Identification of the bacterial community responsible for traditional fermentation during sour cassava starch, cachaça and minas cheese production using culture-independent 16s rRNA gene sequence analysis

We used a cultivation-independent, clone library-based 16S rRNA gene sequence analysis to identify bacterial communities present during traditional fermentation in sour cassava starch, cachaça and cheese production in Brazil. Partial 16S rRNA gene clone sequences from sour cassava starch samples collected on day five of the fermentation process indicated that Leuconostoc citreum was the most prevalent species, representing 47.6 percent of the clones. After 27 days of fermentation, clones (GenBank accession numbers GQ999786 and GQ999788) related to unculturable bacteria were the most prevalent, representing 43.8 percent of the clones from the bacterial community analyzed. The clone represented by the sequence GQ999786 was the most prevalent at the end of the fermentation period. The majority of clones obtained from cachaça samples during the fermentation of sugar cane juice were from the genus Lactobacillus. Lactobacillus nagelli was the most prevalent at the beginning of the fermentation process, representing 76.9 percent of the clones analyzed. After 21 days, Lactobacillus harbinensis was the most prevalent species, representing 75 percent of the total clones. At the end of the fermentation period, Lactobacillus buchneri was the most prevalent species, representing 57.9 percent of the total clones. In the Minas cheese samples, Lactococcus lactis was the most prevalent species after seven days of ripening. After 60 days of ripening, Streptococcus salivarius was the most prevalent species. Our data show that these three fermentation processes are conducted by a succession of bacterial species, of which lactic acid bacteria are the most prevalent.

The Use of Molecular Ecological Methods in the Quality Control of Biofertilizers / 微生物学通报

PCR-DGGE(denaturing gradient gel electrophoresis) and clone library analysis combined with culture dependent isolation methods were used to analyze the population composition and its stability over different production batches of one commercial biofertilizer.DGGE fingerprinting showed that samples from the same production batch had 80%~100% similarity coefficient and those from different batches had 80%~88%,an indication that population composition of the biofertilizer was relative stable within the same batch and from batch to batch.Isolation followed with 16S rRNA clone library analysis showed that the microorganisms contained in the products were not in agreement with the product's label.Only Lactobacillus,one of the 6 microorganisms labeled in the products,was detected in the samples.Other bacteria detected with the two methods were Bacillus,Monascus,Brevibacillus,Psudomonas and Penicillium,which were not listed in the product's label.These results showed that molecular ecological methods may provide a new technology for quality control of biofertilizers.

The Comparative Analysis of Microorganism Diversity in Two Kinds of Packaged Chilled Beef on Sale / 微生物学通报

This research is for the purpose of comparative analysis of the microbial flora structure in the chilled beef with no packing and cling film, which under the same terms of sale. It was used the V3 area fragment of 16S rDNA to carry on PCR-DGGE, Meanwhile used the 16S rDNA sequence to analysis the microbial flora structure of the two samples, according to the technology of clone .The research discovered that the flora structure displays a biggish difference; there was 6 OTU in the chilled beef with cling film, mainly was that Lactococcus(28%), Lactobacillus (26%), Carnobacterium(18%) and Brochothrix (10%); but there was 18 OTU in the chilled beef with no packing, mainly was that Lactococcus(28%), Brchothrix(18%), Acinetobacter (11%). The result indicates that cling film played a certain inhibitory action regarding the Staphylococcus as well as the cold pole bacteria and such bacterium. And it can provide a certain theory ba-sis for the meat processing in the department of microorganism’s control.

Bacteria Composition of Organic Matter-decomposing Inoculant Analyzed with 16S rDNA Clone Library / 微生物学通报

Using 16S rDNA clone library method, the bacteria composition of the Organic Matter-decomposing Inoculants A and B were investigated. The results indicated that: Sample A was clustered into 14 taxonomic operational units (OTUs),the dominant communities are Weissella confuse, Bacillus subtilis and Bacillus pumilus, which accounted for 28.6%,30.4% and 23.2%;Sample B was clustered into 43 OTUs,the dominant communities are Lactobacillus buchneri, Lactobacillus farciminis and Lactobacillus acetotolerans, which accounted for 18.03%,18.86% and 13.12%, respectively. The results had much difference from the samples' labels:there were not bacteria in the lable of sample A and only Bacillus pumilus was the same with the lable of sample B.This study showed that 16S rDNA clone library method has nicer application perspectives in analying the bacteria of microbial inoculant and its quality control.

Advances in Studying Water Microbial Ecology by Molecular Biological Techniques / 微生物学通报

Microbes are important composition of ecology system. Nowadays it's very important to study the microbial diversity and community structure, especially in water bioremediation by microbiological resources. Modern molecular biology techniques provide effective methods to study the microbial ecosystem in aqua. Several techniques were summarized, including 16S rDNA clone library, DGGE (Denaturing gradient gel electrophoresis), RFLP (Restriction Fragment Length Polymorphism) and T-RFLP (Terminal Restriction Fragment Length Polymorphism), while their application to analyze water microbial diversity were introduced.