No abstract

In the present work, we demonstrated the potential use of newly identified lipopeptides produced by B. mojavensis BI2 along with palm waste floor for the bioremediation of heavy metals contaminated water. The enhancement of radish seeds germination was used to evaluate the treatment efficiency. Firstly, better enhancement in the order of 3.8; 2.52; 1.5 and 5 were recorded respectively for 200 mg/L copper, lead, cobalt and mercury with respective lipopeptide quantities of the order of 200; 300; 200 and 400 mg/L. When studying the sequestration of increasing heavy metals concentration, BI2 lipopeptide was effective. Secondly, a mixed bioprocess was evaluated using palm waste floor as heavy metals sequester and BI2 lipopeptides as improver. Optimal biosorption of lead, copper, cobalt and mercury were obtained with 10 g/l waste; 1,000 mg/l metal and 200 mg/l BI2 lipopeptide for 1 hour. The addition of 200 mg/l BI2 lipopeptide improves significantly the efficiency of the treatment.

No abstract

Lipopeptides Biosurfactants are natural surface-active compounds produced by a variety of microorganisms. They have great interest in environmental, biomedical and agro-industrial fields. However, the high cost of culture media and the low yield of production limit their large-scale production and application. The development of efficient and cost-effective bioprocess became of a great interest for the improvement of the yield of biosurfactants and the decrease of production cost. In this aim, we applied the response surface method to optimize an economic biosurfactant production by a newly isolated strain B. mojavensis BI2 on date syrup called “Luegmi” as unique carbon and nitrogen source. Using a Box-Bhenken design, we studied the effect of three independent variables on lipopeptide production; Leugmi concentration, Na 2 HPO 4 and incubation time. The results of this study showed that Leugmi concentration at 25%, Na 2 HPO 4 at 0.1% and incubation time of 24 hours were optimal conditions for biosurfactant production, with a maximum surface tension decreasing capacity of 55% corresponding to 27 mN/m and oil dispersing of 30 cm 2 corresponding to a diameter of 6 cm. Preliminary characterization of the biosurfactant produced on Luegmi by UV-Spectra and Thin Layer Chromatography showed its lipopeptide characters. Physic-chemical characterization of the produced lipopepetide on Leugmi showed its great surface activities and stabilities at different pH, temperature and salts concentration. The results of this study suggested that Leugmi, an agricultural byproducts can be used as a low-cost substrate to enhance the yield of lipopeptide biosurfactants with great surface activities for potential environmental application.