Control of Escherichia coli growth by CO2

Abstract

Escherichia coli B dependence on CO2 for growth was demonstrated. At suboptimal CO2 concentrations the rate of growth was controlled by CO2 concentration. Many techniques used to minimize the lag period preceding culture growth were described in the early microbiological literature, whereas others are a part of the legacy of unpublished observations from many laboratories. The appearance of a lag period after successive transfers of cultures in the same medium always was an enigma that has been subject to a number of theories, but each hypothesis was unable to account for some experimental observations. While determining conditions to obtain reproducible growth of the obligate autotrophic aerobe, Alcaligenes eutrophus, we found that a specific concentration of one component, bicarbonate, produced immediate growth without the customary lag period (6). This prompted a comparative study with an organism at the opposite end ofthe nutritional scale. Anaerobically grown Streptococcus sanguis responded in the same way, but CO2 was the active species (7). In this report we show that growth of a washed stationary-phase inoculum of the facultative aerobe, Escherichia coli, also will grow without a lag period if a suitable concentration of CO2 is provided. With all three organisms the initial and subsequent exponential growth rate was controlled solely by the concentration of CO2 or bicarbonate. These findings indicate that the effect of CO2 or bicarbonate on the conventional lag period and on the growth rate is not an unusual phenomenon and suggest that CO2 or bicarbonate may have the same regulatory function in all microorganisms.Carbon dioxide or its hydrated form, bicarbonate, has been a recognized requirement for cell growth since Valley and Rettger (8) perfonned an extensive survey and demonstrated that none of the more than 100 microorganisms tested would grow if CO2 were excluded. More recently the basis for the CO2 requirement by heterotrophic microorganisms was established; C02-fixing enzymes were isolated and their functions in various metabolic pathways are now known. The qualitative CO2 requirement for growth is not the subject of this report. We wish to emphasize the fundamental physiological effect of C02 concentration on regulation of the growth rate. The lag period appears to be the initial manifestation of the same effect.Walker (9) first showed that added CO2 shortened the lag period of E. coli, and Neidhardt et al. (5) recently reported that the lag period was virtually eliminated when bicarbonate was incorporated in the medium. Quantitative demonstration ofthe effect ofC02 on growth requires a minimal medium and a system for accurately maintining low concentrations of C02. Small incremental increases in C02 concentration must be tested to assure detection of the optimum, for the optimum may span a narrow range of concentrations (6,7).A vessel with a 1-liter working capacity was designed to receive three separate gases (N2, 02, and CO2) which were mixed in the vessel to fonn an atmosphere of any desir...

Effect of acetaldehyde on Saccharomyces cerevisiae and Zymomonas mobilis subjected to environmental shocks

“…To test this explanation, the ability of filtrates from early exponential phase cultures to reduce lag was examined (data not shown); however, the lag reductions observed were no greater than could be predicted on the basis of their acetaldehyde content (and, to a small extent, their slightly reduced pH compared to fresh medium), suggesting that the proposed additional lag-reducing substance may have been lost during filtration and storage. It is possible that the inoculum size effects under these conditions reflect the need to accumulate carbon dioxide in the medium prior to growth: a strong correlation between extracellular carbon dioxide and lag times in bacteria has previously been demonstrated by several workers (Gladstone et al, 1935;Repaske et al, 1974, Repaske andClayton, 1978;Walker, 1932). A similar effect would be expected for S. cerevisiae which conducts various carboxylation reactions (Strathern et al, 1982).…”

The impact of CO2/HCO3-availability on anaplerotic flux in PDHC-deficientCorynebacterium glutamicumstrains

“…In aerobic glucose-based bioprocesses the endogenous production of CO 2 is typically sufficiently high to promote microbial growth even at low cell densities. However, it is a well-known fact that anaerobic growth of some bacteria, like E. coli , requires the external supply of CO 2 /HCO 3 - to avoid long lag phases (26, 55, 56). The critical impact of CO 2 /HCO 3 - levels may become especially evident under conditions when the endogenous CO 2 production rate becomes limiting.…”

Prokaryotic carbonic anhydrases

“…The dependence of bacteria on the presence of CO 2 for growth or for overcoming long lag times (the so-called sparking phenomenon) has been known for 25 years [92,93]. At low pCO 2 and low rates of metabolism, CO 2 is expected to di¡use out of the cell faster than it is hydrated to HCO 3 3 , thereby depleting the intracellular HCO 3 3 needed for carboxylation reactions.…”

“…At low pCO 2 and low rates of metabolism, CO 2 is expected to di¡use out of the cell faster than it is hydrated to HCO 3 3 , thereby depleting the intracellular HCO 3 3 needed for carboxylation reactions. Previous studies have shown that either a large inoculum or the presence of succinate, aspartate or oxaloacetate can overcome the long lag times observed during growth at low pCO 2 by increasing the citric acid cycle rates and the concentration of CO 2 and HCO 3 3 [92,93]. Kozliak et al [91] showed that the growth of wild-type E. coli and the cynS, cynT and cynTSX deletion mutants is negligible when CO 2 is absent from the atmosphere.…”