L. Chernin et al., CHITINOLYTIC ACTIVITY OF THE ACAROPATHOGENIC FUNGI HIRSUTELLA-THOMPSONII AND HIRSUTELLA-NECATRIX, Canadian journal of microbiology, 43(5), 1997, pp. 440-446
Two isolates of the acaropathogenic fungus Hirsutella thompsonii (Nos.
255 and 414), and Hirsutella necatrix, were able to produce and excre
te chitinolytic enzymes. A chitobiase of >205 kDa was excreted by all
fungi and a chitobiase of 112 kDa only by isolate 414. An endochitinas
e of 162 kDa was excreted by isolate 414 and two endochitinases of 66
and 38 kDa were excreted by isolate 255. Both H. thompsonii isolates p
roduced chitinolytic enzymes only under inducible conditions, in the p
resence of colloidal chitin as the sole source of carbon. Hirsutella n
ecatrix produced a chitobiase constitutively when grown in the presenc
e of glucose. In addition to chitinolytic enzymes, the H. thompsonii i
solates excreted proteolytic activities, including elastase, as well a
s alpha-esterase and alpha-amylase activities. Hirsutella necatrix was
unable to use casein, milk powder, or elastin as the sole carbon sour
ce. The acaropathogenicity of these isolates was assayed on the carmin
e spider mite (Tetranychus cinnabarinus). Isolates 414 and 255 and H.
necatrix killed ca. 80, 35, and 15%, respectively, of the infected mit
es. The role of chitinolytic and other enzymatic activities in the aca
ropathogenicity of these fungi is discussed.