Probiotic Characterization, Antioxidant Capacity, and Wound-healing Potential of an Exopolysaccharide from Lactiplantibacillus plantarum CM-4A Isolated from Fermented Maize (Akamu)

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.