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

• Published in: Applied and Environmental Microbiology
• Main Author: Smith, Valdon R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 1984
• Subjects: Marion Island
• Online Access: http://dx.doi.org/10.1128/aem.48.3.594-600.1984; https://journals.asm.org/doi/pdf/10.1128/aem.48.3.594-600.1984

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. Q 10 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.