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1.
J. Ramón De Lucas Susana Valenciano Fernando Laborda Geoffrey Turner 《Archives of microbiology》1994,162(6):409-413
The existence of a second mechanism of catabolite control of isocitrate lyase of Aspergillus nidulans, in addition to the carbon catabolite repression phenomenon recently reported was analysed. Isocitrate lyase was rapidly
and specifically inactivated by glucose. The inactivation was irreversible at all stages in the presence of cycloheximide,
showing that reactivation depends on de novo protein synthesis. In addition, analysis of glucose-induced inactivation of isocitrate
lyase in a creA
d
-30 strain showed that the creA gene is not involved in this process.
Received: 13 May 1994 / Accepted 12 August 1994 相似文献
2.
The effect of soybean oil and glucose on the growth of Torulopsis bombicola and sophorose lipid production in continuous culture was investigated. As the dilution rate in 100 g/l glucose and 100 g/l
soybean oil medium was increased, the dry cell weight and sophorose lipid concentration decreased. Sophorose lipid productivity,
however, was maximum at a dilution rate of 0.03 h−1. The cell yield from glucose and the sophorose lipid production from soybean oil were approximately constant regardless of
the dilution rate. The specific consumption rate of soybean oil was closely related to the specific production rate of sophorose
lipid. These results suggest that soybean oil was used only for sophorose lipid production whereas glucose was used only for
cell mass and maintenance. When the soybean oil concentration was varied at fixed dilution rate in 100 g/l glucose medium,
a high concentration of soybean oil was found to inhibit sophorose lipid production.
Received: 9 January 1997 / Received revision: 5 March 1997 / Accepted: 13 April 1997 相似文献
3.
Bradyrhizobium japonicum, the nitrogen-fixing symbiotic partner of soybean, was grown on various carbon substrates and assayed for the presence of
the glyoxylate cycle enzymes, isocitrate lyase and malate synthase. The highest levels of isocitrate lyase [165–170 nmol min–1 (mg protein)–1] were found in cells grown on acetate or β-hydroxybutyrate, intermediate activity was found after growth on pyruvate or galactose,
and very little activity was found in cells grown on arabinose, malate, or glycerol. Malate synthase activity was present
in arabinose- and malate-grown cultures and increased by only 50–80% when cells were grown on acetate. B. japonicum bacteroids, harvested at four different nodule ages, showed very little isocitrate lyase activity, implying that a complete
glyoxylate cycle is not functional during symbiosis. The apparent K
m of isocitrate lyase for d,l-isocitrate was fourfold higher than that of isocitrate dehydrogenase (61.5 and 15.5 μM, respectively) in desalted crude extracts
from acetate-grown B. japonicum. When isocitrate lyase was induced, neither the V
max nor the d,l-isocitrate K
m of isocitrate dehydrogenase changed, implying that isocitrate dehydrogenase is not inhibited by covalent modification to
facilitate operation of the glyoxylate cycle in B. japonicum.
Received: 10 October 1997 / Accepted: 16 January 1998 相似文献
4.
Two protein bands with strong esterase activity are present in broths of Nocardia lactamdurans MA4213 cultures. One of them shows cephalosporin C acetylhydrolase (CAH) activity. This activity is maximal at 48 h of growth
and shows a pattern of regulation slightly different from that of cephamycin production in medium supplemented with glucose
(166 mM), glycerol (326 mM) or ammonium chloride (60 mM). The CAH activity was purified to homogeneity by DEAE-Sepharose ion-exchange,
Sephadex G-75 gel filtration, and phenyl-Sepharose hydrophobic interaction chromatography. It showed a molecular mass of 72,100 Da.
The N-terminus of the protein was determined and showed the amino acid sequence GGAAPGGPGAHPLWLPAGKD. The enzyme showed K
m values of 7.0 mM and 8.3 mM for cephalosporin C and 7-aminocephalosporanic acid respectively but was not active on cephamycin
C.
Received: 17 December 1999 / Received revision: 22 February 2000 / Accepted: 25 February 2000 相似文献
5.
C. G. Hounsa J. M. Aubry H. C. Dubourguier J. P. Hornez 《Applied microbiology and biotechnology》1996,45(6):764-770
The expression of a recombinant pectate lyase from Bacteroides thetaiotaomicron strain 217 was studied in Escherichia coli strain HB101(pBT4). First, two sets of complete 24 factorial designs were used to evaluate the influences of casamino acids, glucose, magnesium, calcium, tetracycline, ampicillin,
tryptophan and MOPS buffer on pectate lyase production in a basal medium. While casamino acids, glucose and magnesium were
found to be the prevalent factors, the presence of tetracycline, ampicillin and MOPS buffer were necessary for the reproducibility
of the process, probably by increasing the plasmid stability. Secondly, application of the Doehlert design, a response-surface
methodology, allowed a good prediction of pectate lyase production according to the variation in glucose and magnesium concentrations.
