Chaetomium globosum KPC3: An Antagonistic Fungus Against the Potato Cyst Nematode, Globodera rostochiensis

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-1. 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.

The impact of various forms of silver nanoparticles on the rhizosphere of wheat (Triticum aestivum L.) - Shifts in microbiome structure and predicted microbial metabolic functions

The study investigated the effects of different silver nanoparticles (AgNPs) on the soil microbiome and wheat growth. For comparison purposes, a commercial fungicide and silver nitrate (AgNO3) were used. The results revealed three distinct groups of nanoparticles based on their impacts. Small-size AgNPs (10 nm) with a negative charge, as well as fungicide had limited effects on the microbiome, similar to the no-treatment control. Bigger in size (30-60 nm) and a negative charge AgNPs showed the most beneficial effects on soil microbiota shifts. These AgNPs increased the abundance of bacteria with beneficial traits such as nitrogen-fixing, urease, protease, and lignin degradation bacteria. The third type of AgNPs had a positive charge of nanostructure and influenced specific microbial populations, increasing the abundance of anaerobic and autotrophic groups of microorganisms, which could be assessed as a harmful shift for plants growth promotions and was similar to the AgNO3 treatment. Overall, the study emphasized the potential of AgNPs in agriculture not only as biocidal. The conducted study proved that AgNPs with bigger size/negative charge, used in low concentration can have a surprisingly stimulating effect on the positive characteristics of the rhizosphere microbiome. Moreover, the surface charge of AgNPs is a significant factor affecting microbial activity of wheat rhizosphere soil, which in this treatment is significantly similar to the AgNO3 treatment.