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1.
Pseudomonas mendocina MCM B-402 was found to utilize a triphenylmethane dye, methyl violet as the sole source of carbon when incorporated in synthetic
medium. Almost complete decolorization of methyl violet by P. mendocina was observed within 48 h of incubation at ambient temperature (28 ± 2 °C) under aerated culture conditions, when the bacteria
were inoculated into Davis Mingioli's synthetic medium at a concentration of 100 mg/l medium. Methyl violet was mineralized
to CO2 through three unknown intermediate metabolites and phenol. The decolorization of the dye involved demethylation.
Received: 27 November 1998 / Received revision: 2 March 1999 / Accepted: 5 March 1999 相似文献
2.
Fernández MJ Adrio JL Piret JM Wolfe S Ro S Demain AL 《Applied microbiology and biotechnology》1999,52(4):484-488
Growth of Streptomyces clavuligerus NP1 in the presence of methanol or ethanol resulted in a marked increase in production of cephalosporin(s) from penicillin
G by resting cells. The mycelium produced in alcohol-supplemented medium was fragmented and dispersed as compared with growth
in control medium. HPLC analysis showed that at least two products were present in the biotransformation supernatant fluid
after 1 h incubation. One of them has been identified as deacetoxycephalosporin G (DAOG).
Received: 9 December 1998 / Received revision: 29 March 1999 / Accepted: 16 April 1999 相似文献
3.
Xylose utilisation by recombinant strains of Saccharomyces cerevisiae on different carbon sources 总被引:1,自引:0,他引:1
van Zyl WH Eliasson A Hobley T Hahn-Hägerdal B 《Applied microbiology and biotechnology》1999,52(6):829-833
Autoselective xylose-utilising strains of Saccharomyces cerevisiae expressing the xylose reductase (XYL1) and xylitol dehydrogenase (XYL2) genes of Pichia stipitis were constructed by replacing the chromosomal FUR1 gene with a disrupted fur1::LEU2 allele. Anaerobic fermentations with 80 g l−1
d-xylose as substrate showed a twofold higher consumption of xylose in complex medium compared to defined medium. The xylose
consumption rate increased a further threefold when 20 g l−1
d-glucose or raffinose was used as co-substrate together with 50 g l−1
d-xylose. Xylose consumption was higher with raffinose as co-substrate than with glucose (85% versus 71%, respectively) after
82 h fermentations. A high initial ethanol concentration and moderate levels of glycerol and acetic acid accompanied glucose
as co-substrate, whereas the ethanol concentration gradually increased with raffinose as co-substrate with no glycerol and
much less acetic acid formation.
Received: 12 March 1999 / Received revision: 31 June 1999 / Accepted: 5 July 1999 相似文献
4.
The aim of the study was to investigate whether toxic fine chemical production can be improved using the solvent-tolerant
Pseudomonas putida S12 in a two-liquid-phase system consisting of aqueous media and a water-immiscible octanol phase with production of 3-methylcatechol
from toluene as the model conversion. For this purpose the genes involved in this conversion, todC1C2BAD from P. putida F1, were introduced into P. putida S12 with high stable expression. Production of 3-methylcatechol was monitored in batch incubations with different media using
a single medium and a two-liquid medium–octanol system. The maximum concentration of 3-methylcatechol increased two-fold using
the two-liquid medium–octanol system, irrespective of the selected medium.
Received: 29 December 1999 / Received revision: 29 February 2000 / Accepted: 6 March 2000 相似文献
5.
Embryogenic calli were induced from leaf explants of coffee (Coffea canephora) on McCown's woody plant medium (WPM) supplemented with 5 μM N6–(2-isopentenyl)-adenosine (2-iP). These calli were co-cultured with Agrobacterium tumefaciens EHA101 harboring pIG121-Hm, containing β-glucuronidase (GUS), hygromycin phosphotransferase (HPT), and neomycin phosphotransferase
II genes. Selection of putative transgenic callus was performed by gradual increase in hygromycin concentration (5, 50, 100 mg/l).
