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1.
Théophile Bernard Jean-Alain Pocard Bertrand Perround Daniel Le Rudulier 《Archives of microbiology》1986,143(4):359-364
A total of 15 rhizobial strains representing Rhizobium meliloti, Rhizobium japonicum, Rhizobium trifolii, Rhizobium leguminosarum, Rhizobium sp. (Sesbania rostrata) and Rhizobium sp. (Hedysarum coronarium), were studied with regard to growth rate under salt stress in defined liquid media. In the presence of inhibitory concentrations of NaCl, enhancement of growth resulting from added glycine betaine was observed for R. meliloti strains and Rhizobium sp. (Hedysarum coronarium) but not for other Rhizobium species. The concentration of glycine betaine required for maximal growth stimulation was very low (1 mM) in comparison with the osmolarity of the medium. The stimulation was shown to be independent of any specific solutes. Other related compounds like proline betaine, carnitine, choline, -butyrobetaine and pipecolate betaine were also effective compounds in restoring the growth rate of cells grown in medium of elevated osmolarity. High rate of glycine betaine uptake was demonstrated in R. meliloti cells grown in media of increased osmotic strength. The intracellular concentration of this solute was found to be 308 mM in 0.3 M NaCl-grown cells and 17 times lower in minimal medium-grown cells. Glycine betaine was used for growth under conditions of low osmolarity but could not serve as sole carbon or nitrogen source in medium of increased osmotic strength. Experiments with [14C]glycine betaine showed that this molecule was not metabolized by cells subjected to osmotic stress, whereas it was rapidly converted to dimethylglycine, sarcosine and glycine in minimal medium-grown cells.Abbreviations LAS
lactate-aspartate-salts
- LGS
lactate-glutamate-salts
- LS
lactate-succinate
- MSY
mannitol-salts-yeast
- YLS
yeast-lactate-succinate 相似文献
2.
Chlorella pyrenoidosa was labelled by 14CO2 and the nature and amount of excreted organic compounds in nutrient media of different osmotic pressure were determined after a 24 h period. The total rate of excretion of organic bound 14C was about 4 μg 14C per mg harvested algal dry matter or 1% of the total 14C content of the algae at the beginning of the excretion period. The main compounds found in the excretions were unidentified substances with a molecular weight higher than 700, amino acids, organic acids and sugars. The osmotic pressure of the nutrient medium did not affect the total amount of the organic excretions. However, the excreted amounts of some specific compounds differed in respect to the osmotic conditions of the nutrient medium. 相似文献
3.
Probiotic cultures of Lactobacillus plantarum, Lactobacillus rhamnosus, Bifidobacterium longum, Lactobacillus casei and Lactobacillus acidophilus were grown in media having water activities (a w) adjusted between 0.99 and 0.94 with NaCl or with a mixture of glycerol and sucrose in order to find conditions of osmotic stress which would still allow for good growth. Cultures grown at a w?=?0.96 or 0.99 were then recovered by centrifugation, added to a sucrose–phosphate medium and air-dried. In some assays, a 2-h osmotic stress was applied to the cell concentrate prior to air-drying. Assays were also carried out where betaine, glutamate and proline (BGP) supplements were added as protective compounds to the growth or drying media. For most strains, evidence of osmotic stress and benefits of BGP supplementation on growth occurred at a w?=?0.96. Growing the cells in complex media adjusted at a w?=?0.96 did not enhance their subsequent survival to air-drying, but applying the 2-h osmotic stress did. Addition of the BGP supplements to the growth medium or in the 2-h stress medium did not enhance survival to air-drying. Furthermore, addition of BGP to a sucrose–phosphate drying medium reduced survival of the cultures to air-drying. This study provides preliminary data for producers of probiotics who wish to use air-drying in replacement of freeze-drying for the stabilization of cultures. 相似文献
4.
