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  • 1
    Electronic Resource
    Electronic Resource
    Physiological and genetic characterisation of osmosensitive mutants of Saccharomyes cerevisiae (1998)
    Springer
    Archives of microbiology 170 (1998), S. 99-105 
    Details
    ISSN: 1432-072X
    Keywords: Key words Osmosis ; Yeast ; Mutant ; Glycerol ; Solute ; Complementation group
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The screening of 20,000 Saccharomyces cerevisiae random mutants to identify genes involved in the osmotic stress response yielded 14 mutants whose growth was poor in the presence of elevated concentrations of NaCl and glucose. Most of the mutant strains were more sensitive to NaCl than to glucose at the equivalent water activity (aw) and were classified as salt-sensitive rather than osmosensitive. These mutants fell into 11 genetic complementation groups and were designated osr1–osr11 (osmotic stress response). All mutations were recessive and showed a clear 2+ : 2– segregation of the salt-stress phenotype upon tetrad analysis when crossed to a wild-type strain. The complementation groups osr1, osr5 and osr11 were allelic to the genes PBS2, GPD1 and KAR3, respectively. Whereas intracellular and extracellular levels of glycerol increased in the wild-type strains when exposed to NaCl, all mutants demonstrated some increase in extracellular glycerol production upon salt stress, but a number of the mutants showed little or no increase in intracellular glycerol concentrations. The mutants had levels of glycerol-3-phosphate dehydrogenase, an enzyme induced by osmotic stress, either lower than or similar to those of the parent wild-type strain in the absence of osmotic stress. In the presence of NaCl, the increase in glycerol-3-phosphate dehydrogenase activity in the mutants did not match that of the parent wild-type strain. None of the mutants had defective ATPases or were sensitive to heat stress. It is evident from this study and from others that a wide spectrum of genes is involved in the osmotic stress response in S. cerevisiae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050620
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  • 2
    Electronic Resource
    Electronic Resource
    A Saccharomyces cerevisiae mutant defective in the kinesin-like protein Kar3 is sensitive to NaCl-stress (1997)
    Springer
    Current genetics 32 (1997), S. 315-322 
    Details
    ISSN: 1432-0983
    Keywords: Key words NaCl-stress ; KAR3 ; mitosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several mutants of Saccharomyces cerevisiae showing poor growth in the presence of elevated concentrations of NaCl were isolated to identify genes involved in the osmo-stress response. One of these mutants (WAY.5-4A-11; osr11) which showed a clear 2:2 segregation of the salt-stress phenotype upon tetrad analysis when crossed to a wild-type strain has been characterised. The mutation responsible for poor growth under salt-stress was recessive. The corresponding gene was cloned by complementation of the mutant phenotype and a 3.5-kb fragment was isolated. The sequence of this fragment matched that of KAR3, a gene previously identified to be involved in karyogamy and mitosis. Allelism of OSR11 to KAR3 was confirmed by tetrad analysis, and disruption mutants showed the same NaCl-phenotype as the original osr11 mutation. The disruption mutant was more sensitive to high sucrose concentrations than the original mutant was to high glucose concentrations. In a different genetic background (W303-1A), the kar3 disruptants were less sensitive to osmo-stress than the WAY.5-4A strain. Heat-stress, nitrogen-starvation and cultivation on ethanol failed to affect the growth of osr11 and kar3 mutants, pointing to a possible specific involvement of KAR3 in the osmotic-stress response. Microscopic studies showed that cell division of the kar3 mutants was impaired and NaCl-stress conditions aggravated the phenotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002940050283
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  • 3
    Electronic Resource
    Electronic Resource
    Rapid and simple assay for feruloyl and p-coumaroyl esterases (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 239-242 
    Details
    ISSN: 1573-0972
    Keywords: p-coumaric acid ; ferulic acid ; HPLC ; phenolic acid esterase assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A rapid, simple and sensitive method for detection of ferulic and p-coumaric acids using HPLC has been developed which can be used to determine the respective phenolic acid esterase activities of microorganisms. Prior concentration, purification or derivatization of the samples are not required. As little as 0.5 mg ferulic or p-coumaric acid/I could be detected and estimated in 〈 1 h. The method is specific for the two phenolic acids sice no interference by other components was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00360920
