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Title: Investigations into the variability of the soil fungus Mucor ramannianus
Author: Evans, Elizabeth Howell
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1962
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Studies on the distribution of Mucor ramannianus in coniferous woodland and heathland soils of a podsolic nature resulted in the amassing of a number of isolates. Macro and micro morphological observations on these isolates revealed that they could be placed in five distinct groups, A -E.A study of the growth reactions of the isolates under a number of different cultural conditions showed that they also differed physiologically. The isolates could be placed in the same five groups on physiological grounds, as well as on morphological grounds. A study of the growth factor requirements of the species revealed that some isolates were heterotrophic for thiamin, whilst others were autotrophic or incompletely autotrophic for this vitamin. One isolate required some other growth factor, but its exact requirement was not discovered. Variation within the species was thus shown to occur at morphological, physiological and biochemical levels, the last two being related to the morphology of the isolates. Crossing experiments between isolates of the same and different groups produced negative results, i.e. zygospores were not produced. A spontaneous imitation of an autotrophic isolate resulted in sectors which required thiamin for growth. These mutant sectors were exactly similar in morphology, physiology and biochemistry to the isolates of the heterotrophic group. Thus a connection between two of the groups was discovered. Following the observation of occasional hyphal fusion and anastomosis in this species, the possibility of heterokaryosis being a means of variation within the species was considered. Induced biochemical mutants were obtained by use of X-rays and ultra-violet light. Heterokaryons were produced between certain of these mutants and the spontaneous mutant. Investigations into the distribution of M.ramannianus have revealed that there is a relationship between the type of distribution shown by a particular isolate of the species and the group to which that isolate belongs.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Soil Sciences