抑制酸奶后酸化产细菌素乳酸菌的筛选及其产细菌素条件优化

Screening of bacteriocin-producing lactic acid bacteria that inhibit post acidification of yogurt and optimization of bacteriocin-producing conditions

乳酸菌所产细菌素是一种绿色、安全以及高效的天然抑菌物质,但产细菌素乳酸菌数量有限、产量低及价格昂贵等因素极大限制了细菌素的集约化应用.从传统发酵食品分离的16株乳酸菌中,通过微孔板法和琼脂扩散法筛选出一株具有明显抑菌效果的乳酸乳球菌株Q13,通过酸排除试验、过氧化氢排除试验、蛋白酶酶解试验和稳定性试验研究该菌株所产抑菌物质的生物学特性;对菌株产细菌素的发酵条件进行响应面优化,并对细菌素进行了初步应用试验.结果表明,菌株Q13所产抑菌物质是一种具有热稳定性和酸碱稳定性的蛋白类物质;其最优发酵条件为接种量1.4%、发酵初始pH 8.0、发酵温度27.5℃,此条件下,细菌素效价最高,可达618 AU/mL,比优化前200 AU/mL提高了3倍;Q13所产细菌素的后期添加可有效抑制酸奶后酸化,延缓酸奶酸度增加.该研究可为细菌素的工业化应用提供理论数据支撑.

Bacteriocin produced by lactic acid bacteria is a kind of green,safe and efficient natural antimicrobial substance.However,the limited number of bacteriocin-producinglactic acid bacteria,low output and high price have greatly restricted the intensive application of bacteriocins.In this paper,Lactococcuslactis Q13 with obvious antibacterial effect was selected among 16 strains of lactic acid bacteria isolated from traditional fermented food by the microplate method and agar diffusion method.At the same time,acid and hydrogen peroxide exclusion test,proteases enzymolysis test and stability test were used to study the biological characteristics of the antimicrobial substance produced by the strain;furthermore,response surface methodology was used to optimize the fermentation conditions of bacteriocins producing,and preliminary applications of bacteriocins were carried out.The results showed that the antibacterial substance produced by Q13 was a kind of protein with thermal stability and acid-base stability.The response surface experiment model confirmed that the optimal fermentation conditions were 1.4% inoculation amount,initial fermentation pH 8.0,and fermentation temperature 27.5 ℃.Under the conditions,the antibacterial activity of bacteriocin was the highest,reaching 618 AU/mL,which was three times higher than the 200 AU/mL before optimization.In addition,it was found that the addition of bacteriocin produced by Q13 could effectively inhibit post-acidification and delay the increase of acidity in yogurt.This study provides theoretical data support for the industrial application of bacteriocins.