Effect of Carbon Dioxide on Growth-Rates of Selected Microorganisms Isolated from Black Drum (Pogonias cromis)

Abstract

The effect of carbon dioxide (25–100%)-enriched atmospheres on growth rates of a coryneform bacterium, Micrococcus varians, a Vibrio sp., a Moraxella sp. and Pseudomonas fluorescens growing on trypticase soy agar at 4 and 25°C was investigated. Growth rates were determined by measuring the rate of increase in the diameter of colonies on plates packed in laminated plastic pouches containing the CO2-enriched environments. Carbon dioxide caused a significant decrease in the growth rates of all the organisms and the inhibitory effect was greatly enhanced by low temperatures. At 25°C, the gram-positive organisms were more resistant to CO2 than the gram-negative organisms, while at 4°C none of the organisms grew in 25% CO2, the lowest concentration tested. When exposed to air after being incubated in CO2-enriched environments, the organisms in most instances grew at normal rates indicating limited residual effect of CO2. The effect of temperature on relative CO2 inhibition was investigated in detail for the Moraxella sp. and P. fluorescens. In an atmosphere containing 25% CO2 in air at 20°C both organisms showed approximately 25% inhibition as compared to growth in air at the same temperature, while at 10°C P. fluorescens was completely inhibited and the Moraxella sp. showed 95% inhibition.