Presence Of Hydrocarbon-degrading Bacteria Research Articles

Plastisphere microbiome: Methodology, diversity, and functionality.

Broad topics of the plastisphere in various environments are reviewed, including its methodologies, diversity, functionality, and outlook.

New insights into the functioning and structure of the PE and PP plastispheres from the Mediterranean Sea

Plastic debris are accumulating in the marine environment and aggregate microorganisms that form a new ecosystem called the plastisphere. Better understanding the plastisphere is crucial as it has self-sufficient organization and carries pathogens or organisms that may be involved in the pollutant adsorption and/or plastic degradation. To date, the plastisphere is mainly described at the taxonomic level and the functioning of its microbial communities still remains poorly documented. In this work, metagenomic and metaproteomic analyzes were performed on the plastisphere of polypropylene and polyethylene plastic debris sampled on a pebble beach from the Mediterranean Sea. Our results confirmed that the plastisphere was organized as self-sufficient ecosystems containing highly active primary producers, heterotrophs and predators such as nematode. Interestingly, the chemical composition of the polymer did not impact the structure of the microbial communities but rather influenced the functions expressed. Despite the fact that the presence of hydrocarbon-degrading bacteria was observed in the metagenomes, polymer degradation metabolisms were not detected at the protein level. Finally, hydrocarbon degrader (i.e., Alcanivorax) and pathogenic bacteria (i.e., Vibrionaceae) were observed in the plastispheres but were not very active as no proteins involved in polymer degradation or pathogeny were detected. This work brings new insights into the functioning of the microbial plastisphere developed on plastic marine debris.

Characterization of hydrocarbon degrading bacteria at EPEA Station (38º 28’ S – 57º 41’ O) Atlantic coast

Hydrocarbon degrading bacteria (HDB) were monitored since 2006 to 2018 at the Permanent Environmental Studies Station (EPEA), in order to analyze its abundance and the potentiality to metabolize these pollutants. The presence of HDB was detected with counts values ranging between 103 and 105 UFC ml-1. A slight increase was observed over time, which could be linked to changes in marine temperature reported within the last years. Thirty-six HDB were tested for growth on various hydrocarbons and some of them showed a broad biodegradation profile. Moreover, from phenanthrene (Phe) enrichment cultures, five strains were phylogenetically identified as Halomonas sp. E1, E2 and E3; Rhodococcus sp. E4 and Pseudomonas sp. E5. Complete Phe degradation was demonstrated for E4 and E5 strains, while E1, E2, E3 and E4 strains displayed surfactant production. This study contributed with the first knowledge about the intrinsic HC biodegradation potential by bacterial communities at EPEA. Some of the strains exhibited physiological properties that might have ecological significance on environmental alterations as the presence of pollutants. Particularly, Rhodococcus sp. E4 could be an alternative for microbial selection in the degradation of PAHs. Further studies are needed to evaluate the impact of the climate change on microbial-mediated detoxification processes.

Presence of hydrocarbon-degrading bacteria in the gills of mussel Mytilus galloprovincialis in a contaminated environment: a mesoscale simulation study

A number of previous studies have shown that the relationships of symbiosis existing between mussels and microorganisms are directly dependent on the environmental conditions. However, little is known about existing relationships between mussels and bacteria in hydrocarbon-impacted marine environments. The aim of this preliminary study is to investigate the presence of oil-degrading bacteria in the mussel Mytilus galloprovincialis during growth in polluted ecosystems. All the experiments were carried out in a mesocosm system designed to simulate chronic pollution and to enable direct exposure of mussels to chemicals. Quantitative (4′,6-diamidino-2-phenylindole, colony-forming units, Most Probable Number) analyses and screening (presence/absence) of metabolic functional genes were performed to analyse bacterial populations inside the gills of mussels exposed and not exposed to hydrocarbons. The data obtained show that the presence of hydrocarbons affected the abundance of bacteria inside the gills of specimens and determines selection for specific (hydrocarbon-degrading) bacteria (i.e. Alcanivorax sp. and Marinobacter sp.). However, is not yet clear whether the presence of such genera of bacteria inside the mussel is due to symbiosis or as a result of filtration.

Biodegradation of wood in crude oil-polluted soil

A field investigation (April–November) in Nigeria showed that biodegradation of obeche (Triplochiton scleroxylon) wood blocks was initially retarded in crude oil-contaminated soil but later became enhanced as indicated by loss of compression resistance. Further indication of this pattern was the detection of soft-rot cavities and basidiomycete fungi after 2–3 months exposure when compared to control blocks in uncontaminated soil. Laboratory tests with Pleurotus sp., Trametes sp., Gloeophyllum sp. (basidiomycetes) and Chaetomium sp. (soft-rot fungus) confirmed that degradation of crude oil-coated obeche blocks was markedly retarded without the presence of hydrocarbon-degrading bacteria. The filtrate of hydrocarbon-degrading Pseudomonas sp. grown in mineral salt/crude oil medium for 3–4 weeks supported growth of the test fungi better than in carboxymethyl cellulose medium but less than in potato dextrose broth. Similarly, wood blocks immersed in the filtrate became significantly more susceptible to fungal degradation. Pseudomonas sp. from stationary phase growth in crude oil medium depleted residual sugar in basidiomycete-degraded sawdust with a concomitant marked increase in its population. It may be concluded that readily metabolizable products of crude oil degradation by soil organisms and the removal of residual sugar which may have prevented catabolite repression of cellulases, culminated in increased attack on the wood by soil-borne wood-decomposing organisms.