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Growth of Erwinia carotovora, E. atroseptica and Pseudomonas fluorescens in Low Oxygen and High Carbon Dioxide Atmospheres. John M. Wells, Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, Plant Industry Station, Beltsville, Maryland 20705, Present address: USDA, Southeastern Fruit and Tree Nut Research Station, Byron, Georgia 31008; Phytopathology 64:1012-1015. Accepted for publication 22 February 1974. DOI: 10.1094/Phyto-64-1012.

Growth of six isolates of Erwinia carotovora, E. astroseptica, and Pseudomonas fluorescens on a buffered asparagine-yeast extract broth at 21 C in atmospheres of 21, 3, 1, 0.50, 0.25, and 0% O₂ + 3% CO₂ decreased linearly with the logarithm of decreasing O₂ concn. Mean percent growth at 3% O₂ ranged between 54 and 64% of that in air, and at 0% O₂ growth was between 3 and 12.5% of that in air. In the absence of CO₂, Erwinia spp. did not grow at any concn of O₂ within a 24 h experimental period, and the growth of four of six isolates of P. fluorescens at 1% O₂ or below was approximately half of that in the presence of 3% CO₂. In atmospheres containing different concns of CO₂ and either 3 or 21% O₂, the growth of Erwinia spp. and P. fluorescens was inhibited by CO₂ concns in excess of 10%. Growth in 30% CO₂ was 15 to 34% of that in air.