Chitinase Production from Locally Isolated Bacillus cereus GS02 from Chitinous Waste Enriched Soil

Abstract

Background and Objective: Chitin is world’s second most abundant structural carbohydrate in nature and is found as a structural component in the cell wall of fungi and exoskeletons of invertebrates. During senescence, it is degraded by the enzyme, chitinase. In addition, chitinase has been exploited for various commercial applications such as control of insects and fungal pathogens in order to protect the crops, waste management, cosmetics and food industries. Chitinases have been found to be widely distributed in various organisms including viruses, animals, bacteria, fungi, higher plants and insects. In the present study, various soil samples enriched in chitinous waste were screened for the isolation of bacteria capable of producing chitinase.
 Methodology: Chitinase producing bacteria were isolated using serial dilution plating technique onto different agar media. Primary and secondary screening were performed and the isolate producing maximum chitinase was selected for biochemical identification and 16s rRNA sequencing. The secretion of extracellular chitinase by this strain was optimized with respect to pH, temperature, incubation time, substrate concentration, carbon and nitrogen sources and inoculum size. All these components were optimized using OFAT (one factor at a time) approach.
 Results: A total of 29 bacterial isolates were found exhibiting secretion of extracellular chitinase as determined using zones of clearance. Based on the area of zone of clearance, six isolates were selected for secondary screening and the most potent isolate was identified as Bacillus cereus. The maximum chitinase production by this strain was obtained at 37°C and pH 7.0 after 48 hours of incubation. The maximum chitinase secretion was observed on addition of 1% colloidal chitin and 0.05% yeast extract in the medium.

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“…B. cereus JK-XZ3 filtrate cultivated at 30 °C showed the highest nematicidal activity, resulting in 100% mortality of Bursaphelenchus xylophilus [ 40 ]. However, Dukariya and Kumar [ 41 ] reported maximum chitinase productivity at 37 °C.…”

Characterization of Extracellular Chitinase from Bacillus cereus SAHA 12.13 and Its Potency as a Biocontrol of Curvularia affinis

“…This suggests that B. cereus SAHA 12.13 bacteria can produce chitinase enzymes and they are active under various environmental pH conditions. Various reports regarding the chitinase enzyme's character are generally at a neutral pH of 6.0 -7.0, such as B. cereus [7][8] [35] and B. thuringiensis [1] which had optimum activity at pH 7.0.…”

Distribution and Biotechnological Applications of Chitinase: A Review

“…They showed enzyme activity at pH range 5 to 8 and optimum temperature is 40°C. Recently, a chitinase from Bacillus cereus was isolated and produced from chitinous waste enriched soil showed optimum pH 7 for maximum chitinolytic activity [53]. Chitinolytic enzyme of Serratia marcescens exhibited maximum activity at 32°C temperature and at a pH of 8 [9,54].…”