16S rRNA gene profiling of planktonic and biofilm microbial populations in the Gulf of Guinea using Illumina NGS

Abstract

16S rRNA gene profiling using a pipeline involving the Greengenes database revealed that bacterial populations in innermost (proximal to the steel surface) and outer regions of biofilms on carbon steel exposed 3 m below the surface at an offshore site in the Gulf of Guinea differed from one another and from seawater. There was a preponderance of gammaproteobacterial sequences, representing organisms known for hydrocarbon degradation. Total DNA from the innermost layer was 1500 times that recovered from the outermost. Stramenopiles (diatom) sequences were prevalent in the former. Rhodobacteriaceae, key biofilm formers, comprised 14.9% and 4.22% OTUs of inner and outer layers, respectively. Photosynthetic anaerobic sulfur oxidizer sequences were also prominent in the biofilms. Analysis of data using a different pipeline with Silva111 allowed detection of 0.3-0.4% SRB in the biofilms. The high abundance of aerobic micro-algal sequences in inner biofilm suggests they are initial colonizers of carbon steel surfaces in a marine environment. This is the first time that the microbial population of the strongly attached inner layer of the biofilm on steel has been differentiated from the outer, readily removed layer. The accepted scraping removal method is obviously inadequate and the resulting microbial analysis does not offer complete information on the biofilm community structure.

Presence of orange tubercles does not always indicate accelerated low water corrosion

“…Some differences, however, were also observed with Bacteroidetes distributions, for example, being high in seawater through to lowest in the tubercle inner layer in our study (Fig. 4), but the opposite being reported in (22).…”

“…There were some similarities between our bacterial findings and a third MIC study (Zhang 2019), particularly with similar abundances of Proteobacteria and Bacteroidetes. In general, other studies have reported more Firmicutes (X. Li et al (21), S. Celikkol-Aydin et al (22) – mostly Defulfotomaculum ) and sometimes more Actinobacteria (22, 23), compared to our results, but the Proteobacteria and Bacteroidetes are abundant phyla in all these studies.…”

“…It has been suggested (26) that algae then cyanobacteria are primary terrestrial biofilm colonisers and data from S. Celikkol-Aydin et al (22) add credence to the notion they could be primary colonisers in marine metallic corrosion settings. We did not specifically explore algae, and our cyanobacteria were largely only in the seawater sample.…”

Evaluation of microbial proliferation on cementitious materials exposed to biogas systems

“…This difference between the medium and the biofilm in terms of microbial flora might reflect a real dissociation between the composition of the medium and the composition of the biofilm at the surface of the material (Figure 3, Figure 4). Celikkol-Aydin et al [51] characterized a marine biofilm dominated by the phyla Cyanobacteria, Bacteroidetes and Proteobacteria while the seawater in which it was formed was dominated by the phyla firmicutes and proteobacteria [51]. In this study, the steel surface was a favourable environment for the enrichment of Cyanobacteria and Bacteroidetes.…”

Effect of Tidal Cycles on Bacterial Biofilm Formation and Biocorrosion of Stainless Steel AISI 316L

“…At the same time, the development of biological characterization tools in the past few years has provided important insights into specific marine bacterial groups and their significance in biocorrosion under controlled laboratory conditions [32][33][34][35]. More recent studies based on complete community approaches have finally revealed the complexity of real microbial systems and paved the way for a more systematic understanding of the biocorrosion phenomenon [36][37][38][39][40]. The current understanding is that biocorrosion associated with biofilm formation and growth in natural environments is a complex process; the nonlinearity of this process is determined by numerous factors, of both the abiotic and biotic types.…”