Advantages of the Gas Exchange Approach to Microbiological Studies

摘要

Studies of the effects of various chemical or physical stimuli on the growth rates of microorganisms generally involve some measure of biomass. In the case of algae, one might measure the cell number, the chlorophyll concentration, the fluorescence, or the wet weight of the culture as a function of time. Each such measurement requires a sampling of the culture which could be a disturbing factor in the system being measured. Another disadvantage of these traditional measurements is that the times required for significant change to take place in the culture might be hours or days; furthermore, growth rate measurements calculated from the data must be based on the assumption that during the time between measurements the growth rate was constant. This report describes another approach to the problem. It consists simply of monitoring the O2 or CO2 concentration of an air stream passing through the system (the gas exchange method), and it has several distinct advantages: 1) there is no need to take samples of the culture, 2) each measurement is a rate measurement and indicates the performance of the culture at that very moment, and 3) transitory changes in growth rates are readily detected. Examples are given of studies made previously with this method at NRL. Also the possible value of these methods in a study of the corrosion susceptibility of alloys is described. Keywords: Chlorella, Toxicity, O2 production, CO2 uptake.