Physicochemical study of a novel chimeric chitinase with enhanced binding ability

A Contemporary Appraisal on Impending Industrial and Agricultural Applications of Thermophilic-Recombinant Chitinolytic Enzymes from Microbial Sources

The ability of chitinases to degrade the second most abundant polymer, chitin, into potentially useful chitooligomers and chitin derivatives has not only rendered them fit for chitinous waste management but has also made them important from industrial point of view. At the same time, they have also been recognized to have an imperative role as promising biocontrol agents for controlling plant diseases. As thermostability is an important property for an industrially important enzyme, various bacterial and fungal sources are being exploited to obtain such stable enzymes. These stable enzymes can also play a role in agriculture by maintaining their stability under adverse environmental conditions for longer time duration when used as biocontrol agent. Biotechnology has also played its role in the development of recombinant chitinases with enhanced activity, thermostability, fungicidal and insecticidal activity via recombinant DNA techniques. Furthermore, a relatively new approach of generating pathogen-resistant transgenic plants has opened new ways for sustainable agriculture by minimizing the yield loss of valuable crops and plants. This review focuses on the potential applications of thermostable and recombinant microbial chitinases in industry and agriculture.

Thermophilic Chitinases: Structural, Functional and Engineering Attributes for Industrial Applications

Chitin is the second most widely found natural polymer next to cellulose. Chitinases degrade the insoluble chitin to bioactive chitooligomers and monomers for various industrial applications. Based on their function, these enzymes act as biocontrol agents against pathogenic fungi and invasive pests compared with conventional chemical fungicides and insecticides. They have other functional roles in shellfish waste management, fungal protoplast generation, and Single-Cell Protein production. Among the chitinases, thermophilic and thermostable chitinases are gaining popularity in recent years, as they can withstand high temperatures and maintain the enzyme stability for longer periods. Not all chitinases are thermostable; hence, tailor-made thermophilic chitinases are designed to enhance their thermostability by direct evolution, genetic engineering involving mutagenesis, and proteomics approach. Although research has been done extensively on cloning and expression of thermophilic chitinase genes, there are only few papers discussing on the mechanism of chitin degradation using thermophiles. The current review discusses the sources of thermophilic chitinases, improvement of protein stability by gene manipulation, metagenomics approaches, chitin degradation mechanism in thermophiles, and their prospective applications for industrial, agricultural, and pharmaceutical purposes.

Chitinase: diversity, limitations, and trends in engineering for suitable applications

Chitinases catalyze the degradation of chitin, a ubiquitous polymer generated from the cell walls of fungi, shells of crustaceans, and cuticles of insects. They are gaining increasing attention in medicine, agriculture, food and drug industries, and environmental management. Their roles in the degradation of chitin for the production of industrially useful products and in the control of fungal pathogens and insect pests render them attractive for such purposes. However, chitinases have diverse sources, characteristics, and mechanisms of action that seem to restrain optimization procedures and render standardization techniques for enhanced practical applications complex. Hence, results of laboratory trials are not usually consistent with real-life applications. With the growing field of protein engineering, these complexities can be overcome by modifying or redesigning chitinases to enhance specific features required for specific applications. In this review, the variations in features and mechanisms of chitinases that limit their exploitation in biotechnological applications are compiled. Recent attempts to engineer chitinases for improved efficiency are also highlighted.

Thermostable chitinase from Cohnella sp. A01: isolation and product optimization

Twelve bacterial strains isolated from shrimp farming ponds were screened for their growth activity on chitin as the sole carbon source. The highly chitinolytic bacterial strain was detected by qualitative cup plate assay and tentatively identified to be Cohnella sp. A01 based on 16S rDNA sequencing and by matching the key morphological, physiological, and biochemical characteristics. The cultivation of Cohnella sp. A01 in the suitable liquid medium resulted in the production of high levels of enzyme. The colloidal chitin, peptone, and K₂HPO₄ represented the best carbon, nitrogen, and phosphorus sources, respectively. Enzyme production by Cohnella sp. A01 was optimized by the Taguchi method. Our results demonstrated that inoculation amount and temperature of incubation were the most significant factors influencing chitinase production. From the tested values, the best pH/temperature was obtained at pH 5 and 70°C, with K_m and V_max values of chitinase to be 5.6mg/mL and 0.87μmol/min, respectively. Ag⁺, Co²⁺, iodoacetamide, and iodoacetic acid inhibited the enzyme activity, whereas Mn²⁺, Cu²⁺, Tweens (20 and 80), Triton X-100, and EDTA increased the same. In addition, the study of the morphological alteration of chitin treated by enzyme by SEM revealed cracks and pores on the chitin surface, indicating a potential application of this enzyme in several industries.