Polyol production during heterofermentative growth of the plant isolate Lactobacillus florum 2F

Abstract

Aims: This study examined the fermentative growth and polyol production of Lactobacillus florum and other plant-associated lactic acid bacteria (LAB). Methods and Results: Sugar consumption and end-product production were measured for Lact. florum 2F in the presence of fructose, glucose and both sugars combined. The genome of Lact. florum was examined for genes required for mannitol and erythritol biosynthesis. The capacity for other plantassociated LAB to synthesize polyols was also assessed. Conclusions: Lactobacillus florum exhibited higher growth rates and cell yields in the presence of both fructose and glucose. Lactobacillus florum 2F produced lactate, acetate and ethanol as well as erythritol and mannitol. Lactobacillus florum 2F synthesized mannitol during growth on fructose and erythritol during growth on glucose. Gene and protein homology searches identified a mannitol dehydrogenase in the Lact. florum 2F genome but not the genes responsible for erythritol biosynthesis. Lastly, we found that numerous other heterofermentative LAB species synthesize erythritol and/or mannitol. Significance and Impact of the Study: Lactobacillus florum is a recently identified, plant-associated, fructophilic LAB species. Our results show that Lact. florum growth rates and heterofermentation end-products differ depending on the sugar substrates present and growth yields can be improved when combinations of sugars are provided. Lactobacillus florum 2F produces erythritol and mannitol, two polyols that are relevant to foods and potentially also in plant environments. The capacity for polyol biosynthesis appears to be common among plant-associated, LAB species.

Antifungal Activity of Lactobacillus pentosus ŁOCK 0979 in the Presence of Polyols and Galactosyl-Polyols

“…In the presented experiments, L. pentosus ŁOCK 0979 exhibited the ability to partially absorb lactitol, mannitol, and all the tested galactosyl-polyols. While Tyler et al [ 30 ] isolated Lactobacillus florum 2F, a heterofermentative strain which can biosynthesize erythritol and mannitol, the consumption of polyols and galactosyl-polyols by Lactobacillus bacteria represents a new line of research with scant available literature.…”

Abundance, diversity and plant‐specific adaptations of plant‐associated lactic acid bacteria

“…Fructobacillus is comprised of five species ( F. fructosus , F. durionis , F. ficulneus , F. pseudoficulneus and F. tropaeoli ) and has only been isolated from fructose‐rich environments (flowers, fruits and bee digestive tracts) (Endo et al ., ; ). Species of Fructobacillus and several species of Lactobacillus ( L. apinorum , L kunkeei and L. florum ) are categorized as fructophilic LAB (FLAB), which are known for their fructophilic as opposed to glucophilic metabolism (Endo et al ., ; ; Tyler et al ., ). Consistent with the specialization of these bacteria to fructose‐rich environments, the proportions of genes coding for carbohydrate transport and metabolism in FLAB genomes are lower than compared to closely related glucophilic species (Endo et al ., ).…”

“…This species was first isolated from peony ( Paeonia suffruticosa ) and bietou ( Chrysanthemoides monilifera ) flowers and thus far has only been isolated from flowers, fruits and wine (Endo et al ., ; ; Kim et al ., ). Consistent with ecological specialization, the saccharolytic metabolism of L. florum is constrained to fructose and glucose (Endo et al ., ; Tyler et al ., ). Other FLAB only grow well in the presence of fructose.…”

Fructophilic Lactic Acid Bacteria, a Unique Group of Fructose-Fermenting Microbes

“…These results suggest that the strain may be considered a promising candidate for industrial mannitol production. Besides mannitol formation, certain FLAB strains also produce trace amounts of erythritol (15,80), which is a calorie-free polyol that is effective in managing oral health (81).…”