Petrus Jakobus van Zyl Stephanus Gouws Kilian Bernard Alexander Prior 《Applied microbiology and biotechnology》1993,39(2):235-241
When cell suspensions of Zygosaccharomyces rouxii were subjected to osmotic shock with NaCl, the cell volume decreased sharply and plasmolysis was observed. The cell subsequently recovered and volumes similar to those of cells growing at the respective water activity (aw) values were found. Cycloheximide prevented cell recovery, indicating the involvement of protein synthesis in the recovery process. The intracellular glycerol concentration of Z. rouxii incubated in the presence of [14C]glycerol increased from 13 to 96 mmol/l during the initial 20 min after an upshock from 0.998 aw to 0.96 aw. All the intracellular glycerol was labelled and therefore derived from the medium. Labelled glycerol was subsequently utilized and replaced by unlabelled glycerol produced by the cell within 90 min. The initial increase in glycerol concentration following the upshock was confirmed by 13C-nuclear magnetic resonance (NMR) spectroscopic studies of cell extracts. The combined dihydroxyacetone and dihydroxyacetone phosphate concentrations fluctuated during this period, whereas glycerol-3-phosphate initially increased and then remained constant. This indicates that the production of glycerol is regulated. Decreases in ATP and polyphosphate levels were observed following osmotic upshock and may reflect a greater demand for ATP during the period of adjustment to decreased aw. The changes in cell volume and in ATP concentration following osmotic upshock may serve as osmoregulatory signals in Z. rouxii, as suggested previously for other microorganisms.
Correspondence to: S. G. Kilian 相似文献
5.
As glycerol was suggested as an osmotic agent in the salt tolerantDebaryomyces hansenii the concentrations of total, intracellular, and extracellular glycerol produced by this yeast was followed during growth in 4 mM, 0.68 M, and 2.7 M NaCl media. The total amount of glycerol was not directly proportional to biomass production but to the cultural salinity with maximum concentrations just prior to or at the beginning of the stationary phase. In all cultures the cells lost some glycerol to the media, at 2.7 M NaCl the extracellular glycerol even amounted maximally to 80% of the total. A distinct maximum of intracellular glycerol, related to dry weight or cell number, appeared during the log phase at all NaCl concentrations. As the intracellular calculated glycerol concentrations amounted to 0.2 M, 0.8 M, and 2.6 M in late log phase cells at 4 mM, 0.68 M, and 2.7 M NaCl, respectively, whereas the corresponding analysed values for the glycerol concentrations of the media were 0.7 mM, 2.5 mM, and 3.0 mM, glycerol contributes to the osmotic balance of the cells.During the course of growth all cultures showed a decreasing heat production related to cell substance produced, most pronounced at 2.7 M NaCl. At 2.7 M NaCl the total heat production amounted to-1690 kJ per mole glucose consumed in contrast to-1200 and-1130 kJ at 4 mM and 0.68 M NaCl, respectively. TheY
m
-values were of an inverse order, being 129, 120, and 93 at 4 mM, 0.68 M, and 2.7 M NaCl, respectively. 相似文献
6.
X. J. Chen 《Molecular & general genetics : MGG》1997,255(3):341-349
The mgi1-4 and mgi2-1 mutants of the petite-negative yeast Kluyveromyces lactis have mutations in the β- and α-subunits of the mitochondrial F1-ATPase, respectively. The mutants are respiratory competent but can form petites with deletions in mitochondrial DNA. In
this study a cryptic nuclear mutation (lipB-1) was identified which, in combination with the mgi alleles, displays a synergistic respiratory-deficient phenotype on glycerol medium. The gene defined by the mutation was
cloned and shown to encode a polypeptide of 332 amino acids with an N-terminal sequence characteristic of a mitochondrial
targeting signal. The deduced protein shares 27% sequence identity with the product of the Escherichia coli lipB gene, which encodes a lipoyl-protein ligase involved in the attachment of lipoyl groups to lipoate-dependent apoproteins.
