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Appl Environ Microbiol. 1984 September; 48(3): 594-600
Copyright © 1984, American Society for Microbiology. All Rights Reserved.

Effects of Abiotic Factors on Acetylene Reduction by Cyanobacteria Epiphytic on Moss at a Subantarctic Island

Institute for Environmental Sciences, University of the Orange Free State, Bloemfontein, Republic of South Africa, 9301

ABSTRACT

Acetylene reduction (AR) rates by cyanobacteria epiphytic on a moss at Marion Island (46°54' S, 37°45' E) increased from –5°C to a maximum at 25 to 27°C. Q₁₀ values between 0 and 25°C were between 2.3 and 2.9, depending on photosynthetic photon flux density. AR rates declined sharply at temperatures above the optimum and were lower at 35°C than at 0°C. Photosynthetic photon flux density at low levels markedly influenced AR, and half of the maximum rate occurred at 84 µmol m^–2 s^–1, saturation occurring at ca. 1,000 µmol m^–2 s^–1. Higher photosynthetic photon flux density levels decreased AR rates. AR increased up to the highest sample moisture content investigated (3,405%), and the pH optimum was between 5.9 and 6.2. The addition of P, Co, and Mo, individually or together, depressed AR.