PCR-DGGE Analyses Of The Nitrogen-Fixing Bacterial Isolates Originated From Paddy Soil And Screening Of Phenol-Biodegrading Strains

Eight bacterial isolates originated from paddy fields in Fujian were identified and analyzed using16SrDNA-PCR-DGGE.Thirteen N₂-fixing bacterial strains were found to belong to Mesorhizobium sp.,Sphingomonas sp.,Rhizobium sp.,Bradyrhizobium sp.,Klebsiella sp., Burkholderia cepacia,Pseudomonas sp.,Nocardioides and Rhodococcus sp.respectively through sequencing and Blast analysis.Due to the high homology with the related accessions in Genbank.six isolates were selected to grow on four special media and then purified.Their 16SrDNA-PCR products were sequenced and analysed with Blastn.Aligment results showed a comparable taxonomical positions respectively,indicating DGGE is a powerful tools not only for genetic diversity analysis but also for identification for purification of bacterial isolates.Using gene mining procedure,a gene LmPH response for phenol hydroxylase was found in BC2008,which has 98%nucleotide homology and 100%amino acid identity with those of Alcaligenes sp.IS-18.Under The the optimal conditions(pH 6-7 and 25-40℃),BC2008 grew well in the medium in which 600mg/L of phenol was the only source of carbon This result had led to a suggestion that Alcaligenes BC2008 could be one of the candidate strain for bioremediantion in the soil that was contaminated by phone.