Study On Bacterial Community Structures And Metatranscriptomics From Traditional Fermented Food,and Bacterial Spoilers In Yunnan

Fermented foods play a substantial role in human diet, which makes it important to investigate the microbial community structures and metabolisms, so as to exploit the resource of microorganism, improve and control the quality of fermented food, and upgrade the function of health care. In addition, the succession law of bacterial communities of different levels of corruption in food, it is very meaningful to promoting the food quality and enhancing its physiological function. In this research, combining molecular biology method with high-throughput sequencing analysis of bacterial community structure in fermented food, and component analysis of the transcriptome of fermented food, in addition, analysising of bacteria community structure of spoilage food. The main research contents and results are as follows:1. Bacterial community structure of traditional fermented foods in YunnanThe samples were collected from different prefectures and counties of Yunnan province, including Douchi, fermented bamboo shoot, sourdough, yond bap, fermented rice noodle, traditional sour meat. Extracted DNA of all samples, and then carried out PCR amplification with barcoded primer and pyrosequencing, extracted the RNA of Douchi used to analysing for metatranscriptomics. The experimental results show that the different kinds and different fermented foods in the bacterial community structure were different. 1) For the Douchi samples, the bacterial community structure in Dehong and Baoshan were similar, Bacillus?Staphylococcus and Psychrobacter were dominant bacteria. Weissella had a higher proportion of 53% in the Douchi of Lijiang, and also detected the higher proportion of Enteric bacteria cluster(9%), Pediococcus(6%) and Staphylococcus(6%). The Douchi samples of Dali and Qujing had no significant dominant bacteria, and remarkably, Staphylococcus was the dominant bacteria in Douchi of Qujing, the abundance achieved to 31%.2) Different substrate fermented foods have different bacterial composition, fermented bamboo shoot exhibits high similarity(except for JH5), Lactobacillus was the main dominant bacteria, more than 94%, but in the JH5, Anoxybacillus(57%) was the dominant bacteria, followed by Bacillus(22%).In sourdough samples LM17 and LM2, more than 60% of the sequences belonged to Lactobacillus, but it was the second dominant bacteria in LM5, Staphylococcus(41%) was the main dominant bacteria in LM5. In yond bap, Pseudomonas and Lactococcus were common in all of the samples. In SM1 and SM2 of traditional sour meat., Psychrobacter(63%,40%) was the dominant bacteria, but Weissella(41%) and Lactobacillus(27%) were main dominant bacteria in SM3.2. The study of metatranscriptomicsThrough metatranscriptomics analysing fermented Douchi of Dehong, constructing of the main metabolic pathway of microbial which working in the process of fermenting, as a results, carbohydrate metabolism (glucose metabolism) activity was higher, protein and amino acid metabolism activity was also very high, in addition, fermented Douchi also had vitamin metabolism related genes. This study was advantageous to understanding of the production process of a variety of bacterial succession and metabolic mechanisms, and provided favorable information to enhance food quality and nutritional value.3. Study on the bacterial spoilers in the process of minced pork, pasteurized milk's spoilageThe samples of minced pork and pasteurized milk got spoiled in laboratory at room temperature (20?), collected samples every 8 and 12 hours respectively, exploring the succession features of bacteria community in spoilaged food. With the development of food spoilage, the diversity of bacteria in the samples decreased, and picked up at the end of spoilae. Microbial community structure was very different in varying degrees spoilaged samples. In spoilaged minced pork, Staphylococcus? Enteric_Bacteria_cluster and Kurthia were the dominant bacteria, and in spoilaged pasteurized milk, the dominant bacteria were Novosphingobium and Acinetobacter. Exploring the succession features of bacteria community in spoilaged food, and evaluating the sensory indexes, to make clear that the special bacteria and critical period, and provid useful information for the source of spoilage bacteria.