Self-directing optimization of parameters for extracellular chitinase production by Trichoderma harzianum in batch mode

Abstract: Trichoderma spp. have been widely used as antagonistic fungal agents against several pests as well as plant growth enhancers. Faster metabolic rates, anti-microbial metabolites, and physiological conformation are key factors which chiefly contribute to antagonism of these fungi. Mycoparasitism, spatial and nutrient competition, antibiosis by enzymes and secondary metabolites, and induction of plant defence system are typical biocontrol actions of these fungi. On the other hand, Trichoderma spp. have also been used in a wide range of commercial enzyme productions, namely, cellulases, hemicellulases, proteases, and β-1,3-glucanase. Information on the classification of the genus, Trichoderma, mechanisms of antagonism and role in plant growth promotion has been well documented. However, fast paced current research in this field should be carefully updated for the fool-proof commercialization of the fungi. The aim of this review is to sum up the BCA activity potential of these fungi and to shed light on commercial production processes. In this regard, this review focuses on Trichoderma spp. discussing different aspects—pest control, growth promotion, bioremediation, production processes and market values. Nevertheless, more research and review of the information regarding these biocontrol agents are needed to exploit their actual potential, which is the salient objective of this review.

Abstract: Fungal plant diseases are one of the major concerns to agricultural food production world wide. Soil borne pathogenic fungi such as Pythium, Fusarium, Rhizoctonia and Phytopthora attack most of the economically important crop plants (either through seed root before germination or seedling after germination) resulting in loss of billions of dollars. Moreover, the management of chitinous waste is also pressing need today. Mycolytic enzymes (chitinases, proteases and glucanase) producing microorganisms may help in solving these problems. These microorganisms have ability to lyse the fungal cell wall and also have the potential to manage the chitinous waste by producing chitinases. Many chitinolytic microorganisms have potential to control fungal plant pathogens but they are not fully successful in all the cases due to different geological and environmental conditions. Thus, bioprospecting to find novel, highly chitinolytic microorganisms which help in developing potential biocontrol agent. Furthermore, to increase the survivability of biocontrol agents, a formulation may also be necessary. This review is focused on the progress of chitinase genes, chitinolytic microorganisms and their diversity as well as formulation of chitinolytic producers which have the potential to control fungal plant pathogens

Abstract: The nutritional medium requirement for chitinase production by Alcaligenes xylosoxydans IMI no. 385022 was optimized. The important medium components, identified by initial screening method of Plackett–Burman were Tween 20, yeast extract and chitin. Box–Behnken response surface methodology was applied to further optimize chitinase production. The optimal concentration for higher production of chitinase were (g/l): (NH4)2SO4, 1.0; KH2PO4, 1.36; MgSO4·7H2O, 0.3; Tween 20, 0.12; yeast extract, 0.3 and chitin, 15. Using this statistical optimization method, the chitinase production was found to increase from 12 to 29 U/ml.

Abstract: The utilization of shrimp shellfish waste as a substrate for solid-state cultivation of a filamentous fungus, Aspergillus sp. S1-13, was investigated. The organism was selected from among 220 isolates based on the productivity of its chitinolytic enzyme (chitinase), which might reflect microbial growth. The enzyme was produced only when the organism was grown on medium containing the shellfish waste. The addition of 58–65% water (w/w) to the medium was effective in enhancing production, and a certain amount of enzyme was observed in media of higher water content (up to about 75%). The initial pH and nitrogen source (ammonium sulfate) of the solid-state medium also affected the amount of enzyme. The amount of enzyme increased 2-fold in an optimum solid-state medium: 5 g of shrimp shellfish waste and 3 ml of basal medium (pH 5) containing 0.1% (NH 4 ) 2 SO 4 was inoculated with 4 ml of spore suspension; static cultivation at room temperature. The amount increased further (1.5-fold) when the cultivation was carried out at 37°C, with 1.85 units of the enzyme formed from 1 g of shrimp shellfish waste. An analysis by ion-exchange column chromatography suggested the presence of at least two colloidal chitin-hydrolyzing enzymes and one p -nitrophenyl β- d - N -acetylglucosaminide-hydrolyzing enzyme in an extract of the solid-state culture. The elution profile was similar to that obtained with a liquid culture filtrate.

Abstract: The effects of submerged cultivation parameters on the production of chitinase by Verticillium lecanii in a shaker-flask and bioreactors were investigated. The activity of chitinase was 9.95 mU/ml in an optimal culture medium with culture volume at 200 ml, agitation rate at 150 rpm, and 24 °C in shaker-flask cultivation. Based on this result, the scale-up cultivation with a 5-l stirred-tank bioreactor (STR) and a 30-l airlift bioreactor were conducted. The high chitinase activity 18.2 mU/ml was obtained under the optimal cultivation conditions of aeration rate at 0.6 vvm, pH 4, agitation rate at 150 rpm, and 24 °C, with a 5-l STR. The chitinase went up to 19.9 mU/ml by using 30-l airlift bioreactor with 24-mesh net-draft tube at aeration rate of 0.9 vvm, pH 4, and 24 °C. The study revealed that the pH and agitation rate were the most significant factors for the effects on chitinase production. Nevertheless, agitation rate and aeration rate could affect dissolved oxygen (DO) concentration that in turn affected V. lecanii growth and chitinase production.

Abstract: Serratia marcescens was found to be the most active organism of 100 tested for the production of chitinase. Enterobacter liquefaciens produced nearly as much enzyme. Under optimal conditions high y...

Abstract: Trichoderma harzianum excreted β-1, 3-glucanase and chitinase into the medium when grown on laminarin and chitin, respectively, or on cell walls of the pathogen Sclerotium rolfsii, as sole carbon s...

Abstract: There has been a considerable amount of recent research aimed at elucidating the roles of chitinase in fungi and plants. In filamentous fungi and yeasts, chitinase is involved integrally in cell wall morphogenesis. Chitinase is also involved in the early events of host-parasite interactions of biotrophic and necrotrophic mycoparasites, entomopathogenic fungi and vesicular arbuscular mycorrhizal fungi. In plants, induction of chitinase and other hydrolytic enzymes is one of a coordinated, often complex and multifaceted defense mechanism triggered in response to phytopathogen attack. Chitinase induction in plants is not considered solely as an antifungal resistance mechanism. Plant chitinases can be induced by various abiotic factors as well and there is some circumstantial evidence to suggest a morphogenetic role despite the apparent absence of the substrate in plant cells. Finally, some chitinases and other chitin-binding proteins including some plant lectins share chitin-binding domains as part of their molecular structure and provide fuel for the so-called ‘lectin-chitinase’ debate and speculation for the origin of chitinase in plants.

Abstract: A process was conceptualized for bioconversion of shellfish chitin wastes to single-cell protein of value in animal or aquaculture feed formulations or to other products. An extracellular chitinase enzyme system obtained by a submerged culture of microorganisms is contacted with the chitin waste, hydrolyzing it to smaller sugar units. The hydrolysate is converted to a marketable product. Experimental results indicate that Serratia marcescens QMB1466 is suitable for use in the proposed process. Hydrolysis of various chitinous waste preparations shows the culture filtrate to be effective in decomposing the substrate. For crude preparations, hydrolysis slows after approximately 40 hr. Colloidal chitin is almost completely dissolved after 60 hr.