The Research Of Spatial And Temporal Distribution Of Lactic Acid Bacteria In Naturally Fermented Cabbage In Northeastern Part

Fermented cabbage is a kind of popular vegetable pickling product in Northeastern part of China.Because of special geological position,climatic conditions and national culture tradition in three provinces in Northeast China,naturally fermented cabbage has rich sour and mellow taste,and the taste and fragrance are superior to fermented cabbage in other regions.The primary cause for the feature is the richness of microflora.The fermentation process mainly depends on the activity of beneficial microorganism and the accurate control of production conditions.Therefore,fermented cabbage draws the attention of nutritionists,microbiologists and micro-ecologists with the unique nutrition value and rich lactic acid bacteria resources.the research on microbiological resources in the traditional and natural fermentation fermented cabbage in Northeast China becomes a hot spot in the academic circle.The test used 454 FLX+ platform for sequencing,in order to reveal the composition of dominant bacterial community in the traditional and natural fermented cabbage in Northeast China,and the changes of microflora in fermented cabbage in different latitudes,and provide basis for ascertain the evolution laws of bacterial diversity.At the same time,use PCR-DGGE molecular biological technique and 16S rDNA Homology analysis and bioinformatics method to comprehensively and systematically research the lactic acid bacteria in traditional and natural fermented cabbage,discover the actual status of lactic acid bacteria structure in different periods,excavate rich microbial resources and determine the dominant bacterial community in different fermentation stages.It is designed to provide basis for the further research and development of useful lactic acid bacteria in natural fermented cabbage.Collect the naturally fermented cabbage juice in Northeastern part of China as the samples.The fermentation liquid in 3d-60d are taken as the research object to detect the viable count,lactic acid bacteria count and various physiology and biochemistry indicators.Use PCR-DGGE molecular biological technique and 16S rDNA Homology analysis and bioinformatics method to comprehensively and systematically research the lactic acid bacteria in naturally fermented cabbage.The results show that at the early phase of fermentation,the amount of bacteria increases.As the process of fermentation,the fermentation environment changes to anaerobic conditions.The mass propagation and constant acid production of lactic acid bacteria restrain the growth of other bacteria and cause the decrease of bacteria count.In the later phase,the number of bacteria and lactic acid bacteria decreases gradually.The acid content in fermented cabbage gradually increases as the prolonging of fermentation time,causing pH value decrease and tend to stable.The content of soluble protein in fermented cabbage will constantly decrease and tend to be stable as time goes by,and the content of reducing sugar and amino acid nitrogen slightly increases and then decreases,and reaches a stable state in the 35th day.The content of nitrite firstly increases and then decreases and finally change in certain scope.In the 20d,the content of nitrite is less than 20mg/kg,which conforms to the national standard.The results show that in the 40d,the bacteria diversity index and richness index will reach a maximum,namely 3.457 and 6.077,indicating the diversity of bacteria population is highest at the time.The similarity of measured sequence and lactic acid bacteria in 16S rDNA V3 sequence may reach 99%-100%.At the same time,there is rich lactic acid bacteria in the fermentation process,and the main dominant bacteria community is Lactobacillus.In the early phase,the dominant bacteria community is Lactooccus lactis and L.Pentosus;in the later phase,the dominant bacteria community is L.plantarum.In the natural fermentation of Chinese sauerkraut,it is unable to separate L.Coryniformis,L.Salivarius,L.Pentosus,L.Iwatensis with the traditional method and molecular economy method.These results intuitively reveal the diversity of lactic acid bacteria.It is consistent with the dynamic changes of total number of bacteria and lactic acid bacteria obtained with the culture-dependent method in chapter ?.According to the north-south route,climate features and geological positions in three provinces in northeast China,16 places are selected Heihe(HH),Hulun Buir(HLBE),QIQIHAR(QQHE),Daqing(DQ),Kiamusz(JMS),White City(BC),Songyuan(SY),Mudanjiang River(MDJ),Changchun(CC),Gongzhuling(GZHL),Yanbian(YB),Fuxin(FX),Anshan(AS),Chaoyang(CY),Danton(DD),Dalian(DL).454 FLX+ platform is used to sequence.The analysis of Alpha diversity shows that Daqing sample and Songyuan sample have high richness in bacteria population.Divide the 15 samples of the 16 samples(except for the Hulun Buir sample)into three groups according to their provinces(Group 1:Heilongjiang Province;Group2:Jilin Province;Group3:Liaoning Province).From clustering analysis,it is shown that there are few similarities among the three provinces samples in the structure and constitution of the microbial.It could be explained that the dominant bacteria managing the ferment process is different with each other in the samples of different fermented regions.While through the clustering analysis at the genus standard,9 samples have similarities in the constitution of microflora,such as MDJ,QQHE,JMS,BC,GZL,DD,FX,DL,AS samples.The dominant bacteria of the aboved samples in the complished fermentation period is Pseudomonas.In addition,through the clustering analysis at the genus standard,the dominant bacteria in the complished fermentation period is Lactobacillus in DQ,HH,YJ,CY samples.It could be stated that there are a few similarities of the structure of the lactic acid bacteria in every samples in areas.KEGG statistical results show that Groupl>Group2>Group3 in the numbers of genes exerting the function of cell moving,cell information processing to the environment,genetic information transferring,human diseases,metabolism and biological function.It could be explained that there is certain quantity of cold-resistant microorganisms in high latitude area.