Ergosterol Content of Salt-Marsh Fungi: Effect of Growth Conditions and Mycelial Age

ABSTRACT

Species of the ascomycetc genera Phaeosphaeria, Leptosphaeria, and Buergenerula from the Spartina alterniflora decomposition system were analyzed for ergosterol content of their mycelium. Bacterial and algal members of the system were also tested. A standard laboratory liquid medium, a complex, semi-natural liquid medium, and a semi-natural solid medium were used to grow the microorganisms. Ergosterol contents of fungal mycelium ranged from 1.9-2.5 mg·g^-1 dry organic mass in the standard medium, and were 3.4-16.4 mg·g ¹ in the semi-natural liquid medium. For any single growth medium, ergosterol content of mycelium was less variable with mycelial age than has been previously found for glucosamine. For Leptosphaeria obiones, ergosterol content in solid medium was estimated to be similar to that in semi-natural liquid, but for Phaeosphaeria typharum, solid medium yielded much higher (X5) ergosterol estimates, possibly due to underestimated mycelial mass. Partial mycelial autolysis led to low estimates of ergosterol content (1.1 mg·g^-1 dry organic). Bacteria had negligible ergosterol contents, but there was evidence that green-microalgal ergosterol content might not be negligible in some decomposition systems.

Key Words:

• ergosterol
• Spartina
• fungal biomass
• Pseudendoclonium