ABSTRACT
7.5). Overall,the research demonstrates the effect of environmental parameters (temperature and carbon source) on AHL profile production by food-derived Pseudomonas. It lays the foundation for further investigation to elucidate the relationship between quorum sensing and food spoilage,and for the development of new food preservative by blocking the quorum sensing of food spoilage bacteria.
ABSTRACT
Three Gram-negative bacteria from commercial fresh fish were identified as Pseudomonas sp.,an important food spoilage bacteria, on the basis of 16S rDNA sequences.N-aeyl-homoserine lactones (AHLs) were the important quorum sensing molecules and regulated the expression of many characteristics in a cell-density-dependent manner in Gram-negative bacteria.The AHL biosensor detection revealed that three isolates produced AHLs molecules and strains FML05-1 and FML05-2 produced two types of AHLs at least and the main signal mole- cules were N-3-oxo-octanoyl-homoserine lactone(N-3-oxo-C_8-AHL).ALso the amount of AHL in FML05-2 reached to the maximum at 12h throughout growth.This was first study of quorum sensing signal molecule AHLs produced by the pseudomonas from food and layed the foun- dation for new strategies of food preservation based on interfering in quorum sensing of spoilage bacteria.
ABSTRACT
The diversity in Tibetan kefir grains and dynamics of the microbial community during the fermentation of Tibetan kefir by PCR-DGGE fingerprinting technique were studied.The results showed that bacterial community of Tibetan kefir grains was more complex than that of yeast.The bacteria communities between different Tibetan kefir grains showed 78%～84% similarity, and yeast 80%～92%.Bands B, E and N of DGGE profiles of the microbial community during fermentation of Tibetan kefir were present throughout the fermentation.Analysis of sequence date showed the majority of the DGGE bands of bacteria community corresponded to LAB, and the most intense band (band E) was completely homology to Lactococcus lactis.