Fructilactobacillus frigidiflavus sp. nov., a pigmented species, and Levilactobacillus lettrarii sp. nov., a propionate-producing species isolated from sourdough

The sourdough isolates FUA3702, FUA3912 and FUA3913^T, as well as FUA3695^T and FUA3914, could not be identified to known species of the <i>Lactobacillaceae</i>. The 16S rRNA gene sequences of FUA3702 and FUA3913, FUA3695 and FUA3914 were>99% identical to <i>Fructilactobacillus sanfranciscensis</i> and <i>Levilactobacillus lanxiensis</i>, respectively. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of strain FUA3913^T when compared to <i>Fl. sanfranciscensis</i> were 83.67 and 26.60%, respectively. In addition, strains FUA3702, FUA3912 and FUA3913^T produce different levels of a yellow C30 carotenoid, but pigmentation has not been described in <i>Fl. sanfranciscensis</i>. The ANI and dDDH values of FUA3695^T and FUA3914 when compared to <i>Lv. langxiensis</i> were 95.22 and 61.20%, respectively. In addition, FUA3695 and FUA3914 convert lactate to 1,2-propanediol and further to propionate. The conversion of lactate to propionate by a single strain has not been documented for any of the species in the <i>Lactobacillaceae</i>. Based on the genomic and physiological characteristics, we proposed the novel species <i>Fructilactobacillus frigidiflavus</i> sp. nov. FUA3913^T (=DSM 118650^T=LMG 33758^T) and <i>Levilactobacillus lettrarii</i> sp. nov. FUA3695^T (=DSM 118651^T=LMG 33759^T).