Phylogenetic diversity and activity of aerobic heterotrophic bacteria from a hypersaline oil-polluted microbial mat

Raeid M M Abed*, Burhanuddin Zein, Assad Al-Thukair, Dirk de Beer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

The diversity and function of aerobic heterotrophic bacteria (AHB) in cyanobacterial mats have been largely overlooked. We used culture-dependent and molecular techniques to explore the species diversity, degradative capacities and functional guilds of AHB in the photic layer (2 mm) of an oil-polluted microbial mat from Saudi Arabia. Enrichment isolation was carried out at different salinities (5% and 12%) and temperatures (28 and 45 °C) and on various substrates (acetate, glycolate, Spirulina extract and crude oils). Counts of most probable number showed a numerical abundance of AHB in the range of 1.15-8.13×106 cells g-1 and suggested the presence of halotolerant and thermotolerant populations. Most of the 16S rRNA sequences of the obtained clones and isolates were phylogenetically affiliated to the groups Gammaproteobacteria, Bacteriodetes and Alphaproteobacteria. Groups like Deltaproteobacteria, Verrucomicrobia, Planctomycetes, Spirochaetes, Acidobacteria and Deinococcus-Thermus were only detected by cloning. The strains isolated on acetate and glycolate belonged to the genera Marinobacter, Halomonas, Roseobacter and Rhodobacter whereas the strains enriched on crude oil belonged to Marinobacter and Alcanivorax. Members of the Bacteriodetes group were only enriched on Spirulina extract indicating their specialization in the degradation of cyanobacterial dead cells. The substrate spectra of representative strains showed the ability of all AHB to metabolize cyanobacterial photosynthetic and fermentation products. However, the unique in situ conditions of the mat apparently favored the enrichment of versatile strains that grew on both the cyanobacterial exudates and the hydrocarbons. We conclude that AHB in cyanobacterial mats represent a diverse community that plays an important role in carbon-cycling within microbial mats.

Original languageEnglish
Pages (from-to)319-330
Number of pages12
JournalSystematic and Applied Microbiology
Volume30
Issue number4
DOIs
Publication statusPublished - Jun 15 2007

Keywords

  • 16S rDNA cloning
  • Aerobic heterotrophic bacteria
  • Arabian Gulf
  • Bacterial diversity
  • Carbon cycle
  • Cultivation
  • Cyanobacterial mats
  • Oil biodegradation

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology

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