Effects of Temperature and ph on Growth and Composition of Pythium Irregulare and Pythium Vexans

SUMMARY

Temperature and pH significantly affect the growth and composition of Pythium irregulare and P. vexans. The apparent optimum temperature for mycelial production by either fungus was lower in liquid medium than on agar, and P. irregulare produced greater amounts of mycelium than P. vexans under all conditions tested. The percentage of soluble sugar content in both fungi decreased markedly with increased incubation temperatures, whereas protein content increased. Pythium vexans contained more sugar and less protein than P. irregulare on a percentage basis. Lipid and polysaccharide content varied, but there appeared to be a balancing effect of these components with sugar metabolism. Within the ranges studied, temperature exhibited a more pronounced effect than pH on the growth and composition of these fungi.