产抗菌肽乳源乳酸菌的筛选及定向培养

为了获得乳酸菌高效表达抗菌肽的代谢调控方法,对德氏乳杆菌保加利亚亚种等7种乳酸菌进行了产抗菌肽能力的筛选和定向培养。筛选出具有较高抑菌活性的菌株嗜酸乳杆菌和干酪乳杆菌,它们产生的抑菌物质经排除酸、过氧化氢后,仍具有抑菌活性,然而经蛋白酶处理后其抑菌活性明显下降。结果表明,两种菌发酵上清液对金黄色葡萄球菌和大肠杆菌均有抑制作用。经一系列定向培养嗜酸乳杆菌抑菌直径达到(23.53±0.06)mm,与未经定向培养的抑菌直径(11.63±0.15)mm相比抑菌活性提高了102%;经定向培养的干酪乳杆菌抑菌直径达到(21.27±0.25)mm,与未经定向培养的抑菌直径(12.50±0.10)mm相比抑菌活性提高了70.2%。

Selection of milk-source Lactic acid bacteria producing antimicrobial peptides and cultivation for antimicrobial activity

In order to obtain metabolism control methods for high expression of antimicrobial peptides of lactic acid bacteria.In this experiment,Lactobacillus delbrueckii subsp.Bulgaricus etc.seven kinds of lactic acid bacteria were isolated and identified and cultured for antimicrobial activities.Excluding the interference of organic acids and hydrogen peroxide,the high antibacterial activities of these lactic acid bacteria were selected.The fermentation supernatant of these two kinds of lactic acid bacteria lost antimicrobial activity in the presence of trypsin.The fermentation supernatant of Lactobacillus acidophilus and Lactobacillus casei had inhibitory spectrum against Staphylococcus aureus and E.coli.After the series of target cultivation,the antibacterial diameter of Lactobacillus acidophilus was(23.53±0.06)mm,while without the target cultivation Lactobacillus acidophilus antibacterial diameter was(11.63±0.15)mm,the antibacterial activity rised by 102%.After target cultivation,antibacterial diameter of Lactobacillus casei was(21.27±0.25)mm,while without target cultivation the antibacterial diameter of Lactobacillus casei was(12.50±0.10)mm,antimicrobial activity rised by 70.2%.