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

The research team, led by Sana Awan and Krishnaswamy Jayachandran, set out to answer a question that has puzzled plant physiologists working at the intersection of nanotechnology and stress biology: do zinc oxide nanoparticles, fulvic acid, and ascorbic acid work better together than apart? Each of these materials has been studied individually under abiotic stress, but few experiments have compared them under the same crop, salinity level, nanoparticle dose, and sampling conditions, especially in sweet corn. The investigators designed a pot experiment with nine treatments, spanning an untreated control, foliar or irrigation-applied zinc oxide nanoparticles, combinations of the nanoparticles with fulvic acid or ascorbic acid, and each organic acid applied alone. Every treatment was tested under both non-saline and saline conditions, giving a total of 72 pots with four biological replicates per treatment-salinity combination.

The zinc oxide nanoparticles themselves were synthesized through an unusually elegant route. Rather than relying on industrial chemical precursors, the team used avocado seed extract obtained from the USDA Agricultural Research Service Subtropical Horticulture Research Station. A 0.01 M zinc acetate solution was heated to 70 degrees Celsius under continuous stirring, and the avocado seed extract was added dropwise. Sodium hydroxide was then introduced gradually until the pH reached approximately 11, producing a white zinc hydroxide precipitate that was maintained at 70 degrees for five hours to convert into zinc oxide. The resulting nanoparticles were collected by centrifugation at 13,000 rpm and washed repeatedly with deionized water. Powder X-ray diffraction confirmed the formation of crystalline hexagonal wurtzite zinc oxide with an average crystallite size of roughly 18 nanometers, while high-resolution transmission electron microscopy revealed quasi-spherical particles with an apparent diameter near 100 nanometers, suggesting that individual particles may consist of multiple crystalline domains or that aggregation contributed to the larger size observed by TEM.

Sweet corn plants of the cultivar Golden Bantam were grown in 10-inch pots containing sandy loam soil with an initial electrical conductivity below 1 dS per meter. For the saline treatment, sodium chloride was mixed into the soil before sowing, and a 50 mM NaCl solution was applied at two-week intervals thereafter. Soil electrical conductivity was checked regularly with a FieldScout TDR 250 meter to maintain a moderate salinity level of 2 to 3 dS per meter throughout the three-month exposure period. The nanoparticle suspensions were prepared at 200 mg per liter, combined formulations contained either 0.01 percent fulvic acid or 0.01 percent ascorbic acid, and all formulations were adjusted to pH 8.0 before being sonicated for two minutes and applied immediately. Treatments were delivered three times at three-week intervals after germination, with a cumulative dose of 1 mg of zinc oxide per plant.

The biochemical readouts focused on four key indicators of oxidative stress and antioxidant capacity: leaf hydrogen peroxide content, superoxide dismutase activity, catalase activity, and peroxidase activity. Hydrogen peroxide was quantified using the potassium iodide method, with absorbance measured at 390 nanometers against a standard curve. Superoxide dismutase was assessed through the NBT photoreduction assay, catalase through a molybdate endpoint assay, and peroxidase through a guaiacol-based colorimetric method. Salinity, treatment, and their interaction all significantly affected hydrogen peroxide, superoxide dismutase, and catalase, with p values below 0.001. Peroxidase showed significant treatment and interaction effects but no significant salinity main effect, hinting at a more nuanced role for this enzyme in the plant’s response.

The headline finding is striking. Under salinity, hydrogen peroxide in the untreated control rose by 68.5 percent, climbing from 0.169 to 0.284 µmol per gram fresh weight. But when the researchers applied zinc oxide nanoparticles through irrigation combined with ascorbic acid, hydrogen peroxide dropped by 66.2 percent relative to the saline control. The foliar combinations with fulvic acid and ascorbic acid achieved reductions of 65.6 percent and 64.8 percent respectively, and their concentrations did not differ significantly from one another. Ascorbic acid alone was the least effective treatment under salinity, with a hydrogen peroxide concentration of 0.151 µmol per gram fresh weight, though it still remained lower than the untreated control. The message is clear: the nanoparticle-organic acid combinations outperformed the individual components by a wide margin.

