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1.
The aptitude of resting cells of Brevibacterium linens G171 to synthesize S-methyl thioesters was studied in presence of methanethiol and nine short-chain fatty acids individually or as a mixture.
Esterification of acetic, propionic and methyl branched-chain acids occurred with methanethiol alone and was enhanced by fatty
acid addition. Addition of n-chain, 3-hydroxybutyric and 2-hydroxyvaleric acids allowed synthesis of n-chain thioesters up to thiocaproate. The kinetics of production and the effect of concentrations of both substrates and of
cells were tested. The optimum pH for synthesis varied according to the kind of thioesters produced. Results suggested that
thioesters were derived mainly from acyl-CoA from different metabolic breakdowns, such as the degradation of fatty acids or
some amino acids, and that several acyltransferases could be involved.
Received: 1 August 1996 / Received revision: 10 October 1996 / Accepted: 18 October 1996 相似文献
2.
A. Arai S. Masuda A. Matsuyama S. Murakami M. Nakajima 《Applied microbiology and biotechnology》1998,49(3):272-276
The gene for the thermostable pyruvate kinase of Microbispora thermodiastatica IFO 14046, a moderate thermophilic actinomycete, was cloned in Escherichia coli. This gene consists of an open reading frame of 1422 nucleotides and encodes a protein of 474 amino acids with molecular
mass of 50 805 Da. The open reading frame was confirmed as the pyruvate kinase gene by comparison with the N-terminal amino
acid sequence of the purified pyruvate kinase from M. thermodiastatica.
Received: 19 May 1997 / Received last revision: 22 September 1997 / Accepted: 14 October 1997 相似文献
3.
Production of high yields of arachidonic acid in a fed-batch system by Mortierella alpina ATCC 32222
Of six strains of Mortierella tested, Mortierella alpina ATCC 32222 produced the highest yields of arachidonic acid. Supplementation of soy flour (1% w/v) and vegetable oils (1%
v/v) significantly increased the biomass, lipid content and arachidonic acid level. Replacement of NaNO3 with corn steep liquor (1% w/v) also improved arachidonic acid production. A fed-batch culture system at 25 °C, producing
a high biomass (52.4 g/l) and arachidonic acid content (9.1 g/l) in 8␣days, was developed. A fed-batch system at low temperature
(15 °C) gave even higher arachidonic acid levels (11.1 g/l) in 11 days.
Received: 28 October 1996 / Received revision: 3 March 1997 / Accepted: 7 March 1997 相似文献
4.
P. Barghini F. Montebove M. Ruzzi A. Schiesser 《Applied microbiology and biotechnology》1998,49(3):309-314
Pseudomonas fluorescens BF13 is especially capable of promoting the formation of vanillic acid during ferulic acid degradation. We studied the possibility
of enhancing the formation of this intermediary metabolite by using suspensions of cells at high density. The bioconversion
of ferulic into vanillic acid was affected by several parameters, such as the concentration of the biomass, the amount of
ferulic acid that was treated, the carbon source on which the biomass was grown. The optimal yield of vanillic acid was obtained
with 6 mg/ml cells pre-grown on p-coumaric acid and 2 mg/ml ferulic acid. Under these conditions the bioconversion rate was 95% in 5 h. Therefore BF13 strain
represents a valid biocatalyst for the preparative synthesis of vanillic acid.
Received: 1 July 1997 / Received revision: 28 October 1997 / Accepted: 16 November 1997 相似文献
5.
