Starvation-Dependent Inhibition of the Hydrocarbon Degrader Marinobacter sp. TT1 by a Chemical Dispersant

During marine oil spills, chemical dispersants are used routinely to disperse surface slicks, transferring the hydrocarbon constituents of oil into the aqueous phase. Nonetheless, a comprehensive understanding of how dispersants affect natural populations of hydrocarbon-degrading bacteria, particularly under environmentally relevant conditions, is lacking. We investigated the impacts of the dispersant Corexit EC9500A on the marine hydrocarbon degrader Marinobacter sp. TT1 when pre-adapted to either low n-hexadecane concentrations (starved culture) or high n-hexadecane concentrations (well-fed culture). The growth of previously starved cells was inhibited when exposed to the dispersant, as evidenced by 55% lower cell numbers and 30% lower n-hexadecane biodegradation efficiency compared to cells grown on n-hexadecane alone. Cultures that were well-fed did not exhibit dispersant-induced inhibition of growth or n-hexadecane degradation. In addition, fluorescence microscopy revealed amorphous cell aggregate structures when the starved culture was exposed to dispersants, suggesting that Corexit affected the biofilm formation behavior of starved cells. Our findings indicate that (previous) substrate limitation, resembling oligotrophic open ocean conditions, can impact the response and hydrocarbon-degrading activities of oil-degrading organisms when exposed to Corexit, and highlight the need for further work to better understand the implications of environmental stressors on oil biodegradation and microbial community dynamics.

Phylogenetic analysis of hydrocarbon degrading bacteria associated with crude oil polluted soil from Mesogar community, Delta State, Nigeria

This study was carried out to isolate hydrocarbon-degrading bacteria associated with oil polluted soil samples collected from Mesogar community of Delta State, Nigeria. The samples were aseptically collected and the bacteria isolated according to standard microbiological techniques. The isolates with hydrocarbon biodegradative ability were screened on MSM supplemented with 2% crude oil using spectrophotometric method. The amount of crude oil degraded by the highest hydrocarbon degrader was determined using gas chromatographic (GC) assay. A total of seven bacterial isolates were molecularly identified using the 16S rRNA gene sequencing method. The sequences were compared to those deposited in NCBI using the basic local alignment tool (BLAST) algorithm. Phylogenetic analysis of 16S rRNA gene sequences was carried out to determine the evolutionary relationships of the isolated bacterial species. The isolates were identified to have remote similarities with Alcaligenes faecalis SH179a, Alcaligenes faecalis subsp. Phenolicus, Bacillus thuringiensis serovar konkukian, Ochrobactrum anthropi, Alcaligenes faecalis SH179b, Uncultured soil bacterium clone and Alcaligenes faecalis IVN45. Strain OFBR 4 had the highest degrading ability. The use of molecular methods for rapid and accurate detection of diverse strains of hydrocarbon-degraders is of utmost necessity in bioremediation. Keywords: Phylogenetic analysis, oil polluted soil, biodegradative, hydrocarbon degrader, 16S rRNA gene and crude oil.

Complete Genome Sequence of the Marine Hydrocarbon Degrader Alcaligenes aquatilis QD168, Isolated from Crude Oil-Polluted Sediment of Quintero Bay, Central Chile

Alcaligenes aquatilis strain QD168 (= CCUG 69566) is a marine hydrocarbon-degrading bacterium isolated from crude oil-polluted sediment from Quintero Bay, Central Chile. Here, we present the 4.32-Mb complete genome sequence of strain QD168, with 3,892 coding sequences, 58 tRNAs, and a 56.3% G+C content.

Draft Genome Sequence of Bacillus sp. Strain UFRGS-B20, a Hydrocarbon Degrader

ABSTRACT Bacillus sp. strain UFRGS-B20 was isolated in 2012 from Brazilian land-farming soil contaminated with petrochemical oily sludge. This strain was subjected to hydrocarbon biodegradation tests, showing degradation rates of up to 60%. Here, we present the 6.82-Mb draft genome sequence of the strain, which contains 2,178 proteins with functional assignments.