Bacterial diversity of heavy crude oil based mud samples near Omani oil wells

Although crude oil is a difficult environment to live in, because of its high toxicity and hydrophobicity, microbial communities in oil contaminated-extremely arid environments, such as deserts were able to persist in such conditions. In order to find microbes that could be used for bioremediation or biotransformation objectives, diversity analyses from soil samples randomly collected from four oil sludge pits of a sour heavy oil field in Sultanate of Oman were conducted. DNA from the soil samples was extracted and V3-V4 region of 16S rRNA gene was amplified and sequenced using Illumina MiSeq sequencer. Operational taxonomic units (OTU) identification and Greengenes based taxonomic assignment were performed. Bacteria of the phylum Firmicutes dominated across the samples ranging from 30.5% to 35.7% of OTU relative abundance, except in sample S43, where Proteobacteria phylum had the highest abundance (55%), followed by the Firmicutes phylum (24.3%). At genus level, Halanaerobium dominated across all the samples followed by Deferribacter and Desulfovermiculus. As expected, sulfate-reducing bacteria (SRB) were abundant. The findings support the use of contaminated soil with heavy crude oil as a source for bacteria, which are able to survive the harsh conditions, and possibly degrade crude oil for the bioremediation and enhanced oil recovery purposes.