The embryogenic calli surviving on medium containing 100 mg/l hygromycin showed a strong GUS-positive reaction with X-Gluc
solution. Somatic embryos were formed from these putative transgenic calli and germinated on WPM medium with 5 μM 2-iP. Regenerated
small plantlets with shoots and roots were transferred to medium containing both 100 mg/l hygromycin and 100 mg/l kanamycin
for final selection of transgenic plants. The selected plantlets exhibited strong GUS activity in leaves and roots as indicated
by a deep blue color. GUS and HPT genes were confirmed to be stably integrated into the genome of the coffee plants by the
polymerase chain reaction.
Received: 14 December 1998 / Revision received: 12 March 1999 / Accepted: 24 March 1999 相似文献
6.
Revellin C Meunier G Giraud JJ Sommer G Wadoux P Catroux G 《Applied microbiology and biotechnology》2000,54(2):206-211
Commercial soybean inoculants processed with sterilised peat and stored at 20 °C for 1–8 years were used as experimental
materials to assess the changes in the physiological activity of Bradyrhizobium japonicum after storage. Viable counts decreased and physiological characteristics of the bacterium changed during storage, with an
increase in the time taken for colony appearance on a medium without yeast extract, an increase in the lag time for nodule
appearance on soybean grown in glass tubes and a decrease in survival on seeds. All the inoculants produced a significant
increase in grain yield in a field experiment. The percentage of efficient cells in the field (relative to the plate counts)
decreased as the length of storage increased. These results suggest that the physiological activity of B. japonicum cells changes after storage. Practical implications for inoculant quality control are discussed.
Received: 20 September 1999 / Received revision: 3 March 2000 / Accepted: 6 March 2000 相似文献
7.
A novel method for the determination of microbial growth kinetics on hydrophobic volatile organic compounds (VOC) has been
developed. A stirred tank reactor was operated as a fed-batch system to which the VOC was continuously fed via the gas phase,
assuring a constant VOC concentration in the mineral medium. A flow of air was saturated with the VOC, and then mixed with
a further flow of air, to obtain a predetermined VOC concentration. Thus, different VOC concentrations in the mineral medium
could be obtained by altering the VOC concentration in the feed gas. The growth kinetics of Xanthobacter autotrophicus GJ10 on 1,2-dichloroethane (DCE) and of Pseudomonas sp. strain JS150 on MonoChloroBenzene (MCB) were assessed using this method. The growth of strain JS150 was strongly inhibited
at MCB concentrations higher than 160 mg l−1, and the results were fitted using a piecewise function. The growth kinetics of strain GJ10 were described by the Luong model
where maximum growth rate μmax = 0.12 h−1, substrate saturation constant K
S = 7.8 mg l−1, and maximum substrate concentration S
m (above which growth is completely inhibited) = 1080 mg l−1. Varying nitrogen and oxygen flows enabled the effect of oxygen concentration on the growth kinetics of Pseudomonas JS150 to be determined.
Received: 30 November 1998 / Received revision: 19 March 1999 / Accepted: 20 March 1999 相似文献
8.
A two-phase organic/aqueous reactor configuration was developed for use in the biodegradation of benzene, toluene and p-xylene, and tested with toluene. An immiscible organic phase was systematically selected on the basis of predicted and experimentally
determined properties, such as high boiling points, low solubilities in the aqueous phase, good phase stability, biocompatibility,
and good predicted partition coefficients for benzene, toluene and p-xylene. An industrial grade of oleyl alcohol was ultimately selected for use in the two-phase partitioning bioreactor. In
order to examine the behavior of the system, a single-component fermentation of toluene was conducted with Pseudomonas sp. ATCC 55595. A 0.5-l sample of Adol 85 NF was loaded with 10.4 g toluene, which partitioned into the cell containing 1 l
aqueous medium at a concentration of approximately 50 mg/l. In consuming the toluene to completion, the organisms were able
to achieve a volumetric degradation rate of 0.115 g l−1 h−1. This system is self-regulating with respect to toluene delivery to the aqueous phase, and requires only feedback control
of temperature and pH.
