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1.
Manipulation of the DNA coding for the desulphurizing activity in a new isolate of Arthrobacter sp. 总被引:3,自引:0,他引:3
A new bacterial strain able to cleave CS bonds from organosulphur heterocyclic compounds through the 4-S pathway and tentatively
classified as Arthrobacter sp. was recently isolated. In the present short article we describe the cloning and the characterization of the DNA encoding
the enzymes responsible for desulphurization in this microorganism, referred to as Arthrobacter sp. DS7. The desulphurization operon was found to be located in a large plasmid that also bears the genes conferring cadmium
and arsenic resistance. By shortening this plasmid, a new cloning vector was prepared and used to obtain a recombinant derivative
strain that desulphurizes dibenzothiophene despite of the presence of inorganic sulphur in the growth medium.
Received: 25 May 1998 / Received revision: 4 September 1998 / Accepted: 13 September 1998 相似文献
2.
Traditional as well as biotechnological processing of coal leads to complex mixtures of products. Besides chemical and physical
characterization, which provides the information for product application, there is a need for bioassays to monitor properties
that are probably toxic, mutagenic or cancerogenic. Investigations carried out focused on the selection, adaptation and validation
of bioassays for the sensitive estimation of toxic effects. Organisms like bacteria, Daphnia magna and Scenedesmus subspicatus, representing different complexities in the biosphere, were selected as test systems for ecotoxicological and mutagenicity
studies. The results obtained indicate that bioassays are, in principle, suitable tools for characterization and evaluation
of coal-derived substances and bioconversion products. Using coal products, coal-relevant model compounds and bioconversion
products, data for risk assessment are presented.
Received: 17 June 1998 / Received revison: 21 October 1998 / Accepted: 24 October 1998 相似文献
3.
Indirect evidence has suggested that lignin peroxidase (LiP) of the white-rot fungus Phanerochaete chrysosporium catalyses oxidative decolourisation and depolymerisation of macromolecules from brown coal in vivo. In this study we show
that LiP catalyses these transformations in vitro. Unmethylated (USC45 coal) and methylated (MWSC6 coal) fractions of solubilised
macromolecules (M
r > 30 000) from a brown coal were treated with a semi-purified preparation of LiP isozymes from P. chrysosporium. Both coal fractions were decolourised, losing between 26% and 39% of their absorbance at both 280 nm and 400 nm, in reactions
that had an absolute requirement for H2O2 and veratryl alcohol. Neither coal fraction was transformed when the enzyme was heat-inactivated or in the presence of the
LiP inhibitor metavanadate. Gel-permeation chromatography showed that MWSC6 coal but not USC45 was depolymerised and yielded
low-molecular-mass (M
r < 30 000) fragments. Nine monomeric products were identified by GC-MS.
Received: 20 March 1998 / Received revision: 3 September 1998 / Accepted: 3 September 1998 相似文献
4.
The present work describes investigations on the bacterial degradation of the alicyclic molecule cyclododecane. It represents
a structure where the initial degradative steps have to be similar to a “subterminal” attack as there is no “terminal” part
of the molecule. We were able to show that the gram-positive bacterium Rhodococcus ruber CD4 DSM 44394 oxidizes cyclododecane to the corresponding alcohol and ketone, the latter being subject to ring fission by
a Baeyer-Villiger oxygenase. This key enzyme is an NADPH- and O2-dependent flavoprotein with a substrate specificity for bigger rings. The further metabolism of the resulting lactone gives
rise to an ω-hydroxyalkanoic acid that is susceptible to common β-oxidation. Due to its alicyclic character and its ring size,
cyclododecane is comparable to aliphatic bridge components that are an important element in the coal texture. They contribute
to the three-dimensional coal structure and thus could serve as a valuable target for the oxidative abilities of R. ruber CD4 to reduce the molecular mass of coal.
Received: 2 July 1998 / Received revision: 27 October 1998 / Accepted: 30 October 1998 相似文献
5.
