Stable bioemulsifiers are produced by Acinetobacter bouvetii UAM25 growing in different carbon sources

Abstract

Acinetobacter species are identified as producing surface-active and emulsifying molecules known as bioemulsifiers. Production, characterization and stability of bioemulsifiers produced by Acinetobacter bouvetii UAM25 were studied. A. bouvetii UAM25 grew in three different carbon and energy sources: ethanol, a glycerol-hexadecane mixture and waste cooking oil in an airlift bioreactor, showing that bioemulsifier production was growth associated. The three purified bioemulsifiers were lipo-heteropolysaccharides of high molecular weight (4866 ± 533 and 462 ± 101 kDa). The best carbon source and energy for bioemulsifier production was wasted cooking oil, with a highest emulsifying capacity (76.2 ± 3.5 EU mg) as compared with ethanol (46.6 ± 7.1 EU mg) and the glycerol-hexadecane mixture (49.5 ± 4.2 EU mg). The three bioemulsifiers in our study displayed similar macromolecular structures, regardless of the nature (hydrophobic or hydrophilic) of the carbon and energy source. Bioemulsifiers did not decrease surface tension, but the emulsifying capacity of all of them was retained under extreme variation in salinity (0-50 g NaCl L), pH (3-10) and temperature (25-121 °C), indicative of remarkable stability. These findings contribute to understanding of the relationship between: production, physical properties, chemical composition and stability of bioemulsifiers for their potential applications in biotechnology, such as bioremediation of hydrocarbon-contaminated soil and water.

Eco-Friendly Bioemulsifier Production by Mucor circinelloides UCP0001 Isolated from Mangrove Sediments Using Renewable Substrates for Environmental Applications

“…These results corroborate the bioemulsifier synthesized by Acinetobacter bouvetii UAM25 grown in glycerol and residual frying oil [3].…”

“…These results were superior to studies also within 120 days for stability of emulsions formed with Candida lipolytica biosurfactant UCP0988 [29]. The data obtained in this analysis corroborate the thermostable bioemulsifier of Acinetobacter bouvetii UAM25 [3] and the bioemulsifier produced by Bacillus spp. [30].…”

“…The two types of molecule can be distinguished based on their structure and physicochemical properties. Chemically, bioemulsifiers are complex mixtures of heteropolysaccharides, lipopolysaccharides, lipoproteins, and proteins [3]. The combination of polysaccharide, fatty acid, and protein components gives bioemulsifiers better emulsifying potential and emulsion stabilization capacity [2,3].…”

Production, characterization, and applications of bioemulsifiers (BE) and biosurfactants (BS) produced by Acinetobacter spp.: A review

“…Hence, this biosurfactant can be used to remediate the sites polluted by such hydrocarbons . The potential of BS obtained from A. bouvetii UAM25 in the bioremediation of water and soil by removal of hydrocarbon was confirmed when highest emulsifying capacity 76.2 ± 3.5 EU mg −1 was reported after use of wasted cooking oil as a sole source of carbon and energy .…”

“…Molecular weights of few of BE are known such as emulsan RAG 1 (1000 KDa), alasan (45 KDa), proteoglyan (300 KDa) bioemulsifier produced by A. calcoaceticus MM5, and lipo‐hetero‐polysaccharide (1010 KDa) bioemulsifier by Acinetobacter bouvetii UAM25. Lipo‐hetero‐polysaccharide bioemulsifier is noted for its highest molecular weight (1010 KDa) .…”