Clarke and Tracey developed a method to detect chitinase, an enzyme that breaks down chitin, in bacterial culture fluids. They surveyed representative bacterial species and found that some soil and water bacteria produce chitinase while others do not. The detection method involves incubating culture supernatants with finely divided chitin prepared from cuttlefish bones, then measuring acetylglucosamine production using a colorimetric reaction. Key findings include that chitinase appears to be a constitutive enzyme (produced regardless of substrate presence), as no chitin was detected in growth media. The enzyme is fairly stable and works optimally at pH 5. Notably, chitinase production was distributed unevenly across bacterial groups: Chromobacterium, Pseudomonas, and Klebsiella species were among the most active producers, while Escherichia coli and Salmonella were negative. All tested Klebsiella pneumoniae, K. ozaenae, and K. rhinoscleromatis strains produced chitinase, whereas Escherichia coli strains did not. The authors suggest chitinase production may have diagnostic value for bacterial identification and classification.

Key findings

• Chitinase is a constitutive enzyme in many bacterial species, produced independently of chitin or its breakdown products in the growth medium
• Klebsiella species, particularly K. pneumoniae, K. ozaenae, and K. rhinoscleromatis, consistently produce chitinase, while Escherichia coli and Salmonella species do not
• A sensitive colorimetric detection method was developed using acetylglucosamine measurement as an indicator of chitin breakdown
• Chitinase production varies among bacterial groups and may have potential diagnostic value for bacterial classification and identification
• The enzyme is relatively stable and works optimally at pH 5, with activity enhanced by the addition of protein to the assay medium