Comparative analysis of microorganisms and heavy metal contamination of periwinkles (Tympanotonus fuscatus and Pachymalania aurita) in Akwa Ibom State, Nigeria

Abstract

Periwinkles are a common and affordable source of dietary protein in many coastal communities, yet their filter-feeding nature makes them susceptible to accumulating environmental contaminants from polluted waters; therefore, this study assessed the safety of periwinkle (Tympanotonus fuscatus and Pachymelania aurita) harvested from three aquatic ecosystems in Akwa Ibom State by determining microbiological and heavy metal concentrations using standard techniques, with results showing total heterotrophic bacterial counts ranging from 3.4 × 10⁷ ± 0.07 to 4.1 × 10⁷ ± 0.29 CFU/g, total coliforms from 2.8 × 10⁵ ± 0.33 to 4.1 × 10⁵ ± 0.38 CFU/g, total fungi from 1.4 × 10⁵ ± 0.44 to 2.2 × 10⁵ ± 0.25 CFU/g, total Vibrio from 9.2 × 10⁴ ± 2.18 to 1.0 × 10⁵ ± 2.64 CFU/g, faecal coliforms from 1.6 × 10⁵ ± 1.93 to 2.4 × 10⁵ ± 0.14 CFU/g, and total Salmonella-Shigella from 1.9 × 10⁵ ± 2.13 to 2.5 × 10⁵ ± 0.22 CFU/g, while eleven bacterial genera (Bacillus, Salmonella, Escherichia, Enterobacter, Pseudomonas, Shigella, Staphylococcus, Vibrio, Serratia, Proteus, and Streptococcus) and fungi (Aspergillus, Mucor, Penicillium, Rhizopus, and Candida) were isolated, with bacterial isolates showing high resistance to amoxicillin-clavulanate and cefuroxime but high sensitivity to gentamicin among E. coli, Staphylococcus spp., and Pseudomonas spp., and heavy metal concentrations (in mg/kg) for lead (6.076 ± 0.004 to 9.158 ± 0.050), copper (6.621 ± 0.006 to 103.850 ± 0.099), cadmium (0.641 ± 0.980 to 1.054 ± 1.441), chromium (0.050 ± 1.681 to 12.615 ± 2.051), and mercury (0.000 to 1.291 ± 0.185) were measured, revealing a significant correlation (p < 0.05) between microbial loads and heavy metal concentrations, and because all values exceeded permissible limits set by the International Commission on Microbiological Specifications for Foods (ICMSF) and the Federal Environmental Protection Agency (FEPA), proper processing of periwinkle before consumption is critical to prevent adverse health outcomes for consumers.