传统东北酸菜发酵过程中的细菌动态及多样性
Bacterial dynamics and diversity during traditional sauerkraut fermentaiton
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摘要: 为筛选控制酸菜发酵的微生物接种剂,本研究跟踪传统东北酸菜发酵过程,解析其细菌动态和多样性。结果显示,p H在发酵的第8d已下降到4.1,之后稳定在4.0左右;可溶性糖变化主要出现在发酵的前18d,由最初的11.4%干物质(DM)下降到3.9%DM;在发酵的第6d,亚硝酸盐含量最高(31.3mg/kg湿样),到发酵的第30d,下降到4.8mg/kg湿样;发酵结束时体系中的乳酸和乙酸含量分别为6.7g/L和0.6g/L;在体系中检测到了一般细菌Acinetobacter sp.,Pseudomonas fragi,Klebsiella sp.,Citrobacter sp.,Betaproteobacteria sp.和乳酸菌Leuconostoc mesenteroides,Lactobacillus curvatus,Lact.plantarum及Lact.oligofermentans。在发酵第6d,乳酸菌总量占总体的63.8%,异型发酵乳酸菌Leuc.mesenteroides占32.9%;随后乳酸菌比例一直增加,直到发酵的30d,所检测到的细菌全部为乳酸菌;Lact.curvatus在发酵的第6d,达到总体的21.1%,到发酵的第12d,已经达到41.1%,以后一直维持在45%以上;首次检测到Lact.oligofermentans,其在发酵的12d达到增殖高峰,占总比例的21.1%。综上可见,传统东北酸菜发酵过程是以乳酸菌为主导的发酵过程,其发酵过程中的优势乳酸菌为Lact.curvatus,该结果为筛选有效的酸菜发酵菌剂提供了技术参考。Abstract: To provide an effective basis for selecting the inoculant to control sauerkraut fermentation,the bacteria succession and diversity were investigated during sauerkraut fermentation. The p H of the fermentation system decreased from 7.3 at 0d to 4.1 at 8d of fermentation.Subsequently,the p H remained at approximately 4.0.Watersoluble carbohydrate( WSC) content decreased from 11.4% dry matter( DM) to 3.9% DM during the first 18 days of fermentation.The highest nitrite value was 31.3mg / kg fresh matter( FM) at 6d.At 30 d,the nitrite content descreased to 4.8mg / kg FM. The concentrations of lactic acid and acetic acid in fermented juice were 6.7g / L and 0.6g / L,respectively.The bacteria detected in the fermentation system included Acinetobacter sp.,Pseudomonas fragi,Klebsiella sp.,Citrobacter sp.,Betaproteobacteria sp. and lactic acid bacteria( LAB). The LAB contained Leuconostoc mesenteroides,Lactobacillus curvatus,Lactobacillus plantarum and Lactobacillus oligofermentans.At6 d,LAB comprised 63.8% of the bacterial population,with the heterofermentative LAB Leuconostoc mesenteroides comprising 32.9%. Subsequently,the proportion of LAB increased continuously. At 30 d,all microorganisms were LAB. Lact. curvatus comprised 21.1% of the population at 6d,41.1% at 12 d,and greater than 45% at 30 d,dominating the fermentation process. For the first time,Lact. oligofermentans was found to be involved in the fermentation.The highest level of Lact.oligofermentans( 21.1%) was detected at 12 d.Based on the above results,the dominant microorganisms involved in suan- cai fermentation were LAB and Lact. curvatus was the predominant microorganism in the fermentation. This study provides a foundation for screening the inoculant to control the sauerkraut fermentation.