It is critical that an inexpensive electron- donor/carbon-source be found for selenium bioremedia-tion using the selenate-respiring
bacterium, Thauera selenatis. Since acetate is a preferred substrate for growth of this organism, a method was developed for fermenting the lactose in
whey to large amounts of acetate. Indigenous whey microorganisms fermented the whey lactose in this manner when grown in continuous
culture at a very slow dilution rate (D = 0.05 h−1). The successful use of the fermented whey lactose as the carbon-source/electron-donor feed for a laboratory-scale selenium-bioremediation
reactor system, inoculated with T. selenatis, treating selenium-contaminated drainage water was also demonstrated. Selenium oxyanions and nitrate were reduced by 98%.
Received: 30 October 1998 / Received revision: 26 January 1999 / Accepted: 5 February 1999 相似文献
6.
B. Bogovič-Matijašić I. Rogelj I. F. Nes H. Holo 《Applied microbiology and biotechnology》1998,49(5):606-612
Lactobacillus acidophilus LF221 produced bacteriocin-like activity against different bacteria including some pathogenic and food-spoilage species.
Besides some lactic acid bacteria, the following species were inhibited: Bacillus cereus, Clostridium sp., Listeria innocua, Staphylococcus aureus, Streptococcus D. L. acidophilus LF221 produced at least two bacteriocins, acidocin LF221 A and acidocin LF221 B, which were purified by ammonium sulphate
precipitation, ion-exchange chromatography, hydrophobic interaction and reverse-phase FPLC. The antibacterial substances were
heat-stable, sensitive to proteolytic enzymes (trypsin, pepsin, pronase, proteinase K) and migrated as 3500- to 5000-Da proteins
on sodium dodecyl sulphate/polyacrylamide gel electrophoresis. The sequences of 46 amino-terminal amino acid residues of peptide
A and 35 of peptide B were determined. Among the residues identified, no modified amino acids were found. No significant homology
was found between the amino acid sequences of acidocin LF221 A and other bacteriocins of lactic acid bacteria and 26% homology
was found between acidocin LF221 B and brevicin 27. L. acidophilus LF221 may be of interest as a probiotic strain because of its human origin and inhibition of pathogenic bacteria, especially
Clostridium difficile.
Received: 2 October 1997 / Received revision: 12 January 1998 / Accepted: 13 January 1998 相似文献
7.
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
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.
Two coals of different rank, mined in Russia, were treated by an anaerobic methanogenic enrichment culture. The addition
of alkaline enclosing rock to the lower-rank coal increased the pH of the incubation medium and methane production above that
of the higher-rank coal with addition of its enclosing rock. This effect was accompanied by the leaching of cations from the
incubation medium. The coal was processed without a preliminary chemical treatment in a two-stage aerobic/anaerobic bioreactor
containing an anaerobic methanogenic granulated enrichment culture.
Received: 15 January 1998 / Received revision: 2 October 1998 / Accepted: 2 October 1998 相似文献
10.
The gene dak1 encoding a dihydroxyacetone kinase (DHAK) isoenzyme I, one of two isoenzymes in the Schizosaccharomyces pombe IFO 0354 strain, was cloned and sequenced. The dak1 gene comprises 1743 bp and encodes a protein of 62 245 Da. The deduced amino acid sequence showed a similarity to a putative
DHAK of Saccharomyces cerevisiae and DHAK of Citrobacter freundii. The dak1 gene was expressed at a high level in Escherichia coli, and the recombinant enzyme was purified to homogeneity and characterized. The acetone powder of recombinant E. coli cells was used to produce dihydroxyacetone phosphate.
Received: 25 August 1998 / Received revision: 22 September 1998 / Accepted: 11 October 1998 相似文献
11.
Cloning and characterization of an endo-β-1,3(4)glucanase and an aspartic protease from Phaffia rhodozyma CBS 6938 总被引:1,自引:0,他引:1
We describe the identification and expression cloning of two novel enzymes, a β-glucanase and an aspartic protease, secreted
from the basidiomycetous yeast Phaffia rhodozyma. A cDNA library from P. rhodozyma CBS 6938 was constructed, and full-length cDNA encoding an endo-1,3(4)-β-glucanase (bg1) and an aspartic protease (pr1) were cloned by expression cloning in Saccharomyces cerevisiae W3124. The bg1 cDNA encodes a 424-residue precursor protein with a putative signal peptide. The pr1 cDNA encodes a 405-residue prepropolypeptide with an 81-residue leader peptide. The aspartic protease was purified and characterized.
