Crude Antibiotics and Antifungal Metabolites from Chaetomium globosum Cg6 Suppress Pythium aphanidermatum, Causal Agent of Rhizome Rot of Turmeric.

Turmeric is affected by various phytopathogens, which cause huge economic losses to farmers. In the present study, ten isolates of Pythium spp. were isolated from infected turmeric rhizomes and characterized. Besides, forty-five isolates of Chaetomium spp. were isolated and characterized through morphological and molecular methods. Among the 45 isolates, Chaetomium globosum Cg6 exhibited the highest antagonistic activity against Pythium aphanidermatum in vitro. The crude antibiotics produced by C. globosum were characterized and analyzed through TLC, GC/MS, and HPLC. The best isolate, TNAU-Cg6, produced all three antibiotics, viz., chaetoglobosin A, chaetomin, and chaetocin in higher quantity and inhibited the growth of P. aphanidermatum. Liquid formulation of TNAU-Cg6 using modified Glucose Ammonium Nitrate broth supported the highest concentration at the end of 360 days at an optimum dosage of 10 mL l. Besides, it survived as ascospores at 210 days after planting in the soil. It is observed that the sequential application of liquid bioformulated TNAU-Cg6 as rhizome dip and soil drenching significantly reduced the rhizome rot incidence and enhanced the plant growth parameters. Our findings suggested that C. globosum Cg6 can be a potential biocontrol agent against turmeric rhizome rot disease.