Screening of biosurfactant-producing Bacillus strains using glycerol from the biodiesel synthesis as main carbon source

Abstract

Glycerol, a co-product of biodiesel production, was evaluated as carbon source for biosurfactant production. For this reason, seven non-pathogenic biosurfactant-producing Bacillus strains, isolated from the tank of chlorination at the Wastewater Treatment Plant at Federal University of Ceara, were screened. The production of biosurfactant was verified by determining the surface tension value, as well as the emulsifying capacity of the free-cell broth against soy oil, kerosene and N-hexadecane. Best results were achieved when using LAMI005 and LAMI009 strains, whose biosurfactant reduced the surface tension of the broth to 28.8 ± 0.0 and 27.1 ± 0.1 mN m(-1), respectively. Additionally, at 72 h of cultivation, 441.06 and 267.56 mg L(-1) of surfactin were produced by LAMI005 and LAMI009, respectively. The biosurfactants were capable of forming stable emulsions with various hydrocarbons, such as soy oil and kerosene. Analyses carried out with high performance liquid chromatography (HPLC) showed that the biosurfactant produced by Bacillus subtilis LAMI009 and LAMI005 was compatible with the commercially available surfactin standard. The values of minimum surface tension and the CMC of the produced biosurfactant indicated that it is feasible to produce biosurfactants from a residual and renewable and low-cost carbon source, such as glycerol.

Screening and Evaluation of Biosurfactant-Producing Strains Isolated from Oilfield Wastewater

“…The optical density of the culture sample at 600 nm was measured by using a spectrophotometer of UV light visible (Genesys series 20). The concentration of biosurfactant (g/l) was measured using a calibration curve of biomass against optical density [13].…”

“…It can also define the solubility of a surfactant in the aqueous phase [13]. Indeed, even in the presence of a small concentration of biosurfactants, a CMC can be achieved, from which any variation in the surface tension can be observed [17].…”

Produção de biossurfactantes por microrganismos isolados de solo contaminado com óleo diesel

“…4,6,[16][17][18] Contudo, a maior área para aplicação dos biossurfactantes é a indústria do petróleo, tanto para a produção deste como para incorporação nas formulações de óleo, dispersão de derramamento de óleo em solo e no mar, remoção de lodo de óleo de tanques de estocagem, na recuperação melhorada de petróleo e na descontaminação ambiental por meio da biorremediação. 7,19 Os biossurfactantes apresentam vantagens relacionadas à baixa toxicidade, alta biodegradabilidade, variedade de estruturas quí-micas, estabilidade em condições extremas de pH, temperatura e salinidade.…”

“…7,19 Os biossurfactantes apresentam vantagens relacionadas à baixa toxicidade, alta biodegradabilidade, variedade de estruturas quí-micas, estabilidade em condições extremas de pH, temperatura e salinidade. 3,8,18 Dentre os problemas relacionados ao uso de biossurfactantes está o seu alto custo de produção, associado a métodos ineficientes de recuperação do produto e ao uso de substratos caros. A diminuição dos custos de produção destes compostos pode ser realizada a partir da otimização dos processos e dos meios de cultivo utilizados.…”

Microbiotechnology Based Surfactants and Their Applications

“…Abdel-Mawgoud et al (2008) reported a biosurfactant production of 1.12 g/l by B. subtilis BS5 using a mineral medium containing sugarcane molasses. B. subtilis LAMI005 produced 0.3 and 0.44 g/l of biosurfactant growing in media containing cashew apple juice (Oliveira et al, 2013) and raw glycerol derived from biodiesel production (Sousa et al, 2012), respectively. However, in these cases, other nutrients (e.g., carbon or nitrogen sources, salts) were added to the media, thus increasing their prices.…”