A K. lactis strain carrying a disrupted lipB allele is severely compromised for growth on glycerol medium. The growth defect cannot be rescued by addition of lipoic acid,
but cell growth can be restored on medium containing ethanol plus succinate. In addition, it was observed that lipB mutants of K. lactis, unlike the wild-type, are unable to utilize glycine as sole nitrogen source, indicating that activity of the glycine decarboxylase
complex (GDC) is also affected. Taken together, these findings suggest that LIPB is the main determinant of the lipoyl-protein ligase activity required for lipoylation of enzymes such as α-ketoacid dehydrogenases
and GDC.
Received: 16 December 1996 / Accepted: 24 February 1997 相似文献
7.
Intracytoplasmic membrane production inEscherichia coli O111a1: Nutritional parameters 总被引:1,自引:1,他引:0
J. W. Brunson J. M. Shively Kathleen Stralka G. L. Decker J. W. Greenawalt 《Current microbiology》1978,1(2):123-128
Escherichia coli O111a1 ceased growth prematurely and accumulated intracytoplasmic membrane at 42°C in an amino acids-mineral salts medium. The amount
of membrane formed appeared to be proportional to the concentration of amino acids in the medium—the greater the concentration
of amino acids in the medium, the greater the membrane production.E. coli O111a1, did not grow at 42°C in glucose-, glycerol- or acetate-mineral salts medium, but mesosome-like structures were produced
in glucose-grown cells and some intracytoplasmic membrane in cells grown on glycerol and acetate. Supplementation of the glucose
medium with pantothenate and/or thiamine permitted normal growth. The vitamins did not restore growth of the mutant in glycerol
or acetate, but intracytoplasmic membrane production was increased, especially in glycerol. Amino acids plus glucose supported
normal growth with no membrane production. Glycerol and acetate had no effect on the growth in the amino acids medium, but
stimulated the accumulation of membrane. 相似文献
8.
Proline betaine is an osmoprotectant that is at least as effective as glycine betaine, and more effective than L-proline, for various strains of Staphylococcus aureus, and Staphylococcus epidermidis and Staphylococcus saprophyticus. 13C NMR studies revealed that proline betaine accumulated to high levels in osmotically stressed S. aureus, but was also detected in organisms grown in its presence in the absence of osmotic stress. Competition experiments indicated that proline betaine was taken up by the proline transport systems of S. aureus, but not by the high affinity glycine betaine transport system.Abbreviations
PYK
Peptode
- Yeast extract
K2HPO4 相似文献
9.
Glycerol-3-phosphatase (EC 3.1.3.2.1) was studied by following the release of radioactive glycerol from L-(U-14C)glycerol-3-phosphate in Dunaliella tertiolecta enzyme extracts. The reaction showed a neutral pH optimum and had an absolute requirement for Mg2+. The substrate saturation curve was hyperbolic with an apparent K
m value for glycerol-3-phosphate of 0.7 mM in the absence of phosphate. Inorganic orthophosphate was a competitive inhibitor of the enzyme with an estimated K
j of 0.1 mM. The glycerol-3-phosphatase reaction was blocked nearly completely by millimolar Ca2+ concentrations. Ca2+ inhibition did not depend on the presence of calmodulin in the reaction medium. The characteristics of glycerol-3-phosphatase are discussed in relation to the regulation of the cyclic glycerol metabolism in Dunaliella cells during periods of osmotic stress. 相似文献
10.
The osmotolerant yeast Hansenula anomala survives in media at low water activity resulting from increasing NaCl concentrations in the culture medium by producing compatible solutes. High salinity resulted in the use of a large part of the assimilated carbon substrate (glucose) for cell maintenance (28%), required for intracellular synthesis compounds and for osmotic cell regulation. The maintenance coefficient for non-growth-associated glucose consumption was found to be 0.38 mmol glucose g biomass−1 h−1. For decreasing water activity, there is a competition between the pathways leading to glycerol and ethanol production, until an experimental ethanol/total glycerol ratio reached a value 3.4 for 2 mol l−1 NaCl (close to the theoretical value of 4)—illustrating the osmodependent channelling of carbon towards polyols production. This competition leads to a cessation of ethanol production during the stationary state before that of glycerol. Since osmotic adjustment occurred mainly during growth, glycerol production during stationary state can be clearly related to another mechanism other than osmotic: it was excreted by a fermentative mechanism to ensure energy for cell maintenance. 相似文献
11.
