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Researchers tap yeasts as source of 'green' surfactants

Date:
July 28, 2011
Source:
USDA/Agricultural Research Service
Summary:
Surfactants, which are wetting agents that lower a liquid's surface tension, have a long list of uses, from detergents and cosmetics to paints and pesticides. Most surfactants are petroleum-based. But one group of scientists has now focused its attention on sophorolipids, surfactant-like molecules produced by naturally occurring yeasts.
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ARS microbiologist Cletus Kurtzman is screening yeasts like these for their ability to produce surfactant-like molecules called sophorolipids that could be green alternatives to petroleum-derived surfactants.
Credit: Photo courtesy of Cletus Kurtzman, ARS

Surfactants, which are wetting agents that lower a liquid's surface tension, have a long list of uses, from detergents and cosmetics to paints and pesticides. Most surfactants are petroleum-based. But in Peoria, Ill., a team of U.S. Department of Agriculture (USDA) scientists has focused their attention on sophorolipids, surfactant-like molecules produced by naturally occurring yeasts.

Microbiologist Cletus Kurtzman is spearheading the studies at the National Center for Agricultural Utilization Research (NCAUR), operated in Peoria by the Agricultural Research Service (ARS), USDA's chief intramural scientific research agency.

Using phylogenetic analysis and mass-spectrometry, Kurtzman's team screened 19 of the 40 known members of the Starmerella yeast family for their ability to produce the sophorolipids. Phylogenetics, which traces the evolutionary relationships between species or groups, was particularly useful because it enabled the team to determine which Starmerella members produce the molecules based on shared gene sequences for the trait. For example, only a few Candida yeast species had previously been shown to make the sophorolipids -- most notably, C. bombicola and C. apicola.

Kurtzman's team was able to broaden its search by tapping the ARS (microbial) Culture Collection, maintained at the Peoria center's Bacterial Foodborne Pathogens and Mycology Research Unit.

In studies there, the researchers cultured the yeasts on a diet of glucose oleic acid. They then measured the yeasts' sophorolipid production levels over a 24- to 168-hour period using mass-spectrometry analysis, which can identify compounds based on their unique molecular weights.

As expected, C. bombicola and C. apicola boasted the highest sophorolipid yields. They weren't the only ones, though: The team's analysis also turned up three other high-producing yeasts, including a new Candida species.

According to Kurtzman, the findings add to a short list of candidate yeasts with potential use in fermentation-based methods of mass-producing the sophorolipids as green alternatives to petroleum-derived surfactants.

He and ARS team members Neil Price, Karen Ray and the late Tsung-Min Kuo reported their work in FEMS Microbiology Letters.


Story Source:

The above post is reprinted from materials provided by USDA/Agricultural Research Service. The original item was written by Jan Suszkiw. Note: Materials may be edited for content and length.


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USDA/Agricultural Research Service. "Researchers tap yeasts as source of 'green' surfactants." ScienceDaily. ScienceDaily, 28 July 2011. <www.sciencedaily.com/releases/2011/07/110728111540.htm>.
USDA/Agricultural Research Service. (2011, July 28). Researchers tap yeasts as source of 'green' surfactants. ScienceDaily. Retrieved July 30, 2015 from www.sciencedaily.com/releases/2011/07/110728111540.htm
USDA/Agricultural Research Service. "Researchers tap yeasts as source of 'green' surfactants." ScienceDaily. www.sciencedaily.com/releases/2011/07/110728111540.htm (accessed July 30, 2015).

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