Palm wine is produced by the spontaneous fermentation of fresh sap from various palm species, including coconut palm, oil palm, date palm, nipa palm, and raffia palm. Unfermented sap is a colourless, sweet syrup with a sugar content of ten to twelve percent, and its fermentation generates a complex microbial community dominated by yeasts and lactic acid bacteria. Beyond its nutritional value, palm wine holds deep cultural significance across West Africa, featuring prominently in ancestral rites, traditional ceremonies, and folk medicine. Its production also represents a vital economic activity, employing up to seventy-five percent of men in some palm-growing communities and generating approximately ten thousand litres per day.

The research team, led by Hanzi Karen Kouamé from the Laboratory of Biotechnology and Food Microbiology at Nangui Abrogoua University, previously isolated and identified lactic acid bacteria from palm wine produced in Côte d’Ivoire using sixteen S ribosomal RNA sequencing. For the current investigation, they pre-selected ten strains based on their high acidifying power, a discriminating technological criterion for lactic acid bacteria. These strains belonged to species including Lactococcus lactis, Fructobacillus durionis, Lacticaseibacillus paracasei, Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides, and Weissella cibaria. The acidifying assays revealed pH variations between zero point one and two point eight units and increases in titratable acidity ranging from zero point one zero to one point four zero percent after twenty-four hours of incubation, with significant differences observed among strains.

The technological characterization extended to physiological and biochemical stress tolerance. All ten strains grew at three percent sodium chloride, while only eight tolerated six point five percent, and none survived ten percent. Temperature profiling distinguished mesophilic from thermotolerant isolates: all strains grew strongly at thirty degrees Celsius, but only four strains, including Fructobacillus durionis S24 and S28, Lactococcus lactis S7, and Leuconostoc pseudomesenteroides S135, showed robust growth at forty-five degrees Celsius. Growth at pH two was demonstrated by six strains, while all strains grew at pH three, six point five, and eight. Enzymatic profiling using the API-ZYM gallery identified seven enzymes distributed across three subclasses: proteases including leucine and valine arylamidase, phosphatases including naphthol phosphohydrolase, and osidases including beta-galactosidase, alpha-glucosidase, beta-glucosidase, and N-acetyl-beta-glucosaminidase. No lipase activity was detected in any strain.

The probiotic potential assessment began with antimicrobial activity testing against five foodborne pathogenic indicator strains: Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus, and Bacillus cereus. Using the well diffusion method, all ten lactic acid bacteria strains demonstrated inhibitory activity, with inhibition diameters ranging from twelve to thirty-four millimetres. Staphylococcus aureus and Salmonella typhi showed the largest inhibition zones, while Pseudomonas aeruginosa recorded the smallest. This broad-spectrum antagonism is likely linked to the production of organic acids, antimicrobial peptides known as bacteriocins, hydrogen peroxide, diacetyls, and biosurfactants that collectively suppress pathogen growth.

Antibiotic susceptibility profiling revealed a complex and heterogeneous picture. All strains were sensitive to streptomycin and amoxicillin, but universally resistant to penicillin, a finding the authors suggest may reflect overuse of this antibiotic in the region. Resistance to vancomycin was detected in four strains, raising a potential safety concern that the authors emphasize cannot be regarded as merely acceptable. They stress that only genomic characterization can distinguish intrinsic, non-transferable resistance from acquired, potentially transferable determinants, in accordance with European Food Safety Authority guidelines. Notably, two strains of the same species sometimes displayed markedly divergent resistance phenotypes, reinforcing the strain-centred paradigm now demanded by modern probiotic development.

Survival under simulated gastrointestinal conditions formed the core of the probiotic screening. Bile salt tolerance, tested at zero point three percent weight per volume for four hours, yielded viability rates between fifty-one and ninety-eight percent, with Fructobacillus durionis S89 achieving the highest survival at ninety-seven point six seven percent. Pepsin resistance at pH two and three revealed a pH-dependent attrition pattern: all strains survived at pH three, but forty percent failed at pH two, where the highest viability rates were nonetheless recorded, reaching seventy-seven point four five percent for Lactococcus lactis S97. Pancreatin resistance proved remarkably uniform, with all strains exceeding seventy-five percent viability after four hours at pH eight, and Lacticaseibacillus paracasei S43 achieving the highest rate at ninety-four point eight six percent. Cell surface hydrophobicity, an indirect proxy for adhesion to intestinal mucosa, ranged from two to sixty-three percent, with three strains exceeding the fifty percent threshold generally considered indicative of a hydrophobic surface phenotype.

To consolidate the ranking derived from individual phenotypic assays, the researchers implemented a two-tier multivariate statistical framework combining a biologically-weighted hierarchical cluster analysis with a Principal Component Analysis. A phenotypic matrix of ten strains by ten descriptors was constructed, incorporating four technological traits, two functional and safety indicators, and four gastrointestinal survival descriptors. Descriptors were assigned a priori weights ranging from zero point five to one point five based on international consensus in probiotic science, with critical determinants of in vivo functionality such as hydrophobicity, pepsin resistance, and pancreatin viability receiving the highest weight. The Probiotic Potential Index was defined as the sum of weighted normalized values rescaled to a hundred-point maximum.

The weighted hierarchical clustering revealed a clear stratification into two major clades. The upper clade comprised the three top-ranked strains: Lacticaseibacillus paracasei S43 with a Probiotic Potential Index of ninety, Lactococcus lactis S97 with eighty, and Fructobacillus durionis S128 with seventy-five. The Principal Component Analysis biplot, which incorporated no a priori weighting scheme, independently converged on the same three strains in the right hemisphere, providing an unsupervised cross-validation of the clustering-based selection. The first two principal components explained fifty-nine point four percent of total variance, and the strong concordance between the two methodologically independent algorithms minimizes the risk of methodological artifact and reinforces the biological relevance of the pre-selected strains.

The authors emphasize that these findings should be interpreted with appropriate caution. Further validation will require whole-genome sequencing to confirm species-level identification and screen for virulence determinants and transferable antibiotic resistance genes. Comprehensive safety assessment should include haemolytic activity, DNase and gelatinase production, mucin degradation, D-lactate production, platelet aggregation, and cytotoxicity assays on intestinal epithelial cell lines. In vivo validation involving animal models and ultimately well-designed human clinical trials will be required to substantiate proposed health benefits, elucidate immunomodulatory and microbiota-modulating mechanisms, and confirm gastrointestinal colonisation and safety in the host. Within these boundaries, the study contributes a preliminary but valuable body of evidence supporting traditional West African fermented beverages as a potential source of autochthonous lactic acid bacteria with functional interest, and highlights the emerging biotechnological potential of historically underexplored genera such as Fructobacillus and Leuconostoc.

Subject of Research: Microbiology

Article Title: Probiotic and technological properties of lactic acid bacteria isolated from palm wine (Bandji) of Côte D'ivoire: An in vitro assessment

Article References: Kouamé, H. K., Yépié, A. H., Aké, M. D. F., Assohoun-Djéni, M. C., Djéni, N. T., & Djè, M. K. (2026). Probiotic and technological properties of lactic acid bacteria isolated from palm wine (Bandji) of Côte D'ivoire: An in vitro assessment. Current Research in Biotechnology, Article 100428. https://doi.org/10.1016/j.crbiot.2026.100428

Image Credits: AI Generated

DOI: 10.1016/j.crbiot.2026.100428

Keywords: probiotics, lactic acid bacteria, palm wine, antimicrobial resistance, fermented foods, Côte d'Ivoire, Probiotic, technological, properties, lactic, acid, bacteria