自制酵素中乳酸菌群动态分析及对重金属的吸附积累特性

为了分析自制酵素发酵过程中乳酸菌群动态变化,采用高通量测序技术分析了2种酵素不同发酵时段细菌群落结构及乳酸菌群丰度,并分离纯化了主要乳酸菌,测定代表性菌株对重金属Pb~(2+)和Cd~(2+)的耐受性及吸附积累量。结果表明:2种样品在整个发酵过程中菌群变化比较接近;乳酸杆菌属(Lactocacillus)在4个发酵阶段均占优势(相对丰度25.8%~70.9%),发酵20 d时相对丰度最高;种水平上不同发酵时段菌种变化较大,戊糖乳杆菌相对丰度从发酵10(22.5%~26.5%)~20 d(61.6%~65.7%)明显增加,而大肠杆菌(Escherichia coli)相对丰度急剧下降;39株乳酸菌分离菌株中戊糖乳杆菌和短乳杆菌居多;相较于Cd~(2+),3株代表菌对Pb~(2+)具有较强耐受性,其中戊糖乳杆菌AA11对Pb~(2+)去除率达78.47%。结果显示,酵素中以乳酸菌为优势菌群,发酵初期戊糖乳杆菌明显抑制大肠杆菌,并对去除食品中的Pb~(2+)有较好的应用潜力。

Dynamic analysis of lactic acid bacteria flora in self-made Jiaosu and its absorption kinetics of heavy metals

The aims of this study was to examine the lactic acid bacteria(LAB)microflora during Jiaosu(naturally fermented product from plant)fermentation and to determine the heavy metal tolerance of LAB isolates.A high-throughput sequencing approach based on 16S rRNA gene amplicons was used to analyze the bacterial community structure,including LAB and pathogenic bacteria,at different fermentation periods in two tailor-made fermenters.The predominant LAB was isolated and their tolerance and absorption to heavy metals such as Pb 2+and Cd 2+,was determined.Results showed that the changes in the bacterial community were relatively similar in both samples throughout the fermentation process;Lactobacillus was the predominant LAB at all four fermentation stages(relative abundance,25.8%-70.9%),with the highest relative abundance at day 20 of fermentation.As to the species,the diversity varied greatly during different fermentation periods.The relative abundance of Lactobacillus pentosus increased from day 10(22.5%-26.5%)to day 20(61.6%-65.7%),while the relative abundance of Escherichia coli decreased sharply.A total of 39 LAB strains were isolated,of which L.pentosus and L.brevis were the predominant strains.All three representative strains demonstrated stronger tolerance to Pb 2+than to Cd 2+,with a Pb 2+removal rate of 78.47%.in L.pentosus strain AA11.Therefore,Lactobacillus was the dominant bacterial group present in Jiaosu,and L.pentosus not only markedly inhibited E.coli during the early stage of fermentation,but also indicated application potential for removal of Pb 2+in food.