Role of a membrane-bound aldehyde dehydrogenase complex AldFGH in acetic acid fermentation with Acetobacter pasteurianus SKU1108
Role of a membrane-bound aldehyde dehydrogenase complex AldFGH in acetic acid fermentation with Acetobacter pasteurianus SKU1108
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DOI：
10.1007/s00253-018-8940-6
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发表时间：
2018-04
影响因子：
5
通讯作者：
T. Yakushi;Seiya Fukunari;T. Kodama;Minenosuke Matsutani;Shun Nina;Naoya Kataoka;G. Theeragool;
中科院分区：
文献类型：
--
作者：
T. Yakushi;Seiya Fukunari;T. Kodama;Minenosuke Matsutani;Shun Nina;Naoya Kataoka;G. Theeragool;
醋酸发酵被广泛认为是醋酸菌的两种膜结合酶--乙醇脱氢酶和乙醛脱氢酶(ALDH)氧化乙醇的结果。在这里，我们使用无标记基因中断的方法构建了编码异源三聚体ALDH复合体(AldFGH)大催化亚基的突变株SKU1108，以检测AldFGH在醋酸发酵中的作用。ΔaldH菌株在含乙醇的基础上，即在醋酸发酵条件下的生长速度低于野生型菌株，并且显著积累了乙醛。出乎意料的是，完整的ΔaldH细胞和ΔaldH细胞膜的乙醛氧化酶活性水平与野生型相似，这可能是由于额外的一种aldslc同工酶。当细胞在非发酵条件下培养时，野生型细胞和野生型细胞对乙醛的表观KM值相似，野生型细胞和野生型细胞在非发酵条件下生长时对乙醛的表观KM值相同。然而，在发酵条件下生长的野生型细胞的膜的KM值明显低于在非发酵条件下生长的细胞的KM值。在发酵条件下，AldSLC基因的转录水平比非发酵条件下低10倍，而H转录水平在两种条件下变化不大。我们建议这样做。巴氏杆菌SKU1108含有两个ALDH，而AldFGH复合体是醋酸发酵所必需的，也是发酵条件下的主要酶。
Acetic acid fermentation is widely considered a consequence of ethanol oxidation by two membrane-bound enzymes—alcohol dehydrogenase and aldehyde dehydrogenase (ALDH)—of acetic acid bacteria. Here, we used a markerless gene disruption method to construct a mutant of theAcetobacter pasteurianusstrain SKU1108 with a deletion in thealdHgene, which encodes the large catalytic subunit of a heterotrimeric ALDH complex (AldFGH), to examine the role of AldFGH in acetic acid fermentation. The ΔaldHstrain grew less on ethanol-containing medium, i.e., acetic acid fermentation conditions, than the wild-type strain and significantly accumulated acetaldehyde in the culture medium. Unexpectedly, acetaldehyde oxidase activity levels of the intact ΔaldHcells and the ΔaldHcell membranes were similar to those of the wild-type strain, which might be attributed to an additional ALDH isozyme (AldSLC). The apparentKMvalues of the wild-type and ΔaldHmembranes for acetaldehyde were similar to each other, when the cells were cultured in nonfermentation conditions, where ΔaldHcells grow as well as the wild-type cells. However, the membranes of the wild-type cells grown under fermentation conditions showed a 10-fold lower apparentKMvalue than those of the cells grown under nonfermentation conditions. Under fermentation conditions, transcriptional levels of a gene for AldSLC were 10-fold lower than those under nonfermentation conditions, whereasaldHtranscript levels were not dramatically changed under the two conditions. We suggest thatA. pasteurianusSKU1108 has two ALDHs, and the AldFGH complex is indispensable for acetic acid fermentation and is the major enzyme under fermentation conditions.