Molecular Characterization of an Oil-Degrading Cyanobacterial Consortium

Abstract

Recent studies have shown that the cyanobacterium Microcoleus chthonoplastes forms a consortium with heterotrophic bacteria present within the cyanobacterial sheath. These studies also show that this consortium is able to grow in the presence of crude oil, degrading aliphatic heterocyclic organo-sulfur compounds as well as alkylated monocyclic and polycyclic aromatic hydrocarbons. In this work, we characterize this oil-degrading consortium through the analysis of the 16S rRNA gene sequences. We performed the study in cultures of Microcoleus grown in mineral medium and in cultures of the cyanobacterium grown in mineral medium supplemented with crude oil. The results indicate that most of the clones found in the polluted culture correspond to well-known oil-degrading and nitrogen-fixing microorganisms, and belong to different phylogenetic groups, such as the Alpha, Beta, and Gamma subclasses of Proteobacteria, and the Cytophaga/Flavobacteria/Bacteroides group. The control is dominated by one predominant organism (88% of the clones) closely affiliated to Pseudoxanthomonas mexicana (similarity of 99.8%). The presence of organisms closely related to well-known nitrogen fixers such as Rhizobium and Agrobacterium suggests that at least some of the cyanobacteria-associated heterotrophic bacteria are responsible for nitrogen fixation and degradation of hydrocarbon compounds inside the polysaccharidic sheath, whereas Microcoleus provides a habitat and a source of oxygen and organic matter.

Cyanobacterial Farming for Environment Friendly Sustainable Agriculture Practices: Innovations and Perspectives

“…The consortium of Oscillatoria-Gammaproteobacteria can degrade phenanthrene, dibenzothiophene, pristine and n-octadecane (Abed and Köster, 2005). Similarly, consortia of Microcoleus chthonoplastes with organotrophic bacteria can fix atmospheric nitrogen and degrade aliphatic heterocyclic organo-sulfur compounds and hydrocarbons such as alkylated monocyclic and polycyclic aromatic compounds (Sánchez et al, 2005). An artificially designed biofilm consortium of hydrocarbon-degrading bacteria and cyanobacteria on gravel particles and glass plates has been developed that can be used for cleaning up crude-oil contamination of sea water samples (Al-Awadhi et al, 2003).…”

Characterization of Rhizobium naphthalenivorans sp. nov. with special emphasis on aromatic compound degradation and multilocus sequence analysis of housekeeping genes

“…One of the most characteristic features of the isolates is growth by degrading naphthalene as the sole substrate. Although some reports have shown that limited members of Rhizobium have a potential of aromatic hydrocarbon degradation (Ben Said et al, 2008;Sanchez et al, 2005), none of the established Rhizobium species have been described for this trait. To our knowledge, therefore, this paper is the fi rst to offi cially describe a Rhizobium species capable of growing with naphthalene as the sole carbon and energy source.…”

“…While limited information has been available on the potential degradation of aromatic hydrocarbon by members of the genus Rhizobium (Ben Said et al, 2008;Sanchez et al 2005), our Rhizobium isolates were able to utilize naphthalene as the sole carbon and energy source and to degrade biphenyl and dibenzofuran co-metabolically. A genomic DNA region covering a gene encoding putative aromatic-ring-hydroxylating oxygenase (AhDO) in one of the isolates was cloned and identifi ed (Kaiya et al, 2012).…”

Growth of the Cyanobacterium Synechococcus leopoliensis CCAP1405/1 on Agar Media in the Presence of Heterotrophic Bacteria

“…MIT 9215 on the agar medium, and suggested that H 2 O 2 in the medium inhibited the cyanobacterial growth and the heterotrophic bacterial strain helped it by producing catalase. Intimate interactions between cyanobacteria and heterotrophic bacteria have been reported in several ecosystems, including a river biofilm (15), on the surface of concrete (5), in an oil-degrading consortium (27), and in lichen (7). In these cases, cyanobacteria and heterotrophic bacteria are assumed to exchange nutrients such as fixed nitrogen, organic matter, and/or substances essential for their growth.…”