Catalase activity showed the largest relative response to treatment of any enzyme measured. Under non-saline conditions, foliar zinc oxide nanoparticles combined with ascorbic acid produced the highest catalase activity, reaching 51.13 percent hydrogen peroxide degraded, compared with just 2.59 percent in the untreated control. Under salinity, the same foliar combination increased catalase activity by 132.6 percent relative to the saline control, while the foliar combination with fulvic acid and the irrigation combination with ascorbic acid achieved increases of 124.3 percent and 122.6 percent respectively. Superoxide dismutase activity followed a similar pattern, with the foliar zinc oxide plus ascorbic acid treatment raising SOD by 41 percent under salinity, reaching 90.57 percent inhibition of NBT photoreduction. Together, these responses represent the strongest combined SOD-CAT activation observed in the experiment, indicating a coordinated strengthening of the plant’s first line of enzymatic antioxidant defense.

Peroxidase activity told a different story. The salinity main effect was not significant, but the salinity-treatment interaction was highly significant, reflecting increased peroxidase activity in certain treatments under salt stress and decreased activity in others. Ascorbic acid alone maintained the highest peroxidase activity under both conditions, while the foliar combination with fulvic acid showed a pronounced increase under salinity. Guaiacol peroxidase participates in hydrogen peroxide metabolism, phenolic oxidation, and cell-wall processes, so a high peroxidase response alone does not necessarily indicate stronger antioxidant protection. The authors stress that peroxidase should be interpreted alongside hydrogen peroxide, superoxide dismutase, and catalase rather than in isolation.

The mechanistic interpretation is where the study becomes especially interesting. Zinc plays a structural role in proteins, membranes, gene transcription, and copper/zinc superoxide dismutase, and it is commonly deficient in agricultural soils, which is why cereal breeders and agronomists already pursue zinc biofortification. Zinc oxide nanoparticles can serve as a highly reactive zinc source and may shift stress signaling and nutrient status. Ascorbic acid, meanwhile, scavenges ROS directly and keeps the ascorbate-glutathione cycle running, while fulvic acid chelates nutrients, changes their mobility, supports osmotic adjustment, and shapes rhizosphere activity. The application route matters too: foliar application exposes leaves directly to the formulation, whereas irrigation introduces it into soil, where minerals, organic matter, root exudates, and microorganisms may alter aggregation, dissolution, and zinc availability. These distinct pathways may explain why the fulvic acid combination behaved differently depending on whether it was sprayed or delivered through irrigation.

The authors are careful to acknowledge the boundaries of what their design can establish. Tissue zinc, sodium-potassium balance, oxidative damage, nanoparticle uptake, dissolution, localization, photosynthesis, biomass, and yield were not measured, so the responses cannot be attributed exclusively to nanoparticulate zinc oxide. Contributions from dissolved zinc and residual seed-derived compounds cannot be excluded, and the experiment did not provide a formal test of biochemical synergy between the nanoparticles and the organic acids. Field applicability was not evaluated because the study used controlled pot conditions without field-level validation. Still, the findings represent a significant step forward in understanding how green-synthesized nanomaterials and organic acids can be combined to strengthen crop antioxidant responses under salinity, and they underscore the importance of formulation-specific and application-route-specific testing before such approaches can be scaled to real-world agriculture.

Subject of Research: Green-synthesized ZnO nanoparticles combined with fulvic and ascorbic acid strengthen antioxidant responses in sweet corn under salinity stress

Article Title: Green-synthesized ZnO nanoparticles combined with fulvic and ascorbic acid strengthen antioxidant responses in sweet corn under salinity stress

Article References: Awan, S., & Jayachandran, K. (2026). Green-synthesized ZnO nanoparticles combined with fulvic and ascorbic acid strengthen antioxidant responses in sweet corn under salinity stress. Frontiers in Plant Physiology, 4, Article 1948674. https://doi.org/10.3389/fphgy.2026.1948674

Image Credits: AI Generated

DOI: 10.3389/fphgy.2026.1948674

Keywords: Green-synthesized, nanoparticles, combined, fulvic, ascorbic, acid, strengthen, antioxidant, responses, sweet, corn, under