Bioremediation of petroleum hydrocarbons by alkali-salt-tolerant microbial consortia and their community profiles

BACKGROUND Petroleum hydrocarbon pollution has become a global concern, and seeking an appropriate strategy for treatment of petroleum hydrocarbons is necessary, especially under saline-alkaline conditions. In this study, microbial consortia capable of utilizing low-molecular-weight aliphatic petroleum hydrocarbons (n-decane, n-dodecane and n-hexadecane) as the sole carbon source were enriched from crude-oil-contaminated soils, and their community profiles were evaluated using high-throughput sequencing of 16S rRNA gene. RESULTS The microbial consortia were able to degrade 5-100 mL L-1 n-decane, n-dodecane and n-hexadecane by approximately 37.6-97.3%, 52.1-93.2% and 72.4-96.5%, respectively. The consortia also exhibited alkali-tolerant and moderately salt-resistant capability, which enabled them to retain high degradation efficiencies of hydrocarbons within a pH range of 7.0-11.0 and salinities of 5-20 g L-1 NaCl. High-throughput sequencing analysis demonstrated that Pseudomonas, Stenotrophomonas, Achromobacter, Mesorhizobium and Brucella were the core genera (average > 1%) in the consortia, which were more enriched under alkaline condition (pH 11.0). PICRUSt (phylogenetic investigation of communities by reconstruction of unobserved states) prediction revealed a rich set of metabolic functions involved in degradation of hydrocarbons and aromatics, and the critical functional gene, alkane 1-monooxygenase, was more abundant in the microbial consortia under alkaline condition. CONCLUSIONS The results suggested that these alkali-salt-tolerant microbial consortia could be a promising candidate for bioremediation of petroleum hydrocarbons. (c) 2020 Society of Chemical Industry (SCI)

Automated summary

This study enriched microbial consortia capable of degrading petroleum hydrocarbons under saline-alkaline conditions from crude-oil-contaminated soils. The consortia exhibited high degradation efficiencies of hydrocarbons within a pH range of 7.0-11.0 and salinities of 5-20 g L-1 NaCl, making them a promising candidate for bioremediation of petroleum hydrocarbons. High-throughput sequencing analysis revealed core genera enriched under alkaline conditions, and PICRUSt prediction showed a rich set of metabolic functions involved in hydrocarbon degradation.