Osmoprotective activity for Escherichia coli in mammalian renal inner medulla and urine. Correlation of glycine and proline betaines and sorbitol with response to osmotic loads.

Abstract

Escherichia coli are protected against hypertonic NaCI by human urine. We have shown that this is due in part to the presence of glycine betaine and proline betaine. Several investigators have proposed that betaines and sorbitol are concentrated in the cells of the renal inner medulla where they exert a protective role against urea and extracellular osmotic forces. E. coli was used in the present studies as an "osmosensor" to detect osmoprotective activity in mammalian tissues. The greatest activity was found in extracts of renal inner medulla and to a lesser extent in the renal outer medulla and cortex of several mammalian species. Liver extracts were more active than other nonrenal tissues. Bacterial osmoprotectiye activity and concentration of glycine betaine in the renal inner medulla of rabbits were found to correlate closely with urinary osmolarity. Concentrations of sorbitol were found to be also increased in the renal inner medulla during osmotic stress, but this compound is not osmoprotective for E. coli. Glycine and proline betaine were recovered in urine of rabbits and were increased in those given high osmotic loads. Only small amounts of proline betaine were recovered in the renal inner medulla. The source from which proline betaine is derived is unknown.

The Effect of Urine Concentration and pH on the Growth of Escherichia Coli in Canine Urine In Vitro

“…Possible reasons for these discrepancies are inherent differences between in vivo and in vitro study designs, differences among E. coli strains with regard to osmotolerance, and species differences in the content of urinary osmoprotective substances. For example, in 1 in vitro study, osmotically stressed E. coli were able to grow in hyperosmotic urine by utilization of urinary glycine and proline betaine as osmoprotective molecules. In that study, differences were found in urinary glycine and proline betaine concentrations among species resulting in differences in growth thresholds in a hyperosmotic environment.…”

Influence of the RpoS (KatF) sigma factor on maintenance of viability and culturability of Escherichia coli and Salmonella typhimurium in seawater

“…The development of such a hyperresistant state in enteric bacteria grown in media of high osmolarity and low oxygen content might have interesting ecological and sanitary implications. It is now well documented that both the intestinal content and the urine are media with high osmotic strengths (24,28,46) in which enteric bacteria can grow and exhibit structural and physiological adaptations to hyperosmolarity (5)(6)(7)24), such as OmpC porins (40) that lower the VNC response of E. coli in seawater (12). Moreover, the very high resistance to seawater of freshly voided fecal coliforms from human origin has been reported recently (13).…”

Osmoregulatory transporter ProP influences colonization of the urinary tract by Escherichia coli

“…Current research on the role of bacterial osmoadaptation in urinary tract infection was triggered by the observation that urinary glycine betaine and proline betaine provide osmoprotection to E. coli (Chambers & Kunin, 1987). Glycine betaine raises the salt tolerance of E. coli to 1 M (according to the criterion described above; Kunin et al ., 1992).…”