Microbial and Fungal Contamination of Staple Foods in Port Harcourt, Nigeria: Special Attention to High Aflatoxin Risk

Microbial and fungal contamination of agricultural produce has been a health challenge over the years. The present study surveyed microbial and aflatoxin contamination in groundnut, maize, and cowpea collected from Port Harcourt, Nigeria.

Ninety samples of maize, groundnut, and cowpea were purchased from six major markets in Port Harcourt, Nigeria. The samples were first examined for insect pest infestation, then Moisture Content (MC), microbial, and aflatoxin contamination. Characterization of bacterial isolates was determined based on their morphological and cultural characteristics. Statistical analyses were performed using SPSS 20.0

Data showed that 50% of groundnut samples and 33.33% of maize samples had total aflatoxins levels above World Health Organization (WHO) acceptable limits of 0.5-15 µg/kg. MC for groundnut, maize, and cowpea samples significantly ranged from 2.48-5.55%, 9.00-11.25%, and 9.50-12.48%, respectively. The mean bacterial count for groundnut, maize, and cowpea samples ranged from 0.7×108-1.7×108 Colony Forming Unit (CFU)/g, 0.3×108-1.7×108 CFU/g, and 0.7×108-1.9×108 CFU/g, respectively. Bacterial isolates, including Pseudomonas sp., Streptococcus sp., and Clostridium sp. were isolated from groundnut while Bacillus sp., Staphylococcus sp., Proteus sp., and Escherichia coli were isolated from maize and cowpea. Fungal isolates, including Aspergillus flavus and A. niger were isolated from groundnut and maize.

This study revealed the health risk exposure of consumers of the assayed staples in Port Harcourt of Nigeria, especially groundnut which had very high aflatoxin levels in most of the markets.