Department of Food, Aroma and Cosmetic Chemistry, Tokyo University of Agriculture, Hokkaido, Japan.
Bioinformation and DDBJ Center, National Institute of Genetics, Shizuoka, Japan.
Appl Environ Microbiol. 2019 Oct 1;85(20). doi: 10.1128/AEM.01077-19. Print 2019 Oct 15.
Fructophilic lactic acid bacteria (FLAB), composed of spp., , and , are unique in that they prefer d-fructose over d-glucose as a carbon source. Strain F192-5, isolated from the peel of a satsuma mandarin and identified as , grows well on d-fructose but poorly on d-glucose and produces mainly lactate and acetate, with trace amounts of ethanol, from the metabolism of d-glucose. These characteristics are identical to those of obligate FLAB. However, strain F192-5 ferments a greater variety of carbohydrates than known FLAB. Comparative analyses of the genomes of strain F192-5 and reference strains of revealed no signs of specific gene reductions, especially genes involved in carbohydrate transport and metabolism, in the genome of F192-5. The bifunctional alcohol/acetaldehyde dehydrogenase gene () is conserved in strain F192-5 but is not transcribed. This is most likely due to a deletion in the promoter region upstream of the gene. Strain F192-5 did, however, ferment d-glucose when transformed with a plasmid containing the allochthonous gene. F192-5 is an example of a pseudo-FLAB strain with a deficiency in d-glucose metabolism. This unique phenotypic characteristic appears to be strain specific within the species This might be one of the strategies lactic acid bacteria use to adapt to diverse environmental conditions. Obligate fructophilic lactic acid bacteria (FLAB) lack the metabolic pathways used in the metabolism of most carbohydrates and differ from other lactic acid bacteria in that they prefer to ferment d-fructose instead of d-glucose. These characteristics are well conserved at the genus or species level. F192-5 shows similar growth characteristics. However, the strain is metabolically and genomically different from obligate FLAB. This is an example of a strain that evolved a pseudo-FLAB phenotype to adapt to a fructose-rich environment.
嗜果糖乳酸细菌（FLAB）由 spp.、、和组成，它们的独特之处在于它们更喜欢 d-果糖而不是 d-葡萄糖作为碳源。菌株 F192-5 从温州蜜柑果皮中分离出来，被鉴定为，它在 d-果糖上生长良好，但在 d-葡萄糖上生长不良，并且主要从 d-葡萄糖代谢产生乳酸和乙酸，只有痕量的乙醇。这些特征与专性 FLAB 相同。然而，菌株 F192-5 比已知的 FLAB 发酵更多种类的碳水化合物。对 F192-5 菌株和参考菌株的基因组进行比较分析表明，F192-5 基因组中没有特定基因减少的迹象，特别是涉及碳水化合物运输和代谢的基因。双功能醇/乙醛脱氢酶基因（）在 F192-5 菌株中保守，但不转录。这很可能是由于 基因上游启动子区域的缺失。然而，当 F192-5 菌株转化含有异源基因的质粒时，它确实可以发酵 d-葡萄糖。F192-5 是一种缺乏 d-葡萄糖代谢的假 FLAB 菌株的例子。这种独特的表型特征在种内似乎是菌株特异性的。这可能是乳酸菌适应不同环境条件的策略之一。专性嗜果糖乳酸细菌（FLAB）缺乏大多数碳水化合物代谢中使用的代谢途径，与其他乳酸细菌不同的是，它们更喜欢发酵 d-果糖而不是 d-葡萄糖。这些特征在属或种水平上很好地保守。F192-5 表现出相似的生长特征。然而，该菌株在代谢和基因组上与专性 FLAB 不同。这是一个菌株适应富含果糖环境而进化出假 FLAB 表型的例子。
