Biodegradation of oil-based paint by Bacillus species monocultures isolated from the paint warehouses

Environmental pollution by oil-based paint effluents is of great concern nowadays due to widespread applications of oil-based paints that cause discharge and accidental spillages into the environment. The present study sought to explore the potential use of indigenous bacterial isolates for biodegradation of oil-based paints. The oil-based-paint-biodegrading potential of three Bacillus species isolated from paint-polluted soil samples of different paint warehouses was investigated by the enumeration, screening and taxonomic characterization of oil-based-paint-degrading bacteria using soil enrichment technique in mineral salt medium (MSM). The screened isolates were identified based on morphological, biochemical and 16S rRNA gene sequence homology methods. The bioremediation potential of each bacterial isolate was determined for a period of 14 days at 37 °C and 160 rpm in 250-ml shake flask containing 100 ml MSM plus oil paint (final conc. 300 ppm, w/v). The percent removal of oil-based paint was determined against a standard curve of oil-based paint prepared by using UV–Vis spectrophotometer at 285 nm (λ Max.). Three bacterial isolates, Bacillus subtilis strain NAP1 (GenBank: KJ872852), B. subtilis strain NAP2 (GenBank: KJ872853) and B. subtilis strain NAP4 (GenBank: KJ872855) were isolated and identified. All the isolated strains were characterized as potential oil-based paint degraders. Maximum oil-based paint removal was recorded with strains NAP1 (66.5 %), followed by NAP2 (61.4 %) and NAP4 (55.9 %). The oil-based-paint-polluted environments are a promising source of oil-based-paint-degrading bacteria. The bacterial isolates of present study offer substantial potential for future environmental applications.