Production of Aspergillus quadrilineatus MT083999 Chitinase, β-1,3-Glucanase and Nano-silver Important for Biocontrol of Fusarium spp. Infecting Crops

Abstract

In our search for an active biocontrol agent against F. solani and F. oxysporum, the major species causing wilt, root rot and damping-off in plants affecting crops. The fungal isolate genetically identified as Aspergillus quadrilineatus MT083999 displayed high antagonistic activities against the tested root-rot fungi, and presented valuable chitinase and β-glucanase activities of 235.484 and 508.953 U/gds, respectively. Solid state fermentation conditions were optimized by applying Three–factor–five–level central composite design (CCD) with twenty experiments and two responses of chitinase R1 and β-glucanase R2 activities, respectively. The optimum activities of chitinase (386.70 U/gds) and β-glucanase (1094.70 U/gds) were obtained in trial 4 and 2 respectively, with about 1.64-fold increase in chitinase activity and 2.15-fold increase in β-glucanase activity when compared with initial fermentation. Biosynthesis of nano-silver from A. quadrilineatus was evaluated in 10 experiments of another design of 2–factors–5–levels. The antifungal effects of each biosynthesized nano-silver against F. solani (R1) and F. oxysporum (R2) were evaluated as Inhibition zone diameter (IZD). The high fungicide nano-silver against both tested phytopathogens was characterized by UV–visible spectrophotometry, transmission electron microscopy (TEM), Zeta dynamic light scatter (DLS) and Fourier transform infrared spectroscopy (FTIR). The results indicated that A. quadrilineatus MT083999 chitinolytic enzymes and nano-silver can be applied as a novel candidate in biocontrol of Fusarium wilt infecting crops worldwide.