This optimization strategy allowed the production of biomass and recombinant pectate lyase respectively to be increased from
0.2 g l-1 to 1.9 g l-1 (dry weight) and from 10 units ml-1 to 210 units ml-1 within 24 h at 30°C in shake flasks.
Received: 26 July 1995/Received revision: 22 January 1996/Accepted: 29 January 1996 相似文献
6.
The effects of alginate on the physiological activities of plant cells were studied. Addition of alginate oligomer (AO) to
the suspension culture of Catharanthus roseus L. or Wasabia japonica cells promoted the production of antibiotic enzymes such as 5′-phosphodiesterase or chitinase respectively. Ajmalicine (a
secondary metabolite) production by C. roseus CP3 cells was also promoted when AO was added to the suspension culture. On the basis of these results, we assumed that alginate
is an elicitor-like substance. We therefore compared the effect of AO on C. roseus L. and W. japonica cells with those of chitosan oligomer (CO) and oligo-galacturonic acid (OGA), which are well known as an exogenous elicitor
and endogenous elicitor respectively. The effects of various concentrations of AO, OGA, and CO on the physiological activities,
membrane permeability and protoplast formation of C. roseus L. or W. japonica cells were investigated. AO and OGA showed similar physiological effects, which were quite different from those of CO. Since
alginate appeared to have similar effects to galacturonic acid, we concluded that alginate acts as an endogenous elicitor.
Both alginate and galacturonic acid are uronic acids, and we considered their structural similarity. The effects of esterification
of the carboxylic groups of alginate by propylene oxide were also studied. The greater the degree of esterification, the less
the secretion of 5′-phosphodiesterase. Hence we assumed that carboxylic groups have an important role in the initiation of
the elicitation reaction in plant cells, as shown in the case of galacturonic acid.
Received: 18 January 1999 / Received revision: 2 April 1999 / Accepted: 1 May 1999 相似文献
7.
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
8.
Cysteine 195 in isocitrate lyase from Escherichia coli has been replaced by directed mutagenesis. Substitution by Ser yields enzyme with a kcat that is 0.03% that of wild type, and substitution by Ala, Gly, Thr, or Val yields completely inactive enzyme. The present
results are consistent with a functional role of Cys 195.
Received: 26 March 1997 / Accepted: 29 April 1997 相似文献
9.
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
10.
Thermal sensitivity of mitochondrial function in the Antarctic Notothenioid Lepidonotothen nudifrons 总被引:4,自引:0,他引:4
I. Hardewig H. O. Pörtner L. S. Peck 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(8):597-604
The thermal sensitivity of mitochondrial function was investigated in the stenothermal Antarctic fish Lepidonotothen nudifrons. State 3 respiration increases with increasing temperature between 0 °C and 18 °C with a Q
10 of 2.43–2.63. State 4 respiration in the presence of oligomycin, an inhibitor of mitochondrial ATP synthase, quantifies the
leakage of protons through the inner mitochondrial membrane, which causes oxygen consumption without concomitant ATP production.
This parameter shows an unusually high Q
10 of 4.21 ± 0.42 (0–18 °C), which indicates that proton leakage does not depend merely on ion diffusion but is an enzyme-catalysed
process. The differential thermal sensitivity of oxidative phosphorylation (=state 3) and proton leakage (=state 4 in the
presence of oligomycin) leads to progressive uncoupling of the mitochondria and decreased efficiency of oxidative phosphorylation
under in vivo conditions if the body temperature of L. nudifrons increases.
Accepted: 2 September 1999 相似文献
11.
Plant mitochondria contain an alternative oxidase (AOX) acting as a terminal electron acceptor of the alternative pathway
in the electron transport chain. Here we describe the production of inducible antisense Aox1a plants of Arabidopsis thaliana (L.) Heynh. and the procedures used to determine the resulting alternative pathway activity. The Arabidopsis Aox1a cDNA sequence was cloned behind a copper-inducible promoter system in the antisense orientation. Arabidopsis thaliana (Columbia) plants were transformed by in-planta vacuum infiltration with Agrobacterium containing the antisense construct. Whole-leaf ethanol production was used as a measure to investigate alternative pathway
activity in the presence of antimycin A. After 24 h, leaves from the copper-induced, antisense line F1.1 produced up to 8.8
times more ethanol (via aerobic fermentation) than the non-induced and wild-type leaves, indicating effective cytochrome pathway
inhibition by antimycin A and a decreased alternative pathway activity in induced F1.1 leaves. Transgene expression studies
also revealed no expression in non-induced leaves and up until 24 h post-induction. Copper-induced transgenic leaves were
less susceptible to alternative pathway inhibition than non-induced transgenic leaves, as seen via tissue-slice respiratory
studies, and mitochondrial respiration, using F1.1 cell cultures, also supported this. These results demonstrate the successful
production of a transgenic line of Arabidopsis in which the alternative pathway activity can be genetically manipulated with an inducible antisense system.