Received: 16 November 1998 / Received revision: 28 March 1999 / Accepted: 9 April 1999 相似文献
9.
A Pichia pastoris strain with stereoselective nitrile hydratase activity has been constructed by engineering the co-expression of three genes
derived from Pseudomonas putida. Using a technique that could be widely applicable, the genes encoding nitrile hydratase α and β structural subunits and
P14K accessory protein were first assembled as individual expression cassettes and then incorporated onto one plasmid, which
was integrated into the P. pastoris chromosome. The resulting strain can be used as a catalyst for bioconversions requiring stereospecific nitrile hydrolysis.
Received: 3 November 1998 / Received revision: 25 February1999 / Accepted: 14 March 1999 相似文献
10.
Chernyavskaya OG Shishkanova NV Il'chenko AP Finogenova TV 《Applied microbiology and biotechnology》2000,53(2):152-158
The ability of yeast to synthesize α-ketoglutaric acid (KGA) from ethanol has been studied. Thiamine-auxotrophic yeasts of
different genera and species may be able to produce KGA; the main condition of synthesis is growth limitation by thiamine.
Using a model culture, mutant Yarrowia lipolytica N 1, the principal conditions affecting KGA oversynthesis were identified. These were: thiamine concentration in medium and
in cells, nitrogen and oxygen concentration in medium, and pH level. A KGA concentration of 49 g/l and a yield from ethanol
consumed of 42% were achieved. Based on the results of the analysis of the activities of the key enzymes participating in
ethanol metabolism and KGA synthesis, a concept of the mechanism of KGA biosynthesis by Y. lipolytica yeast is suggested and discussed.
Received: 1 March 1999 / Received revision: 28 June 1999 / Accepted: 5 June 1999 相似文献
11.
Hairy roots of Panax ginseng were obtained after root disks were infected with wild-type strain Agrobacterium rhizogenes 15834. Three lines of hairy roots with different pigmentation were selected. Embryogenic callus was induced on Murashige
and Skoog medium containing 1.0 mg/l 2,4-D. The frequency of embryogenic callus formation was 37.4% in a line with red pigmentation.
Somatic embryo development from embryogenic callus was efficiently achieved by lowering the concentration of 2,4-D (0.5 mg/l).
After the germination of somatic embryos on medium with 10 mg/l GA3, the embryos were transferred to 1/2-MS medium without GA3. The transformed ginseng plantlets had an actively growing root system with abundant lateral roots. The phenotypical alteration
of transformed ginseng plants might be valuable character for increasing root yield.
Received: 27 March 1999 / Revision received: 18 May 1999 / Accepted 8 July 1999 相似文献
12.
The purified lipase from Burkholderia cepacia was immobilised on a porous polypropylene support and its biocatalytic properties were compared with those of the free enzyme
in organic media. For both lipase preparations, the rate of p-nitrophenyl ester hydrolysis in n-heptane was not restricted by mass transfer limitations. The immobilisation changed neither the temperature at which the
reaction rate was maximal, nor the activation energy of the reaction. The enzyme stability was slightly decreased (1.3-fold)
upon immobilisation. Moreover, the immobilised enzyme displayed fewer variations of activity with fatty acid chain length.
Interestingly, for all the different p-nitrophenyl esters used, the immobilised enzyme was more active (from 5.8- to 18.9-fold) than the free enzyme. Therefore,
it would be very useful to use B. cepacia lipase immobilised onto porous polypropylene for applications in organic media, as it displayed high activities on a larger
range of substrates.
Received: 8 February 1999 / Received revision: 19 March 1999 / Accepted: 20 March 1999 相似文献
13.
