Pseudofructophilic Leuconostoc citreum Strain F192-5, Isolated from Satsuma Mandarin Peel

Abstract

Fructophilic lactic acid bacteria (FLAB), composed of Fructobacillus spp., Lactobacillus kunkeei, and Lactobacillus apinorum, 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 Leuconostoc citreum, 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 L. citreum 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 (adhE) 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 adhE gene. Strain F192-5 did, however, ferment d-glucose when transformed with a plasmid containing the allochthonous adhE gene. L. citreum 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 L. citreum. This might be one of the strategies lactic acid bacteria use to adapt to diverse environmental conditions. IMPORTANCE 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. Leuconostoc citreum 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.

Tangerine, banana and pomegranate peels valorisation for sustainable environment: A review

“…For TPW, we found only a few studies that showed the value of its microorganisms, such as the study of Ling et al [ 288 ] that has focused to identify new endophytic yeast strains able to produce Indole-3-acetic acid (IAA) from TPW. Also, Maeno et al [ 289 ] have isolated Pseudofructophilic Leuconostoc citreum Strain F192-5 from TPW able to produce mainly lactate and acetate, with trace amounts of ethanol, from d -glucose metabolism. For PPW, El Barnossi et al [ 283 ] have isolated and identified a Bacillus sp.…”

Unique Niche-specific Adaptation of Fructophilic Lactic Acid Bacteria and Proposal of Three Apilactobacillus Species as Novel Members of the Unique Group 

“…Lactobacillus kosoi, isolated from a sugar-vegetable fermented beverage [21], was recently classi ed as a member of the genus Apilactobacillus [10] but was only recently considered a later heterotypic synonym of A. micheneri [22]. Recent study found a strain of Leuconostoc citreum showing FLAB-like poor D-glucose metabolic property, due to the absence of an active promoter region upstream of the adhE gene [14]. The strain showed distinct genomic characteristics from FLAB, and the strain was thus classi ed as pseudo-FLAB.…”

“…The growth characteristics was due to an inactivation of the adhE gene by deletion of the promoter region upstream of the gene [14]. However, the strain did not have speci c reduction of total CDS and genes involved in carbohydrate transport and metabolism, observed in typical FLAB, and the strain was thus described as pseudo-FLAB.…”

“…The genomic characteristics suggest that FLAB underwent reductive evolution to adapt to fructose-rich niches. Recent study reported a pseudo-FLAB strain belonging to Leuconostoc citreum from satsuma mandarin peel [14]. The strain showed similar growth characteristics to FLAB, i.e.…”

Characterization of fructooligosaccharide metabolism and fructooligosaccharide-degrading enzymes in human commensal butyrate producers

“… 71 Assembly and annotation of the sequences, and quality check of the resulting genomic data were conducted by methods described previously. 72 The genomic data were used to search for GH family enzymes using dbCAN2 in the CAZy database with HMMER, DIAMOND, and Hotpep tools. 73 GH proteins were identified when detected by two of the three tools, as recommended by the database.…”