Microbiologist Cletus Kurtzman has been carrying out research at the National Centre for Agricultural Utilisation Research (NCAUR) that is operated by the Agricultural Research Service (ARS).
The ARS is the United States Department of Agriculture’s (USDA) main research agency.
The team has been researching sophorolipids, which are surfactant-like molecules produced by naturally occurring yeasts.
Kurtzman and his team have focused on the Starmerella yeast family and have screened 19 out of 40 known members for their ability to produce sophorolipids.
The different yeast family members were screened using phylogenetic analysis and mass spectrometry; phylogenetics traces the evolutionary relationships between species or groups.
The research team stated that the use of phylogeny allowed them to determine which of the Starmerella members produced the molecules based on shared gene sequences for the trait.
The research consisted of yeast cultures on a diet of glucose oleic acid; the yeasts’ sophorolipid production levels were measured over a period of 24-to-168 hours, using mass spectrometry, which can identify compounds based on their unique molecular weights.
Among the five Starmerella members which produced sophorolipids, the two that had the highest yields were C. bombicola and C. apicola.
Alternative to petroleum
According to Kurtzman, the findings add to a short list of yeasts which have the potential for use in fermentation-based methods to mass produce sophorolipids as green alternatives to petroleum-derived surfactants.
“Yields from this study are good, and I am sure they could be enhanced markedly in scale-ups,” commented Kurtzman.
Annually, approximately 10 million tonnes of surfactants, which are wetting agents that lower a liquid’s surface tension, are produced.
Most of these surfactants are petroleum-based and thus rely on limited supplies of fossil fuels.