Parshikov IA Freeman JP Williams AJ Moody JD Sutherland JB 《Applied microbiology and biotechnology》1999,52(4):553-557
Cultures of the fungi Aspergillus niger, Cunninghamella verticillata, and Penicillium simplicissimum, grown in a sucrose/peptone medium, transformed N-acetylphenothiazine to N-acetylphenothiazine sulfoxide (from 13% to 28% of the total) and phenothiazine sulfoxide (from 5% to 27%). Phenothiazin-3-one
(4%) and phenothiazine N-glucoside (4%) were also produced by C. verticillata. The probable intermediate, phenothiazine, was detected only in cultures of P. simplicissimum (6%).
Received: 15 January 1999 / Received revision: 7 May 1999 / Accepted: 21 May 1999 相似文献
14.
M. C. de O. Souza I. C. Roberto A. M. F. Milagres 《Applied microbiology and biotechnology》1999,52(6):768-772
We investigated xylanase production by Thermoascus aurantiacus using semisolid fermentation. Multivariant statistical approaches were employed to evaluate the effects of several variables
(initial moisture in the medium, cultivation time, inoculum level, and bagasse mass) on xylanase production. The initial moisture
content and bagasse mass were the most important factors affecting xylanase activity. The xylanase activity produced by the
fungus under the optimized conditions (81% moisture content and 17 g bagasse) was found to be 2700 U per gram of initial dry
matter, whereas its value predicted by a polynomial model was 2400 U per gram of initial dry matter.
Received: 4 December 1998 / Received revision: 15 March 1999 / Accepted: 16 May 1999 相似文献
15.
J. Oddou C. Stentelaire L. Lesage-Meessen M. Asther B. Colonna Ceccaldi 《Applied microbiology and biotechnology》1999,53(1):1-6
High-density cultures of Pycnoporus cinnabarinus were tested with a view to optimisation of ferulic acid bioconversion into vanillin. The dry weight was increased fourfold
by using glucose, fructose or a mixture of glucose and phospholipids as carbon source instead of maltose, the carbon source
previously used. 5 mmol l−1 vanillin, i.e. 760 mg l−1, was produced over 15 days with glucose-phospholipid medium. In contrast, formation of vanillin was lower using glucose or
fructose compared to the maltose control. A bioreactor (2 l) with a glucose-phospholipid medium gave a molar yield of vanillin
of 61% (4 mmol l−1). An alternative strategy was to grow the fungus on a glucose or fructose medium for 3 days, then switch to maltose during
the bioconversion phase: this method allowed 3.3 mmol l−1 vanillin to be obtained in 10 days. Many by-products such as methoxyhydroquinone and vanillyl alcohol were also produced.
Received: 19 February 1999 / Received revision: 4 June 1999 / Accepted: 4 June 1999 相似文献
16.
More than 70% of n-hexadecane-grown cells of Cladosporium resinae ATCC 22711 were converted to spheroplasts when they were treated with chitinase and lytic enzyme from Trichoderma harziamum. The light mitochondrial fraction, containing microbodies, mitochondria and vacuoles, was isolated from spheroplasts. Vacuoles
in cells were demonstrated by the inability of acridine orange to stain organelles previously treated with 2.5 μM Bafilomycin
A1, a vacuolar ATPase inhibitor. Microbodies, mitochondria and vacuoles were separated from the light mitochondrial fraction
by self-generated density-gradient ultracentrifugation using iodixanol as gradient medium. NADH-dependent n-alkane monooxygenase activity and fatty alcohol oxidase activity were located in the cytoplasm and mitochondrial fractions
respectively.
Received: 21 September 1998 / Received revision: 21 January 1999 / Accepted: 31 January 1999 相似文献
17.
