Interactions between nitrogen sources and xylose affecting growth, sporulation, and polyphenoloxidase activity in Bipolaris maydis race T

Abstract

The effect of 23 organic and 3 inorganic nitrogen sources on growth, sporulation, and polyphenoloxidase activity was measured in Bipolaris maydis race T incubated with or without a xylose supplement. Mycelial dry weight tends to be highest on acidic and other polar amino acids and least on nonpolar ones; organic nitrogen sources generally result in greater dry weight than inorganic ones. Changes in nitrogen concentration and pH of media influence growth and sporulation, but only pH alters the relative effectiveness of the nitrogen sources on these processes. The addition of xylose to the growth media has little effect on growth. However, in the presence of lysine, serine, asparagine, glycine, γ-alanine, alanine, and α-aminobutyrate, xylose causes an increase in sporulation and a concomitant decrease in polyphenoloxidase activity. There is no consistent pattern resulting from xylose addition in the presence of the other nitrogen sources.