Ami Ben-Amotz 《Journal of phycology》1975,11(1):50-54
The holophilic alga Dunaliella parva produces glycerol as a major product of photosynthetic 14CO2 incorporation and accumulates very large amounts of intracellular glycerol. A method was adopted for the determination of the cell water space based on the distribution of 14C sorbitol and 3H2O between the cells and the medium. Using these measurements the internal concentration of glycerol was found to be isoomotic with that of the medium over a broad range of 0.6 to 2.1 m NaCl. When the extracellular salt concentration of an algal suspension was increased or decreased, the intracellular water content immediately varied so as to keep an osmotic equilibrium between the cells and the medium. During the following 90 min under metabolic conditions, glycerol content changed until a new level was reached. Since no leakage of intracellular glycerol was observed above 0.6 m NaCl, these alterations in glycerol content are interpreted as due to metabolic formation and degradation of intracellular glycerol. Determination of the glycerol sensitivity of enzymic and photosynthetic reactions of cell-free preparations from D. parva showed a broad range of tolerance to high concentrations of glycerol. These results indicate that osmoregulation in Dunaliella depends on the synthesis or degradation of intracellular glycerol in response to the external salt concentration. A proposed scheme of glycerol synthesis in Dunaliella is suggested. 相似文献
12.
Dr. Emilia Quesada Victoria Bejar María José Valderrama Alberto Ramos-Cormenzana 《Current microbiology》1987,16(1):21-25
Growth characteristics ofDeleya halophila (CCM 3662T), were determined using a defined medium.Deleya halophila presented its optimal growth at 7.5% (wt/vol) total salts when it was grwon at incubation temperatures of 32° and 42°C; when the temperature was lowered to 22°C, it had optimal growth at 5% (wt/vol) total salts. This bacterium had an absolute requirement for the Na+ cation; it could not be replaced by other cations. NaBr, Na2SO4, or Na2S2O3 could be substituted for NaCl in the growth medium, but, when MgCl2, KCl, LiCl, NaI, NaF, or NaNO3 was substituted for NaCl, the medium did not support growth. Growth rates of the strain were diverse when NaCl was partially replaced by other sodium salts. Finally,D. halophila suffered loss of viability when the culture was diluted into different low NaCl concentrations (0, 0.5%, and 1%, wt/vol) at various incubation temperatures. 相似文献
13.
Summary The influence of various osmotic agents (carbohydrates) on the morphogenesis and growth of callus ofActinidia deliciosa cv Hayward was studied. Sucrose supported the highest level of growth and the lowest was supported by the sugar alcohols
used in the experiments (glycerol, mannitol, sorbitol). The growth and survival of callus were evaluated with different osmotic
sources in media containing glycerol, mannitol, or sorbitol at a concentration of 0.2M each for an extended period of eight subcultures (360 days). Two crucial points were identified: until the third subculture
(135 days) the vitality seemed to be elevated; whereas the fifth (225 days) seemed to be a “point of no return” for tissues
grown in glycerol and mannitol. Pretreatment with osmotic carbohydrates was shown to increase the magnitude of the morphogenetic
events of callus subsequently transferred to sucrose-containing medium. Callus grown in the presence of mannitol and sorbitol
showed a similar frequency of morphogenetic response. With respect to the media containing glycerol and sucrose, these induced
more intense regeneration of shoots. When glycerol was present in the medium, however, we observed a synchronization of the
morphogenetic response. Our results suggest that it is possible both to stimulate and to synchronize morphogenesis utilizing
osmotic conditioning subcultures. 相似文献
14.
