【摘要】 【目的】为提高分离自藏灵菇的鼠李糖乳杆菌zrx01产细菌素的能力,对其产细菌素的发酵条件进行优化,并分析其抑菌活性。【方法】采用单因素试验,分析鼠李糖乳杆菌zrx01产细菌素的最适发酵条件,即发酵时间、温度、培养基初始pH值、接种量等4个因素对其产细菌素能力的影响,在此基础上利用Box-Behnken法设计四因素三水平正交试验进行响应面优化,利用优化条件提取细菌素并对大肠杆菌进行抑菌试验。【结果】响应面法优化的鼠李糖乳杆菌zrx01产细菌素的最佳发酵条件为发酵时间20h、发酵温度35℃、培养基初始pH 6.5、接种量2.5%(体积比),此时细菌素的相对效价为(242.02±10.24)AU/mL,比优化前的相对效价(118.40±10.36)AU/mL提高了104.41%。获得的发酵上清液用乙酸乙酯萃取浓缩,作用于大肠杆菌指示菌和鼠李糖乳杆菌zrx018h,鼠李糖乳杆菌zrx01不产生抑菌圈,而大肠杆菌抑菌圈明显。扫描电镜显示,该细菌素对鼠李糖乳杆菌zrx01自身无作用,但可使大肠杆菌的菌体表面形成孔洞,从而抑制大肠杆菌的生长。【结论】分离自藏灵菇中的鼠李糖乳杆菌zrx01所产细菌素,在食品防腐方面具有很好的应用前景。更多还原

【Abstract】 【Objective】To improve the bacteriocin producing ability of Lactobacillus rhamnosus zrx01 isolated from Tibetan Mushroom,this study optimized the fermentation conditions and analyzed its antibacterial activity.【Method】The single factor experiments were used to analyze the optimum fermentation conditions of culture time,temperature,initial pH of medium and inoculum size for bacteriocin production by Lactobacillus rhamnosus zrx01.On this basis,the Box-Behnken method was used to design a four-factor and three-level orthogonal test to optimize the conditions,extract bacteriocins with optimized conditions,and conduct antibacterial tests on Escherichia coli.【Result】The optimum conditions for bacteriocins production of Lactobacillus rhamnosus zrx01 obtained by the response surface method were fermentation time20 h,temperature 35℃,initial pH of culture medium 6.5,and inoculum 2.5%(V/V).The bacteriocin relative potency of bacteriocins was(242.02±10.24)AU/mL,with an increase of 104.41%from the original value of(118.40±10.36)AU/mL.The obtained fermentation supernatant was extracted and concentrated with ethyl acetate.Escherichia coli and Lactobacillus rhamnosus zrx01 were then exposed for 8 h.Lactobacillus rhamnosus zrx01 showed no inhibition zone,while Escherichia coli had clear inhibition zone.Scanning electron microscopy showed that the bacteriocin had no effect on Lactobacillus rhamnosus zrx01 itself,but it inhibited the growth of Escherichia coli by generating holes on the bacteria surface.【Conclusion】The bacteriocin produced by Lactobacillus rhamnosus zrx01 isolated from Tibetan Mushroom has good application prospect in food preservation.更多还原