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Yeast biocontrol of grain spoilage moulds

mode of action of Pichia anomala

Ädel Druvefors, Ulrika (2004). Yeast biocontrol of grain spoilage moulds. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Agraria, 1401-6249 ; 466
ISBN 91-576-6493-5
[Doctoral thesis]

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The biocontrol yeast Pichia anomala J121 prevents mould spoilage by Penicillium roqueforti and prolongs the safe storage of moist cereal grain in malfunctioning airtight storage systems. P. anomala is naturally occurring on grain and is classified as safe, i.e. biosafety level 1 microorganism. Strain J121 does not grow above 37°C and is sensitive to commonly used antifungal drugs. The ability of P. anomala to prevent mould growth during 14 months of wheat grain storage was evaluated in outdoor silos with different air permeability. P. anomala rapidly consumed O2 leaking into the silo during the spring, and P. roqueforti did not grow in treatments inoculated with P. anomala. A connection between production of the ester ethyl acetate and biocontrol activity was found. The biocontrol effect was enhanced when complex medium or glucose was added to grain minisilos. The addition did not markedly influence yeast cell numbers, but products of glucose metabolism, ethyl acetate in particular and ethanol, increased. When a diploid and a haploid strain of Pichia anomala were tested at two water activities (aw) for biocontrol ability in grain minisilos, the two yeast strains grew and inhibited mould growth equally well and showed similar patterns of ethyl acetate production at the higher aw. However, at lower aw the growth, biocontrol performance and ethyl acetate production of the haploid strain were reduced. The biocontrol activity of an additional 57 yeast species was evaluated in grain minisilos. Most yeast species grew to levels comparable to that of P. anomala J121, but only six other species strongly inhibited P. roqueforti. The biocontrol activity of Candida fennica and Candida silvicultrix is reported for the first time. The ability of 27 yeast species to grow to high CFU values without inhibiting mold growth, and the increase in biocontrol activity after nutrient addition, indicates that nutrient competition is not the main reason for mould inhibition in the system. Instead, a combination of ethyl acetate production and rapid consumption of oxygen leaking into the system could be the main inhibitory mechanism.

Authors/Creators:Ädel Druvefors, Ulrika
Title:Yeast biocontrol of grain spoilage moulds
Subtitle:mode of action of Pichia anomala
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Agraria
Year of publishing :May 2004
Number of Pages:44
ALLI. Fredlund, E., Druvefors, U. Boysen, M.E., Lingsten, K-J. & Schnürer, J. (2002). Physiological characteristics of the biocontrol yeast Pichia anomala J121. FEMS Yeast Research. 2:395-402. II. Druvefors, U., Jonsson, N., Boysen, M.E. & Schnürer J. (2002) Efficacy of the biocontrol yeast Pichia anomala during long-term storage of moist feed grain under different oxygen and carbon dioxide regimens. FEMS Yeast Research. 2: 389-394. III. Druvefors, U.Ä. & Schnürer, J. Mould inhibitory activity of different yeast species during wheat grain storage. (Submitted). IV. Druvefors, U.Ä., Passoth, V. & Schnürer, J. Nutrient effects on biocontrol of Penicillium roqueforti by Pichia anomala J121 in cereal grain. (Manuscript). V. Fredlund, E., Druvefors, U.Ä., Olstorpe, M.N., Passoth, V. & Schnürer, J. Influence of ethyl acetate production and ploidy level on the anti-mould activity of Pichia anomala. (Submitted).
Place of Publication:Uppsala
ISBN for printed version:91-576-6493-5
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:J Handling, transport, storage and protection of agricultural products > J10 Handling, transport, storage and protection of agricultural products
Subjects:Not in use, please see Agris categories
Agrovoc terms:yeasts, pichia, penicillium roquefortii, biological control, candida, storage, moulds
Keywords:Pichia anomala, Penicillium roqueforti, ethyl acetate, competition for nutrients, airtight storage, Candida fennica, Candida silvicultrix, Pichia farinosa, antifungal, biocontrol
Permanent URL:
ID Code:552
Department:(NL, NJ) > Dept. of Microbiology (until 161231)
Deposited By: Ulrika Ädel Druvefors
Deposited On:04 May 2004 00:00
Metadata Last Modified:02 Dec 2014 10:05

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