Early bacterial biofilm colonizers in the coastal waters of Mauritius

Background: The past years have witnessed a growing number of researches in biofilm forming communities due to their environmental and maritime industrial implications. To gain a better understanding of the early bacterial biofilm community, microfiber nets were used as artificial substrates and incubated for a period of 24 h in Mauritian coastal waters. Next-generation sequencing technologies were employed as a tool for identification of early bacterial communities. Different genes associated with quorum sensing and cell motility were further investigated. Results: Proteobacteria were identified as the predominant bacterial microorganisms in the biofilm within the 24 h incubation, of which members affiliated to Gammaproteobacteria, Alphaproteobacteria and Betaproteobacteria were among the most abundant classes. The biofilm community patterns were also driven by phyla such as Firmicutes, Bacteroidetes, Chloroflexi, Actinobacteria and Verrucomicrobia. The functional analysis based on KEGG classification indicated high activities in carbohydrate, lipid and amino acids metabolism. Different genes encoding for luxI, lasI, agrC, flhA, cheA and cheB showed the involvement of microbial members in quorum sensing and cell motility. Conclusion: This study provides both an insight on the early bacterial biofilm forming community and the genes involved in quorum sensing and bacterial cell motility.

Jatropha curcas L:Phytochemical, antimicrobial and larvicidal properties

Objective: To evaluate antimicrobial activities as well as the phytochemical and lav-icidal properties of different parts of Jatropha curcas L. (J. curcas) growing in Mauritius. Methods: Determination of the presence of phytochemicals in the crude plants extracts by test tube reactions. Disc diffusion method and microdilution method were used to detect the antimicrobial sensitivity and activity (minimal inhibitory concentration). The crude solvent extracts were also tested on the larvae of two insects, Bactrocera zonata and Bactrocera cucurbitae (Diptera, Tephritidae). Results: The antimicrobial activities were significantly dependent for the different crude plant extracts on the thirteen microorganisms tested. For the Gram-positive bacteria, the crude ethyl acetate extract was more efficient compared to the Gram-negative bacteria with both solvents being effective. The crude ethyl acetate extract of J. curcas bark and mature seed oil showed the highest efficacy. The highest mortality percentage was observed after 24 h for both Diptera flies with (66.67 ± 2.89)%of Bactrocera cucurbitae larvae killed by ethyl acetate extract of J. curcas bark. Conclusions: This paper compared the different J. curcas plant sections with respect to the effectiveness of the plant as a potential candidate for new pharmaceuticals. The lar-vicidal effect was also studied in order to demonstrate the dual purpose of the plant.