Degradation of Nickel Protoporphyrin Disodium and Vanadium Oxide Octaethylporphyrin by Philippine Microbial Consortia

Abstract

ABSTRACTMicrobial degradation of nickel and vanadium porphyrins is an economically important and environment-friendly alternative to physicochemical processes currently used in refining crude oil. This study involved the screening of 23 microbial isolates from crude oil–contaminated soils in the Philippines. Two microbial consortia concocted out of four bacteria and three fungi from Guimaras Island Province degraded significantly higher amounts of nickel protoporphyrin disodium (NiPPDS) and vanadium oxide octaethyl porphyrin (VOOEP) than their corresponding member components. Culture parameters were varied and then optimized by the Taguchi method in assays in minimal salt medium supplemented with metalloporphyrins. Optimal degradations by consortium GI-2,3 (Bacterium megaterium–Enterobacter cloacae) were 79 ± 1.5% for NiPPDS at 40 mg/L, pH 7, 30°C and 89 ± 1.7% for VOOEP at 20 mg/L, pH 6, 30°C. For consortium As-2,P (Aspergillus unguis–Penicillium griseofulvum), optimal degradations w`ere 71 ± 1.3% for NiPPDS at 20 mg/L, pH 5.5, 30°C and 90 ± 2.8% for VOOEP at 20 mg/L, pH 4.5, 40°C.