Microbial Chitinase: production process and applications




Microbial Chitinase: production process and applications
Microbial Chitinase: production process and applications

Chitinase:

  • 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 30oC, growth till spore suspension.
  • Inoculum preparation:
    • Spore is inoculated in a broth medium containing starch+ glucose +peptone +yeast extract+ ammonium nitrate+ others.
    • Incubation: at 30oC 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: 30oC
    • 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