Distinctive behaviour of invertase in a thermophilic fungus, Thermomyces lanuginosus.

Invertase (β- d-fructofuranosidase, EC 3.2.1.26) activity appeared in cultures and mycelial suspensions of a thermophilic fungus. Thermomyces lanuginosus, only when sucrose or raffinose was added as the carbon source to the medium. The enzyme activity disappeared rapidly following the exhaustion of sugar in the culture medium. Extracellular invertase activity was not detected. The maximal enzyme activity occurred prior to the maximal growth of the fungus. The appearance of invertase activity was dependent on growth. The enzyme activity was not stable in cell-free extracts of mycelia. The lability of the enzyme was also observed in mycelia incubated in the presence of cycloheximide. In the above respects the behaviour of invertase in T. lanuginosus differs from invertase of yeasts and molds (mesophiles) which have been studied. [ABSTRACT FROM AUTHOR]