Formation of O-Ethylhomoserine during the Controlled Production of Resistant Sporangia in Allomyces macrogynus

Abstract

Evidence is presented that O-ethylhomoserine which accumulates in the amino acid pools of A. macrogynus before the development of resistant sporangia is synthesized from homoserine and ethanol, the enzyme being produced in response to methionine deficiency. A requirement for suboptimal aeration in the development of the sporangia is accounted for by a need to produce ethanol from glucose. A. macrogynus has a limited ability to synthesize methionine and it is suggested that accumulation of O-ethylhomoserine inhibits this synthesis.

Oxygen and Morphological Changes in Allomyces macrogynus

“…It was known that the oxygen requirement for vegetative growth of Allomyces species was less than the requirement for the production of gametangia (Kobr and Turian 1967) and of zoosporangia (Youatt et al 1971). The production of resistant sporangia was favoured relative to zoosporangia at reduced levels of aeration (Youatt 1982) and was associated with the formation of O-ethylhomoserine, indicating that there had been fermentative production of ethanol (Youatt 1983). Increased hyphal extension at lowered oxygen tension had also been recorded (Youatt 1982).…”

DNA Synthesis in Relation to Hyphal Branching and Wall Composition in Allomyces macrogynus

“…Methionine concentrations were relevant to the control of branching and the type of sporangium which developed. Recently it appeared that the organism had some ability to synthesize methionine (Youatt 1983). Most of the precursors of methionine are not suitable for testing whether they support growth by culture methods and an alternative test was developed using hyphal branching as the indicator (see Appendix).…”