Summary auto-generated
Two Lactobacillus strains (OND 32T and YAM 1) were isolated from cassava sour starch fermentation in Colombia. These strains are Gram-positive, non-spore-forming, catalase-negative rods that produce only L-lactic acid through homofermentation. Both strains can degrade starch, though OND 32T produces extracellular amylase while YAM 1 has cell-linked amylolytic activity. The strains grow at pH 5.0-7.0 (optimal at 6.0) and temperatures of 15-45°C (optimal at 30°C), with DNA G+C content of 48.4±0.2 mol%. Molecular analysis, including 16S rRNA gene sequencing and SDS-PAGE protein profiling, revealed these isolates represent a previously undescribed species. The new isolates cluster phylogenetically with the Lactobacillus casei group but form a distinct lineage. Based on morphological, physiological, biochemical, and genetic characterization, the authors propose the name Lactobacillus manihotivorans for this species, with OND 32T as the type strain. This discovery represents an addition to the limited known amylolytic lactic acid bacteria from food fermentation ecosystems.
Key findings
- Two new Lactobacillus strains isolated from Colombian cassava fermentation represent a novel species designated Lactobacillus manihotivorans, with OND 32T as the type strain
- Both strains are homofermentative, producing only L-lactic acid, and possess starch-degrading capability, with different localization of amylolytic activity between strains
- Phylogenetic analysis of 16S rRNA gene sequences shows the new species is most closely related to Lactobacillus casei group but forms a separate and distinct lineage
- The strains have DNA G+C content of 48.4±0.2 mol% and share 99.4% 16S rRNA similarity, confirming species identity while being distinct from previously described amylolytic lactobacilli
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Abstract
Two Lactobacillus strains were isolated from sour cassava starch fermentation. The cells were Gram-positive, catalase-negative, non-spore-forming, nonmotile rods. They produced only L(+)lactate and were homofermentative. Growth occurred at pH values of 5·0-7·0 and optimum growth occurred at pH 6·0. Growth was positive at 15 and 45 °C. The DNA G+C content was 48·4±0·2 mol%. Sequence analysis of the 16S rRNA gene revealed that strains OND 32Tand YAM 1 clustered with, but were separate from Lactobacillus casei-related taxa. Protein pattern and sequence analyses of the 16S rRNA gene confirmed that the two new isolates represent a new Lactobacillus species, for which the name Lactobacillus manihotivorans is proposed; strain OND 32Tis the type strain of this species.