freezing period, and the highest increase was observed in the mutton juice. The increase in hydrophobicity of S. Typhimurium was higher than L. monocytogenes. The acid resistance of both bacteria, especially L. monocytogenes, was increased with increasing freezing time.
Freezing stress and meat juice model type could change the survival, hydrophobicity, and acid resistance of L. monocytogenes and S. Typhimurium. The mutton juice model showed the highest protective effect on both bacteria during the freezing period. Meanwhile, the bacteria inoculated in the mutton juice model exhibited significantly higher hydrophobicity than those in other meat juices. The acid resistance of L. monocytogenes was significantly increased, especially in the mutton juice model, at the end of the freezing period.
食源性病原体在食品加工环境中的存活及其对抗菌剂耐药性的增加是食品安全领域最关键的挑战之一。本研究旨在探究冷冻期（0 - 60天）和肉汁模型（牛肉汁、羊肉汁和山羊汁）对单核细胞增生李斯特菌和鼠伤寒沙门氏菌的存活、疏水性及耐酸性的影响。
采用菌落计数法测定单核细胞增生李斯特菌和鼠伤寒沙门氏菌在不同肉汁模型中冷冻期（0、1、2、3、4、7、14、21、30和60天）的存活率。通过细菌对碳氢化合物的粘附试验测定细菌的细胞表面疏水性。通过测定最低抑菌浓度（MIC）和最低杀菌浓度（MBC）评估细菌对乙酸和乳酸耐药性的变化。
两种细菌在羊肉汁中的存活率均显著高于其他汁液（p < 0.05）。单核细胞增生李斯特菌在冷冻条件下的存活率高于鼠伤寒沙门氏菌。冷冻期内疏水性增加，且在羊肉汁中增加幅度最大。鼠伤寒沙门氏菌疏水性的增加高于单核细胞增生李斯特菌。两种细菌，尤其是单核细胞增生李斯特菌的耐酸性随冷冻时间的延长而增加。
冷冻应激和肉汁模型类型可改变单核细胞增生李斯特菌和鼠伤寒沙门氏菌的存活、疏水性及耐酸性。在冷冻期，羊肉汁模型对两种细菌的保护作用最强。同时，接种于羊肉汁模型中的细菌疏水性显著高于其他肉汁中的细菌。在冷冻期结束时，单核细胞增生李斯特菌的耐酸性显著增加，尤其是在羊肉汁模型中。
