Probiotic Characterization, Antioxidant Capacity, and Wound-healing Potential of an Exopolysaccharide from Lactiplantibacillus plantarum CM-4A Isolated from Fermented Maize (Akamu)
Chioma Adaobi Mmeremikwu *
Department of Microbiology, Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, Abia State, Nigeria.
Chijioke E. Onwuakor
Department of Microbiology, Michael Okpara University of Agriculture, Umudike, P.M.B. 7267, Umuahia, Abia State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Lactic acid bacteria from traditional fermented foods are promising sources of exopolysaccharides (EPS) with potential probiotic, antioxidant, and biomedical applications. However, EPS-producing strains originating from African cereal fermentations remain comparatively underexplored, particularly regarding their combined probiotic characteristics, antioxidant activity, and wound-healing potential.
Aims: To isolate EPS-producing lactic acid bacteria (LAB) from Nigerian fermented maize (akamu), identify the most productive strain, and evaluate the probiotic attributes, antioxidant capacity, and preliminary wound-healing potential of its purified exopolysaccharide (EPS).
Study Design: A laboratory-based experimental study combining microbial isolation, molecular identification, in vitro probiotic and antioxidant assays, and a preliminary in vivo wound-healing evaluation.
Place and Duration of Study: The study was conducted at the Department of Microbiology, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria, between February 2025 and August 2026.
Methodology: Akamu samples were collected from local producers in Umuahia and screened for EPS-producing LAB on sucrose-supplemented MRS agar. The highest-yielding isolate was identified by 16S rRNA gene sequencing and assessed for acid and bile-salt tolerance and haemolytic activity. Its EPS was extracted, purified, and characterised by FTIR, DPPH radical-scavenging assay, and a preliminary rat excision-wound model (three groups, n = 2: saline, penicillin ointment, EPS gel).
Results: Fifteen presumptive LAB were recovered; four produced EPS. The top producer, isolate E1, yielded 240 mg L⁻¹ and was identified as Lactiplantibacillus plantarum CM-4A (GenBank PV111320.1; 99.9% identity). The strain retained 92.9–80.0% viability at pH 4.0–2.0 and survived exposure to 0.1–0.3% bile salts (83.5–69.4%), with no haemolysis. FTIR confirmed a carbohydrate-rich biopolymer with hydroxyl, carbonyl, and glycosidic groups. The EPS scavenged 42.2% of DPPH radicals at 5 mg mL⁻¹ (ascorbic acid: 57.0%). Topical EPS gel produced faster wound contraction (52.3% by day 3, 74.0% by day 7) than saline (37.5%, 54.4%) or penicillin ointment.
Conclusion: Because the in vivo phase used two animals per group, the wound-healing findings are descriptive and require confirmation in an adequately powered study. L. plantarum CM-4A and its EPS show promise as affordable, cereal-derived candidates for antioxidant and wound-care applications in low-resource settings.
Keywords: Lactiplantibacillus plantarum, exopolysaccharide, fermented maize (akamu), probiotic characterisation, DPPH radical scavenging, wound healing, FTIR