Lactobacillus casei rhamnosus的抑菌作用及最佳抑菌作用发酵条件优化

Antimicrobial Activity of Lactobacillus casei rhamnosus and Optimization of Its Fermentation Conditions for Optimal Inhibitory Effects

为了研究Lactobacillus casei subsp.rhamnosus LCR 719产生抑菌作用的原因,应用牛津杯琼脂扩散法测定LCR719在MRS上清液的抑菌作用。LCR719在MRS中发酵时,醋酸先升后降,乳酸不断增加,乳酸和醋酸的摩尔浓度比从6h的0.28增加到60h的2.63。最佳抑菌作用的培养条件为:初始pH6.5,吐温8010.0ml/L,葡萄糖20.0g/L,培养温度37℃,培养时间为42h。该条件下的上清液对S.aureus抑菌圈直径达42mm,对枯草芽孢杆菌和肠炎沙门氏菌也有很好的抑菌效果,可降低E.coli及EHEC O157菌群密度,对酵母无抑制作用。结果表明,LCR719是一种潜在的可用于生物防腐的保护性菌种。

In order to investigate the cause of antimicrobial activity produced by Lactobacillus casei subsp, rhamnosus LCR 719, the inhibitory activity of LCR 719 culture supernatants in MRS was measured by means of the agar well diffusion system. The concentration of acetic acid increases and then decreases, but the concentration of lactic acid continues to increase during fermentation of LCR 719 in MRS. During the whole fermentation, the molecular ratio between lactic acid and acetic acid increases from 0.28 at 6 h to 2.63 at 60 h. The inhibitory activity is the highest at 37 ℃ for 42 h under initial pH 6.50 anaerobicly in MRS, containing 20.0 g/L glucose, 10 ml/L Tween 80. The inhibitory diameter is 42 mm under these optimal conditions against S. aureus. Also the culture supematants show good inhibitory activity against B. subtilis, S. typhimurium and have weak inhibitory activity against E. coli and EHEC O157. No inhibitory activity of culture supernatants is observed against yeast. These results show that LCR 719 can be used as a potential protective strain in bio-protective.