Microbial communities in the larval midgut of laboratory and field populations of cotton bollworm (Helicoverpa armigera).

We compared the bacterial communities in the larval midgut of field and laboratory populations of a polyphagous pest, the cotton bollworm (Helicoverpa armigera), using denaturing gradient gel electrophoresis (DGGE) of amplified 16S rDNA sequences and 16S library sequence analysis. DGGE profiles and 16S rDNA library sequence analysis indicated similar patterns of midgut microbial community structure and diversity: specific bacterial types existed in both populations, and a more diverse microbial community was observed in caterpillars obtained from the field. The laboratory population harbored a rather simple gut microflora consisting mostly of phylotypes belonging to Enterococcus (84%). For the field population, phylotypes belonging to Enterococcus (28%) and Lactococcus (11%), as well as Flavobacterium (10%), Acinetobacter (19%), and Stenotrophomonas (10%) were dominant members. These results provided the first comprehensive description of the microbial diversity of the midgut of the important pest cotton bollworm and suggested that the environment and food supply might influence the diversity of the gut bacterial community.

[Analysis of Bifidobacteria spp. composition in human gut via temperature gradient gel electrophoresis (TGGE)].

Temperature Gradient Gel Electrophoresis (TGGE) method combined with 16S rDNA clone library profiling was used to analyze Bifidobacteria spp. composition in human gut in this study. Bifidobacteria group-specific TGGE patterns of 10 healthy human individuals showed that the Bifidobacteria population in humans was host-specific. The genomic diversity and species composition of Bifidobacteria in different individual was dissimilar. Through sequencing and TGGE comigration analysis of the Bifidobacteria group-specific amplicons for one healthy boy, it was revealed that the TGGE bands of this individual represented species Bifidobacterium bifidum, B. infantis, B. longum, B. adolescentis, B. pseudocatenulatum and one potentially new species, respectively. B. pseudocatenulatum was the most common species of tested samples. While as control, only two species- B. pseudocatenulatum and B. longum were isolated using traditional culture method. Bifidobacteria group-specific PCR based TGGE method combined with 16S rDNA clone library profiling is a sensitive and effective approach to resolve the population structure of Bifidobacteria in microflora of human intestinal tract.