Lipopeptides production by a newly Halomonas venusta strain: Characterization and biotechnological properties.

A halotolerant marine strain PHKT of Halomonas venusta was isolated from contaminated seawater as an efficient biosurfactant producer candidate, on low-value substrate (glycerol). The produced biosurfactants (Bios-PHKT) were characterized as lipopeptides molecules, belonging to surfactin and pumilacidin families, by using Thin Layer Chromatography (TLC), Fourier Transform Infrared Spectroscopy (FT-IR) and Tandem Mass Spectrometry (MALDI-TOF/MS-MS). Bios-PHKT has a critical micelle concentration (CMC) of 125 mg/L, and showed a high steadiness against a wide spectrum of salinity (0-120 g/L NaCl), temperature (4-121 °C) and pH (2-12), supporting its powerful tensioactive properties under various environmental conditions. Likewise, the cytotoxic test revealed that the biosurfactant Bios-PHKT, at concentrations lower than 125 µg/mL, was not cytotoxic for human HEK-293 cells since the cell survival is over than 80%. Furthermore, Bios-PHKT lipopeptides showed excellent anti-adhesive and anti-biofilm activities, being able to avoid and disrupt the biofilm formation by certain pathogenic microorganisms. In addition, the biosurfactant Bios-PHKT showed a remarkable anti-proliferative activity towards tumor B16 melanoma cell line. Besides, Bios-PHKT exhibited an excellent in vitro and in vivo wound healing process. In light of these promising findings, Bios-PHKT could be successfully used in different biotechnological applications.

A non-toxic microbial surfactant from Marinobacter hydrocarbonoclasticus SdK644 for crude oil solubilization enhancement.

This study aims to investigate the ability of a biosurfactant produced by Marinobacter hydrocarbonoclasticus strain SdK644 isolated from hydrocarbon contaminated sediment to enhance the solubilization rate of crude oil contaminated seawater. Phylogenetic analysis shows that strain SdK644 was very closely related to M. hydrocarbonoclasticus with 16S rRNA gene sequence similarity of 97.44%. Using waste frying oil as inducer carbon source, the producing biosurfactant by strain SdK644 was applied to improve crude oil solubilization in seawater. The preliminary characterization of the produced biosurfactant by FT-IR analysis indicates its possible classification in a glycolipids group. Results from crude oil solubilization assay showed that SdK644 strain biosurfactant was 2-fold greater than Tween 80 surfactant in crude oil solubilization and 12-fold higher than seawater control, as shown by GC-MS analysis of aliphatic compounds. Furthermore, this bioactive compound was shown to be nontoxic against Artemia larvae in short-term acute toxicity bioassay. Generally, the results showed the possible use of M. hydrocarbonoclasticus strain SdK644 biosurfactant in bioremediation processes of the marine environments.