Effect of myoinositol on sporangiospore-yeast transformation of Mucor circinelloides Tieghem cultivated in synthetic broth.

Mucor species exhibit fungal dimorphism in controlled environments. In this work, we examined the effect of myoinositol supplementation on the growth and morphology of Mucor circinelloides. Using sporangiospores as inoculums, diverse morphologies were induced in synthetic broth incubated at pH 4.5, temp. 20 degrees C, ambient. The morphologies included thallic suptypes (holoblastic-, holothallic-, enterothallic conidia as well as vesicular conidial headgroups), which were determinate in growth, and proliferating yeast forms. Analysis of variance, p<0.05, showed that time had significant impact on growth. A separation of means, l.s.d. 14.34, p<0.05, indicated that myoinositol supplementation at 500 microM supported the least growth, but 2.0-3.0 mM levels had the higher values, and this was followed by the control, 300 microM, 1.0, 2.0, 5.0 mM supplementations. Although the predominant morphology, that is, terminal budding yeast cells was not quantitated, observation showed that it was more preponderant, had optimal size and cell shape became more regular at 2.0 mM myoinositol supplementation.

Auxotrophic requirement for sporangiospore--yeast transformation of Dimorphomyces diastaticus strain C 12.

The filamentous microorganism tentatively known as Dimorphomyces diastaticus originally isolated from fermenting soursop extract, in contradistinction grew in the considiogeneous form in glucose-ammonium sulphate-basal salts buffered medium which induced polar budding yeast cells of another dimorphic microorganism, D. pleomorphis (1). Further experiments using this medium showed that a number of growth factors including inositol, thymine and uracil separately incorporated inducted yeast morphology. Carbon substrates gave rise to polar budding yeast cells in the following order: galactose, malic acid, maltose, but mycelial fragments were preponderant in the reverse order. There was no growth with citric acid as substrate. With maltose-substrate and uracil incorporation in buffered basal salts medium, only polar budding yeast cells were induced, while granular particles abound with thymine supplementation. It was concluded that D. diastaticus strain C12 auxotrophically required a dissacharide, maltose, and pyrimidine base, uracil, for sporangiospore-yeast transformation in buffered ammonium sulphate-basal salts medium, pH 3.5.

Dimorphic fungi isolated from spontaneously fermented juice of soursop, Annona Muricata L.

Two new fungi isolated from fermenting juice of soursop Annona Muricata L., exhibited dimorphism. Aerobic hyphae were coenocytic bearing sporangia while vegetative filaments were septate. Growth in broth was in discrete units. Glucose--yeast extract-peptone broth inoculated with sporangiospores of strain C12 induced arthroconidiospores but it was yeast cells, yeastlike cells, pseudohyphae and pseudomycelia bearing blastospores when strain C13 was inoculated. On the other hand, soursop extract induced arthrospores and yeast cells, yeast like cells and blastospore-bearing pseudomycelia respectively with strain C12 and strain C13 inoculation. Physiological characteristics were distinct. Strain C12 fermented soluble starch and raffinose completely while strain C13 proved weak for both sugars but complete in glucose utilization. The two dimorphic strains along with Saccaharomyces latis were negative in inulin fermentation. The three strains assimilated all carbon and nitrogen sources tested and grew at 37 degrees C. Based on cultural, morphological and biochemical differences, a tentative genus, Dimorphomyces was created for the dimorphic strains. D. diastaticus strain C12 and D. pleomorphis strain C13 were thought to initiate spontaneous fermentation which was brought to completion along with S. latis strain C14.

Modelling Sporangiospore-yeast transformation of Dimorphomyces strain.

Two types of buffered media, strictly defined-Ammonium sulphate-basal salts and complex Peptone-basal salts, were used for the cultivation of Dimorphomyces pleomorphis, one of two dimorphic fungi isolated from fermenting juice of soursop fruit, Annona muricata L. The growth count was taken every twenty-four hours. Transient morphologies were observed to change from sporangiospores through enlarged globose cells, to granular particles and eventually, polar budding yeast cells in the strictly defined medium at 15 degrees, 20 degrees, or 37 degrees C, but the complex medium casually terminally induced polar budding yeast cells and multipolar budding yeast like cells in between the growth phases, at 15 degrees and 20 degrees C, while mainly multipolar budding yeastlike morphology was observed at elevated temperature. There was obvious influence of nutritional factor or morphological expression (p < 0.01). After analysis of variance, the growth data could not fit into predictive quadratic polynomial model because the organism's response curves were incongruent with basic assumptions of the model. Furthermore, a stepwise regression analysis gave very low coefficients of determination, r2, for the interactive combinations. They were therefore, considered unfit for the data. Construction of the pII-profiles led to inference being drawn from the chemiosmotic theory, polyelectrolyte theory to account for the behaviour in the buffered multiionic media. It was also thought that inherent cellular mitotic division and glycolytic activity led to a prelogarithmic growth response.