Isolation and characterization of aniline degradation slightly halophilic bacterium, Erwinia sp. Strain HSA 6

SummaryThe isolated strain HSA6 is classified as Erwinia amylovora based on 16S rDNA sequence and the morphological and physiological properties. Strain HSA6 is the first reported E. amylovora in pure culture growing with aniline as sole electron donor and carbon source. The suitable pH for strain HSA6 is wide (from 5 to 11). Strain HSA6 is slightly halophilic with growth occurring at 0–10% (v/v) NaCl, and the suitable NaCl concentration for strain HSA6 is from 0% to 6%. The number of bacteria appeared to decrease with an increase in aniline concentration. The number of bacteria appeared to be constant as the wastewater concentration increased from 0% to 20%. However, the number of cells decreased with an increase in wastewater concentration from 30% to 50% and grew very slowly at 50%. The degradation rate of aniline was 100% at 0.5% aniline concentration after 24 h culture. The degradation rate of aniline was found to descend as the concentration of aniline increased from 0.5% to 3% and rose as the culture time increased. Strain HSA6 contains a plasmid with molecular weight higher than 42 kDA. Plasmid curing test and quantitative degradation test showed that strain requires the plasmid for aniline degradation. The gene cluster degrading aniline was determined in the plasmid by PCR amplification.