Received: 31 March 2000 / Accepted: 10 May 2000 相似文献
12.
S. Paul R. L. Bezbaruah R. S. Prakasham M. K. Roy A. C. Ghosh 《Folia microbiologica》1997,42(3):211-213
The role of sesame oil as part of the carbon source on growth and cephalosporin C production byCephalosporium acremonium was studied in shake-flask fermentation. The growth and antibiotic production were maximum on the fifth and sixth day, respectively,
irrespective of the presence of sesame oil. Sesame oil enhanced cephalosporin C production by 54%. Analysis of fatty acid
profile indicated that C18∶1, C18∶2 and C18∶3 are the major fatty acids inC. acremonium. The percentage of C18∶2 was higher in the culture grown with sesame oil. 相似文献
13.
Transient expression and stable transformation of soybean using the jellyfish green fluorescent protein 总被引:13,自引:6,他引:7
Embryogenic soybean [Glycine max (L.) Merrill.] suspension cultures were bombarded with five different gene constructions encoding the jellyfish (Aequorea victoria) green fluorescent protein (GFP). These constructions had altered codon usage compared to the native GFP gene and mutations
that increased the solubility of the protein and/or altered the native chromophore. All of the constructions produced green
fluorescence in soybean cultures upon blue light excitation, although a soluble modified red-shifted GFP (smRS-GFP) was the
easiest to detect based on the brightness and number of foci produced. Expression of smRS-GFP was visible as early as 1.5 h
after bombardment, with peak expression at approximately 6.5 h. Large numbers of smRS-GFP-expressing areas were visible for
48 h postbombardment and declined rapidly thereafter. Stably transformed cultures and plants exhibited variation in the intensity
and location of GFP expression. PCR and Southern hybridization analyses confirmed the presence of introduced GFP genes in
stably transformed cultures.
Received: 23 September 1998 / Revision received: 4 January 1999 / Accepted: 15 January 1999 相似文献
14.
C. Suresh A. K. Dubey S. Srikanta S. Umesh Kumar N. G. Karanth 《Applied microbiology and biotechnology》1999,51(5):673-675
A UV-induced mutant strain of Aspergillus niger (CFTRI-1105-U9) overproduced a starch-hydrolysing enzyme with properties characteristically different from the known amylases
of the fungus. The purified enzyme of 4.0 pI had an apparent molecular mass of 125 kDa and it dextrinised starch and then
saccharified the dextrins. Patterns of the enzyme activity on starch, resulting in glucose at 60 °C and glucose, maltose and
maltodextrins at 70 °C as primary products, suggested significant applications for the enzyme in starch-processing industries.
Received: 29 October 1998 / Received revision: 11 January 1999 / Accepted: 19 January 1999 相似文献
15.
Cephalosporin production by Streptomyces clavuligerus is known to be negatively regulated by carbon sources, e.g., glycerol and starch, and by phosphate at high concentrations.
Formation of lysine ɛ-aminotransferase (LAT) activity, the first enzyme of the biosynthetic pathway, was affected by a high
concentration of carbon source. Whereas 3% starch more than doubled LAT activity production as compared to 1% starch, 3% glycerol
repressed LAT activity formation by 20%–30%. LAT activity production was not affected by 100 mM K2HPO4. Our results thus show that the negative effects of 2% glycerol and 3% starch and 100 mM phosphate on cephalosporin production
are not due to an effect on production of LAT activity. However, repression of LAT activity by 3% glycerol would be expected
to play a negative role in antibiotic production.
Received: 13 June 1997 / Received revision: 20 August 1997 / Accepted: 25 August 1997 相似文献
16.
K. Hofvendahl E. W. J. van Niel B. Hahn-Hägerdal 《Applied microbiology and biotechnology》1999,51(5):669-672
Lactococcus lactis ssp. lactis ATCC 19435 is known to produce mixed acids when grown on maltose. A change in fermentation conditions only, elevated temperatures
(up to 37 °C) and reduced pH values (down to 5.0) resulted in a shift towards homolactic product formation. This was accompanied
by decreased growth rate and cell yield. The results are discussed in terms of redox balance and maintenance, and the regulation
of lactate dehydrogenase and pyruvate formate-lyase.
Received: 14 December 1998 / Received revision: 12 January 1999 / Accepted: 22 January 1999 相似文献
17.
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
18.
