Isolation and characterization of halophilic bacterial consortium from seagrass, Jeddah coast, for the degradation of petroleum hydrocarbons and treatment of hydrocarbons-contaminated boat fuel station wastewater

Abstract

The halophilic consortium enriched from seagrass present in Jeddah coast region, Saudi Arabia, potently degraded different petroleum hydrocarbons such as phenanthrene (PHE), fluorene (FLU), pyrene (PY) and hexadecane (HD) under saline condition (4%). The halophilic consortium recorded complete degradation of PHE and FLU up to 400 ppm. At 600 ppm of PHE and FLU, the consortium revealed 98% and 99% degradation in 10 days. Further increase in concentration to 800 ppm showed slight decline in the percent degradation of PHE (92%) and FLU (95%) by the halophilic consortium. Pyrene was selected as model compound from high molecular weight hydrocarbons recorded 84% and 78% degradation by the consortium at 50 ppm and 100 ppm in 8 and 10 days, respectively. The halophilic consortium revealed complete degradation of HD at 0.5% and 1% concentration under saline condition. The consortium was able to degrade 93% and 71% of HD at 1.5 and 2% concentration in 6 and 8 days under saline condition. Under different high saline conditions such as 8%, 12%, 16% and 20%, the halophilic consortium exhibited PHE (95%, 90%, 85%, 65%) and FLU (97%, 92%, 86%, 66%) degradation in 7, 10, 14 and 18 days. Addition of urea and yeast extract at high salinity enhanced the biomass production and reduced the time taken for degradation. The surface tension of the biosurfactant produced by the consortium was 36 ± 1 mN/m. The treatment of hydrocarbons-contaminated boat fuel station wastewater in continuous stirred tank reactor recorded 92% Chemical Oxygen Demand removal in 40 days. The potential halophilic strains present in the consortium responsible for petroleum hydrocarbon degradation were identified as Marinobacter, Rhodococcus, Ochrobactrum, Martelella, Pseudomonas, Stenotrophomonas and Sedimentibacter.