The morphological and associated physiological aspects of the chemoorganotrophic and photoorganotrophic appendaged (prosthecate) bacteria were considered. Initially work centred on the enrichment, isolation and enumeration of the chemoorganotrophic species Ancalomicrobium,Caulobacter and IIyphomicrobium from freshwater sources which varied in eutrophication levels. Induction and repression of the multiappendaged form of an Ancalomicrobium isolate, induced by environmental stimuli, was indicated. Additionally the morphological diversity of IIyphomicrobium found to be expressed in response to carbon source variation (methanol to methylamine) brings into doubt the validity of generic classification on the grounds of morphology. Of the appendaged photoorganotrophic (Athiorhodaceae) species isolated, the growth, and reproduction of a Rhodomicrobium species was studied in detail. This microorganism was shown to be similar physiologically to Rh.vannielii (Duchow and Douglas, 1949) but differed in that it produced exospores in profusion during the stationary phase. The formation, germination and physiological characteristics of these resting cells were examined. Information from the growth and reproduction studies, correlated with ultrastructural work, was used to formulate a model for growth and replication applicable to the vegetative cell 'and exospore. The obligatory, sequential, differential events required for growth and replication of the Rhodomicrobium. swarm cell lead to exploitation of this system as a model for the study of differentiation. A selective synchronisation procedure was formulated and the resulting synchronised swarm cell population characterised morphologically and physiologically with respect to the differential cycle. Contrary to reports in the literature no extrachromosomal (plasmid) DNA could be detected In any of the appendaged, obligate life cycled genera. In addition, sub- division of these genera by reference to their mole percent G + C content was found to be of little value.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:595035 |
| Date | January 1973 |
| Creators | Dow, Crawford S. |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/72139/ |
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