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  • 4
    Electronic Resource
    Electronic Resource
    The kinetics and regulation of M-xylose transport in Candida utilis (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 357-360 
    Details
    ISSN: 1573-0972
    Keywords: Candida utilis ; inhibition ; kinetics ; regulation ; sugar ; transport ; xylose ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Low-affinity (K m=67.6±3.2 mM) and high-affinity (K m=1.9±1.2 mM) D-xylose transport occur in Candida utilis grown, respectively, on D-glucose or D-xylose. Starvation of glucose-grown cells decreases the K m value (10.5±2.6 mm). The high-affinity system appearing during starvation required protein synthesis and it was inactivated when cells were exposed to glucose, by a process independent of protein synthesis. High-affinity transport was accompanied by transient alkalinization of yeast suspensions, indicating that it is a proton symport, whereas low-affinity transport was not. Both systems, however, were inhibited by metabolic inhibitors and by replacing H2O in the transport assay with D2O, indicating that both may be proton symports. Glucose and acetic acid also inhibited both high-and low-affinity xylose transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00383080
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  • 5
    Electronic Resource
    Electronic Resource
    Adaptation ofZygosaccharomyces rouxii to changes in water activity in transient continuous culture (1990)
    Springer
    Biotechnology letters 12 (1990), S. 361-366 
    Details
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The polyols glycerol and arabitol were accumulated against an increasing concentration ratio in response to aW reduction. Glycerol was the main osmoregulatory solute accumulated and arabitol accumulation only occurred during the initial transitory phase. The polyols were accumulated to concentrations less than that required to maintain equilibrium across the membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01024432
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  • 6
    Electronic Resource
    Electronic Resource
    Role of hydrolysis conditions in the enzyme-mediated release of reducing sugars from sulphite pulp (1995)
    Springer
    Biotechnology letters 17 (1995), S. 821-826 
    Details
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The release of reducing sugars from sulphite pulp treated with an Aureobasidium pullulans xylanase preparation was studied. Hydrolysis conditions such as pH, buffer, temperature and time of enzyme treatment were optimized in terms of their effect on sulphite pulp for production of dissolving pulp with an improved quality. Enzyme hydrolysis of pulp was found to be most effective at a temperature of 55°C and at pH 4.7 using sodium acetate buffer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00129011
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  • 7
    Electronic Resource
    Electronic Resource
    Ethanol tolerance of Pichia stipitis and Candida shehatae strains in fed-batch cultures at controlled low dissolved oxygen levels (1989)
    Springer
    Applied microbiology and biotechnology 30 (1989), S. 53-58 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Fed-batch cultivations of Pichia stipitis and strains of Candida shehatae with d-xylose or d-glucose were conducted at controlled low dissolved oxygen tension (DOT) levels. There were some marked differences between the strains. In general growth was inhibited at lower ethanol concentrations than fermentation, and ethanol levels of up to 47 g·l-1 were produced at 30°C. Ethanol production was mainly growth associated. The yeast strains formed small amounts of monocarboxylic acids and higher alcohols, which apparently did not enhance the ethanol toxicity. The maximum ethanol concentration obtained on d-xylose could not be increased by using a high cell density culture, nor by using d-glucose as substrate. The latter observation suggested that the low ethanol tolerance of these xylose-fermenting yeast strains was not a consequence of the metabolic pathway used during pentose fermentation. In contrast with the C. shehatae strains, it was apparent with P. stipitis CSIR-Y633 that when the ethanol concentration reached about 28 g·l-1, ethanol assimilation exceeded ethanol production, despite cultivation at a low DOT of 0.2% of air saturation. Discontinuing the aeration enabled ethanol accumulation to proceed, but with concomitant xylitol production and cessation of growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00255996
