泡菜母水中细菌群落的动态变化规律及结构解析

Dynamic Changes and Structural Analysis of the Bacterial Community in Paocai Brine

细菌是泡菜发酵过程中的主要微生物类群,本研究采用扩增子序列变体(Amplicon sequence variants,ASV)高通量测序技术,持续跟踪并解析了泡菜制作完成后30 d内,25℃恒温、密闭保存条件下母水中的细菌群落结构及其动态变化规律。结果显示,30 d内共鉴别出10门、205属细菌,其中,优势属(占总体系含量>1%)12个,占比94.7%~97.8%;次优势属(0.1%<占总体系含量<1%)13个,占比2.1%~3.3%;稀有属(占总体系含量<0.1%)180个,占比0.08%~2.7%。在保存起始的1~7 d内,群落相对稳定(A阶段);8~20 d次优势属和稀有属细菌发生持续变化(B阶段),其中第8 d稀有属与次优势属发生非常剧烈的变化;22~30 d内优势属、次优势属、稀有属细菌都发生明显变化(C阶段)。Chao1、Ace指数在1~30 d内呈上升趋势,Shannon、Simpson指数在22~30 d(C阶段)达到高峰。由此,A和B、B和C阶段的群落相似,但A与C的群落不同,同时三个阶段内母水pH也发生了相对应的变化。在25℃、密闭储存泡菜母水中稀有属和次优势属的细菌动态变化使母水细菌群落结构在30 d内发生了持续改变并出现累积效应,母水的pH与细菌群落相互影响;在25℃、密闭条件下泡菜母水的最佳保存时长为一周。

Bacteria are the key group of micro-organisms during the fermentation of Paocai.This study applied the highthroughput sequencing technology to trace the dynamics of Paocai brine bacterial community structures at constant temperature(25℃)under airtight microcosm condition.The results showed that there were 10 phyla and 205 genera had been detected within 30 days after the experiment setup.Among them,there were 12 dominant genera which accounted for 94.7%~97.8% of the total OTUs.The sub-dominant were 13 genera and accounted for 2.1%~3.3%.The rare genera were 180 genera and accounted for 0.08%~2.7%.During the 1~7 days after the experiment setup,the community was relatively stable(phase A).From the 8~20 days,the sub-dominant and rare genera were continuously changing(phase B),and on the 8th day,the communities of sub-dominant and rare genera were acutely fluctuated.From 22~30 days,all of the genera changed obviously(phase C).Meanwhile,the Chao1,Ace indices were increasing during 1~30 days,in addition,the Shannon and Simpson indices reached the thresholds during phase C.Therefore,phase A and B,phase B and C had the similar communities,but not the phase A and C,while the pH during the three phases changed correspondingly.The results also showed that at 25℃,the dynamics of sub-dominant and rare genera were the key factor which caused the dynamic of the bacterial communities in Paocai brine during the 30 days experiment.In addition,the accumulated effect had been detected,the pH and the bacterial communities havd mutual influences.The optimal preservation time for the Paocai brine was one week under airtight condition at 25℃.The functional effects of rare genera from Paocai brine need pay more attentions on.