德式乳杆菌和德式乳杆菌保加利亚亚种抑菌特性研究及发酵条件优化与保鲜效果评价

Isolation, Bacteriostatic Properties, and Preservative Effects of Lactic Acid Bacteria Producing Antimicrobial Peptides from Fermented Food

摘要:

为获得产抗菌肽且保鲜效果较好的乳酸菌，该研究从发酵食品中分离具有广谱抑菌活性的乳酸菌，分析其发酵上清液的主要抗菌物质成分，从热&酸碱耐受性、细胞壁完整性、细胞膜通透性及葡萄糖利用度等研究乳酸菌发酵上清液的抑菌特性；并利用单因素分析和响应面实验优化乳酸菌发酵条件，最后验证发酵上清液对猪肉和鱼肉的保鲜效果。结果表明：分别从酸豆角、发酵乳中分离得到的德式乳杆菌（Lactobacillus delbrueckii、L. delbrueckii）M2和德式乳杆菌保加利亚亚种（Lactobacillus delbrueckii subsp. Bulgaricus、L. delbrueckii subsp. bulgaricus）M6具有广谱抑菌作用，它们的抑菌成分主要为热、酸碱稳定性较好的蛋白质或肽类物质，其中，M2抑菌物质强碱耐受性优于M6。该两株乳酸菌最优发酵条件均为：接种体积分数3.00%，葡萄糖质量分数2.00%，大豆蛋白胨质量分数3.00%，在此条件下进行验证试验，测得M2和M6的抑菌效果比优化前分别提高了25.47%和22.64%。进一步研究发现：M2、M6发酵上清液通过破坏细菌细胞壁完整性、细胞膜通透性及影响葡萄糖利用而达到抑菌作用。冷鲜肉的保鲜试验证实：M2、M6发酵上清液能减少冷鲜肉菌落总数，延长猪肉和鱼肉货架期2~4 d。研究结果将为广谱新型的生物防腐剂的开发和应用提供理论指导。

Abstract:

Lactic acid bacteria with broad-spectrum antibacterial activities were isolated from fermented foods. These specific strains of lactic acid bacteria were capable of producing antimicrobial peptides, which were effective food preservatives. The main antibacterial substances present in the fermentation supernatant were analyzed for their properties, including heat, acid, and alkali tolerances; cell wall integrity; membrane permeability; and glucose availability. The fermentation conditions were optimized using single-factor analysis and response surface experiments. The effects of the resulting product on the preservation of pork and fish were examined. Lactobacillus delbrueckii (L. delbrueckii) M2 and L. delbrueckii subsp. bulgaricus M6 were isolated from sour bean and fermented milk, respectively, which exhibited broad-spectrum antibacterial activities. Their main antimicrobial components consisted of proteins or peptides with high thermal and acid-base stability. Moreover, the alkali tolerance of the antimicrobial substances from M2 was higher than those from M6. The optimal fermentation conditions for the two Lactobacillus strains were a 2.00% mass fraction of glucose, 3.00% mass fraction of soybean peptone, and 3.00% inoculation volume fraction. The antibacterial effects of L. delbrueckii M2 and L. delbrueckii subsp. bulgaricus M6 were 25.47% and 22.64% stronger under these conditions than under the baseline conditions, respectively. The supernatant of the two strains disrupted cell wall integrity and membrane permeability, leading to alterations in glucose utilization and ultimately producing the observed antibacterial effects. Their fermentation supernatants reduced the total viable bacteria counts and prolonged the shelf life of chilled pork and fish by 2~4 days. This study provides theoretical insights for the development and application of new broad-spectrum biological preservatives.