Molecular diversity analysis and bacterial population dynamics of an adapted seawater microbiota during the degradation of Tunisian zarzatine oil

Abstract

The indigenous microbiota of polluted coastal seawater in Tunisia was enriched by increasing the concentration of zarzatine crude oil. The resulting adapted microbiota was incubated with zarzatine crude oil as the only carbon and energy source. Crude oil biodegradation capacity and bacterial population dynamics of the microbiota were evaluated every week for 28 days (day 7, day 14, day 21, and day 28). Results show that the percentage of petroleum degradation was 23.9, 32.1, 65.3, and 77.8%, respectively. At day 28, non-aromatic and aromatic hydrocarbon degradation rates reached 92.6 and 68.7%, respectively. Bacterial composition of the adapted microflora was analysed by 16S rRNA gene cloning and sequencing, using total genomic DNA extracted from the adapted microflora at days 0, 7, 14, 21, and 28. Five clone libraries were constructed and a total of 430 sequences were generated and grouped into OTUs using the ARB software package. Phylogenetic analysis of the adapted microbiota shows the presence of four phylogenetic groups: Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Diversity indices show a clear decrease in bacterial diversity of the adapted microflora according to the incubation time. The Proteobacteria are the most predominant (>80%) at day 7, day 14 and day 21 but not at day 28 for which the microbiota was reduced to only one OTU affiliated with the genus Kocuria of the Actinobacteria. This study shows that the degradation of zarzatine crude oil components depends on the activity of a specialized and dynamic seawater consortium composed of different phylogenetic taxa depending on the substrate complexity.

Change in Bacterial Diversity After Oil Spill in Argentina

“…The use of diversity index in microbial ecology studies have been described previously by several authors (Hill et al, 2003;Hughes et al, 2001;Zrafi-Nouira et al, 2009;Pedrós-Alió, 2006). Our results are in agreement with Zrafi-Nouira et al (2009) and Brakstad & Lødeng (2004), which indicate that the reduction of microbial diversity is observed early, from day 4 to day 164 after the spill. In fact, the crude oil spill can dramatically reduce bacterial diversity (Röling et al, 2002).…”

Characterization of Coastal Urban Watershed Bacterial Communities Leads to Alternative Community-Based Indicators

“…Detailed descriptions of the communities are included in Table S2. From published sequencing studies, we calculated the BBC∶A ratios of bacterial communities from 54 mammalian intestines [32], 5 sewage-associated samples [33], [34], [35], [36], [37], and 19 non-fecal samples [23], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53]. Likewise, from PhyloChip-analyzed samples, we determined the BBC∶A ratios from communities of 11 gut [Brodie et al, unpublished; Marchesi et al, unpublished; Nguyen et al, unpublished; This study] [54], 17 sewage-associated [Conrad et al, unpublished; Sercu et al unpublished; Wu et al, unpublished], and 18 non-fecal samples [Sercu et al, unpublished; This study] [55].…”

Microbial diversity in two cold springs on the Qinghai-Tibetan Plateau

“…The Alphaproteobacteria contained nine OTUs, representing 17 sequences (5.8% and 21.5% of the total sequences in QCSB1 and QCSB2, respectively), and most of these sequences were closely related to clones retrieved from cold habitats, such as glaciers and lakes on the Tibetan Plateau (Liu et al, 2006;Liu et al, 2009;Xiang et al, 2009;Xing et al, 2009), soils and ice in Arctic and Antarctic (Mosier et al, 2007;Wallenstein et al, 2007;Simon et al, 2009). One clone (QCSB1-009) is also closely related (identity: 100%) to Ochrobactrum tritici strain Y13 isolated from a petroleum-oil contaminated soil and to a clone sequence retrieved from the cleaning seawater from Tunisian oil reservoirs (Zrafi-Nouira et al, 2009).…”