ABSTRACT
Sustainable increase in agricultural productivity to feed the growing population demands eco-friendly remedies including the use of biocontrol agents to control diseases in food crops. Trichoderma spp. is one such agent which provides multiple plant health benefits, like disease control, plant growth promotion, development of resistance and stress tolerance. However, inappropriate concentration and less effective formulations with a poor shelf life of Trichoderma spp. have hampered its customized applications at large scale. Here, we studied the influence of various parameters on growth and mass production of customized applications of Trichoderma spp., including carrier materials, its shelf life and evaluation of antifungal activity of T. viridae. We observed optimum growth of T. viridae at 40°C, pH 6.0, maximum sporulation at 45°C and pH 6.0, with cellulose and carboxymethyl cellulose as a best utilizable carbon source. Neem cake came out as an excellent carrier as it gave a prolonged shelf life of 200 days during storage at 28°C with 35.78×106 cfu g-1 of T. viridae. Antifungal assay against plant pathogenic fungi revealed complete inhibition of growth and sporulation of fungal pathogens.
ABSTRACT
Contamination of food by aflatoxin of Aspergillus flavus is a major global problem affecting trade, quality, utility of food and human health. While all the members of A. flavus does not produce aflatoxin, sensitive, cost effective and reproducible methods for large scale screening and differentiation of toxigenic A. flavus from atoxigenic ones are scarce. Here, we made one such attempt using coconut milk agar (CMA), yeast extract sucrose agar (YESA), ammonium hydroxide vapour tests, enzyme linked immuno sorbent assay (ELISA) and polymerase chain reaction (PCR) for large scale screening of toxigenic strains of A. flavus. Fifty nine isolates of A. flavus obtained from major chilli growing regions of India were categorized into toxigenic and atoxigenic strains by using cultural, analytical and molecular methods. Forty two (71.18 %) isolates showed positive response in coconut milk agar (CMA), 17 (28.81%) isolates did not match while 23 (38.98 %) isolates showed red colour and 36 (61.01%) isolates did not produce red colour upon exposure to ammonia vapour in YESA. Out of 59 isolates, isolates CAF43 came out as highly toxigenic, as it produced 3128.20 μg kg-1 aflatoxin B1 followed by CAF 42 which produced 3035.10 μg kg-1. Among 59 isolates, eight A. flavus isolates were amplified with two regulatory (aflR and aflJ) and two structural (norA and ver1) genes at a region of 900, 450, 400 and 450 bp, respectively.