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Weak-acid preservatives commonly used to prevent fungal spoilage of low pH foods include sorbic and acetic acids. The "classical weak-acid theory" proposes that weak acids inhibit spoilage organisms by diffusion of undissociated acids through the membrane, dissociation within the cell to protons and anions, and consequent acidification of the cytoplasm.(More)
Weak-acid preservatives, such as sorbic acid and acetic acid, are used in many low pH foods to prevent spoilage by fungi. The spoilage yeast Zygosaccharomyces bailii is notorious for its extreme resistance to preservatives and ability to grow in excess of legally-permitted concentrations of preservatives. Extreme resistance was confirmed in 38 strains of Z.(More)
The early stages of development of Aspergillus niger conidia during outgrowth were explored by combining genome-wide gene expression analysis (RNAseq), proteomics, Warburg manometry and uptake studies. Resting conidia suspended in water were demonstrated for the first time to be metabolically active as low levels of oxygen uptake and the generation of(More)
Genome-wide analysis was performed to assess the transcriptional landscape of germinating A. niger conidia using both next generation RNA-sequencing and GeneChips. The metabolism of storage compounds during conidial germination was also examined and compared to the transcript levels from associated genes. The transcriptome of dormant conidia was shown to be(More)
The ability to resist anti-microbial compounds is of key evolutionary benefit to microorganisms. Aspergillus niger has previously been shown to require the activity of a phenylacrylic acid decarboxylase (encoded by padA1) for the decarboxylation of the weak-acid preservative sorbic acid (2,4-hexadienoic acid) to 1,3-pentadiene. It is now shown that this(More)
Moulds are able to cause spoilage in preserved foods through degradation of the preservatives using the Pad-decarboxylation system. This causes, for example, decarboxylation of the preservative sorbic acid to 1,3-pentadiene, a volatile compound with a kerosene-like odour. Neither the natural role of this system nor the range of potential substrates has yet(More)
The food spoilage yeast Zygosaccharomyces bailii shows great resistance to weak-acid preservatives, including sorbic acid (2, 4-hexadienoic acid). That extreme resistance was shown to be due to population heterogeneity, with a small sub-population of cells resistant to a variety of weak acids, probably caused by a lower internal pH reducing the uptake of(More)
AIMS To assess whether assimilation tests in isolation remain a valid method of identification of yeasts, when applied to a wide range of environmental and spoilage isolates. METHODS AND RESULTS Seventy-one yeast strains were isolated from a soft drinks factory. These were identified using assimilation tests and by D1/D2 rDNA sequencing. When compared to(More)
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