It has a molecular mass of 36 kDa, an isoelectric point of pH 7.5, a pH activity optimum at 4.0–6.0, and a temperature activity
optimum around 40 °C. Both enzymes show only low sequence identity to other known enzymes.
Received: 6 August 1998 / Received revision: 29 October 1998 / Accepted: 30 October 1998 相似文献
12.
R. Beaudet M.-J. Lévesque R. Villemur M. Lanthier M. Chénier F. Lépine J.-G. Bisaillon 《Applied microbiology and biotechnology》1998,50(1):135-141
Anaerobic biodegradation of pentachlorophenol (PCP) in a contaminated soil from a wood-treating industrial site was studied
in soil slurry microcosms inoculated with a PCP-degrading methanogenic consortium. When the microcosms containing 10%–40%
(w/v) soil were inoculated with the consortium, more than 90% of the PCP was removed in less than 30 days at 29 °C. Less-chlorinated
phenols, mainly 3-chlorophenol were slowly degraded and accumulated in the cultures. Addition of glucose and sodium formate
to the microcosms was not necessary, suggesting that the organic compounds in the soil can sustain the dechlorinating activity.
Inoculation of Desulfitobacterium frappieri strain PCP-1 along with a 3-chlorophenol-degrading consortium in the microcosms also resulted in the rapid dechlorination
of PCP and the slow degradation of 3-chlorophenol. Competitive polymerase chain reaction experiments showed that PCP-1 was
present at the same level throughout the 21-day biotreatment. D. frappieri, strain PCP-1, inoculated into the soil microcosms, was able to remove PCP from soil containing up to 200 mg PCP/kg soil.
However, reinoculation of the strain was necessary to achieve more than 95% PCP removal with a concentration of 300 mg and
500 mg PCP/kg soil. These results demonstrate that D. frappieri strain PCP-1 can be used effectively to dechlorinate PCP to 3-chlorophenol in contaminated soils.
Received: 14 November 1997 / Received revision: 29 January 1998 / Accepted: 24 February 1998 相似文献
13.
M. Arnold A. Reittu A. von Wright P. J. Martikainen M.-L. Suihko 《Applied microbiology and biotechnology》1997,48(6):738-744
A biofiltration process was developed for styrene-containing off-gases using peat as filter material. The average styrene
reduction ratio after 190 days of operation was 70% (max. 98%) and the mean styrene elimination capacity was 12 g m−3 h−1 (max. 30 g m−3 h−1). Efficient styrene degradation required addition of nutrients to the peat, adjustment of the pH to a neutral level and efficient
control of the humidity. Maintenance of the water balance was easier in a down-flow than in an up-flow process, the former
consequently resulting in much better filtration efficiency. The optimum operation temperature was around 23 °C, but the styrene
removal was still satisfactory at 12 °C. Seven different bacterial isolates belonging to the genera Tsukamurella, Pseudomonas, Sphingomonas, Xanthomonas and an unidentified genus in the γ group of the Proteobacteria isolated from the microflora of active peat filter material were capable of styrene degradation. The isolates differed in
their capacity to decompose styrene to carbon dioxide and assimilate it to biomass. No toxic intermediate degradation products
of styrene were detected in the filter outlet gas or in growing cultures of isolated bacteria. The use of these isolates in
industrial biofilters is beneficial at low styrene concentrations and is safe from both the environmental and public health
points of view.
Received: 30 May 1997 / Received revision: 22 August 1997 / Accepted: 25 August 1997 相似文献
14.
M. Eriksson G. Dalhammar A.-K. Borg-Karlson 《Applied microbiology and biotechnology》1999,51(4):532-535
A hydrocarbon mixture containing p-xylene, naphthalene, Br-naphthalene and straight aliphatic hydrocarbons (C14 to C17) was aerobically degraded without lag phase by a natural uncontaminated potting soil at 20 °C and 6 °C. Starting concentrations
were approximately 46 ppm for the aromatic and 13 ppm for the aliphatic compounds. All aliphatic hydrocarbons were degraded
within 5 days at 20 °C, to levels below detection (ppb levels) but only down to 10% of initial concentration at 6 °C. Naphthalene
was degraded within 12 days at 20 °C and unaffected at 6 °C. At 20 °C p-xylene was degraded within 20 days, but no degradation occurred at 6 °C. Br-naphthalene was only removed down to 30% of initial
concentration at 20 °C, with no significant effect at 6 °C. The biodegradation was monitored with head space solid-phase microextraction
and gas chromatography–mass spectrometry.
