Study On Microbial Communities In Sichuan Pickles And Isolation,Selection Of Preferable Lactic Acid Bacteria

Aiming at solving the problems such as the long period of fermentation, quality instability, high content of Nitrite and implementing DVS(Direct Vat Set) efficiently we could keep it’s own flavor when the quality problems caused by traditional mode of production are worked out. The presentation focused mainly on the analysis of Sichuan pickle bacterium crowd to study the microbial diversity and provide excellent strains for pickle fermentation through isolating and selecting high performance lactic acid bacteria. Also to improve it’s process and to provide theory evidences for manual control fermentation, we studied distribution and accumulative dynamic variation of microbe groups in greengrocery salting process through PCR-DGGE.1. The results by observing the physico-chemical properties and count the isolated microbe groups originated from traditional Sichuan pickle and such enterprise’s showed that the aerobic bacterial count from enterprise’s salt water sample is102～105cfu/mL,10～105cfu/mL for lactic acid bacteria,10-105cfu/mL for yeast; lactobacillus took advantage in traditional fermented pickle samples for it has high content even reaching18cfu/mL. yeast and a spot of vinegar organism is also existed. Most samples are polluted by pseudomonas and bacillus at a certain extent, the other small groups of samples are caused by mould. The salt content have crucial impact on micro-organism and also the quantity was closely related to pH&acidity of the samples.2.5strains which had higher nitrite degradation ability were selected from170strains of suspected lactic acid bacteria by inspecting it’s calcium dissolving ability and observing color reaction of N-Naphthylethylenediamine Dihydrochloride. The result determined by atomic absorption spectrometer showed that they could even degrade more than99%nitrite sodium. By controlling the pH of MRS liquid medium(pH>5.0), strain N2was approved to degrade nitrite most efficiently. Strain N2was identified as Lactobacillus plantarum by morphologic observation, biochemical identification and sequence analyse of16S rDNA.The pH and nitrite concentration were measured on the spontaneous and inoculation fermented(with strain N2as fermentation agent)cabbages. The results indicated that nitrite in sauerkraut can be degradated well by strain N2. 3. We take PCR-DGGE to analysis the diversity and dynamic change of germ and fungus during the process of greengrocery fermentation. It turned out to be that it contained Halomonas sp, Marinilactibacillus psychrotolerans, Lactobacillus kimchii, Chromohalobacter sp., Uncultured bacterium and Uncultured Halomonas sp. during the salting process. And Saccharomyces cerevisiae, Rhodotorula mucilaginosa, Aspergillus niger, Debaryomyces hansenii, Candida sp., Uncultured fungus as the fungus also play a role.It should be pointed out that the quantity of Halomonas sp., Marinilactibacillus psychrotolerans, Saccharomyces cerevisiae, Rhodotorula mucilaginosa changed little and are existed in the whole process.This presentation studied the microflora and dynamic changing regularity of Sichuan pickle systematically to select an excellent strain of lactic acid bacteria. It not only gives theory evidences for a better method of DVS but also provides excellent strains. It has a certain theoretical significance and the practical value.