Various strains of coryneform bacteria, Micrococcaceae and commercial starters of Lactococcus lactis and Leuconostoc were compared for their aptitude to form S-methyl thioesters. Resting cells were incubated with methanethiol alone at pH 7 and in conjunction with a mixture of straight,
branched and hydroxy short-chain fatty acids up to C6 at pH 7 and 5. Results showed that all the strains synthesized at least S-methyl thioacetate, with strains that were low and high producers in each group. This is the only thioester formed in small
amount by Leuconostoc. Brevibacterium linens (six strains) and Micrococcaceae (five strains) were able to form branched-chain thioesters especially from their intracellular
fatty acids at neutral pH, and straight-chain thioesters mostly from exogenous fatty acids at acid pH. Coryneform bacteria
other than B. linens (four strains) and L. lactis (four starters) synthesized thioesters up to S-methyl thiobutyrate from endogenous or exogenous fatty acids but not branched-chain ones, except for one starter which formed
a very little thioisovalerate. Some particular effects of pH and added fatty acids revealed differences between species or
strains in their specific enzymatic systems.
Received: 7 April 1997 / Received revision: 5 June 1997 / Accepted: 7 June 1997 相似文献
6.
I. Schneegaß M. Hofrichter K. Scheibner W. Fritsche 《Applied microbiology and biotechnology》1997,48(5):602-605
The main manganese peroxidase isoenzyme MnP2 of the South American white-rot fungus Nematoloma frowardii b19 was purified to homogeneity using anion-exchange chromatography (Mono Q) and preparative isoelectric focusing. The purified
enzyme has a molecular mass of 44 kDa and a pI of 3.2.
Received: 23 May 1997 / Received revision: 1 July 1997 / Accepted: 4 July 1997 相似文献
7.
5-Hydroxypyrazine-2-carboxylic acid, a versatile building block for the synthesis of new antituberculous agents, was prepared
by whole-cell biotransformation from 2-cyanopyrazine via pyrazinecarboxylic acid using Agrobacterium sp. DSM 6336. By developing a fermentation process for this two-enzyme-step bioconversion, a product concentration of 286 mM
(40 g/l) was obtained. After the isolation method had been optimized the total yield was 80%.
Received: 28 February 1997 / Received revision: 28 April 1997 / Accepted: 4 May 1997 相似文献
8.
P. Ledent H. Michels G. Blackman H. Naveau S. N. Agathos 《Applied microbiology and biotechnology》1999,51(3):370-374
Anionic, cationic, amphoteric and non-ionic surfactants inhibited spore germination and subsequent growth of a mixture of
two Bacillus strains at surfactant concentrations ranging from 1 ppm to 50 ppm. Germination appeared to be more affected than cell growth
by the presence of surfactants, the inhibitory thresholds being largely increased when media were inoculated with vegetative
cells. The bacterial species forming the consortium were incapable of growing on liquid and agar-solidified media prepared
with non-diluted domestic wastewater. Addition of hydrolases (protease, cellulase, α-amylase and lipase) to the wastewater
medium allowed the germination of spores and their vegetative growth.
Received: 9 July 1998 / Received revision: 26 October 1998 / Accepted: 30 October 1998 相似文献
9.
Acetic acid fermentation is the biochemical process by which, under strict conditions of aerobiosis, Acetobacter aceti oxidises the ethanol contained in alcoholic substrates into acetic acid. This paper studies the effect of temperature on
the specific growth rate of the microorganisms (μ
C), in particular, the mathematical modelling of this process, with the aim of developing previous studies of the mathematical
relationships between μ
C of A. aceti and the concentrations of substrate (ethanol), product (acetic acid) and dissolved oxygen. Until now this relationship has
not been widely studied, and only a few studies have looked at the influence of temperature on growth kinetics of this bacteria.
We have developed an extensive experimental system, to determine precisely the influence of temperature on the maximum specific
growth rate.
Received: 15 July 1997 / Received revision: 7 October 1997 / Accepted: 19 October 1997 相似文献
10.
