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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Foodborne Toxin Detection and Prevention Research » Research » Publications at this Location » Publication #245146
Title: Fluorescent viability stains to probe the metabolic status of aflatoxigenic fungus in dual culture of Aspergillus flavus and Pichia anomala

Author
item Hua, Sui Sheng
item Brandl, Maria
item Hernlem, Bradley - Brad
item Eng, Jeffrey
item Sarreal, Siov

Submitted to: Mycopathologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2010
Publication Date: 8/2/2010
Citation: Hua, S.T., Brandl, M., Hernlem, B.J., Eng, J.G., Sarreal, S.L. 2011. Fluorescent viability stains to probe the metabolic status of aflatoxigenic fungus in dual culture of Aspergillus flavus and Pichia anomala. Mycopathologia. 171(2):133-138.

Interpretive Summary: Both FUN-1 stain and the combinatorial use of DiBAC4(5) with CDFA-AM stain demonstrated that P. anomala not only inactivated the ATP generating system in A. flavus, but also caused damage in hyphal cell walls and decreased membrane potentials. This study demonstrates the great potential for using viability staining in the evaluation of biocontrol yeast. As we learn more about mechanisms utilized by yeasts to control the target fungus, more effective methods for selecting, formulating and applying biocontrol agents will emerge. Several strains of the yeast species, P. anomala, have been demonstrated to control storage mold in small grains to reduce fruit rot in apple (10) as well as to prevent aflatoxin and ochratoxin contamination by A. flavus and Penicillium roqueforti The Food and Agriculture Organization (FAO) estimates that 25% of the world’s food crops are affected by mycotoxinsof which the most harmful are aflatoxins Therefore the yeast species, P. anomala may be a potential biocontrol agent to reduce mycotoxins in a variety of commodities.

Technical Abstract: The metabolic activity of aflatoxigenic fungus, Aspergillus flavus co-cultured with a biocontrol yeast, Pichia anomala was examined using several vital stains. Both the FUN-1 stain and the combined use of DiBAC4(5) with CDFA-AM stains demonstrated that P. anomala inactivated the ATP generating system in A. flavus and caused damage in hyphal cells as well as decreasing the membrane potential. Reduced metabolic function in conjunction with cell wall damage of A. flavus hindered the growth and biomass production of this fungus. Viability stains, such as FUN-1 and DiBAC4(5) with CDFA-AM may assist in the study of biocontrol interactions by allowing for the visualization of the antagonistic effect of yeast on target fungi in situ. In addition, our results demonstrate great potential for using viability staining in the evaluation of antagonistic activities for screening effective biocontrol yeasts agents against fungal pathogens.