This study sought to identify microbial succession during a laboratory scale-bioremediation of oily sludge. During the 12 week bioremediation study, samples were obtained, diluted and treated to a cocktail of spread-plating on nutrient, potatoes dextrose and Bushnell Haas agar were employed for heterotrophic, fungal and hydrocarbon utilizing bacterial and fungal count. Tentatively, biochemical, morphologic and microscopic evaluation was used to identify and select the most frequent bacterial isolates prior to 16S rRNA analysis on genomic extract on a universal primer. Total heterotrophic count for 150 g SMC amended set up increased from 8.3x105cfu/g to 6.6x107cfu/g, hydrocarbon utilizing bacterial count increased from 7.0x103 to 1.1x104cfu/g, total fungal count increased from 1.91x104 to 3.0x104cfu/g at the week 12 of the remediation. During remediation, Pseudomonas sp, Aeromonas sp and Micrococcus sp were most successive in the remediation study while the fungal isolates obtained during the study were Aspergillus versicolor, Aspergillus calidoustus, Candida glabrata, Aspergillus terreus, Candida rugosa, Candida krusel, Microsporium nanum and Candida tropicalis. Molecular evaluation of the dominant microbial isolates revealed the presence of Micrococcus luteus, Octadecabacter temperatus SB1, Bacillus atrophaeus JCM 9070 and Pseudomonas guguanensis with accession numbers KX664101, KT250766.1, KC525245.1 and CP007437.1. The study underscores the efficacy of biostimulation and bioaugmentation using cow dung and spent mushroom compost as eco-friendly approach to the remediation of industrial sludge.

Keywords: Bioremediation, biostimulation, bioaugmentation, microbial succession and molecular evaluation.