Factors affecting protoplast isolation and regeneration in Microsporum gypseum

Factors affecting high yields, regeneration frequencies, and viablity of protoplasts from clonal cultures of Microsporum gypseum were investigated. Maximum yields of protoplasts were obtained after 6 hr digestion of 2-4 days old mycelium with Novozyme 234 using CaCl2 [0.4M] as an osmotic stabilizer and glycine [+] HCL [pH 4.5] as the buffer system. Mercaptoetoethanol + dithi-othreitol [0.01 M] proved to be the best pretreatment of mycelium prior to digestion with enzyme. A regeneration frequency of 94.4% was obtained using the top agar method with complete medium [pH 6.5] containing 0.5% agar and 0.4 M CaCl2 as an osmoticum. Colonies from regenerated protoplasts on medium containing were pigmented and completely powdery with high sporulation

Factors affecting the development of the mycelial or yeast forms of Histoplasma duboisii

Culture conditions for the exclusive development of the mycelial and the yeast forms of Histoplasma duboisii from conidia in a rich, defined medium were established. Only the mycelial morphology developed when the pH of the medium was adjusted between 4.0 and 5.0 and the conidia were incubated at 25°, regardless of aeration. When the pH of the medium was adjusted between 6.5 and 8.0 and the conidia were incubated with aeration at 35°, only the yeast form was obtained. Development of the mycelial form was observed with all of the carbon sources tested [glucose, fructose, mannose, arabinose, sucrose and starch] while the yeast form was developed only