?固定与释放条件对乳酸菌活性的影响?

马红梅 唐超英 皮子瑶 张汉花

摘 要：为优化乳酸菌固定成球的条件，研究以海藻酸钠为载体，通过单因素试验和正交试验考察了海藻酸钠浓度、CaCl2浓度、菌液添加量、滴球速度等对乳酸菌固定成球的影响，并以柠檬酸-柠檬酸钠缓冲液释放固定化小球，考察处理时间与pH值对乳酸菌固定化小球释放效果的影响。结果表明：当海藻酸钠浓度为2.0%、CaCl2浓度为2.5%、菌液添加量为20 mL（菌液添加量与无菌水比值为1∶1）时，乳酸菌固定化小球成球性能最佳;pH值为6.0～6.5柠檬酸-柠檬酸钠缓冲液可在30 min内完全释放固定化小球。研究还测定了德氏乳杆菌（Lactobacillus delbrueckii）、嗜热链球菌（Streptococcus thermophilus）和屎肠球菌（Enterococcus Faecium）3种乳酸菌固定化前后菌体的活性，发现德氏乳杆菌和嗜热链球菌的活性在固定化前后差异不显著，但屎肠球菌的活性在固定化前后的差异较大。

关键词：乳酸菌;固定化;释放;活性

中图分类号：Q937文献标识码：A文章编号：1006-060X（2020）10-0050-03

Abstract： In order to optimize the conditions for solidifying lactic acid bacteria into pellets， this study used sodium alginate as a carrier to investigate the effects of sodium alginate concentration， CaCl2 concentration， the amount of bacteria solution and dropping speed on the solidification of lactic acid bacteria into pellets by single factor test and orthogonal test. Furthermore， the solidified lactic acid bacteria pellets were dissolved in citric acid-sodium citrate buffer solution to detect the effects of treatment time and pH value on the activity release of lactic acid bacteria. The results showed the pellet-forming performance of lactic acid bacteria was the best when the concentration of sodium alginate was 2.0%， the concentration of CaCl2 was 2.5%， and the addition of bacterial solution was 20 mL （the ratio of bacterial solution to aseptic water was 1∶1）. Citric acid-sodium citrate buffer （ pH 6.0 ～ 6.5） can completely dissolve lactic acid bacteria pellets within 30min. The activities of Lactobacillus delbrueckii， Streptococcus thermophilus and Enterococcus faecium were detected before and after solidification. It was found that the activities of Lactobacillus delbrueckii and Streptococcus thermophilus had no significant difference before and after solidification， but the activity of Enterococcus faecium varied obviously before and after solidification.

Key words： lactic acid bacteria; solidification; release; activity

微生物的固定化是指将微生物固定在不溶性的载体上，它不仅可提高单位体积内微生物的生产效率和生产能力，还能延长微生物的生长周期，便于微生物的回收和利用[1]。在固定微生物的过程中，需要选择合适的载体。最常用的载体为包埋载体，它有2种类型，一种是无机载体，另一种是有机载体，前者包括活性炭等，后者包括海藻酸钠、聚乙烯醇等。 由于琼脂和壳聚糖凝胶的硬度差，聚乙烯醇和聚丙烯酰胺凝胶有毒，而海藻酸钠凝胶具良好的综合性能，不会毒害生物细胞，且易降解，更适用于微生物细胞的固定[2-3]。……