MUTHUSAMY RAJKUMAR, RADHAKRISHNAPILLAI ARAVIND AND PRAMOD KUMAR PANDEY
Abstract
Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene segments was used to profile microbial populations in different biofloc systems cultured with Litopenaeus vannamei. Biofloc tanks, filled with 350 L of water, were fed with sugarcane molasses (BFTS), tapioca flour (BFTT), wheat flour (BFTW) and clean water as a control without biofloc. The extracted microbial community 16S rRNA fragment of the sample was amplified with GC-clamped F968 and R1378 and evaluated in the DGGE and the distinct bands were removed from the gel after the silver staining. The eluted DNA samples were re-amplified with the same set of primers but without GC clamp. Individual DGGE bands were sequenced and subjected to BLAST search on the GenBank nucleotide database National Centre for Biotechnology Information to identify the sequences with higher similarity. From sequence analyses, totally Fifteen isolates were found in biofloc and the bacteria containing the DNA fragments of Band 5, 8 & 9 were not found in the NCBI database so it will be considered to be a newly identified bacterial species. The results we obtained by using DGGE will be the basic information, to further study the microbes reaction involved in the nitrogen reduction in the biofloc system.