Genomic characterization of a fructophilic bee symbiont Lactobacillus kunkeei reveals its niche-specific adaptation

<i>Lactobacillus apinorum</i> belongs to the fructophilic lactic acid bacteria

“…Strong NADH oxidase activity (2,982 mU/mg protein) was recorded, but no ADH or ALDH activity was recorded. These results corresponded with those recorded for Fructobacillus species [5, 8]. This agreed well with our previous finding that L. apinorum JCM 30765 T lacks the adhE gene encoding AdhE protein with bifunctional alcohol/acetaldehyde dehydrogenase activities [5].…”

“…It is thus not unusual to isolate FLAB from fructose-rich environments, including flowers, fruits and the guts of fructose-feeding insects [1, 3]. The unique characteristics in FLAB were suggested to be obtained by a reductive evolution that took place to adapt to specific niches [4, 5]. All five species of the genus Fructobacillus are representatives of this unique microbial group [2, 6].…”

“…All five species of the genus Fructobacillus are representatives of this unique microbial group [2, 6]. Until now, Lactobacillus kunkeei has been the only obligate FLAB species reported in the genus Lactobacillus [1, 5]. …”

“…L. apinorum produces acids only from the fermentation of d -glucose and d -fructose [7]. In our previous study [5], we revealed that L. apinorum lacks the bifunctional alcohol/acetaldehyde dehydrogenase gene ( adhE ) essential in heterolactic fermentation. These characteristics implied that the species would be a member of FLAB.…”

“…NADH oxidase activity, which is essential for the oxidation of NADH to NAD + when LAB are grown in the presence of oxygen, was also determined. Culturing, preparation of cell-free extracts and enzyme assays were performed as described previously [5], but with a slight modification. The cells were disrupted in a test tube containing 0.3 g sterile glass beads (0.1 mm in diameter).…”