The Effects of Alkalinity and Hypertonicity on the Morphology and Motility of Leptospira interrogans (biflexa) strain B16

Abstract

S U M M A R YEffects of alkalinity and hypertonicity on the motile behaviour of Leptospira interrogans (bzflexa) B I 6 were observed, quantified, and compared with effects previously shown by similar factors on the motility of eubacteria. Leptospira interrogans tolerated relatively high concentrations of hydroxide ions. Motility similar to that in controls was observed at pH values up to 9-8; but at pH 10.0 motility declined sharply with time of exposure, and there was structural alteration, visible as a blebbing of the cell envelope. Unlike the behaviour of eubacteria, immobilization of L. interrogans induced by hydroxide ions could not be reversed by lowering the pH. It is suggested that by restricting entry of hydroxide ions, the cell envelope protects its motility apparatus from adverse effects.Leptospira interrogans was completely immobilized in 0.5 M and I so M-sucrose solutions. Unlike the eubacteria, leptospires were incapable of spontaneous reversion to motile forms and resumption of motility was dependent on both concentration and time of exposure to sucrose. Deuterium oxide did not affect movement, suggesting that even though leptospire endoflagella and the exoflagella of eubacteria are analogous, the motile behaviour of L. interrogans is significantly different from that of eubacteria. I N T R O D U C T I O NAlthough the motion of leptospires has fascinated bacteriologists for decades, little is known about their motility and how it is affected by environmental factors. Furthermore, descriptions of leptospiral motility are generally subjective and qualitative rather than quantitative.Kaiser & Doetsch (I 975) showed that translational movement of Leptospira interrogans (bzjlexa) B I~ was enhanced in viscous solutions. In SM4 medium supplemented with methyl cellulose, there was a marked increase both in the number of individual organisms exhibiting translational movement and in the velocity they attained, with maxima at viscosities exceeding 300 cP. The motile behaviour observed in such very viscous solutions contrasts markedly with that of flagellated bacteria, which show an increase in velocity as viscosity is elevated to 2 to 5 CP (depending on the organism and its flagellar arrangement), but then a rapid decrease in velocity at higher viscosities (Schneider & Doetsch, 1974). Thus environmental viscosity affects the motility of leptospires differently from that of flagellated bacteria.Two other environmental factors known to influence the motility of eubacteria are pH and hypertonicity. Alkaline pH, in the range 9-4 to 10.0, causes immobilization of various Gram-negative bacteria, presumably by paralysing their flagella-activating system (Schuetze & Doetsch, 1967). Reversal of paralysis may readily be accomplished by lowering the pH. Plasmolysis of eubacteria with either sucrose solutions (Okrend & Doetsch, 1969)

Enumeration and selective isolation of rumen spirochetes

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Effect of osmolarity and viscosity on the motility of pathogenic and saprophytic Leptospira

“…Therefore, the motility of Leptospira is thought to play a critical role in invasion of animals or migration within them. However, L. biflexa cells are reportedly immobilized by hypertonic solutions, for example, 0.5 and 1.0 M sucrose solutions . As mentioned above, pathogenic Leptospira cells are excreted in the urine .…”

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