Biochemical and Molecular Identification of Bacteria in Spontaneous Fermented Cashew Nut Milk

Edem VE, Kayode RMO, Abiodun OA and Elijah AI

Published on: 2025-02-04

Abstract

Spontaneous fermentation, which relies on a wide range of microorganisms, is a natural process where microorganisms such as bacteria, molds, and yeast initiate the fermentation process to produce products with unique taste and flavor. This study was undertaken in order to identify bacteria in spontaneous fermented cashew nut milk using biochemical characterization and molecular methods.  Microbiological analyses were conducted using standard microbiological techniques. Data obtained for microbial counts were expressed as means + SD. Results showed that total aerobic bacteria count, which was grown on nutrient agar (NA), was 286 x 10⁹ cfu/mL, while bacterial counts on De Man, Rogosa, and Sharpe (MRS) agar were 192 x 10⁹ cfu/mL. The biochemical characterization and identification of pure isolates from NA revealed the presence of Salmonella spp., Escherichia coli, Klebsiella spp., Streptococcus sp., Staphylococcus aureus, Pseudomonas aeruginosa, Enterobacter sp., Proteus sp., Citrobacter sp., and Bacillus cereus, while molecular identification of pure isolates grown on MRS agar showed all the isolates having percentage identity over 99% with Bacillus cereus. Hence, the predominant microorganism on MRS agar was Bacillus cereus. This study established that lactic acid bacteria could not grow in/on cashew nut milk under spontaneous conditions, except when intentionally introduced into the medium.