Biosurfactant production by yeasts isolated from hydrocarbon polluted environments

Abstract

Thirty-two yeast isolates were retrieved from four soil samples collected from hydrocarbon-polluted locations of Hisar, Haryana, using enrichment culture technique with 1% (v/v) diesel as carbon source. Total nine isolates showing blood agar haemolysis were screened further for biosurfactant production. Yeast isolate, YK32, gave highest 8.4-cm oil displacement which was found to be significantly higher as compared to positive control, 0.2% (w/v) SDS (6.6 cm), followed by 6.2 and 6.0 cm by isolates YK20 and YK21, respectively. Maximum emulsification index was obtained in case of isolates YK20 and YK21 measuring 53.8%, after 6 days of incubation utilizing glucose as carbon source, whereas isolate YK32 was found to be reducing surface tension up to 93 dynes/cm and presented 99.6% degree of hydrophobicity. Olive oil has supported maximum surface tension reduction in isolates YK32 and YK21 equivalent to 53 and 48 dynes/cm and gave 88.3 and 88.5% degree of hydrophobicity, respectively. Diesel was not preferred as carbon source by most of the isolates except YK28 which generated 5.5-cm oil displacement, 25% emulsification index, reduced surface tension to the level of 38 dynes/cm and presented 89% degree of hydrophobicity. Conclusively, isolates YK20, YK21, YK22 and YK32 were marked as promising biosurfactant producers and were subjected to identification. Based on microscopic examination and biochemical peculiarities, isolates YK21 and YK22 might be identified as Candida spp., whereas, isolates YK20 and YK32 might be identified as Saccharomycopsis spp. and Brettanomyces spp., respectively. Interestingly it is the first report indicating Saccharomycopsis spp. and Brettanomyces spp. as a potential biosurfactant producer.

Candida pseudoglaebosaandKodamaea ohmeriare capable of degrading alkanes in the presence of heavy metals

“…About 10 genera of hydrocarbonoclastic Saccharomycetales yeasts have been described from 2011 to date, including the following species: Brettanomyces, Candida, Lypomyces, Meyerozyma, Pichia, Pseudozyma, Saccharomycopsis, Starmerella, Yamadazyma, and Yarrowia [30][31][32][33][34][35][36]. To our knowledge, this is the first report of a hydrocarbonoclastic phenotype for a K. ohmeri or C. pseudoglaebosa strain.…”

Candida pseudoglaebosa and Kodamaea ohmeri are capable of degrading alkanes in the presence of heavy metals

“…About 10 genera of hydrocarbonoclastic Saccharomycetales yeasts have been described from 2011 to date, including the following species: Brettanomyces , Candida , Lypomyces , Meyerozyma , Pichia , Pseudozyma , Saccharomycopsis , Starmerella , Yamadazyma , and Yarrowia . To our knowledge, this is the first report of a hydrocarbonoclastic phenotype for a K. ohmeri or C. pseudoglaebosa strain.…”

Fungal biosurfactants, from nature to biotechnological product: bioprospection, production and potential applications

“…The fungus surface is considered hydrophobic when more than 50% of the cells migrate from the buffer (PUM—phosphate, urea, magnesium) to the hexadecane. On the other hand, it is considered hydrophilic when more than 50% of the cells remain in the buffer [ 199 ].

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