Wall Structure and spore Germination in Fusarium culmorum

The conidial and germ-tube walls of Fusarium culmorum (W. G.Smith) Sacc. have been examined by various chemical and electron-microscopetechniques. On the basis of these results and hypothesis isproposed for the organization of these walls. Microchemicaltests indicate the presence of chitin in the walls and suggestthat the mucilaginous layer around the conidium is mainly composedof xylan. Chemical analyses of isolated wall material confirmthe presence of chitin constituents in the wall, and a rylanlayer around the conidium. Furthermore, the wall contains apolypeptide moiety which has a different amino acid compositionfrom the rest of the protein of the cell. Electron microscopestudies of replicas and sections of conidia, germ tubes, andhyphae reveal a layered structure for the wall. The centrallayer is non-microfibrillar and is overlaid on both sides witha layer of randomly orientated microfibrils. The mucilaginouslayer of the conidium obscures the microfibrillar structurebeneath it unless the mucilage is removed by hydrolysis. Theproblem of hyphal growth is discussed on the basis of the structureof germ-tube tips and mature hyphae observed.     

Effect of the Copper Content of Distillery Spent Wash on its Utilization for Single-cell Protein Production by Geotrichum candidum, Hansenula anomala and Candida kruzei

Geotrichum candidum, Hansenula anomala and Candida kruzei were grown in batch and continuous culture on samples of the spent wash from a malt whiskey distillery containing levels of dissolved copper up to 22 mg/l. In batch culture some inhibition of growth at the higher copper concentrations and as much as a sixfold accumulation of copper in the biomass were observed. In Geotrichum candidum this accumulation occurred in three distinct phases during the period of batch growth. Although biomass yields in mixed continuous culture declined with increasing dilution rate there was a corresponding increase in cell copper concentration such that total copper removal from the medium remained approximately constant.