Studies with Clinical Isolates of Cunninghamella II. Physiological and Morphological Studies

SUMMARY

Studies were made to determine whether distinctions between Cunning-hamella elegans and C. bertholletiae, and between clinical and saprophytic isolates of C. bertholletiae, can be made on a physiologic and/or morphologic basis. Results indicate that temperature tolerance is the key differential feature for C. elegans, which does not grow at 40 C. Strains of C. bertholletiae were variable with respect to temperature tolerance. All of the clinical isolates of the latter, but only five of seven saprophytic strains, grew well at 40–45 C. As a group, however, clinical and saprophytic isolates of C. bertholletiae could not be differentiated. Temperature tolerance may also be a key differential feature in identifying neutral isolates of Cunninghamella which lack conidia with long echinula- tions. One of the clinical isolates of C. bertholletiae which failed to produce zygospores when paired with both (+) and (-) mating types of C. elegans and C. bertholletiae was identified on the basis of growth at 40 C and minor characteristics common to other clinical isolates.