No abstract

Microbial consortium that is present in fish gut systems works together to achieve unknown specific roles. Here, we collected guppy fish from hydrocarbon- and trace metal-contaminated wastewater to assess the relationships between gut microbiota and host fish adaptation. Targeted genes and 16S rRNA amplicon sequencing have been used to identify gut bacteria of guppies. Mineral-conditioned medium contributes to identify bacteria with the ability to grow and/or to tolerate hydrocarbon and trace metals. Additionally, trace metals’ tolerance minimum inhibitory concentration (MIC) of microbiota was evaluated. We first isolated bacteria from the gut system, and we showed that Bacillus spp., Staphylococcus spp., Shigella spp., Salmonella spp, Pseudomonas spp., Citrobacter spp., Salmonella enterica ssp.arizonae sp., Enterobacter spp, and Acinetobacter spp. are part of guppy gut microbiota. Some representative species are able to degrade and/or tolerate gasoline and/or diesel fuel hydrocarbons. Tolerance to trace metals was observed in Gram-positive and Gram-negative bacteria. We showed that minimal inhibitory concentration (MIC) of some microbiota isolated from gut systems has been found including for mercury (Hg) between 2 and 4‰, cobalt (Co) Co (2 and 5‰), zinc (Zn) (9 and 18‰), and plomb (Pb) (22 and 27‰). Zn and Pb were the trace metals for which the rate of tolerance was significantly higher. Finally, we showed that cytochrome c oxidase is not interfering in presence of trace metals. The working consortium showed that bacteria should work together to achieve their best.

No abstract

This study characterized microbial strains isolated from diesel fuel samples collected from the tank of a generating set at the Institute of Research for Development in Pointe-Noire (Congo). Two bacterial isolates (G2 and G3) were distinguished by their color on agar plates and were characterized by their API 20E biochemical profiles and by 16S rRNA gene sequencing. The phenotypic properties of these isolates were consistent with their assignment to the genus Pseudomonas. Comparative 16S rRNA gene sequence analysis demonstrated that the G2 and G3 isolates were close relatives of P. aeruginosa strain GIM 32 and P. aeruginosa strain NV2, respectively, with 97% sequence identity. These two P. aeruginosa strains were able to grow in a mineral salt medium supplemented with 2% diesel fuel or SAE 90 gear oil as the only source of carbon. P. aeruginosa G3 showed faster growth and was able to emulsify diesel fuel (53%), gasoline (90%) and hexane (95%) more strongly than P. aeruginosa G2.

No abstract