E. V. Eneyskaya A. A. Kulminskaya A. N. Savel'ev N. V. Savel'eva K. A. Shabalin K. N. Neustroev 《Applied microbiology and biotechnology》1999,52(2):226-231
Mechanisms regulating post-secretory limited proteolysis, carried out by the acid protease from Trichoderma reesei, were studied by following the release of α-galactosidase and multiple forms of cellobiohydrolase from this species. Both
the rate of the proteolysis and the mode of action of the protease were affected by the pH of the culture medium, and only
weakly depended on the amount of the enzyme. At pH between 2.7 and 3.5 the proteolytic reaction was limited, while at lower
pH proteins were completely digested. Proteolysis depended on the degree of glycosylation of secreted enzymes. Inhibition
of post-secretory deglycosylation decreased the rate of limited proteolysis in the culture medium in the course of fungal
growth. Glucose and cellobiose, the main products of cellulose degradation carried out by the fungal cellulolytic complex,
inhibited the proteolysis of the cellobiohydrolase in a concentration-dependent manner. A 32-kDa aspartic protease (EC 3.4.23.18)
secreted by T. reesei was purified to homogeneity. The acid protease cleaved α-galactosidase and cellobiohydrolase into the same proteolytic fragments
that had been isolated from the culture medium.
Received: 4 December 1998 / Received revision: 22 February 1999 / Accepted: 5 March 1999 相似文献
18.
Transgenic yellow lupin (Lupinus luteus L.) plants have been generated by meristem co-cultivation with Agrobacterium tumefaciens. The binary plasmid pPZBNIa contains the bar gene under the control of a CaMV 35 S promoter. The transformation method involves inoculation of embryonic axis explants
with A. tumefaciens, flooding the meristem with glufosinate, and initial culture on non-selective medium. Shoots were transferred to culture
medium containing 20 mg/l glufosinate. Following subculture, shoots were grafted onto non-transgenic narrow-leafed lupin (L. angustifolius L.) seedling rootstocks, or rooted in vitro. The overall transformation efficiency, as determined at the T1 generation, was 0.05%–0.75%. The transgenic nature of plants grown to the T6 generation was confirmed by phosphinothricin acetyl transferase, PCR and Southern analyses.
Received: 20 March 1999 / Revision received: 17 July 1999 / Accepted: 17 August 1999 相似文献
19.
Addition of sodium acetate to chemically defined MP2 medium was found to increase and stabilize solvent production by Clostridium beijerinckii BA101, a solvent-hyperproducing mutant derived from C. beijerinckii NCIMB 8052. C. beijerinckii BA101 demonstrated a greater increase in solvent production than C. beijerinckii NCIMB 8052 when sodium acetate was added to MP2 medium. In 1-l batch fermentations, C. beijerinckii BA101 produced 32.6 g/l total solvents, with butanol at 20.9 g/l, when grown in MP2 medium containing 60 mM sodium acetate
and 8% glucose. To our knowledge, these values represent the highest solvent and butanol concentrations produced by a solventogenic
Clostridium strain when grown in batch culture.
Received: 29 September 1998 / Received revision: 13 February 1999 / Accepted: 26 February 1999 相似文献
20.
A recently developed method for analyzing metabolic networks using 13C-labels was employed for investigating the metabolism of a high- and a low-yielding strain of Penicillium chrysogenum. Under penicillin-producing conditions, the flux through the pentose phosphate (PP) pathway in the high- and the low-yielding
strains was estimated to 70 and 66, respectively. When the high-yielding strain was cultivated in a medium without the penicillin
side chain precursor, phenoxyacetic acid, the PP pathway flux was estimated as 71. Thus, in all three experiments, the flux
through the PP pathway was almost constant with an average value of 69 ± 3, and the method therefore allows for a very reproducible
estimation of the PP pathway flux. Phenoxyacetic acid was found to be a source of cytosolic acetyl-CoA and thereby a source
of precursors for the biosynthesis of 2-aminoadipic acid, which is a central amino acid in penicillin biosynthesis. However,
the labeling patterns also indicated the presence of an unrecognized pathway to cytosolic acetyl-CoA.
Received: 20 December 1999 / Received revision: 7 March 2000 / Accepted: 10 March 2000 相似文献