Received: 5 October 1998 / Received revision: 4 December 1998 / Accepted: 5 December 1998 相似文献
15.
Intermediary sulfur compounds in pyrite oxidation: implications for bioleaching and biodepyritization of coal 总被引:6,自引:0,他引:6
Accumulation of elemental sulfur during pyrite oxidation lowers the efficiency of coal desulfurization and bioleaching. In
the case of pyrite bioleaching by Leptospirillum ferrooxidans, an iron(II)-ion-oxidizing organism without sulfur-oxidizing capacity, from the pyritic sulfur moiety about 10% elemental
sulfur, 2% pentathionate, and 1% tetrathionate accumulated by a recently described cyclic pyrite oxidation mechanism. In the
case of pure cultures of Thiobacillus ferrooxidans and mixed cultures of L. ferrooxidans and T. thiooxidans, pyrite was nearly completely oxidized to sulfate because of the capacity of these cultures to oxidize both iron(II) ions
and sulfur compounds. Pyrite oxidation in acidic solutions, mediated chemically by iron(III) ion, resulted in an accumulation
of similar amounts of sulfur compounds as obtained with L. ferrooxidans. Changes of pH to values below 2 or in the iron ion concentration are not decisive for diverting the flux of sulfur compounds.
The literature on pyrite bioleaching is in agreement with the findings indicating that the chemistry of direct and indirect
pyrite leaching is identical.
Received: 20 April 1998 / Received revision: 27 August 1998 / Accepted: 3 September 1998 相似文献
16.
Purification and characterization of a soybean-milk-coagulating enzyme from Bacillus pumilus TYO-67 总被引:7,自引:0,他引:7
M. Yasuda M. Aoyama M. Sakaguchi K. Nakachi N. Kobamoto 《Applied microbiology and biotechnology》1999,51(4):474-479
Bacillus pumilus TYO-67 was isolated from tofu (soybean curd) as the best producer of a soybean-milk-coagulating enzyme, induced by the addition
of soybean protein to the growth medium. The enzyme was purified approximately 30-fold with an 11% yield. The homogeneous
preparation of the enzyme showed that it is a monomer with a molecular mass of about 30 kDa and has an isoelectric point at
pH 9.75. The results of amino acid composition analyses showed that the enzyme is rich in alanine, aspartic acid, glycine,
serine and valine. Although the amino-terminal amino acid (alanine) was identical with that of subtilisins, the amino-terminal
sequence was different from those of subtilisins. The α-helix content of the enzyme was calculated to be 28.2%. The optimum
pH and temperature were observed at 6.0–6.1 and 65 °C respectively. The enzyme was significantly activated by the addition
of 1 mM Mn2+, Ca2+, Mg2+, and Sr2+ ions in the reaction mixture, and its thermal stability was significantly increased by Ca2+ ion.
Received: 31 August 1998 / Received last revision: 1 December 1998 / Accepted: 20 December 1998 相似文献
17.
High-level expression of an endoxylanase gene from Bacillus sp. in Bacillus subtilis DB104 for the production of xylobiose from xylan 总被引:1,自引:0,他引:1
K. J. Jeong I. Y. Park M. S. Kim S. C. Kim 《Applied microbiology and biotechnology》1998,50(1):113-118
To produce xylobiose from xylan, high-level expression of an endoxylanase gene from Bacillus sp. was carried out in Bacillus subtilis DB104. A 1.62-kb SmaI DNA fragment, coding for an endoxylanase of Bacillus sp., was ligated into the Escherichia coli/B. subtilis shuttle vector pJH27Δ88, producing pJHKJ4, which was subsequently transformed into B. subtilis DB104. A maximum endoxylanase activity of 105 U/ml was obtained from the supernatant of B. subtilis DB104 harboring pJHKJ4. The endoxylanase was purified to homogeneity by ion-exchange chromatography and the production profile
of xylooligosaccharides from xylan by the endoxylanase was examined by HPLC with a carbohydrate analysis column. Xylobiose
was the major product from xylan at 40 °C and its proportion in the xylan hydrolyzates increased with the reaction time; at
12 h, over 60% of the reaction products was xylobiose. These results suggest that xylobiose, which has a stimulatory effect
on the selective growth of the intestinal bacterium Bifidobacterium, can be mass-produced effectively by the endoxylanase of Bacillus sp. cloned in B. subtilis.