Qiu L Bedding RA 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2002,131(4):757-765
Two hypotheses on the synthesis of the protectants glycerol and trehalose of the infective juveniles (IJs) of Steinernema carpocapsae during osmotic dehydration were tested and utilised to evaluate the function and importance of glycerol on survival of the nematodes during osmotic dehydration. This was achieved by comparing the changes in survival, morphology, behaviour and levels of glycerol, trehalose and permeated compounds of the IJs dehydrated in seven hypertonic solutions at two temperature regimes: (1) 5 °C for 15 days; and (2) 23 °C for 1 day followed by 5 °C for another 14 days. The results substantiate both hypotheses tested: (1) the permeability of the IJs to various compounds, such as sucrose or ethylene glycol, when they are dehydrated in hypertonic solutions of these compounds; and (2) suppression of the synthesis of protectant glycerol but not trehalose when IJs are dehydrated at low temperature. The results also showed that: (1) although trehalose was the preferred dehydration protectant, glycerol played an important role in rapidly balancing the osmotic pressure when IJs were exposed in hypertonic solutions; (2) the presence of glycerol was essential for the IJs to survive and function properly even under moderate osmotic dehydration, especially when IJs were dehydrated in salt solutions; and (3) some exogenous compounds permeated into IJs during osmotic dehydration such as ethylene glycol, may function in the same way as glycerol and significantly improve the survival and function of the IJs. The results indicate that each of the protectants glycerol and trehalose has a specific function and neither is replaceable by the other. 相似文献
15.
Yoshio Kawahara Yasuhiko Yoshihara Shigeho Ikeda Yoshio Hirose 《Applied microbiology and biotechnology》1990,33(5):574-577
Summary Osmoregulation of Brevibacterium lactofermentum was examined. Exogenous glycine betaine was found to stimulate the growth rate of the bacterium in media of inhibitory osmotic strength. The stimulation was independent of any specific solute, electrolyte, or non-electrolyte. The bacterium did not utilize glycine betaine as a sole carbon source or nitrogen source, or degrade it even in complete medium. The changes in intracellular proline and glycine betaine concentrations were measured in media of different osmolarity. Brevibacterium lactofermentum grown in media without glycine betaine did not accumulate it, but synthesized several hyndred millimoles of proline inside the cells. On the other hand, when glycine betaine was added to the growth media, it accumulated in the cell instead of proline. These data indicate that glycine betaine is an osmoprotective compound for B. lactofermentum.
Offprint requests to: Yoshio Kawahara 相似文献
16.
David L. Goldstein James Frisbie Andrew Diller Ram Naresh Pandey Carissa M. Krane 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(8):1257-1265
Cope’s gray treefrogs, Hyla chrysoscelis, accumulate glycerol during the period of cold acclimation that leads to the development of freeze tolerance. Glycerol must
cross cell membranes in numerous processes during this time, including exit from hepatocytes where glycerol is synthesized
and entry into other tissues, where glycerol is cryoprotective. Thus, we hypothesized that erythrocytes from H. chrysoscelis would be permeable to glycerol and that that permeability would be up-regulated during cold acclimation. Further, we hypothesized
that glycerol permeability would be associated with the expression of aquaporins, particularly those from the glyceroporin
sub-family. Erythrocytes from warm-acclimated treefrogs had high glycerol permeability at 20°C, as assessed by the time required
for osmotic lysis following suspension in 0.2 M glycerol. That osmotic lysis, as well as uptake of radio-labeled glycerol,
was inhibited by 0.3 mM HgCl3. Permeability assessed via osmotic lysis was markedly reduced at 5°C. These properties were similar in animals deriving from
northern (Ohio) and southern (Alabama) populations, although suggestive (through statistical interactions) of greater glycerol
permeability in northern animals. Erythrocytes expressed mRNA and protein for a previously described glyceroporin, HC-3. In
cold-acclimated animals, HC-3 protein expression was up-regulated, but we could not detect a concomitant enhancement of glycerol
permeability. 相似文献
17.
