Biodegradation of heptadecane in hydrocarbon polluted dune sands using a newly-isolated thermophilic bacterium, Brevibacillus borstelensis TMU30: statistical evaluation and process optimization

Abstract

An enrichment culture was established to isolate a thermophilic hydrocarbon-degrading bacterium from contaminated soil samples from the Tehran Petroleum Refinery. The bacterium was characterized based on 16S rRNA and identified as Brevibacillus borstelensis TMU30. It is registered at NCBI under accession number KF181624.1. The capability of the bacterium for degradation of heptadecane as a representative contaminant in polluted dune sand was evaluated in a slurry bubble column bioreactor. The aeration rate, inoculum content and pulp density were optimized to maximize the degradation of heptadecane using the central composite design of response surface methodology. The results showed that maximum heptadecane reduction reached 48% at an aeration rate of 62 ml min⁻¹, inoculum content of 9.3% (v/v) and pulp density of 63 g l⁻¹ only after 4 days. This study highlights an important potential use of thermophilic degradative bacteria to eliminate contamination in a slurry bioreactor while shortening dramatically the treatment time.