Abundance of sulphur-oxidizing bacteria in coastal aquaculture using soxB gene analyses

摘要

Molecular techniques based on sequencing of metagenomic clone libraries provide an insight into the diversity of microbial populations. Using nucleic acid-based methods, the diversity of soxB genes was examined to detect and characterize sulphur-oxidizing bacteria in Indian coastal aquaculture environments. Gene-specific degenerate primers were used to amplify various fragments (710, 753, 483–503, 280 and 239 bp) of soxB genes. Metagenomic clone libraries were constructed for 753, 483–503 and 239 bp fragments of soxB genes. The abundance of soxB revealed the presence of sulphur-oxidizing organisms. Amino acids in parts of the soxB-encoded proteins were aligned to known conserved amino acid residues. The level of conservation ranged from 23% to 30%. A phylogenetic tree constructed from aligned amino acid sequences of SoxB revealed different clusters associated with the branches of phototrophic - and -proteobacteria. In general, soxB is widespread among the various phylogenetic groups, although this does not necessarily mean that the organism can use sulphur compounds. Our results suggest that the chemolithoautotrophy based on sulphur oxidation in coastal aquaculture is primarily sustained by the presence of sulphur oxidizers, which involve the soxB gene. This study aids identification of the phylogenetic characteristics related to sulphur bioremediation in poorly characterized coastal aquaculture environments.