A survey on chitinolytic bacteria in shrimp farming ponds

Objective: Chitinases produced by pathogens of many marine organisms including chitinus invertebrates (Crustaceans) and shrimp pathogens can play two related but different roles: they can assist to penetration of the host exoskeleton, and they can provide nutrients both directly in the form of amino-sugars, and indirectly by exposing other host material to enzymatic digestion. Chitinolytic pathogens may establish their parasitic relationship by themselves, or by being a partner for another invader microorganism in a mutualistic approach. This parasitic action results in invasive infection and eventually death of fish and other marine food resources such as shrimps. Method & Materials: Isolation and screening of chitinase-producing strains: The isolated microorganisms were screened on agar plates containing 1% Colloidal chitin, 0.1% K2HPO4, 0.05% MgSO4, 7H2O, and 1.5% agar powder. Those organisms obtained from the screening were subcultured in liquid media in flasks at 30 ºC. After incubation for 3 days, the culture broth was centrifuged and the supernatants were collected for the measurement of chitinase activity. Chitinase assay: The mixture of enzyme solution and substrate was incubated at 50 ºC for 30 min. The amount of reducing sugar produced in the supernatant was determined by DNS method. Results & Conclusion: In this preliminary research, seven shrimp farming ponds in Chabahar and Abadan went under investigation between August and October 2008. To our knowledge, study on the chitinase of Shrimp Farming soils, water and Wastewater remains very superficial. Colloidal chitin, prepared from residues of shells of some crustaceans such as lobster and shrimp, was supplemented in synthetic solid media. Water samples from above mentioned ponds were plated on these solid culture media and incubated under appropriate conditions. These experiments resulted in isolation of a number of chitinolytic Eubacteria. The main result indicates that those sampled shrimp breeding industries are at risk of pathogenic microorganisms. Further studies on characterization of culprit microorganisms and their relative enzymes are in the way.

کلیدواژه ها:

Chitin ، chitinase ، shrimp farming ponds ، pathogenic bacteria