Lactobacilli Cultures against Ochratoxin A Producing Moulds Isolated from Cocoa in the South West Region of Cameroon

Abstract

The presence of ochratoxin A (OTA) in cocoa beans is a major health concern, due to its deleterious effects on humans and animals. During the traditional processing and storage of cocoa, fungi contamination occurs. Many of these fungi, produce mycotoxins that can cause acute or chronic intoxication and damage to human and animals after ingestion of the contaminated food and feed. The bio-control of ochratoxigenic moulds by lactic acid bacteria (LAB) could provide a safer alternative compared to the use of fungicides. The present study aims at investigating the potential of selected lactobacilli strains to inhibit the growth of OTA producing moulds. Cocoa samples were collected in the South West region of Cameroon. The mycoflora of cocoa beans were isolated and identified using phenotypic characteristics on Potato Dextrose Agar (PDA) and microscopy after application of lactophenol cotton blue stain. LAB used were isolated from fermented palm and raffia wines and fermented pineapple juice by pour plate method on De Man Rogosa and Sharpe Agar. Phenotypic identification of LAB were identified using API 50 CHL kit. Colony PCR was used to confirm whether the isolates belong to LAB group. The inhibitory activity of Lactobacillus sp against ochratoxigenic moulds was carried out on agar using the overlay method and in broth by turbidimetric analysis. Aspergillus sp were the most prevalent fungi in cocoa samples. Aspergillus flavus, Aspergillus ochraceus, Aspergillus niger were isolated in all samples. Lactobacillus. plantarum exhibited the highest inhibitory activity against OTA producing moulds. The percentage of inhibition was ranged from 10 to 46.5%. A. ochraceus was the most susceptible mould with the various LAB isolates. The quantification of OTA using ELISA kit showed significant reduction in OTA production (p<0.05) during mixed culture of moulds with lactobacilli. Lactobacilli from fermented drinks could be used for biological control of OTA producing fungi.