IngentaConnect Yeast proteinsurfactant complexes uncouple microbial electron tra...

Authors: Podella, C.W.¹; Hooshnam, N.¹; Krassner, S.M.²; Goldfeld, M.G.¹

Source: Journal of Applied Microbiology, Volume 106, Number 1, January 2009 , pp. 140-148(9)

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Abstract:

Aims:

To explore the combined effect of yeast proteins and surfactants on bacterial metabolism. Methods and Results:

Protein-rich cell-free supernatant from heat-shocked yeast Saccharomyces cerevisiae was combined with certain synthetic surfactants. These blends affected the metabolism of a Polyseed inoculum of aerobic bacteria, accelerating CO₂ production and consumption of nutrients from a sterile nutrient broth solution, without a concomitant accumulation of biomass. It is suggested that in the presence of the yeast protein-surfactant complexes, bacterial electron transport is uncoupled from biomass accumulation. The `uncoupling hypothesis' is supported by experiments with model membranes, in which the same complexes induced proton leak similar to standard chemical uncouplers, such as dinitrophenol, indicating that uncoupling may occur at the stage of generation of the transmembrane pH gradient as the driving force for ATP production. Conclusions:

Yeast protein-surfactant complexes behave as uncouplers of oxidative metabolism in bacteria and appear to do so by increasing proton permeability of membranes. Significance and Impact of the Study:

Yeast proteins may be of interest as nontoxic, environmentally benign and economically sound agents accelerating oxidative bacterial metabolism while uncoupling it from biomass accumulation. There are actual and potential implications in waste water/soil decontamination, degreasing and other environmental technologies.

Keywords: degreasing; heat-shock proteins; microbial metabolism; proton transfer; soil decontamination; uncoupling; water; yeast

Document Type: Research article

DOI: 10.1111/j.1365-2672.2008.03986.x

Affiliations: 1: Advanced Biocatalytics Corporation, Irvine, CA, USA 2: Department of Developmental and Cell Biology, University of California, Irvine, CA, USA

Yeast protein-surfactant complexes uncouple microbial electron transfer and increase transmembrane leak of protons