Inhibitory Effect of Lactic Acid Bacteria on Aflatoxin B1 Producing Aspergillus flavus Isolated from Garri

Abstract

Among the potential benefits of probiotic lactic acid bacteria (LAB) is their practical use for biopreservation of foods, fungal decontamination, and novel biotherapy. A number of ready to eat foods hawked in streets of Nigeria such as garri are prone to contamination by mycotoxin-producing fungi. In this study the inhibitory effect of lactic acid bacteria (LAB) (sourced from local foods (nono and kunun- zaki)) and their bacteriocins-derivatives on aflatoxin B1 -producing Aspergelius flavus was conducted. Out of the five LAB isolates screened three (two strains of Lactococcus and one of Pediococcus sp had high indices of probiotic potentials and bacteriocins extracts were obtained from them and used for the inhibition study. Fourty samples of garri sold in Jos metropolis were screened for A. flavus and their abilities to produce Aflatoxin B1 using the Coconut Extract Agar (CEA) and Ammonia Vapour Test (AVP) methods. The three most probiotic LAB and their respective crude baterioncin extracts were used to test for their inhibitory effect on aflatoxin producing A. flavus isolates. The results of the study showed that while only 17 samples (42.50%) had A. flavus in them, only three of the fungi ((17.65%) demonstrated capacity to produce Aflatoxin B1, making (7.5% of the total number of garri samples that had aflatoxin-producing A. flavus. The inhibition of fungal growth by LAB and bacteriocins was dose dependent. At an inoculum concentration of 1 ml, Pediococcus sp had the highest mean zone of inhibition of 43.0 mm followed by Lactococcus sp (Strain LAC20G with radial diameter 38.0mm and Lactococcus sp (LAC20G) which had a radial diameter of 29.3mm respectively. The results of the study portend that the growth of aflatoxin producing Aspergillus flavus in ready to eat foods such as garri could be prevented by application of appropriate dosages of bacteriocins extracts from lactic acid bacteria.