A new isolated Bacillus mojavensis strain I4 was found as producer of biosurfactants by different screening methods, such as parafilm M test, hemolytic activity, oil displacement test, emulsification index, surface tension, and lipase production assay. Enhanced biosurfactants production was obtained using glucose and glutamic acid as carbon and nitrogen sources, respectively. The optimal production of the biosurfactants was obtained by using a C/N ratio of 17, pH of 7.0, and temperature of 37°C. The surface tension was reduced to 29 mN/m and the emulsification index E24 of 62% was achieved after 72 h of culture. The purified biosurfactants showed stability with regard to surface tension reduction and emulsification in a wide range of temperatures (4–120°C), pH (4–10), and salinity (2–12% of NaCl). The thin‐layer chromatography showed that the produced biosurfactants were lipopeptides. The biosurfactants were characterized as a group of anionic lipopeptides with zeta potential measurement. Chromatographic characterization using HPLC revealed that I4 lipopeptides contained numerous isoforms and surfactin was the major component. Moreover, the I4 lipopeptides showed interesting angiotensin‐converting enzyme‐inhibitory activity.
Aiming at the potential application of lipopeptide biosurfactant (BioS) in bioremediation, we studied its production by a novel, isolated strain of Bacillus sp. MI27. Using the experimental design methodology, a sucrose-based medium composed of 2% sucrose, 0.27% Na2HPO4, 0.2% ammonium sulfate, 0.02% NaCl, 0.02% CaCl2, 0.02% MgSO4, 0.001% MnSO4, 0.06% KH2PO4, 0.005% FeSO4 and 0.005% ZnSO4 was optimized. With this composition, strain MI27 produces 1.4 g/L with maximum surface tension (ST) reduction of 23 mN/m and a dispersion diameter of around 10 cm. Emulsifying and foaming activities have been also confirmed. The critical micelle concentration (CMC) value of about 120 mg/L with a maximal decrease of ST of 23 mN/m with a maximum dispersion and an emulsification index (EI) of about 12 cm and 45% at 1,000 mg/L. Moreover, the foaming capacity is about 80% at 1,000 mg/L stable over 1 h of incubation. Additionally, we studied the effect of different values of pH, temperature and salinities on MI27 BioS activity and stability. Obtained results showed interesting surface activities at extreme physicochemical conditions, especially at acidic and alkaline pH values, high and low temperatures and higher salinities. All these characteristics enable the possible application of BioS in water treatment biotechnology under diverse environmental conditions.
Thanks to their multifunctional properties, such as foaming, emulsifying and skin hydrating activity, biosurfactants are potentially used in the cosmetic industry. In the present work, firstly, skin cream formulations using chemical surfactant agents and lipopeptide biosurfactants isolated from Bacillus subtilis SPB1 were investigated. The efficiency of the selected formula, containing 15% biosurfactant, was tested. Their physicochemical properties were satisfying. In fact, it shows a spreading ability of 23 mm, a water activity of 0.72 and a pH value of 5. In addition, their biological activities were interesting. As a result, it shows a zone of inhibition against Gram-positive bacteria ranging from 8 to 15 mm. Moreover, it presents an antiradical effect against diphenyl-1-picrylhydrazyl (DPPH) with an IC50 of the order of 68 mg/mL. Second, seeking a highly stable SPB1 biosurfactant formulation for an easy commercial trend, a combination of biosurfactant, Gum Arabic (GA) and glycerol was optimized using the Box–Behnken (BB) design. As analysed, the model predicts an optimal value of the surface tension (ST) equal to 40.18 ± 0.39 mN/m when the respective values of the percentages of SPB1 BioS, glycerol and GA are equal to 72.62, 7.5 and 1.5%. Under these conditions, the emulsification index (EI)-24% is of the order of 81.76 ± 0.14%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.