Received: 2 January 1998 / Received revision: 4 March 1998 / Accepted: 4 March 1998 相似文献
18.
Towards a high-yield bioconversion of ferulic acid to vanillin 总被引:13,自引:2,他引:11
Natural vanillin is of high interest in the flavor market. Microbial routes to vanillin have so far not been economical as
the medium concentrations achieved have been well below 1 g l−1. We have now screened microbial isolates from nature and known strains for their ability to convert eugenol or ferulic acid
into vanillin. Ferulic acid, in contrast to the rather toxic eugenol, was found to be an excellent precursor for the conversion
to vanillin, as doses of several g l−1 could be fed. One of the isolated microbes, later identified as Pseudomonas putida, very efficiently converted ferulic acid to vanillic acid. As vanillin was oxidized faster than ferulic acid, accumulation
of vanillin as an intermediate was not observed. A completely different metabolic flux was observed with Streptomyces setonii. During the metabolism of ferulic acid, this strain accumulated vanillic acid only to a level of around 200 mg l−1 and then started to accumulate vanillin as the principal metabolic overflow product. In shake-flask experiments, vanillin
concentrations of up to 6.4 g l−1 were achieved with a molar yield of 68%. This high level now forms the basis for an economical microbial production of vanillin
that can be used for flavoring purposes.
Received: 15 October 1998 / Received revision: 13 January 1999 / Accepted: 18 January 1999 相似文献
19.
Three different mechanisms can be envisaged that are used by fungi to solubilize coal: the production of alkaline substances,
the extrusion of chelators and, of special interest in the scope of biotechnology, the action of enzymes. Whether these mechanisms
are operating separately or in various combinations has not yet been finally assessed. The two deuteromycetes Fusarium oxysporum and Trichoderma atroviride solubilize coal by synergistic effects of various different mechanisms depending on the cell metabolism. F. oxysporum seems to solubilize coal by increasing the pH of the mycelial surroundings and by the action of chelators induced during
growth in glutamate-containing media (without involvement of enzymes). T. atroviride, on the other hand, appears to use, in addition to an alkaline pH and a high chelator activity, at least two classes of enzyme
activity to attack coal: hydrolytic activity for coal solubilization and ligninolytic activity for degradation of humic acids.
Received: 3 February 1998 / Received revision: 31 August 1998 / Accepted: 3 September 1998 相似文献
20.
Composition of the cell walls of several yeast species 总被引:14,自引:0,他引:14
Cell walls, representing 26%–32% of the cell dry weight, were prepared from several strains of the yeasts Kloeckera apiculata, Debaryomyces hansenii, Zygosaccharomyces bailii,Kluyveromyces marxianus and Saccharomyces cerevisiae. Extraction of the walls with potassium hydroxide at 4 °C, followed by saturation of the alkali-soluble extract with ammonium
sulphate gave fractions of mannoprotein, alkali-soluble glucan and alkali-insoluble glucan. Chitin was associated with the
alkali-insoluble glucan. The proportions of the different fractions within the walls varied with the species and strain. Mannoprotein
comprised between 25% and 34% of the walls, the content of alkali-insoluble glucan ranged from 15% to 48%, and the content
of alkali-soluble glucan ranged from 10% to 48%. There was significant variation in the physical appearance of the alkali-soluble
glucans and the relative viscosity of suspensions of these glucans. The yeasts could represent novel sources of polysaccharides
with industrial and medical applications.
Received: 30 December 1997 / Received revision: 24 March 1998 / Accepted: 27 March 1998 相似文献