Biosurfactant and bioemulsifier as promising molecules produced by Mucor hiemalis isolated from Caatinga soil

BACKGROUND: The present study describes the production of biosurfactant (BS) and emulsifier (BE) by the filamentous fungus Mucor hiemalis UCP 0039, as well as the characterization and stability of the both biomolecules for environmental or industrial applications. RESULTS: Biosurfactants and bioemulsifiers are amphiphilic compounds and are produced as extracellular molecules. The results showed that bioproduct obtained by shaker condition reduced the water surface tension of 72 to 32 mN/m and reached an emulsification index of 96%, while the static cultivation resulted in a biomolecule with a surface tension of 40 mN/m and an emulsification index of 96%, suggesting the production of a biosurfactant and bioemulsifier, respectively. The compounds showed glycolipid nature but the biosurfactant presented cationic charge, while the bioemulsifier, anionic charge. Thus, the results confirmed that M. hiemalis produced two distinct biomolecules under different parameters and in the same culture medium. CONCLUSIONS: It is the first time that biosurfactant and emulsifier production has been described in the same medium and under different physical conditions by Mucor hiemalis. Both biomolecules showed thermal stability, as well as have significant effect on the viscosity of hydrophobic compounds, indicating the excellent potential for environmental safety or industrial applications to improve the efficiency of sustainable and economic technologies.

Alternative methodology for isolation of biosurfactant-producing bacteria

Wide biosurfactant application on biorremediation is limited by its high production cost. The search for cheaper biossurfactant production alternatives has guided our study. The use of selective media containing sucrose (10 g.L-1) and Arabian Light oil (2 g.L-1) as carbon sources showed to be effective to screen and maintain biosurfactant-producing consortia isolated from mangrove hydrocarbon-contaminated sediment. The biosurfactant production was assayed by kerosene, gasoline and Arabian Light Emulsification activity and the bacterial growth curve was determined by bacterial quantification. The parameters analyzed for biosurfactant production were the growth curve, salinity concentration, flask shape and oxygenation. All bacteria consortia screened were able to emulsify the petroleum derivatives tested. Biosurfactant production increased according to the incubation time; however the type of emulsification (non-aqueous phase or aqueous phase) did not change with time but with the compound tested. The methodology was able to isolate biosurfactant-producing consortia from superficial mangrove sediment contaminated by petroleum hydrocarbons and was recommended for selection of biosurfactant producing bacteria in tropical countries with low financial resources.

A ampla aplicação de biossurfactantes em biorremediação é limitada pelo seu alto custo de produção. A procura de alternativas de produção mais baratas motivou nosso estudo. O uso de meio seletivo, contendo sacarose (10 g.L-1) e óleo Arabe Leve (2 g.L-1), mostrou-se eficiente na triagem e manutenção de consórcios bacterianos isolados de sedimento de mangue contaminado com hidrocarboneto. A produção de biossurfactante foi avaliada pela Atividade Emulsificante do querosene, gasolina e Arabe Leve e a curva de crescimento foi determinada pela quantificação bacteriana. Os parâmetros analisados para a produção de biossurfactante foram: curva de crescimento, concentração da salinidade, forma do frasco e oxigenação. Todos os consórcios bacterianos pesquisados foram capazes de emulsificar os derivados de petróleo testados. A produção de biossurfactante aumentou de acordo com o tempo de incubação, entretanto, o tipo de emulsificação aquosa e não-aquosa não mudou com o tempo, mas com o composto testado. A metodologia permitiu o isolamento de consórcios bacterianos produtores de biossurfactante de sedimento superficial de mangue contaminado com hidrocarbonetos do petróleo, sendo indicada para seleção de bactéria produtora de biossurfactante em países tropicais com baixos recursos financeiros.

New bioemulsifiers produced by Candida lipolytica using D-glucose and babassu oil as carbon sources

Candida lipolytica IA 1055 produced extracellular biosurfactants with emulsification activity by fermentation using babassu oil and D-glucose as carbon sources. Natural seawater diluted at 50 percent supplemented with urea, ammonium sulfate, and phosphate was used as economic basal medium. The best results were achieved with the YSW-B2 medium, which contained urea, ammonium sulfate, and babassu oil and with YSW-B3 medium, which contained urea, ammonium sulfate, phosphate, and babassu oil, kept under fed batch fermentation for 60 hours with 5 percent of babassu oil. For the two media, the maximum specific growth rates were 0.02 h-1 and 0.04 h-1; the generation times were 34.6 h-1 and 17.3 h-1, and the emulsification activities were 0.666 and 0.158 units, respectively. The molecules of these new bioemulsifiers were contituted of carbohydrates, proteins and lipids.