培养基不同营养水平对一株植物乳杆菌发酵生长及保存的影响

摘要

[Objective] The purpose of this study is to investigate the effects of nutrient level on the growth and viability of a strain of Lactobacillus plantarum,and to provide theoretical reference for the production and preservation of L.plantarum.[Method] The growth curve of L.plantarum under liquid shake culture was measured with spectrophotometer in order to determine the end of logarithmic phase,the meddle and the late of stationary phase under different nutrient levels.The corresponding residual sugar content was determined by the sulfuric acid-anthrone method,and viable count in the process of saving was also measured.[Result] In the period of 30 hr and under liquid shake culture condition,the growth curve of the bacterial was observed with a lag phase,logarithmic phase and stable phase,but decline phase was not found in all nutritional conditions.The highest level of viable count occurred under the nutrient level of oligotrophic,which was 1012 cfu/mL.During standing preservation after liquid shake culture,viable count continued to decline in the three fermentation broths,which remained above 1010 cfu/mL at 30th day.But after that,viable count in the oligotrophic and normal medium decreased rapidly,while it was still at a high level and remained above 1010 cfu/mL even after being saved for 60 days in the eutrophic medium.[Conclusion] The results showed that the growth curves of L.plantarum were similar under the three nutrient levels.The highest level of viable count occurred under the oligotrophic level,while the eutrophic level was more favorable for the preservation of viable bacteria.Therefore,the oligotrophic level can be used for fermentation to increase viable count,and nutrition can be added after fermentation to facilitate the preservation of viable bacteria.%[目的]研究培养基营养水平对一株植物乳杆菌生长以及对菌液保存过程中活菌数的影响,为植物乳杆菌的发酵生产和保存提供理论参考.[方法]用分光光度仪测定液体振荡培养条件下,植物乳杆菌的生长曲线,并确定在培养基不同营养水平下植物乳杆菌的对数生长末期、平稳期中期、平稳期末期,用硫酸-蒽酮法测定相应的残糖含量和活菌数,并测定液体振荡培养后静置保存过程中的活菌数.[结果]在30 h的液体振荡培养中,植物乳杆菌在富营养、正常和寡营养三种营养水平条件下,该菌的生长曲线都经历了迟缓期、对数期、稳定期,未见到衰亡期.寡营养水平下,植物乳杆菌最大活菌数达到最高水平,达到1012 cfu/mL以上.在静置过程中,三种发酵培养液中活菌数持续下降.在静置30 d时,三种水平下的活菌数都保持在1010 cfu/mL以上.在此之后,寡营养和正常水平培养基中活菌数快速下降,而富营养培养基中活菌数仍处于较高水平,直至静置60 d后仍保持在101o cfu/mL以上.[结论]三种营养水平下,植物乳杆菌生长曲线类似,在寡营养水平下,发酵液中的活菌数最高,富营养水平则更有利于发酵液中活菌的长时间保存.在进行液体深层发酵生产时,可以采用寡营养水平,以利于提高活菌数;发酵完成后可补充营养利于活菌的保存.