Development and Validation of Biocontrol Agent utilizing the Bioactive Compounds in Aspergillus giganteus against Aflatoxigenic Aspergillus flavus in Maize

Abstract

Agricultural economy plays a major role in developing countries and there is a pressurized newlineneed for sustainable production from agriculture. In India, maize being the third most important staple newlinecrop, is particularly vulnerable to aflatoxin contamination and the existing control measures focus on newlinethe use of environmentally hazardous chemical based pesticides. The use of novel and effective newlinemicrobial biocontrol agents are considered as a better alternative and hence this current study focused newlineon evaluating and validating the antagonistic potential of the fungi Aspergillus giganteus against the pathogenic newlinefungi Aspergillus flavus which infects maize crops. This was carried out sequentially in four phases where the newlineresults from Phase 1 indicated that the culture filtrates from A. giganteus consisted of active metabolites that newlinecontributed to the consolidated antagonistic effect against the pathogenic A. flavus. The second phase of this newlinestudy dealt with metabolite profiling and a series of purification steps of the culture filtrates from Aspergillus newlinegiganteus that confirmed the presence of the bioactive compounds in the form of fatty acid derived metabolites newlineand the Calmodulin like protein fragment in the culture filtrates implying that these compounds might be newlineinvolved in membrane perturbations of the pathogenic A. flavus. The subsequent phase focused on the presence newlineof the cell wall degrading marker enzymes such as chitinase, glucanase, protease, amylase and cellulase that newlinewere considered as markers to determine degree of biocontrol effect. The enzymes were triggered at higher newlinelevels in the presence of the cell wall of the pathogen. In the final phase, a field study was performed by using newlinethe whole culture filtrates on maize plants as biofungicide. The filtrates were less cytotoxic and were capable of newlinereducing the pathogen count in soil. The distinctness and uniformity of the maize plant growth were not affected newlinedue to the treatment with culture filtrates and thus the study strongly supported the use of culture filt