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.

A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes

“…According to single-cell analysis based on 15 N 2 -labelling, N 2 fixation in these mats is performed by the cyanobacterial members (Lyngbya phylotypes) with no apparent contribution from deltaproteobacterial SRB (Woebken et al, 2015). In oil-polluted cyanobacterial microbial mats from Wadi Gaza, Palestine, and constructed wetlands in the Arabian Peninsula, SRB are supposed to be involved in anaerobic hydrocarbon degradation and sulphur cycling (Abed, Al-Kharusi, Prigent, & Headley, 2014;Abed, Musat, Musat, & Mussmann, 2011). Chemotrophic microbial mats harbour lithotrophic prokaryotes (Bailey, Orphan, Joye, & Corsetti, 2009), e.g., sulphur-oxidizing bacteria or methane-oxidizing consortia (see Section 3.6).…”

Open pond cultures of indigenous algae grown on non-arable land in an arid desert using wastewater

“…Algae ponds were constructed on site of the Bauer Nimr water treatment plant (Abed et al 2014). The growth media used was made up of pPW (440-550 mg/L SO 4 , N-NH 3 0.3-0.6 mg/L, N-NO 3 0.2-1.0 mg/L, P-PO 4 \0.2 mg/L, salinity 7-12 ppt; analysis kindly provided by Bauer Nimr LLc; values measured before the addition of fertilizer) and 0.5 % (v/v) Wuxal.…”

Comparative Genomics of DNA Recombination and Repair in Cyanobacteria: Biotechnological Implications

“…N 2 -fixing cyanobacteria can be used to fertilize soils (Singh et al, 2016), in place of industrial N-fertilizers whose production consumes large amounts of fossil fuels (Grizeau et al, 2015). In colonizing a wealth of wastewater ecosystems that contain high levels of nitrate and phosphate (Abed et al, 2014) and/or heavy metals, cyanobacteria could be used for wastewater treatment (Abed et al, 2014; Singh et al, 2016). …”