Lysis of Vibrio costicolus by Osmotic Shock

Abstract

SUMMARY : Suspensions of the halophilic organism Vibrio costicolus lysed when subjected to sufficient osmotic shock; this was revealed as a marked fall in optical density. Organisms in the logarithmic phase of growth, grown in media containing M-NaCl, when suspended in NaCl or LiCl solutions with concentrations M or lower lysed when the concentration was below 0.33 M : when the organisms were suspended similarly in KCl or NH,CI solutions, lysis began at a concentration above 0 . 8~.Older organisms were more resistant to lysis. Lysis was little affected by replacement of chloride by other univalent anions, by pH values from 4 to 10 or by previous incubation with M-mercuric chloride. Addition of cetyltrimethylammonium bromide (200 pg./ml.) increased resistance to lysis in both NaCl and KCl solutions, Organisms grown in media of NaCl concentrations ranging from 0.5 to 3 . 0~ began to lyse a t a NaCl concentration one-third of that present during growth. Organisms suspended in NaCl solutions of one-half the concentration in which they had been grown equilibrated promptly to the new environment ; this was shown by a decrease of 5 0 % in the salt concentration at which lysis then began. When organisms were transferred to salt concentrations higher than that of the growth medium, the osmotic sensitivity was not affected. It is concluded that the osmotic status of these organisms is controlled chiefly by small ions or molecules which leak rapidly from the cells on transfer to dilute environments.Many types of bacteria lyse when transferred from concentrated growth media to more dilute solutions or to water, and this behaviour is particularly common among halophilic strains. Robinson & Katznelson (1953) noted that the extremely halophilic Pseudomonus salinaria, grown in a medium containing 16 yo (w/v) NaC1, underwent rapid plasmoptysis on transfer to 1 , 2 or 4 yo NaCl and showed some deterioration of structure in 8 % NaC1. However, no attempts appear to have been made to study quantitatively the degree of lysis resulting from osmotic shock. Christian & Ingram (1959) found that the freezing-point depression of heated bacteria was similar to that of their growth medium over a wide range of salt concentra.tions. It was of interest, therefore, to investigate the relationship between the osmotic sensitivity of such organisms and the salt concentration of the environment. This paper describes a technique for measurement of osmotic lysis, and reports the effects of a number of factors on the osmotic sensitivity of a moderate halophile, Vibrio costicolus. METHODS Organism.The test organism was a strain of Vibrio costicolus kindly supMedia. The organism was grown in liquid media containing 0.5% (w/v)

Proton motive force and Na+/H+ antiport in a moderate halophile

“…V. costicola can use the energy of respiration for proton efflux at alkaline pHo. When the bacteria were incubated anaerobically in a solution containing 1.0 M KCI to prevent lysis (9) and to maintain equal osmolarity to the growth medium, an oxygen pulse was followed by a rapid acidification of the medium (Fig. 2).…”

“…A role for antiport activity in pH regulation of the cytosol can also explain the broad pH range for optimal growth, extending to the alkaline extreme of pH 9.0. Vibrio costicola is a moderately halophilic bacterium which requires 1 M NaCl for optimal growth (13) and lyses in media of low osmotic strength (9). Lysis can be prevented by salts other than NaCl, but there is a specific Na+ requirement for carrier-mediated transport (24).…”

The Freezing Points of Bacterial Cells in Relation to Halophilism

“…It has also been shown (Christian & Ingram, 1959) that the osmotic sensitivity of both halophilic and non-halophilic…”

Bleb Formation on the Cell Envelope of Osmotic Shocked Cells of Vibrio parahaemolyticus.

“…One of the characteristics of this organism is its osmotic fragility, which causes the cells to lyse and become rapidly inactivated in distilled water (Lee, 1972;Yanagizawa, 1964) . Several investigations have been reported with regard to the lytic phenomenon of halophilic bacteria (Buckmire and MacLeod, 1965;Christian and Ingram, 1959;MacLeod and Matula, 1962;Unemoto, 1979) . Lysed cells generally leak intracellular materials, while maintaining its morphology.…”