Entomopathogenic isolates of Metarhizium anisopliae, Beauveria bassiana, and Aspergillus flavus produce multiple extracellular chitinase isozymes
St. Leger, R.J. | Staples, R.C. | Roberts, D.W.
Multiple extracellular chitinase isozymes were detected in culture filtrates from Metarhizium anisopliae, Beauveria bassiana, and Aspergillus flavus following electrophoresis on sodium dodecyl sulfate-polyacrylamide gels. Following renaturation, lytic zones of glycol chitin included in the gel were revealed by UV illumination after staining with Calcofluor White M2R. The method was applied to a study on the mode of regulation of chitinolytic enzymes. High chitinase activities where present only in chitin-containing media. Addition of alanine, a readily utilized nutrient source, repressed chitinase production in M. anisopliae indicating that each isozyme was similarly regulated by products of chitin degradation by an inducer-repressor mechanism. However, a chitinase-deficient mutant of M. anisopliae demonstrated reduced production of all but one of the chitinase isozymes. The remaining activity (48 kDa) is evidently under separate control from the other isozymes which presumably are jointly controlled from a single regulatory gene. The implications of entomopathogens producing multiple forms of chitinase are discussed in terms of pathogenicity and future research prospects.
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