An extracellular antifungal chitinase from Lecanicillium lecanii: purification,properties, and application in biocontrol against plant pathogenic fungi

Abstract

IntroductionChitin, a homopolymer of N-acetyl glucosamine (GlcNAc) residues linked by β-1,4 bonds, is widely distributed in nature as a component of crustacean exoskeleton, insect outer shell, diatoms, fungal cell walls, and squid pens. It is the second most abundant biopolymer next to cellulose, as well as a constant source of renewable raw materials on earth (Tharanathan and Kittur, 2003). Two enzymes catalyzing hydrolysis of the chitin chain to its monomer by synergistic and consecutive action are endochitinases (EC 3.2.1.14), which randomly hydrolyze the β-1,4 glycosidic bonds of chitin, and N-acetylglucosaminidases (chitobiase, EC 3.2.1.30), which preferentially break lower chitooligomers to produce N-acetyl glucosamine (GlcNAc) monomers (Patil et al., 2002).Chitinases play important roles in biological activities such as nutrient intake, morphological change, defense, and attack. Fish and squid can digest chitinous substances as food by using chitinases in the stomach and liver (Matsumiya and Mochizuki, 1996;Matsumiya et al., 1998), whereas insects and shellfish use chitinases to degrade chitinous substances in the exoskeleton during ecdysis (Kramer and Koga, 1986). In plants, chitinases serve to attack fungal pathogens that contain chitinous substances for self-defense (Singh et al., 2007). Chitinases have received considerable attention due to potential applications in the biocontrol of plant pathogenic fungi and insects (Patil et al., 2002) as a target for biopesticides. Chitinases play an important role in the virulence of many bacteria and fungi for insects and fungi by lysing their cell walls. In addition, chitinases inhibit spore germination and germ tube elongation of the phytopathogenic fungi (Mathivanan et al., 1998). Chitinases can be used widely in the production of (GlcNAc)n and GlcNAc, the formation of yeast and fungal spheroplast and protoplast, and the bioconversion of chitin waste to single cell protein for animal feed (Mathivanan et al., 1998).Chitinases are produced by various microorganisms such as bacterial (Singh et al., 2008) and fungal antagonists of other fungal mycoparasistes, nematophagous and entomopathogenic fungi, and others (Rocha-Pino et al., 2011). Because of their wide range of biotechnological applications, chitinases have been purified and characterized.

Characterization of chitinase from Streptomyces luridiscabiei U05 and its antagonist potential against fungal plant pathogens

“…Antifungal activity of chitinase was determined according to the modified method described by Nguyen, Quyen, Nguyen, and Vu (). A hundred microlitres of fungal plant pathogenic spores (10 8 /ml) was spread on PDA plates.…”

Optimization of cellulase and chitinase enzymes production by plant growth promoting rhizobacteria

“…Bacillus, Pseudomonas, Aeromonas, Vibrio, Serratia, Enterobacter), yeasts, actinomycetes, fungi, plants and animals. Many of these chitinase producing microorganisms are recently used as important biocontrol agents against fungal phytopathogens, by degrading the chitin component of the fungal cell wall (Nguyen et al, 2015), and also control insect pests (Rathore and Gupta, 2015). In addition, they act as plant growth-promoting, as they promote nutrients absorption and self-defense of the plants (Sahai and Monacha, 1993).…”

Intergeneric fusant development using chitinase preparation of Rhizopus stolonifer NCIM 880

“…The approximate molecular weight of chitinase produced by R. stolonifer was 22 kDa, which is comparatively lower than the 50 kDa of R. oryzae (Chen et al 2013), 68 kDa of P. ochrochloron MTCC 517 (Patil et al 2013). K m of R. stolonifer chitinase was 1.66 mg/ml which was lower as compared to other chitinases like 4.02 mg/ml of Rhizomucor miehei (Yang et al 2016), but higher than the 0.82 mg/ml chitinase of Lecanicillium lecanii (Nguyen et al 2015). …”