Batch and continuous cultivation of Anaerobiospirillum succiniciproducens for the production of succinic acid from whey 总被引:3,自引:0,他引:3
Batch and continuous cultivation of Anaerobiospirillum succiniciproducens were systematically studied for the production of succinic acid from whey. Addition of 2.5 g l−1 yeast extract and 2.5 g l−1 polypeptone per 10 g l−1 whey was most effective for succinic acid production from both treated and nontreated whey. When 20 g l−1 nontreated whey and 7 g l−1 glucose were used as cosubstrates, the yield and productivity of succinic acid reached at the end of fermentation were 95%
and 0.46 g (l h)−1, respectively. These values were higher than those obtained using nontreated whey alone [93% and 0.24 g (l h)−1 for 20 g l−1 whey]. Continuous fermentation of A. succiniciproducens at an optimal dilution rate resulted in the production of succinic acid with high productivity [1.35 g (l h)−1], high conversion yield (93%), and higher ratio of succinic acid to acetic acid (5.1:1) from nontreated whey.
Received: 23 July 1999 / Received revision: 17 November 1999 / Accepted: 24 December 1999 相似文献
19.
R. R. Farrera F. Pérez-Guevara M. de la Torre 《Applied microbiology and biotechnology》1998,49(6):758-765
A response-surface methodology was used to study the effect of carbon:nitrogen ratio (C:N) and initial concentration of total
solids (C
TS) on insecticidal crystal protein production and final spore count. Bacillus thuringiensis var. kurstaki HD-73 was grown in a stirred-tank reactor using soybean meal, glucose, yeast extract, corn steep solids and mineral salts.
Soybean meal and glucose were added according to a central composite experimental design to test C:N ratios ranging from 3:1
to 11:1 and C
TS levels from 60␣g/l to 150 g/l. Cry production was quantified using sodium dodecyl sulfate/polyacrylamide gel electrophoresis.
The response-surface model, adjusted to the data, indicated that media with a C:N of 7:1 yielded the highest relative Cry
production at each C
TS. The spore count was higher at low C:N ratio (4:1) and high C
TS (near 150 g/l). Specific Cry production varied from 0.6 to 2.2 g Cry/1010 spores. A 2.5-fold increase in C
TS resulted in a six-fold increase of protoxin production at a 7:1 C:N ratio. It is concluded that the best production conditions
for Cry and for spores are different and optimization of B. thuringiensis processes should not be done on a spore-count basis but on the amount of Cry synthesized.
Received: 5 September 1997 / Received revision: 22 December 1997 / Accepted: 2 January 1998 相似文献
20.
Recent trends in the biochemistry of surfactin 总被引:49,自引:0,他引:49
The name surfactin refers to a bacterial cyclic lipopeptide, primarily renowned for its exceptional surfactant power since
it lowers the surface tension of water from 72 mN m−1 to 27 mN m−1 at a concentration as low as 20 μM. Although surfactin was discovered about 30 years ago, there has been a revival of interest
in this compound over the past decade, triggered by an increasing demand for effective biosurfactants for difficult contemporary
ecological problems. This simple molecule also looks very promising as an antitumoral, antiviral and anti-Mycoplasma agent. Structural characteristics show the presence of a heptapeptide with an LLDLLDL chiral sequence linked, via a lactone
bond, to a β-hydroxy fatty acid with 13–15 C atoms. In solution, the molecule exhibits a characteristic “horse saddle” conformation that
accounts for its large spectrum of biological activity, making it very attractive for both industrial applications and academic
studies. Surfactin biosynthesis is catalysed non-ribosomally by the action of a large multienzyme complex consisting of four
modular building blocks, called the surfactin synthetase. The biosynthetic activity involves the multicarrier thiotemplate
mechanism and the enzyme is organized in structural domains that place it in the family of peptide synthetases, a class of
enzymes involved in peptidic secondary-metabolite synthesis. The srfA operon, the sfp gene encoding a 4′-phosphopantetheinyltransferase and the comA regulatory gene work together for surfactin biosynthesis, while the gene encoding the acyltransferase remains to be isolated.
Concerning surfactin production, there is no indication whether the genetic regulation, involving a quorum-sensing mechanism,
overrides other regulation factors promoted by the fermentation conditions. Knowledge of the modular arrangement of the peptide
synthetases is of the utmost relevance to combinatorial biosynthetic approaches and has been successfully used at the gene
level to modify the surfactin template. Biosynthetic and genetic rationales have been described for building variants. A fine
study of the structure/function relationships associated with the three-dimensional structure has led to the recognition of
the specific residues required for activity. These studies will assist researchers in the selection of molecules with improved
and/or refined properties useful in oil and biomedical industries.
Received: 9 October 1998 / Received revision: 29 January 1999 / Accepted: 31 January 1999 相似文献