Production and characterization of surfactin-like biosurfactant produced by novel strain Bacillus nealsonii S2MT and it's potential for oil contaminated soil remediation

Abstract

Background: Biosurfactants, being highly biodegradable, ecofriendly and multifunctional compounds have wide applications in various industrial sectors including environmental bioremediation. Surfactin, a member of lipopeptide family, which is considered as one of the most powerful biosurfactants due to its excellent emulsifying activities as well as environmental and therapeutic applications. Therefore, the aim of this study was to investigate the newly isolated bacterial strain S2MT for production of surfactin-like biosurfactants and their potential applications for oilcontaminated soil remediation. Results: In this study, the strain S2MT was isolated from lake sediment and was identified as Bacillus nealsonii based on transmitted electron microscopy (TEM) and 16S rRNA ribo-typing. The strain S2MT produced biosurfactant that reduced the surface tension (34.15 ± 0.6 mN/m) and displayed excellent emulsifying potential for kerosene (55 ± 0.3%). Additionally, the maximum biosurfactant product yield of 1300 mg/L was achieved when the composition of the culture medium was optimized through response surface methodology (RSM). Results showed that 2% glycerol and 0.1% NH 4 NO 3 were the best carbon/nitrogen substrates for biosurfactant production. The parameters such as temperature (30 °C), pH (8), agitation (100 rpm), NH 4 NO 3 (0.1%) and NaCl (0.5%) displayed most significant contribution towards surface tension reduction that resulted in enhanced biosurfactant yield. Moreover, the extracted biosurfactants were found to be highly stable at environmental factors such as salinity, pH and temperature variations. The biosurfactants were characterized as cyclic lipopeptides relating to surfactin-like isoforms (C 13-C 15) using thinlayer chromatography (TLC), Ultra high performance liquid chromatography and mass spectrometry (UHPLC-MS). The crude biosurfactant product displayed up to 43.6 ± 0.08% and 46.7 ± 0.01% remediation of heavy engine-oil contaminated soil at 10 and 40 mg/L concentrations, respectively. Conclusion: Present study expands the paradigm of surfactin-like biosurfactants produced by novel isolate Bacillus nealsonii S2MT for achieving efficient and environmentally acceptable soil remediation as compared to synthetic surfactants.

Purification and identification of a surfactin biosurfactant and engine oil degradation by Bacillus velezensis KLP2016

“…All these methods strongly detected the biosurfactant nature of B. Velezensis KLP2016, as it reduced surface tension upto 40 mN.m −1 in an in vitro assay at 35 ºC after using cell-free broth of B. velezensis grown in LB broth.The critical micelle concentrations (cmc) of cell-free broth of B. velezensis grown in LB at 35 ℃ and 25 ℃ were 17.2 µg/mL and 17.4 µg/mL, respectively while in MSM broth at 35 ℃ and 25 ℃ were 17.6 µg/mL and 18.1 µg/mL respectively. The present results of cmc were found to be lower than the earlier reports [ 38 , 39 ], who observed cmc (40 mg/L) for both Bacillus subtilis MG495086 and Bacillus nealsonii S2MT. E 24 % of the cell-free broth of B. velezensis was observed as 65.7%, 59.0%, 56.1%, 61.0%, 52.3%, 65.2% and 56.2% against benzene, pentane, cyclohexane, xylene, n -hexane, toluene and engine oil, respectively.…”

Valorization of Date Syrup by the Production of Lipopeptide Biosurfactants by a Bacillus mojavensis BI2 strain: Bioprocess Optimization by Response Surface Methodology and Study of Surface Activities

“…Generally, lipopeptides can be produced using a wide range of carbohydrate-like hydrophilic carbon substrates and hydrophobic substrates separately or on the two substrates at the same time (Mnif &Ghribi 2015b). Biosurfactants can be produced using a wide range of carbohydrate-like hydrophilic carbon substrates (Zhang et al 2016); (Ghazala et al 2017); (Hmidet et al 2017); (Phulpoto et al 2020) or hydrophobic substrates such as vegetable oils and hydrocarbons (Ndlovu et al 2017); (Ohadi et al 2017); (Patowary et al 2017) and this either as the sole source of carbon or in combination (Sarubbo et al 2016); (Joy et al 2017). However, glucose remains the primary source for the production of biosurfactants (Eswari et al 2016).…”

“…Complex compounds such as soybean our peptone and casein acid hydrolysate have been assayed too (Beltran-Gracia et al 2017). Moreover, several inorganic nitrogen compounds have been tested in lipopeptide production like ammonium nitrate, ammonium sulphate, sodium nitrate, urea and glutamic sodium (Beltran-Gracia et al 2017); (Moshtagh et al 2019); (Phulpoto et al 2020). The nitrogen source may in some cases affect the nature of the biosurfactant produced (Mnif &Ghribi 2015b) .…”

“…In addition to nutritional parameters, some physicochemical factors such as the incubation temperature, the initial pH of the culture medium and the rate of agitation can in uence the production of lipopeptides (Beltran-Gracia et al 2017); (Moshtagh et al 2019); (Phulpoto et al 2020). Generally, moderate agitation in the range of 150 to 200 rpm promotes good production of biosurfactants (Mnif &Ghribi 2015b).…”

“…Besides the different nutritional and physic-chemical parameters affecting lipopeptide production, optimization of the different factors by the experimental methodology remains the best strategy to maximize biosurfactant production (Bertrand et al 2018); (Singh et al 2019); (Moshtagh et al 2019); (Phulpoto et al 2020). Therefore, in our study aiming to reduce the cost of biosurfactant production by a newly isolated strain B. mojavensis BI2, we choose the use of an agriculture byproduct along with the application of planning experimental methodology to optimize the yield of production.…”