The biosynthesis of poly(hydroxyalkanoates) (PHA) by Pseudomonas resinovorans from triglyceride substrates was investigated. Each triglyceride, whether animal fat or vegetable oil, supported cellular
growth to relatively high average cell yields (3.3 ± 0.2 g/l). PHA yields ranged from 1.1 g/l to 2.1 g/l, representing approximately
45% of the bacterial cell dry weight. The repeat-unit composition of the polymers was determined by gas chromatography (GC)
and GC/mass spectrometry of the β-hydroxyalkanoate methyl esters from the hydrolyzed polymers. With the exception of PHA from
soybean oil (PHA-soy), each polyester was composed of β-hydroxyacyl moieties with chain lengths ranging from C4 to C14, with C8 and C10 being the predominant species. PHA-soy contained an additional fraction (2%) of C16 monomers. The alkyl side-chains of the PHA contained varying degrees of unsaturation. PHA from coconut oil was composed entirely
of saturated side-chains, whereas PHA-soy contained 4.2 mol% olefinic groups in its side-chains. The increase in the degree
of side-chain unsaturation caused decreased melting temperatures, enthalpies of fusion, and glass transition temperatures.
The molar masses of the polymers were relatively constant and ranged from 6.5 × 104 to 10.1 × 104 g/mol.
Received: 2 September 1997 / Received revision: 21 November 1997 / Accepted: 2 January 1998 相似文献
11.
Elucidation of anaplerotic pathways in Corynebacterium glutamicum via 13C-NMR spectroscopy and GC-MS
S. M. Park C. Shaw-Reid A. J. Sinskey G. Stephanopoulos 《Applied microbiology and biotechnology》1997,47(4):430-440
We have obtained direct evidence indicating the presence of pyruvate-carboxylating activity in Corynebacterium glutamicum, a lysine-overproducing bacterium. This evidence was obtained through the use of 13C nuclear magnetic resonance (NMR) spectroscopy and gas chromatography/mass spectrometry (GC-MS) of secreted metabolites in
a lysine fermentation. The distribution of 13C label after multiple turns in the tricarboxylic acid cycle was accounted for properly to obtain predictions for [13C] metabolite enrichments that were employed in the interpretation of 13C-NMR and GC-MS data. Of critical importance in arriving at the conclusions was the use of C. glutamicum mutants with deletions of the pyruvate kinase and/or phosphoenolpyruvate carboxylase enzymes. Our results demonstrate the presence of pyruvate-carboxylating pathway(s) in C.␣glutamicum operating simultaneously with phosphoenolpyruvate carboxylase, with the latter enzyme contributing approximately 10 % of the total oxaloacetate synthesis during the
lysine-production phase with pyruvate and gluconate as carbon sources. These findings are important for developing strategies
to increase the total carbon flux for synthesis of amino acids of the aspartate family through metabolic engineering.
Received: 11 June 1996 / Received revision: 30 October 1996 / Accepted: 15 November 1996 相似文献
12.
H. Dominguez M. Cocaign-Bousquet N. D. Lindley 《Applied microbiology and biotechnology》1997,47(5):600-603
Growth of Corynebacterium glutamicum on mixtures of glucose and fructose leads to simultaneous consumption of both sugars in which the uptake of each sugar is
directly related to the expression of the corresponding sugar uptake mechanism. The overall rate of sugar uptake was higher
on sugar mixtures than on either glucose or fructose alone and was similar to that observed during sucrose metabolism. The
results suggest that sugar uptake limits metabolic rates though, in the case of fructose, overflow metabolism of both lactate
and dihydroxyacetone was observed. Such products could reflect a higher flux through glycolysis rather than the pentose pathway
during catabolism of fructose.
Received: 24 October 1996 / Received revision: 10 January 1997 / Accepted: 10 January 1997 相似文献
13.
Y. Pagot A. Le Clainche J.-M. Nicaud Y. Wache J.-M. Belin 《Applied microbiology and biotechnology》1998,49(3):295-300
γ-Decalactone is a peachy aroma compound resulting from the peroxisomal β-oxidation of ricinoleic acid by yeasts. The expression
levels of acyl-CoA oxidase (gene deletion) and 3-ketoacyl-CoA thiolase activities (gene amplification on replicative plasmids)
were modified in the yeast Yarrowia lipolytica. The effects of these modifications on β-oxidation were measured. Overexpression of thiolase activity did not have any effect
on the overall β-oxidation activity. The disruption of one of the acyl-CoA oxidase genes resulted in an enhanced activity.
