Role of Marine Fungi in the Biochemistry of the Oceans. II. Effect of Glucose, Inorganic Nitrogen, and Tris (Hydroxymethyl) Amino-Methane on Growth and pH Changes in Synthetic Media

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Abstract
Cellulolytic isolates of Halosphaeria mediosetigera, Culcitalna achraspora, Humicola alopallonella, and Orbimyces spectabilis were variously studied and reference growth curves established. Maximum growth occurred at maximum glucose concentrations in the presence of THAM buffer but was inversely related to NH4NO3 concentration. Salts of NH4 with strong acids invariably caused low pH during growth. Organic acids were probably not responsible and it was hypothesized that metabolic H-ion was being exchanged into the medium for NH4. Conversely KNO2 and KNO3 caused pH increases. The benefits of pH stabilization by THAM were offset by the toxicity of the amine at effective concentrations. Alkalinity also increased THAM toxicity. All cultures grew on NH4, NO2, and NO3 but preferred NH4 Halopallonella alone failed to grow best at marine-like pH (7.5-8.). Environmental implications are discussed.