• Chitinases are hydrolytic enzymes with the size ranging from 20kDa to about 90kDa.
• Chitinase present in wide range of organisms such as bacteria, fungi (molds), actinomycetes, plants, arthropods, and humans.
• Chitinases have the ability to degrade chitin directly to low molecular weight, chitooligomers by acting on glycoside bonds of chitins.
• Chitooligomers have broad applications in industrial, agricultural and medical field and it also acts as anti-tumour agent.
• Chitin is the component of cell walls of fungi and exoskeletal element of some animals including worms and arthropods.
• Chitinases are commonly found in organisms that either need to reshape their own chitin or dissolve and digest the chitin of fungi or animals.
• Types of chitinase:
  • Three types depending on pH optima:
    • Acidic chitinase
    • Neutral chitinase
    • Alkaline chitinase
• On the basis of function, chitinases are of two types:
  • Exo-chitinases
  • Endo-chitinases
• Exochitinase cut down from non-reducing end of chitin and give rise through dicetylchilobiose.
• Endochitinase randomly cleaves internally forming the dimer dicetylchitobiose and soluble low molecular mass multimass such as chitotriose and chitotetraose.

Chitinase producing Microorganisms:

• Most important: Actinomycetes, Streptomyces spp., Nocardia spp., Streptoverticillium spp., Actinoplane, Trichoderma spp.
• Other: Acromonas spp., Bacillus spp., Pseudomonas spp., Vibrio, Escherichia, Serratia spp.

Production process of chitinase:

• Inoculum:
  • Improved strain of Streptomyces viridificans
• Growth of Inoculum:
  • Growth in media like starch casein agar, outmeal agar.
  • Incubation for 10-12 days at 30^oC, growth till spore suspension.
• Inoculum preparation:
  • Spore is inoculated in a broth medium containing starch+ glucose +peptone +yeast extract+ ammonium nitrate+ others.
  • Incubation: at 30^oC for 48hrs.
  • Aeration: 0.2vvm
  • Agitation: 150rpm
• Fermentation process:
  • Top fermentation: Lyophilized culture of S. viridificans is used.
  • Batch culture is usually used.
  • Fed batch can also be used.
  • Stirred tank bioreactor is used.
  • Substrates: starch from plant usually from potato or starch corns.
  • Nitrogen source: oat milk, soya milk and yeast extract.
  • Inducer: 4-5%chitin
  • Other: Mg, P etc.
  • Inoculum size: 8-10%
  • Temperature: 30^oC
  • pH = 7.2(+ or – 0.2)
  • Aeration: 0.2-1 vvm
  • Agitation =150rpm
  • Duration: 3-4 days
• Product recovery:
  • Whole substrate is extracted vacuum filtration and centrifugation and the recovered substance is concentrated by evaporation to yield chitinase and thus obtained crude enzyme is further purified.

Applications of chitinase

• Mostly used in pesticides formulation to control insect pest. E.g. Bacculoviruses is used for biological control of insect pest, also produces chitinases for pathogenesis.
• Pharmaceutically, used as anti-cancer compound.
• Used for degradation of high chitin containing biomass into useful components.
• Chitinase activity in human serum have a role in defense against fungal pathogens.

Microbial Chitinase: production process and applications

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