ABSTRACT
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 Δ
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.
摘要
腐败酵母
酵母菌
将食品防腐剂山梨酸(2,4-己二烯酸)降解为一种挥发性碳氢化合物,经气相色谱质谱鉴定为 1,3-戊二烯。负责的基因被确定为
PAD1
该基因以前与将芳香羧酸肉桂酸、阿魏酸和香豆酸分别脱羧为苯乙烯、4-乙烯基愈创木酚和 4-乙烯基苯酚有关。损失
PAD1
的缺失导致了山梨酸和肉桂酸脱羧活性的同时丧失。因此,Pad1p 是一种不同寻常的脱羧酶,能够接受芳香族和脂肪族羧酸作为底物。所有
酵母菌
属(sensu stricto)的所有成员都能对山梨酸和肉桂酸进行脱羧。
PAD1
的同源物和脱羧活性。
白念珠菌、杜布林念珠菌、汉森德巴里酵母菌
和
Pichia anomala
.山梨酸的脱羧作用被评估为腐败酵母菌产生抗性的一种可能机制。山梨酸或肉桂酸的脱羧作用在酵母菌中均未检测到。
酵母菌、卡扎兹塔尼亚酵母菌
(
酵母菌
saccharomyces)、
酵母菌
或
酵母属
这些属含有最臭名昭著的腐败酵母菌。散点图显示,山梨酸脱羧程度与腐败酵母菌对山梨酸的抗性之间没有相关性。山梨酸的抑制浓度对于
野生型和
野生型和
pad1
菌株的山梨酸抑制浓度几乎相同。我们的结论是,Pad1p 介导的山梨酸脱羧作用并不构成腐败酵母菌抵抗弱酸性防腐剂的重要机制,即使脱羧作用会通过产生难闻的气味而导致腐败。