Degradation of 4-nitrophenol in presence of heavy metals by a halotolerant Bacillus sp. strain BUPNP2, having plant growth promoting traits

Abstract

A halotolerant 4-nitrophenol (4-NP) degrading bacterial strain designated as BUPNP2 was isolated by enrichment culture technique from the rhizospheric soil of rice plants (Oryzae sativa) of an agricultural field located in Memari within Burdwan district of West Bengal, India. It was identified as a member of genus Bacillus by 16S rRNA gene based molecular phylogenetic approach. The strain was capable of degrading 4-NP (0.3 mM) as sole source of carbon through 4-nitrocatechol (4-NC) as intermediate. The strain also tolerated up to 12 % NaCl (w/v). The degradation capacity of 4-NP was enhanced by this strain up to 0.6 mM in presence of cellulose, starch and glucose. The strain could tolerate several heavy metals such as cadmium, chromium, iron, lead, nickel and zinc and it was degrading 4-NP in presence of each of these heavy metals. Glucose, starch and cellulose also enhanced 4-NP degradation capacity of the strain even in presence of each of these heavy metals. The strain BUPNP2 also possessed important plant growth promoting (PGP) traits such as production of siderophore, indole acetic acid (IAA), ammonia; phosphate solubilization along with protease, lipase, amylase and cellulase activities. Thus, the halotolerant strain BUPNP2 has biotechnological potential and can be utilized for bioremediation of heavy metal infested 4-NP contaminated agricultural soil (common in industrial belt) where it might also help in plant growth promotion.