Lactobacillus paragasseri lg94 With High L-Lactic Acid Production and Probiotic Potential

Lactobacillus paragasseri strains are widely used as probiotics. According to modern requirements, it is necessary to characterize their morphological, cultural, physiological-biochemical, and antagonistic properties, as well as to determine their virulence, toxigenicity, toxicity, and secondary metabolite production, to study their potential and safety. The main aim of the study was to determine the probiotic potential of the L. paragasseri lg94 strain based on its biochemical features and genomic landscape.

L. paragasseri lg94 was isolated from human feces. The genus and species were determined by mass spectrometry using the MALDI Biotyper. The main cultural, biochemical, and genomic characteristics of L. paragasseri lg94 were established. The biochemical profile and L-lactic acid content of the strain were determined. Additionally, the strain's resistance to bile and low pH stress, as well as its antibiotic susceptibility, were assessed. The genomic sequence of strain lg94 was obtained using Illumina NextSeq550 sequencing.

In this study, the strain lg94 isolated from the feces of a healthy child was identified as L. paragasseri. After 24 h of cultivation in API 50 CH/CHL medium, strain lg94 exhibited positive results in the fermentation of 25 carbohydrates. Strain lg94 exhibited intense L-lactic acid production, reaching a concentration of 6.41 g/L in 24 h of cultivation, indicating high acid-forming capacity. The results showed that L. paragasseri lg94 demonstrated low resistance to acid stress (pH 2.0) but high resistance to 0.3% bile, with no changes in colony morphology observed. The disk diffusion assay revealed that L. paragasseri lg94 was phenotypically susceptible to several antibiotics, including ampicillin, amoxicillin, penicillin G, tetracycline, erythromycin, and chloramphenicol, with intermediate resistance to oxacillin and resistance to fosfomycin, gentamicin, and clindamycin. The whole-genome of L. paragasseri lg94 was sequenced. The absence of antibiotic resistance, pathogenicity, and virulence determinants in the genome was confirmed. Strain lg94 has genes for the production of gassericin T, enterolysin A, and helveticin J.

The results of the studies showed that L. paragasseri lg94 has probiotic potential, and it is recommended to continue studying its antagonistic activity and secondary metabolite production.