The interaction of carbon, nitrogen and sterilization of the medium on pycnidial production of Endothia parasitica

Abstract

The carbon source and concentration and the nitrogen concentration in a Millipore sterilized medium were varied simultaneously, and the effect of this on asexual sporulation of E. parasitica was studied. The availability of a carbon source for sporulation depended on its concentration and on the nitrogen concentration. It was concluded that in nutritional experiments it was essential to study several variables to get meaningful results for any one. Autoclaving the fructose medium greatly reduced sporulation compared with that in the sterile filtered medium. There was less difference between the amount of sporulation on autoclaved and that on sterile filtered sucrose medium. Sporulation also depended on whether the sugar and mineral salts were autoclaved together or in separate containers. Sterilization by autoclaving is not satisfactory for nutritional studies because of chemical changes it causes in the medium. Results with autoclaved media may be a reflexion of the toxicity or availability of the breakdown products of the substance under study.