An obligate requirement for selenium is demonstrated in axenic culture of the coastal marine diatom Thalassiosira pseudonana (clone 3H) (Hust.) Hasle and Heimdal grown in artificial seawater medium. Selenium deficiency was characterized by a reduction in growth rate and eventually by a cessation of cell division. The addition of 10−10 M Na2SeO3 to nutrient enriched artificial seawater resulted in excellent growth of T. pseudonana and only a slight inhibition of growth occurred at Na2SeO3 concentrations of 10−3 and 10−2 M. By contrast, Na2SeO4 failed to support growth of T. pseudonana when supplied at concentrations less than 10−7 M and the growth rate at this concentration was only one quarter of the maximum growth rate. The addition of 10−3 and 10−2 M Na2SeO4 to the culture medium was toxic and cell growth was completely inhibited. Eleven trace elements were tested for their ability to replace the selenium requirement by this alga find all were without effect. In selenium-deficient and selenium-starved cultures of T. pseudonana cell volume increased as much as 10-fold as a result of an increase in cell length (along the pervalvar axis) but cell width was constant. It is concluded that selenium is an indispensable element for the growth of T. pseudonana and it should be included as a nutrient enrichment to artificial seawater medium when culturing this alga. 相似文献
18.
The effect of glycerol on xylose-to-xylitol bioconversion by Candida guilliermondii was evaluated by its addition (0.7 and 6.5 g/l) to semidefined media (xylose as a substrate). The glycerol concentrations
were chosen based on the amounts produced during previous studies on xylitol production by C. guilliermondii. Medium without glycerol addition (control) and medium containing glycerol (53 g/l) in substitution to xylose were also evaluated.
According to the results, the addition of 0.7 g/l glycerol to the fermentation medium favored not only the yield (Y
P/S = 0.78 g/g) but also the xylitol productivity (Q
P = 1.13 g/l/h). During the xylose-to-xylitol bioconversion, the formation of byproducts (glycerol and ethanol) was observed
for all conditions employed. In relation to the cellular growth, glycerol as the only carbon source for C. guilliermondii was better than xylose or xylose and glycerol mixtures, resulting in a maximum cellular concentration (5.34 g/l). 相似文献
19.
The production of vitamin B6 (B6) compounds with a cell-suspension of Achromobacter cycloclastes A.M.S. 6201 under various conditions were examined. An obvious accumulation of B6 compounds in the incubation medium with a cell-suspension of the organism harvested at the middle to later part of exponential phase of growth was observed. γ-Aminobutyric acid or β-alanine was found to stimulate the B6 production markedly, when they were added to the incubation mixture together with glycerol. Some discussion on the implication of these compounds as precursors of B6 was presented. 相似文献
20.
Lena Gustafsson 《Archives of microbiology》1979,120(1):15-23
In a study of the halotolerant yeast Debarymyces hansenii cultured in 4 mM and 2.7 M NaCl the intracellular ATP pool, the heat production, the oxygen uptake, and, in the high culture salinity also, the intracellular glycerol concentration were found to be correlated. The intracellular ATP in the 2.7 M NaCl culture had a constant concentration of 3.5 mM ATP during the second half of the lag phase, while in 4 mM NaCl it rose to a maximum of 3.1 mM during the late log phase. The intracellular glycerol concentration in 2.7 M NaCl was about 1.3M during the entire exponential growth phase. Sine the glycerol concentration of the medium was not more than 0.23 mM, glycerol must contribute to the osmotic balance of the cells in high salinity. The corresponding maximum values for the 4 mM NaCl culture were 0.16 M and 0.08 mM. The experimental enthalpy changes were approximately the same for the two salinities, viz. about-1200 kJ per mole consumed glucose. The Y
m-values for the 4 mM and 2.7 M NaCl cultures were 91 and 59, respectively, the difference being a consequence of the decreased efficiency of growth in high salinity.Abbreviations CFU
colony-forming units
- PCA
perchloric acid
- TCA
trichloroacetic acid 相似文献