title: Diversity, distribution and hydrocarbon biodegradation capabilities of microbial communities in oil-contaminated cyanobacterial mats from a constructed wetland.
abstract: Various types of cyanobacterial mats were predominant in a wetland, constructed for the remediation of oil-polluted residual waters from an oil field in the desert of the south-eastern Arabian Peninsula, although such mats were rarely found in other wetland systems. There is scarce information on the bacterial diversity, spatial distribution and oil-biodegradation capabilities of freshwater wetland oil-polluted mats. Microbial community analysis by Automated Ribosomal Spacer Analysis (ARISA) showed that the different mats hosted distinct microbial communities. Average numbers of operational taxonomic units (OTUsARISA) were relatively lower in the mats with higher oil levels and the number of shared OTUsARISA between the mats was <60% in most cases. Multivariate analyses of fingerprinting profiles indicated that the bacterial communities in the wetland mats were influenced by oil and ammonia levels, but to a lesser extent by plant density. In addition to oil and ammonia, redundancy analysis (RDA) showed also a significant contribution of temperature, dissolved oxygen and sulfate concentration to the variations of the mats' microbial communities. Pyrosequencing yielded 282,706 reads with >90% of the sequences affiliated to Proteobacteria (41% of total sequences), Cyanobacteria (31%), Bacteriodetes (11.5%), Planctomycetes (7%) and Chloroflexi (3%). Known autotrophic (e.g. Rivularia) and heterotrophic (e.g. Azospira) nitrogen-fixing bacteria as well as purple sulfur and non-sulfur bacteria were frequently encountered in all mats. On the other hand, sequences of known sulfate-reducing bacteria (SRBs) were rarely found, indicating that SRBs in the wetland mats probably belong to yet-undescribed novel species. The wetland mats were able to degrade 53-100% of C12-C30 alkanes after 6 weeks of incubation under aerobic conditions. We conclude that oil and ammonia concentrations are the major key players in determining the spatial distribution of the wetland mats' microbial communities and that these mats contribute directly to the removal of hydrocarbons from oil field wastewaters.
authors.affiliation: Sultan Qaboos University, College of Science, Biology Department, P.O. Box: 36, postal code 123, Al Khoud, Sultanate of Oman.
authors.forename: Raeid M M
authors.initials: RM
authors.lastname: Abed
authors.affiliation: Sultan Qaboos University, College of Science, Biology Department, P.O. Box: 36, postal code 123, Al Khoud, Sultanate of Oman.
authors.forename: Samiha
authors.initials: S
authors.lastname: Al-Kharusi
authors.affiliation: BAUER Resources, Constructed Wetland Competence Centre, P.O. Box 1186, P.C. 114, Al Mina, Muscat, Sultanate of Oman.
authors.forename: Stephane
authors.initials: S
authors.lastname: Prigent
authors.affiliation: BAUER Resources, Constructed Wetland Competence Centre, P.O. Box 1186, P.C. 114, Al Mina, Muscat, Sultanate of Oman.
authors.forename: Tom
authors.initials: T
authors.lastname: Headley
mesh_terms: D000641:Ammonia / Q000032:analysis; D001419:Bacteria / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001673:Biodegradation, Environmental; D044822:Biodiversity; D000458:Cyanobacteria / Q000235:genetics* / Q000378:metabolism; D016172:DNA Fingerprinting; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D006838:Hydrocarbons / Q000378:metabolism*; D008969:Molecular Sequence Data; D010100:Oxygen / Q000032:analysis; D059392:Petroleum Pollution / Q000032:analysis*; D012529:Saudi Arabia; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013431:Sulfates / Q000032:analysis; D013696:Temperature; D053833:Wetlands
chemical_list: D021903:DNA, Ribosomal Spacer; D006838:Hydrocarbons; D013431:Sulfates; D000641:Ammonia; D010100:Oxygen