Variation in bacterial ATP concentration during rapid changes in extracellular pH and implications for the activity of attached bacteria

Abstract

In this study we investigated the relationship between a rapid change in extracellular pH and the alteration of bacterial ATP concentration. This relationship is a key component of a hypothesis indicating that bacterial bioenergetics - the creation of ATP from ADP via a proton gradient across the cytoplasmic membrane - can be altered by the physiochemical charge-regulation effect, which results in a pH shift at the bacteria's surface upon adhesion to another surface. The bacterial ATP concentration was measured during a rapid change in extracellular pH from a baseline pH of 7.2 to pH values between 3.5 and 10.5. Experiments were conducted with four neutrophilic bacterial strains, including the Gram-negative Escherichia coli and Pseudomonas putida and the Gram-positive Bacillus subtilis and Staphylococcus epidermidis. A change in bulk pH produced an immediate response in bacterial ATP, demonstrating a direct link between changes in extracellular pH and cellular bioenergetics. In general, the shifts in ATP were similar across the four bacterial strains, with results following an exponential relationship between the extracellular pH and cellular ATP concentration. One exception occurred with S. epidermidis, where there was no variation in cellular ATP at acidic pH values, and this finding is consistent with this species' ability to thrive under acidic conditions. These results provide insight into obtaining a desired bioenergetic response in bacteria through (i) the application of chemical treatments to vary the local pH and (ii) the selection and design of surfaces resulting in local pH modification of attached bacteria via the charge-regulation effect.

Physiological characterization and quantitative proteomic analyses of metabolically engineered E. coli K4 strains with improved pathways for capsular polysaccharide biosynthesis

“…Briefly, 10 OD 600 of biomass for each strain were washed, suspended in 1 ml of PBS and mixed for 15 s with 1 ml of NRB solution (0.05% alkyl‐dimethyl‐benzyl‐ammonium chloride in Tris‐Mg 2+ buffer) to lyse cells and inactivate ATPases. ATP assays were performed on a Luminometer (Glowmax Discover, Promega) as previously reported (Albert & Brown, ). Error bars indicate standard deviations of three independent experiments.…”

Tight control of genomic phosphorothioate modification by the ATP‐modulated autoregulation and reusability of DndB

“…In addition to arsenate and bleomycin, a variety of stresses result in variations in bacterial ATP levels. For example, an immediate increase in ATP concentration is induced in response to UV radiation, a growth temperature upshift from 30 to 42°C, and reduced turgor pressure, while a decrease in ATP occurs after a rapid increase in extracellular pH or cold shock (Villaverde et al ., ; Ohwada and Sagisaka, ; Soini et al ., ; Albert and Brown, ). Theoretically, these pronounced changes in ATP concentration could modulate the expression of the dndBCDE genes and, possibly, cellular PT levels, as we observed in cells treated with bleomycin and arsenate.…”

Implications of Adenylate Metabolism in Hygiene Assessment: A Review

“…On the average, there are 10 À15 g of ATP per bacterial cell compared with 10 À12 g of ATP per yeast or mammalian cell (112) or, as reported in moles, an average of 10 À18 mol of ATP per bacterial cell and 10 À15 mol of ATP per mammalian cell (67). It has also been shown that the age of the cells, stage in the growth cycle (61,106), nutritional status, oxygen levels (72), pH (6,44,104), temperature (80), and even specific organism can influence ATP content (9,44,104,111,131) through ATP synthesis, utilization, or decay.…”