Enhanced Biodegradation of Naphthalene by Newly Isolated Pseudomonas Putida Strain KD4 from Municipal Sludge

Polycyclic aromatic hydrocarbons (PAHs) are a group of top priority environmental pollutant. In this report, Naphthalene biodegradation property of Pseudomonas putida strain KD4 was studied. The strain KD4 was isolated from municipal sludge through enrichment isolation. The strain designated KD4 was found to efficiently degrade 96.98 % of 500mgL-1 naphthalene within 10 days in carbon deficient minimal medium (CSM), t1/2 and degradation rate constant (k) was estimated to be 3.51 and 0.219 days respectively. The strain was identified by biochemical test and 16SrRNA gene sequence analysis. Substrate inhibition kinetic model of naphthalene 1,2-dioxygenase (nahAc) with different concentration of naphthalene (150mgL-1 – 2500mgL-1) had been tested with Pseudomonas putida strain KD4. The observed Km and Ki were estimated to be 138.6 and 1400mgL-1 respectively. The first order kinetic parameters in soil by strain KD4 had shown efficient biodegradation potency with a higher concentration of naphthalene (2500mg kg-1 soil), t1/2 = 12.57 days-1. However, biodegradation by un-inoculated control soil was found slow (t1/2 = 157.67 days-1) than Pseudomonas putida strain KD4. This study enlightened the ecological expansion of gene responsible for PAH degradation. The strain KD4 could be good bio-resource for in-situ or ex-situ biodegradation of polycyclic aromatic hydrocarbon

Keywords:

Polycyclic aromatic hydrocarbons , Naphthalene biodegradation , Pseudomonas putida KD4 , Secondary carbon supplement