Osmotic stress conditioning for induction of acquired osmotolerance in Escherichia coli.

Abstract

Escherichia coli cells exhibited osmotolerance and grew well even in hyperosmotic medium containing 1.2 M NaCI (or 2.0 M sorbitol) if they had been previously exposed to moderate osmotic stress for a short time (30min). Untreated cells showed repressed growth. This acquirement of osmotolerance against hyperosmolarity was dependent on the concentration of the osmoticum in the osmotic stress conditioning. The most effective conditioning occurred when almost the same moderate osmolarity of electrolytes (about 0.4-0.6 M NaCI or KCl) and non-electrolytes (about 0.8-1.2 M sorbitol or sucrose) was used as osmoticum. The acquired osmotolerance could be inhibited markedly by chloramphenicol or rifampicin, but not by nalidixic acid. Experiments with 35S-methionine incorporation suggest that the synthesis of several proteins might be related to the acquiring of osmotolerance.Osmotolerance is essential to survival for bacterial cells exposed to higher osmotic strengths in their habitat environment. "Ordinary" non-halophilic bacteria as well as halophilic bacteria are thought to develop a variety of strategies for hyperosmolarity. Many species are known to accumulate high concentrations of compatible solutes, such as potassium, proline and betaine, in cells when grown in a hyperosmotic medium (3,6,7,9). These bacteria are thought to maintain intracellular concentrations of such compatible solutes at levels at least as high as those of external concentrations. Among these bacteria, Escherichia coli has been studied extensively with respect to the accumulation of compatible solutes (2,4,10,(14)(15)(16)20) and osmoregulation concerning gene expression response to the hyperosmolarity of the culture medium (1,5,7,(17)(18)(19)23). However, there are only a few * Address

Inhibition of succinic acid production in metabolically engineered Escherichia coli by neutralizing agent, organic acids, and osmolarity

“…As a macronutrient for E. coli growth, potassium is involved in a number of fundamental biological processes including maintaining the osmotic balance of cells 25. NaOH is a widely available low‐price commodity chemical, and E. coli has been reported to grow in media containing high concentrations of sodium 26. Na 2 CO 3 and K 2 CO 3 were used to investigate if additional carbonate would increase the carbon flux to succinate.…”

“…This conclusion is further substantiated by the results from the fermentations supplemented with glycine betaine (Table 2). There are numerous studies and reviews on osmotic stress and osmotolerance in bacteria 26, 29–31. E. coli subjected to osmotic stress respond by accumulating compatible solutes, such as glycine betaine, proline, and trehalose 32, 33.…”

DNA Strand Breaks Signal the Induction of DNA Double-Strand Break Repair in Saccharomyces cerevisiae

“…It has been shown that the stresses are capable of inducing a response that may be specific or global, offering cross protection to different challenging stresses. Conditions such as pH (13), osmolarity (14) and heat (15,16) induce different stress-response pathways. The essential signal required to induce a particular pathway and the threshold required for this induction are currently receiving attention, but they remain poorly understood.…”

The effect of salinity stress on the accumulation of compatible solutes related to the induction of salt-tolerance in Escherichia coli.

“…We have recently reported (12,13) that the osmotolerance of E. coli cells against hyper-osmolarity could be acquired easily by prior exposure to a moderate salinity stress for a short time (about 30 min). However, it is not at all clear why the moderate salinity stress was effective on the induction of acquired osmotolerance in E. codi.…”

“…coli ATCC-9637 was aerobically cultured as described by Ishida et al (12) in a nutrient broth (pH 7.0) containing 10 g of yeast extract (Dried yeast extract D-3, Nihonseiyaku KK, Tokyo, Japan), 10 g of polypeptone (Nihonseiyaku KK), and 2 g of NaCI in 1,000 ml of distilled water. After 12 h of culture, cells were collected by centrifugation (10,000 X g for 5 min, 4°C), washed twice with distilled water unless otherwise stated, and stored at 4°C until used.…”