Pentadiene production from potassium sorbate by osmotolerant yeasts

b Sorbic acid and acetic acid are among the weak organic acid preservatives most commonly used to improve the microbiological stability of foods. They have similar pK a values, but sorbic acid is a far more potent preservative. Weak organic acids are most effective at low pH. Under these circumstances, they are assumed to diffuse across the membrane as neutral undissociated acids. We show here that the level of initial intracellular acidification depends on the concentration of undissociated acid and less on the nature of the acid. Recovery of the internal pH depends on the presence of an energy source, but acidification of the cytosol causes a decrease in glucose flux. Furthermore, sorbic acid is a more potent uncoupler of the membrane potential than acetic acid. Together these effects may also slow the rate of ATP synthesis significantly and may thus (partially) explain sorbic acid's effectiveness.

mentioning

confidence: 99%

Distinct Effects of Sorbic Acid and Acetic Acid on the Electrophysiology and Metabolism of Bacillus subtilis

Beilen

Mattos

Hellingwerf

et al. 2014

“…Some mold and yeast species decarboxylate and thereby detoxify sorbic acid, and their contamination of foods and beverages supplemented with sorbic acid typically leads to "hydrocarbon-like" or "kerosene-like" odors due to 1,3-pentadiene production (3,4,8,10). We have shown recently that S. cerevisiae Pad1p, an enzyme that has been shown previously to decarboxylate cinnamic acid to styrene (5), facilitates the decarboxylation of sorbic acid to the volatile compound 1,3-pentadiene (17).…”

mentioning

confidence: 99%

The Weak-Acid Preservative Sorbic Acid Is Decarboxylated and Detoxified by a Phenylacrylic Acid Decarboxylase, PadA1, in the Spoilage Mold Aspergillus niger

Plumridge

Stratford

Lowe

et al. 2008

“…Z. bailii has also been shown to metabolize benzoic acid and sorbic acid in the presence of the ZbYME2 gene, with benzoic acid being converted via 4-hydroxybenzoic acid (25,26). Sorbic acid decarboxylation to 1,3-pentadiene was reported for Debaryomyces hansenii and Zygosaccharomyces rouxii (4,3).…”

mentioning

confidence: 99%

Decarboxylation of Sorbic Acid by Spoilage Yeasts Is Associated with the PAD1 Gene

Stratford

Plumridge

Archer

2007

The spoilage yeast Saccharomyces cerevisiae degraded the food preservative sorbic acid (2,4-hexadienoic acid) to a volatile hydrocarbon, identified by gas chromatography mass spectrometry as 1,3-pentadiene. The gene responsible was identified as PAD1, previously associated with the decarboxylation of the aromatic carboxylic acids cinnamic acid, ferulic acid, and coumaric acid to styrene, 4-vinylguaiacol, and 4-vinylphenol, respectively. The loss of PAD1 resulted in the simultaneous loss of decarboxylation activity against both sorbic and cinnamic acids. Pad1p is therefore an unusual decarboxylase capable of accepting both aromatic and aliphatic carboxylic acids as substrates. All members of the Saccharomyces genus (sensu stricto) were found to decarboxylate both sorbic and cinnamic acids. PAD1 homologues and decarboxylation activity were found also in Candida albicans, Candida dubliniensis, Debaryomyces hansenii, and Pichia anomala. The decarboxylation of sorbic acid was assessed as a possible mechanism of resistance in spoilage yeasts. The decarboxylation of either sorbic or cinnamic acid was not detected for Zygosaccharomyces, Kazachstania (Saccharomyces sensu lato), Zygotorulaspora, or Torulaspora, the genera containing the most notorious spoilage yeasts. Scatter plots showed no correlation between the extent of sorbic acid decarboxylation and resistance to sorbic acid in spoilage yeasts. Inhibitory concentrations of sorbic acid were almost identical for S. cerevisiae wild-type and ⌬pad1 strains. We concluded that Pad1p-mediated sorbic acid decarboxylation did not constitute a significant mechanism of resistance to weak-acid preservatives by spoilage yeasts, even if the decarboxylation contributed to spoilage through the generation of unpleasant odors.