Effect of Potassium Ions on Protoplast Generation during Yeast Induction from Mucor circinelloides Tieghem.

C O Omoifo

doi:10.5402/2013/734612

Abstract

Mucor circinelloides aerobically exhibits coenocytic thallic growth habit with straight and circinate sporangiophores which culminate in globose or pyriform columellae enclosed within sporangial walls. It undergoes dimorphic switch with its conversion to multipolar budding yeast-like cells or thallic conidia. This paper confirms the induction of plurality of reproductive structures of the pleomorphic microorganism in minimal medium. Furthermore, construction of pH differentials at inflection points in the biphasic profiles during sporangiospore-yeast transformation indicated the intensity of H+ release from intracellular medium of the growing microorganism in a study conducted with K+ levels (0.0, 0.5, 0.7, 0.9, 1.0,1.10 g/L)-mediated broths. Optimum proton release was at 0.00 and 1.0 g/L K+-supplemented broths, but specific growth rate was least in the latter. It also coincided with a preponderance of neoplastic units, protoplasts, and terminal budding yeast cells. On either side of this K+ level, variation in morphologies, including neoplasts, protoplasts, septate hyphae, thallic, holothallic, and holoblastic conidia, was greater, although olive-green septate hyphae with vesicular conidiogenous apparatus occurred at all K+ levels tested. This study suggested that following the establishment of transmembrane pH gradient across protoplast membrane, operation of Mitchellian proton pump was further promoted, thus leading to active transport mechanism, a prelude to yeast morphology induction.

Highlights

Fungi produce spores so as to reproduce the species
Monotypic with coenocytic thallic growth, it speciates by the possession of two types of columellae, which are spherical and pyriform, and two types of sporangiophores, upright and circinate—from which it derives its name [1]
An additional growth form, thallic conidia formation, like the arthric conidia of the nature of Geotrichum candidum [3], was shown by McIntyre et al [4] when this fungus was grown in minimal Vogels medium. e formation of thallic conidia by M. circinelloides was con rmed by L bberh sen et al [5] who found that such conidia were multinucleate

Summary

Introduction

Fungi produce spores so as to reproduce the species. Zygomycetes are well known for zygospore formation in sexual reproduction but sporangiospores in asexual reproduction. Us, the need was elicited for an understanding of its physiological processes for evolution of speci c morphologies, since form of growth is a process parameter in any industrial set-up [5] In response to this advice, Omoifo and Awalemhen [6] studied the growth of this organism in wellde ned minimal medium and found that the microorganism exhibited a plurality of structures. We have had for M. circinelloides induced asexual structures such as holoblastic, holothallic, and thallic conidia and yeast cells [6], each of which is proliferate [7] It was shown in the study of Omoifo and Awalemhen [6] that during the growth process, intermedial ionic communication occurred and this appeared to correlate with the occurrence of speci c morphologies. We found that protoplasts were copiously generated at optimum K+ level, but H+ release intensity from intracellular medium appeared to have signi cant effect on the generation of protoplasts, which subsequently led to the nonpersistent yeast morphology

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Conclusion