The complete mineralization of crude oil into carbon dioxide, water, inorganic compounds and cellular constituents can be carried out as part of a bioremediation strategy. This involves the transformation of complex organic contaminants into simpler organic compounds by microbial communities, mainly bacteria. A crude oil sample and an oil sludge sample were obtained from Saudi ARAMCO Oil Company and investigated to identify the microbial communities present using PCR-based culture-independent techniques. In total, analysis of 177 clones yielded 30 distinct bacterial sequences. Clone library analysis of the oil sample was found to contain Bacillus, Clostridia and Gammaproteobacteria species while the sludge sample revealed the presence of members of the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Clostridia, Spingobacteria and Flavobacteria. The dominant bacterial class identified in oil and sludge samples was found to be Bacilli and Flavobacteria, respectively. Phylogenetic analysis showed that the dominant bacterium in the oil sample has the closest sequence identity to Enterococcus aquimarinus and the dominant bacterium in the sludge sample is most closely related to the uncultured Bacteroidetes bacterium designated AH.KK.

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Purpose Contaminated sites from man-made activities such as old-fashioned tanneries are inhabited by virulent microorganisms that exhibit more resistance against extreme and toxic environmental conditions. We investigated the effect of different Gamma radiation doses on microbial community composition in the sediment of an old-fashioned tannery. Methods Seven samples collected from the contaminated sites received different gamma radiation doses (I = 0.0, II = 5, III = 10, VI = 15, V = 20, VI = 25, and VII = 30 kGy) as an acute exposure. The shift in microbial community structure was assessed using the high throughput 454 pyrosequencing. Variations in diversity, richness, and the shift in operational taxonomic units (OTUs) were investigated using statistical analysis. Result Our results showed that the control sample (I) had the highest diversity, richness, and OTUs when compared with the irradiated samples. Species of Halocella, Parasporobacterium, and Anaerosporobacter had the highest relative abundance at the highest radiation dose of 30 kGy. Members of the Firmicutes also increased by 20% at the highest radiation dose when compared with the control sample (0.0 kGy). Representatives of Synergistetes decreased by 25% while Bacteroidetes retained a steady distribution across the range of gamma radiation intensities. Conclusion This study provides information about potential “radioresistant” and/or “radiotolerant” microbial species that are adapted to elevated level of chemical toxicity such as Cr and Sr in tannery. These species can be of a high biotechnological and environmental importance.

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This environmental engineering study was conducted to investigate and correlate the fundamental mineralogical compositions of phosphate rock in the Hazm Al-Jalamid area of Saudi Arabia at different layers originating from an open-pit mine. Microbial communities within these layers and the associated correlations between the mineralogical compositions at different geological and textural profiles were investigated. Three representative phosphaterock layers, upper, middle, and lower, were investigated. The dominated crystal structure of the upper layer was calcite, while dolomite, and quartz were in middle and lower layers, respectively. In contrast, Phosphate concentrations reached levels around 3.12%, 7.66%, and 3.92% of the overall content of representative samples in the upper, middle, and lower layers, respectively. The same trends were observed for both fluorapatite and phosphorus pentoxide. The microbiome of the phosphate-ore samples was evaluated. The phylum Proteobacteria dominated the upper and middle layers, while the well-known phosphate-solubilizing bacteria species Pseudomonas putida were present at 46% and 50% in both the upper and middle layers, respectively. In contrast, the actinobacterium Saccharopolyspora flava dominated the lower layer. Increasing selective phyla and species that associated with the elevated content of phosphorus from one layer to another within mine enhanced the understating of these microorganisms as extremophiles.