产类细菌素的乳酸菌的筛选及其抑菌特性研究

Screening of lactic acid bacteria producing bacteriocin-like substance and studing on its antibacterial properties

从青藏高原传统牦牛酸奶中筛选出一株乳酸菌,排除酸和过氧化氢的干扰后,对金黄色葡萄球菌(Staphylococcus aureu)和大肠杆菌(Escherichia coli)有明显的抑制作用.经形态学、生理生化特征及16S rDNA序列同源性分析等手段鉴定该菌株为乳明串珠菌(Leuconostoclactis).用蛋白酶处理该菌株的发酵上清液后,抑菌活性丧失;发酵上清液具有较好的热稳定性(经121℃处理20 min仍有较强抑菌活性)和pH稳定性(在pH 3.0～10.0之间保持活性),因此初步认为该菌株产生的抑菌物质属于类细菌素.研究发现该菌株在培养8 h后出现抑菌活性,在20 h时抑菌活性达到最大并一直到发酵结束.

A lactic acid bacteria screened from kurut collected from Qinghai-Tibet Plateau, showed apparent inhibition activity against both Staphylococcus aureu and Escherichia coli, by eliminated the effects of organic acids and hydrogen peroxide. Through detection of its appearance, physiological and biochemical characteristics and 165 rDNA gene sequencehomology analysis, it was identified as Leu- conostoc lactis. The inhibition activity was totally lost after treatment with protease. The fermentation supernatant was heat-stable （even at 121 ℃for 20 min） and remained stable at a wide pH range （3.0- 10.0）. So it is preliminary thinked as bacteriocin-like substance. Leuconostoc lactis LY7 started to pro- duce bacteriocin at 8 h. Maximum bacteriocin production was reached at 90 h and remained constant until fermentation end.