The enhancement led to an increase of overall β-oxidation activity but reduced the γ-decalactone production rates. This seemed
to indicate a non-rate-limiting role for β-oxidation in the biotransformation of ricinoleic acid to γ-decalactone by the yeast
Yarrowia lipolytica. All strains produced and then consumed γ-decalactone. We checked the ability of the different strains to consume γ-decalactone
in a medium containing the lactone as sole carbon source. The consumption of the strain overexpressing acyl-CoA oxidase activity
was higher than that of the wild-type strain. We␣concluded that peroxisomal β-oxidation is certainly involved in γ-decalactone
catabolism by the yeast Y.␣lipolytica. The observed production rates probably depend on an equilibrium between production and consumption of the lactone.
Received: 13 June 1997 / Received revision: 2 October 1997 / Accepted: 14 October 1997 相似文献
14.
D. Naki C. Paech G. Ganshaw V. Schellenberger 《Applied microbiology and biotechnology》1998,49(3):290-294
Mutants that secrete increased amounts of enzyme into a selection medium can be efficiently enriched from large populations
of mutagenized microorganisms during growth in hollow fibers. Under these conditions, each colony grows in its own microenvironment
and cross-feeding between neighboring colonies is limited. We applied the technique to B. subtilis carrying a plasmid-encoded protease gene. The plasmid was subjected to random mutagenesis and clones secreting up to fivefold-increased
amounts of enzyme were selected using a medium containing bovine serum albumin as the sole nitrogen source.
Received: 22 May 1997 / Received revision: 21 October 1997 / Accepted: 7 November 1997 相似文献
15.
M. Kunioka 《Applied microbiology and biotechnology》1997,47(5):469-475
The biosynthesis and chemical reactions of poly(amino acid)s produced by microorganisms are reviewed. A large amount of γ-poly(glutamic
acid) (PGA) has been produced by Bacillus strains. ε-Polylysine (PL) has been produced by Streptomyces albulus. As a modification of PGA and PL, pH-sensitive hydrogels have been prepared by means of γ irradiation or the addition of
a crosslinking agent to an aqueous solution of PGA and PL.
Received: 4 September 1996 / Received revision: 27 January 1997 / Accepted: 28 January 1997 相似文献
16.
Residues and coal fractions that remained after the biosolubilization of Rhenish brown coal by strains of Lentinula edodes and Trametes versicolor have been studied by Curie-point pyrolysis/gas chromatography/mass spectrometry using tetraethylammonium hydroxide (NEt4OH) at 610 °C. To differentiate methyl derivatives of esters and ethers from free or bound hydroxyl and carboxyl groups NEt4OH was used in the thermochemolysis experiments instead the commonly used tetramethylammonium hydroxide. A comparison of humic
acid fractions before and after fungal attack shows considerable alteration of the soluble macromolecules of coal. Depending
on the coal fraction studied and the fungi used, the assortment of fatty acid esters released during the pyrolysis varies
significantly. Furthermore, dicarbonic acid ethyl diesters as well as ethyl derivatives of aromatic ethers and acids yield
information about humic acid structure and the biosolubilization of brown coal. Variations in the mixture produced are possibly
caused by differences in the pattern of extracellular enzymes secreted that attack the macromolecular structural elements
of brown coal. Therefore pyrolysis of native and microbiologically altered geomacromolecules using NEt4OH allows one to differentiate between free hydroxyl groups as well as substances that are attached to humic substances via
ester or ether bridges, and their methylated counterparts.
Received: 13 July 1998 / Received revision: 12 October 1998 / Accepted: 16 October 1998 相似文献
17.
J. B. Sutherland J. P. Freeman A. J. Williams 《Applied microbiology and biotechnology》1998,49(4):445-449
Streptomyces viridosporus T7A (ATCC␣39115), during growth in tryptone/yeast extract broth, cometabolized five heterocyclic nitrogen-containing compounds.