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  • 8
    Electronic Resource
    Electronic Resource
    Enzymatic prebleaching of sulphite pulps (1994)
    Springer
    Applied microbiology and biotechnology 42 (1994), S. 492-498 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The ability of a crude enzyme preparation ofAureobasidium pullulans containing xylanase [61 units (U)/ml] and xylosidase (3 U/ml) activity to remove pentosans from unbleached sulphite pulps was investigated. Greater amounts of pentosans and reducing sugars were released from the pulp when the enzyme dosages and incubation times were increased. A combination of enzyme hydrolysis and alkali extraction resulted in a greater removal of pentosans than using the enzyme preparation alone. By treatment with a xylanase loading of 450 U/g pulp for 24 h followed by alkaline extraction, 35% of the pentosans were removed. The kappa number decreased up to 30% whereas viscosity was only slightly affected by these treatments. Enzymatic hydrolysis released mainly xylose whereas xylobiose was the main product liberated by alkaline extraction. Scanning electron micrographs indicated improved fibrillation and flexibility of the fibre structure by enzyme treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00902763
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of aeration on xylose fermentation by Candida shehatae and Pachysolen tannophilus (1984)
    Springer
    Applied microbiology and biotechnology 19 (1984), S. 261-266 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The ability of a Candida shehatae and a Pachysolen tannophilus strain to ferment D-xylose to ethanol was evaluated in defined and complex media under different levels of aeration. Aeration enhanced the ethanol productivity of both yeasts considerably. C. shehatae maintained a higher fermentation rate and ethanol yield than P. tannophilus over a wide range of aeration levels. Ethanol production by C. shehatae commenced during the early stage of the fermentation, whereas with P. tannophilus there was a considerable lag between the initiation of growth and ethanol production. Both yeasts produced appreciable quantities of xylitol late in the fermentation. P. tannophilus failed to grow under anoxic conditions, producing a maximum of only 0.5 g · l-1 ethanol. In comparison, C. shehatae exhibited limited growth in anoxic cultures, and produced ethanol much more rapidly. Under the condition of aeration where C. shehatae exhibited the highest ethanol productivity, the fermentation parameters were: maximum specific growth rate, 0.15 h-1; maximum volumetric and specific rates of ethanol production, 0.7 g (l · h)-1 and 0.34 g ethanol (g cells · h)-1 respectively; ethanol yield, 0.36 g (g xylose)-1. The best values obtained with P. tannophilus were: maximum specific growth rate, 0.14 h-1; maximum volumetric and specific rates of ethanol production, 0.22 g (l · h)-1 and 0.07 h-1 respectively; ethanol yield coefficient, 0.28. Because of its higher ethanol productivity at various levels of aeration, C. shehatae has a greater potential for ethanol production from xylose than P. tannophilus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00251848
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  • 10
    Electronic Resource
    Electronic Resource
    Enzymatic prebleaching of sulphite pulps (1994)
    Springer
    Applied microbiology and biotechnology 42 (1994), S. 492-498 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The ability of a crude enzyme preparation of Aureobasidium pullulans containing xylanase [61 units (U)/ml] and xylosidase (3 U/ml) activity to remove pentosans from unbleached sulphite pulps was investigated. Greater amounts of pentosans and reducing sugars were released from the pulp when the enzyme dosages and incubation times were increased. A combination of enzyme hydrolysis and alkali extraction resulted in a greater removal of pentosans than using the enzyme preparation alone. By treatment with a xylanase loading of 450 U/g pulp for 24 h followed by alkaline extraction, 35% of the pentosans were removed. The kappa number decreased up to 30% whereas viscosity was only slightly affected by these treatments. Enzymatic hydrolysis released mainly xylose whereas xylobiose was the main product liberated by alkaline extraction. Scanning electron micrographs indicated improved fibrillation and flexibility of the fibre structure by enzyme treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00902763
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    Paper (German National Licenses)
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