Aflatoxigenic Aspergillus flavus Outgrows Aspergillus niger in Perturbation Induced Competitive Interaction in Corn Kernels

Contamination of food grains by carcinogenic Aspergillus flavus continues to pose a serious public health threat. Principle of Competitive Exclusion states that any two species competing for the same and limited nutrient resource typically cannot coexist. We have investigated the phenomenon of competitive conflict between carcinogenic Aspergillus flavus and nontoxic Aspergillus niger within corn kernel with and without perturbation experimentally and theoretically. Here we show that perturbation breaks down the Lotka-Volterra model based principle of competitive exclusion. We have found that A. niger competitively prevents the growth of A. flavus and consumes more corn protein reaching a higher growth level as shown in phase-plane where its values dive above the stable manifold in the stable node on Y-axis rather than on the X-axis. In contrast, when both grow in the presence of small perturbation, Lotka-Volterra model breaks down and A. flavus prevents the proliferation of A. niger, consuming more nutrient resource and reaching a higher growth level, diving below the stable manifold in the stable node on X-axis. Also, perturbation induces deviations from “Principle of Competitive Exclusion”, generating fluctuations and heterogeneity, changing the structural stability of phase-plane diagram and reflecting the typical second order phase transition. Thus the deterministic competitive interaction broadens into distribution of levels revealing intrinsic heterogeneity, which has hitherto been unexplored in the competitive conflict. This rigorous perturbation scheme with their equilibrium values and vibrational levels may help nullify natural perturbative effect in ecosystem and food industry. The experimental data fit well with the perturbation approach and offers to design effective strategy to free food grains from A. flavus and carcinogenic aflatoxin.