The Water Relations of Vibrio Metohnikovi at 30°C

Marshall, Betty J.; Scott, W. J.

doi:10.1071/bi9580171

Cited by 7 publications

(6 citation statements)

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“…Taking into account the 95% confidence limits of roughly f 1 0 % for the enthalpy of a given material (see Table I ) , and neglecting the error for the value of the water content, this range is in good agreement with the value of 40-65 J / g for the melting enthalpy of a similarly superstructured, fibrillar biopolymer, namely, c01lagen.l~ It is generally accepted2' that the IFs in keratins are formed by a fraction of proteins called low-sulfur (LS) proteins, which in purified form are about 63% a -h e l i~a l .~~ Taking the amino acid analysis of this fraction, as determined by Marshall and Gillespie,33 and calculating the weighed mean gives a molecular weight of 114 g/mol. This value leads to an estimated range for the denaturation enthalpy of a-helical material in keratin between AH = 6.5 kJ/mol and A H = 7.8 kJ/mol, on the basis of 30 and 25% a-helical material, respectively.…”

Section: Discussionsupporting

confidence: 55%

Characterizing keratins using high‐pressure differential scanning calorimetry (HPDSC)

Wortmann¹,

Deutz²

1993

J of Applied Polymer Sci

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SYNOPSISApplying differential scanning calorimetry (DSC) for temperatures up to 18O"C, the denaturation transition of the a-helical material of various keratins in excess water was studied at conditions of equilibrium water vapor pressure (high-pressure DSC) . The results show a generally cystine content and material invariate denaturation range of 20-30°C with peak temperatures around 140°C. Though analysis of variance and multiple comparison tests show a pronounced inhomogeneity of the enthalpy data, the results generally support the material invariance of the denaturation enthalpy and hence of the helix content of the keratins. The denaturation enthalpy for the helical coiled-coil-structures in the intermediate filaments is determined as AH = 6.5-7.8 kJ/mol. A significant positive correlation was found between the denaturation temperatures and the cystine content. It is concluded, that the helix denaturation temperatures are kinetically controlled by the amount and/or the chemical composition of the surrounding nonhelical matrix, and that the double-peak endotherms observed for wool and other keratins originate from two cell types that are sufficiently different in sulfur content to allow endotherm separation. In the case of wool the cell types can be identified as "ortho-" and "paracortical" cells.

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Section: Discussionsupporting

confidence: 55%

Characterizing keratins using high‐pressure differential scanning calorimetry (HPDSC)

Wortmann¹,

Deutz²

1993

J of Applied Polymer Sci

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“…Good agreement between counts from successive dilutions was obtained with this medium, which was similar in composition to those reported by Marshall & Scott (1958) to give the greatest plate count for V. metchnikovi. These workers found that the plate count of this organism was remarkably sensitive to variations in the ionic and osmotic properties of the medium used.…”

Section: Viabk Countssupporting

confidence: 65%

“…It is of interest that the most favourable a, value for rehydrating t? metchnikovi was usually between 0-96 and 0.98, considerably less than the optimum for growth, which was shown by Marshall & Scott (1958) to be about 0-995 for this osmotically sensitive organism. Iljin (1953) discussed the need to control the rate of rehydration of dried plant cells, and stated that rehydration in sucrose solution was beneficial.…”

Section: Discussionmentioning

confidence: 99%

“…After further tenfold dilutions in 0.15 M-NaCl, viable counts were made. Saline of this approximate strength (0*15~-NaCl; a, 0.995; a, = thermodynamic activity of water in the solution) was shown to be a suitable diluent for viable counts of Vibrio metchnikovi (Marshall & Scott, 1958). Unless otherwise noted rehydration was carried out at room temperature (18-25').…”

Section: Rehydration Of Suspensionsmentioning

confidence: 99%

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The Influence of Rehydration on the Viability of Dried Micro-Organisms

Leach

Scott

1959

Journal of General Microbiology

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SulMMARY : F'reeze-dried preparations of certain organisms may suffer considerable mortality during reconstitution to the wet state, For Vibrio metchnikowi the mortality was greatly decreased by rehydration with small volumes of water, or with various volumes of relatively concentrated solutions of some solutes. Within certain limits, slow dropwise addition of water resulted in higher viable counts than did rapid addition of the same volume of water. In preliminary tests Mgcoplasma mycoides and two coliphages were also affected by the volume of water used for rehydration, but no significant effects were observed with nine other bacteria. Comparisons of rehydration at several temperatures showed greatest destruction at 37O for V . metchn i k d , but at 0' for three other bacteria. The importance of rehydration rates and of exposure to hypotonic solutions is discussed.

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“…That this dramatic effect is not confined to halophilic bacteria has been demonstrated recently by Marshall & Scott (1958) with Vibrio metchnikovi.…”

Section: Discussionmentioning

confidence: 90%

Lysis of Vibrio costicolus by Osmotic Shock

Christian

Ingram

1959

Journal of General Microbiology

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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)

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The Water Relations of Vibrio Metohnikovi at 30°C

Abstract: For a strain of Vibrio metchnikovi the rate of growth in liquid media and the number of colouies forming on solid media were both greatly increased by reducing the water activity (awl from c. 0�999 to 0�995.

Cited by 7 publications

References 7 publications

Characterizing keratins using high‐pressure differential scanning calorimetry (HPDSC)

Characterizing keratins using high‐pressure differential scanning calorimetry (HPDSC)

The Influence of Rehydration on the Viability of Dried Micro-Organisms

Lysis of Vibrio costicolus by Osmotic Shock

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