The metabolites produced from the azaarenes were identified by high-performance liquid chromatography, UV/visible absorption
spectroscopy, and mass spectrometry. Isoquinoline was transformed to 1(2H)-isoquinolinone (14%), phenanthridine to 6(5H)-phenanthridinone (25%), phthalazine to 1(2H)-phthalazinone (46%), quinazoline to 2,4(1H,3H)-quinazolinedione (4%), and quinoxaline to 2(1H)-quinoxalinone (8%) and 1-methyl-2(1H)-quinoxalinone (12%).
Received: 29 July 1997 / Received revision: 19 November 1997 / Accepted: 29 November 1997 相似文献
18.
Xanthomonas campestris pv. translucens IFO13599 could produce xanthan gum (18.5 mg/100 mg, lactose) with lactose as the growth substrate in spite of a low level
of β-galactosidase. This productivity corresponded to one-fifth that with glucose. This strain could also produce ice-nucleating
material having an ice-nucleating temperature, T
50, of −2.8 °C with xanthan gum in the culture broth. We found that this strain produced both materials in whey medium from
which the insoluble components had been removed. The production of xanthan with ice-nucleating material reached a maximum
after cultivation for 168 h under optimum conditions. Furthermore, the xanthan obtained had a low viscosity because of its
variant structure revealed, by TLC and HPLC analyses, to be lacking pyruvic acid. Furthermore, we concluded that this mixture
had considerable potential as a regeneratic agent, when compared to other regeneratic agents such as carboxymethylcellulose.
Received: 29 August 1997 / Received revision: 17 November 1997 / Accepted: 18 November 1997 相似文献
19.
K. M. J. Van Laere G. Beldman A. G. J. Voragen 《Applied microbiology and biotechnology》1997,47(3):231-235
An arabinofuranohydrolase (AXH-d3) was purified from a cell-free extract of Bifidobacterium adolescentis DSM 20083. The enzyme had a molecular mass of approximately 100 kDa as determined by gel filtration. It displayed maximum
activity at pH 6 and 30 °C. Using an arabinoxylan-derived oligosaccharide containing double-substituted xylopyranosyl residues
established that the enzyme specifically released terminal arabinofuranosyl residues linked to C-3 of double-substituted xylopyranosyl
residues. In addition, this arabinofuranohydrolase released arabinosyl groups from wheat flour arabinoxylan polymer but showed
no activity towards p-nitrophenyl α-l-arabinofuranoside or towards sugar-beet arabinan, soy arabinogalactan, arabino-oligosaccharides and arabinogalacto-oligosaccharides.
Received: 15 July 1996 / Received revision: 18 October 1996 / Accepted: 18 October 1996 相似文献
20.
Plant cell suspension culture in a bench-scale fermenter with a newly designed membrane stirrer for bubble-free aeration 总被引:1,自引:0,他引:1
C. Böhme M.-B. Schröder H. Jung-Heiliger J. Lehmann 《Applied microbiology and biotechnology》1997,48(2):149-154
In this paper, tests of an optimized membrane-stirrer geometry for bubble-free aeration of a plant cell suspension culture
are described. Cell attachment and clogging of a previously described system [Piehl et al. (1988) Appl Microbiol Biotechnol
29:456–461] led to the development of a new stirrer. The volumetric oxygen transfer capacity has been measured in aqueous
medium. The mass transfer coefficient, k
l
a, was 3.75 h−1 at 25 °C and at a stirrer speed of 34 rpm. The overall oxygen transfer capacity was investigated with a suspension culture
of Aesculus hippocastanum. It was shown that the oxygen mass transfer was sufficient even at the maximum biomass of 10–12 g dry weight/l, which was
obtained by using this system. Furthermore, special attention was given to medium components like C and N sources, to avoid
growth limitation due to a shortage of nutrients.
Received: 22 October 1996 / Revised version: 11 March 1997 / Accepted: 14 March 1997 相似文献