Isolation and characterization of hydrocarbon-degrading and biosurfactant-producing yeast strains obtained from a polluted lagoon water

Abstract

Microbial surfactants are environmentally friendly products with amazing properties and spectrum of applications. It is therefore, not surprising that research has increased in recent time with the objectives of sourcing for novel surface-active compounds with dual functions in oil and pharmaceutical industries. Evaluation of hydrocarbon degrading potentials and emulsifying activities indicated that biosurfactants were produced by two newly isolated and promising yeast strains, Saccharomyces cerevisiae and Candida albicans, obtained from a polluted lagoon water. Both strains were able to grow effectively on crude oil and diesel as sole sources of carbon and energy. Growth curves on diesel were obtained to establish the relation between cell growth and biosurfactant production. The growth peak was on the 8th day while the specific growth rate ranged insignificantly (P \ 0.05) between 0.46 and 0.48 day -1 . Interestingly, biosurfactant was detected on the 2nd day when growth was almost inexistent, with maximal production obtained at stationary/death phase of growth. The partially-purified biosurfactants exhibited antimicrobial activities by completely inhibiting the growth of clinical strains of Escherichia coli and Staphylococcus aureus at all concentrations tested. Although C. albicans appeared to be a better diesel-utilizer and biosurfactant-producer (E 24 = 64.2%), the potency of its surfactant was smaller than that of S. cerevisiae. These strains represent a new class of biosurfactant producers that have potential for use in a variety of biotechnological and industrial processes particularly in the pharmaceutical industry.

Aislamiento e Identificación de Bacterias y Levaduras Resistentes a Petróleo

“…1), siendo la más frecuente Pseudomonas aeruginosa (50.0%), seguida de Escherichia coli (31.25%) y Enterobacter aerogenes, Proteus mirabilis y Candida albicans (6.25%) (Figura No.1), lo que indica que los microorganismos aislados desarrollaron la resistencia y tal vez el mecanismo de degradación del petróleo en un medio ambiente contaminado con el mismo, lo cual coincide con una gran variedad de estudios, pues a partir de diferentes fuentes, se han aislado diferentes microorganismos con la capacidad de resistencia y degradación del petróleo (Auffret et al, 2009;Saadoun et. al., 2008;Tang et al, 2007;Emtiazi et al, 2005;Ilori et. al., 2008;Rivera-Cruz et al, 2002;Husaini et al, 2008 Posteriormente, se incubaron en presencia de 1.0 mL de petróleo crudo las ocho cepas aisladas de P. aeruginosa (3 días) y C. albicans (7 días), y se les determinó el crecimiento por peso seco, encontrando que todas las bacterias crecen mejor en presencia del hidrocarburo, presentando mayor y menor crecimiento la P. aeruginosa aislada del Río Coy, y la del Río Valles (Calera) con un crecimiento de 4.5 (139 mg de peso seco) y 1.0 veces (34 mg de peso seco) respectivamente, (Figura No.…”

“…al.,) y Pseudomonas aeruginosa sp (Tang et al, 2007;Emtiazi et al, 2005), las levaduras Saccharomyces cerevisiae y Candida albicans (Ilori et. al., 2008), y los hongos filamentosos Penicillium sp y Aspergillus sp (Rivera-Cruz et al, 2002) Trichoderma asperellum (Husaini et al, 2008).…”

Potential Application of Bacillus subtilis Lipopeptides in Toothpaste Formulation

“…Produced lipopeptide can be extracted by acid alkali method [10], with phosphate-buffered saline (PBS) [2],by HCl Precipitation[3], [9],centrifugation, filteration [6], [14],acetone precipitation [14].…”

“…The cell growth and the accumulation of metabolic products of a lipopeptide biosurfactant process are strongly influenced by medium compositions such as carbon sources, nitrogen sources, phosphorous sources, growth factors, and inorganic salt concentrations [5].Among the biosurfactant producing potential microbes, Bacillus subtilis are known to produce cyclic lipopeptides (CLPs) including Surfactins, iturins, fengycins, and lichenysins, as the major classes of biosurfactants. Surfactin-cyclic lipopeptide biosurfactant produced by B. subtilis is one of the most effective biosurfactant which can lower the ST and IFT of water and water-n-hexadecane system from 72 to 27 mN/m and 43 to 1 mN/m respectively [3] Bushnell and Hass (1941) were among the first to demonstrate bacterial production of biosurfactants by isolating Corynebacterium simplex and a strain of Pseudomonas in a mineral media containing either kerosene, mineral oil or paraffin [14]. Bacillus subtilis and Bacillus licheniformis are well-known producers of surface active metabolites.…”

“…In this sense, microbial surfactants (also known as biosurfactants) could be among those alternatives given that they are more biodegradable and less cytotoxic than their chemical homologs with the advantage that they can be produced using renewable substrates [13].For many commercial applications in the petroleum and food processing industries biosurfactants play an important role. The potentials of biosurfactants with antimicrobial properties in combating diseases in a world plagued with an increasing prevalence of antibiotics resistance are certainly enormous [14].Bacillus subtilis is also used to produce PHA, PHA is biodegradable, water insoluble, non-toxic, bio-compatible, piezoelectric, thermoplastic, and/or elastomeric. These features make them suitable for applications in the packaging industry and as substitute for hydrocarbon-based plastics [30].…”