Open Access
Positive selection on D‐lactate dehydrogenases of Lactobacillus delbrueckii subspecies bulgaricus
Author(s) -
Zhang Jifeng,
Gong Guangyu,
Wang Xiao,
Zhang Hao,
Tian Weidong
Publication year - 2015
Publication title -
iet systems biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.367
H-Index - 50
eISSN - 1751-8857
pISSN - 1751-8849
DOI - 10.1049/iet-syb.2014.0056
Subject(s) - lactobacillus delbrueckii subsp. bulgaricus , phylogenetic tree , lactobacillus , lactic acid , biology , phylogenetics , gene , biochemistry , domestication , lactobacillus acidophilus , lactobacillaceae , fermentation , genetics , bacteria , probiotic
Lactobacillus delbrueckii has been widely used for yogurt fermentation. It has genes encoding both D‐ and L‐type lactate dehydrogenases (LDHs) that catalyse the production of L(+) or D(−) stereoisomer of lactic acid. D‐lactic acid is the primary lactate product by L. delbrueckii , yet it cannot be metabolised by human intestine. Since it has been domesticated for long time, an interesting question arises regarding to whether the selection pressure has affected the evolution of both L‐LDH and D‐LDH genes in the genome. To answer this question, in this study the authors first investigated the evolution of these two genes by constructing phylogenetic trees. They found that D‐LDH‐based phylogenetic tree could better represent the phylogenetic relationship in the acidophilus complex than L‐LDH‐based tree. They next investigated the evolutions of LDH genes of L. delbrueckii at amino acid level, and found that D‐LDH gene in L. delbrueckii is positively selected, possibly a consequence of long‐term domestication. They further identified four amino acids that are under positive selection. One of them, V261, is located at the centre of three catalytic active sites, indicating likely functional effects on the enzyme activity. The selection from the domestication process thus provides direction for future engineering of D‐LDH.