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1.
The production of feruloyl esterase activity by Bacillus spp. and lactobacilli can be detected in an agar-plate assay. The assay involves the substitution of the main carbon source
in specific agar with ethyl ferulate. A number of Bacillus spp., predominantly B. subtilis strains, were found to exhibit feruloyl esterase activity by this method. Of the examined lactobacilli, Lb. fermentum (NCFB 1751) showed the highest level of ferulic acid esterase activity. The enzyme was released from harvested cells by sonication
and showed pH and temperature optima of 6.5 and 30 °C respectively.
Received: 2 February 1998 / Received revision: 20 April 1998 / Accepted: 27 April 1998 相似文献
2.
A transketolase mutant was first isolated from Corynebacterium glutamicum, an organism of industrial importance. The mutant strain exhibited an absolute requirement for shikimic acid or the aromatic
amino acids and vitamins for growth, and also failed to grow on ribose or gluconic acid as sole carbon source, even with the
aromatic supplement. All of these defective properties were fully restored in spontaneous revertants, indicating the existence
of a single transketolase in C. glutamicum that was indispensable both for aromatic biosynthesis and for utilization of these carbohydrates in vivo. The transketolase
mutant accumulated ribulose extracellularly when cultivated in glucose medium with shikimic acid, but no ribose was detected.
Received: 10 April 1998 / Received revision: 26 May 1998 / Accepted: 14 June 1998 相似文献
3.
Y. Morita Q. Hasan T. Sakaguchi Y. Murakami K. Yokoyama E. Tamiya 《Applied microbiology and biotechnology》1998,50(6):669-675
Protease activity was detected in the culture medium of Flavobacterium balustinum P104 grown at 10 °C, which was isolated from salmon (Oncorhynchus keta) intestine. The enzyme, designated as CP-70 protease, was purified to homogeneity from the culture broth by ion exchange
and gel filtration chromatographyies. The molecular mass of the protease was 70 kDa, and its isoelectric point was close to
3.5. Maximal activity toward azocasein was observed at 40 °C and from pH 7.0 to 9.0. The activity was strongly inhibited by
phenylmethylsulfonyl fluoride, suggesting that the enzyme is a serine protease. The n-terminal amino acid sequence was Asp-Thr-Arg-Gln-Leu-Leu-Asn-Ala-Asn-Ser-Asp-Leu-Leu-Asn-Thr-Thr-Gly-Asn-Val-Thr-Gly-Leu-Thr-Gly-Ala-Phe-Asn-Gly-Glu-Asn.
A search through the database for sequence homology yielded no significant match. The initial cleavage sites for oxidized
insulin B-chain were found to be the Glu13-Ala14 and Phe24-Phe25 bonds. The result of the cleavage pattern of oxidized insulin
B-chain suggests that CP-70 protease has a broader specificity than the other cold-active proteases against the peptide substrate.
Received: 17 April 1998 / Received last revision: 17 June 1998 / Accepted: 10 July 1998 相似文献
4.
Extraction of medium after incubation of the fungus, Cunninghamella elegans, with 0.03% (w/v) 1-methylnaphthalene produced mainly 1-hydroxymethylnaphthalene together with some 1-naphthoic acid and
hydroxynaphthoic acid. Higher concentrations of substrate were inhibitory to biotransformation. Similar incubations with 1-naphtoic
acid as substrate resulted in reduction of the carboxyl group to give 1-hydroxymethylnaphthalene. When 6-methylquinoline was
used, the main product was 6-hydroxymethylquinoline but also some quinoline-6-carboxylic acid and some 6-methylquinoline-N-oxide were identified. In a 2-l fermenter 2.5 g substrate was transformed in 324 h. The 6-hydroxymethylquinoline was also
produced by reduction of quinoline-6-carboxylic acid by the organism.
Received: 9 March 1998 / Received revision: 15 June 1998 / Accepted: 19 June 1998 相似文献
5.
B. L. García A. S. Ball J. Rodríguez M. I. Pérez-Leblic M. E. Arias J. L. Copa-Patiño 《Applied microbiology and biotechnology》1998,50(2):213-218
Streptomyces avermitilis CECT 3339 produces extracellular ferulic acid esterase (FAE) activity during growth on a range of lignocellulose substrates.
Maximal levels of FAE activity were detected in culture filtrates from S. avermitilis CECT 3339 grown in media containing wheat bran and yeast extract as carbon and nitrogen sources respectively. Biochemical
characterization of this enzyme activity revealed that it was 100-fold higher when wheat bran was pretreated with Celluclast
(a mix of hydrolytic enzymes). FAE was found to be end-product-inhibited. Characterization of the properties of the enzyme
showed that FAE exhibited an activity optimum pH at 6 with pH stability between pH 6 and 8. The optimum temperature was 50 °C
while the temperature stability was between 30 °C and 40 °C, with rapid inactivation at 60 °C and above. The characteristics
and stability of FAE from S. avermitilis CECT 3339 suggest a potential role for this enzyme in combination with endoxylanases for the upgrading of plant-residue silage
and for biopulping.
Received: 17 November 1997 / Received revision: 13 March 1998 / Accepted: 13 April 1998 相似文献
6.
L. Mojovic Z. Knezevic R. Popadic S. Jovanovic 《Applied microbiology and biotechnology》1998,50(6):676-681
Lipase from Candida rugosa was immobilized by adsorption onto a macroporous copolymer support. Under optimum conditions the maximum amount of protein
bound was 15.4 mg/g and the immobilization efficiency was 62%. The kinetics of lipase binding to the selected polymer carrier
was assessed by using a general model of topochemical reactions. The effect of temperature on adsorption was thoroughly investigated,
as was the adsorption mechanism itself. Analysis of the proposed kinetic model and the specific kinetic parameters measured
suggest that surface kinetics control the adsorption process. According to the activation energy (E
a) and the rate constant, k, the enzyme has rather a high affinity for the support's active sites. The immobilized enzyme was used to catalyse the hydrolysis
of palm oil in a lecithin/isooctane reaction system, in which the enzyme's activity was 70% that of the free enzyme. Kinetic
parameters such as maximum velocity (V
max) and the Michaelis constant (K
m) were determined for the free and the immobilized lipase. Following repeated use, the immobilized lipase retained 56% of
its initial activity after the fifth hydrolysis cycle.
Received: 3 April 1998 / Received revision: 28 July 1998 / Accepted: 29 July 1998 相似文献
7.
Very good solvent formation rates were observed when Clostridium beijerinckii NRRL B592 was cultivated on different whole potato media. The increase in whole potato concentration contributed to the increased
final solvent concentrations, while the addition of yeast extract or mineral salts gave negative effects. To obtain good solvent
productivities and high final solvent concentrations during batch fermentation, no enzymatic hydrolysis of the potato starch
was necessary, indicating high activity of the clostridial amylases produced by the strain applied.
Received: 17 April 1998 / Received revision: 22 June 1998 / Accepted: 27 June 1998 相似文献
8.
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
9.
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
10.
A. Blanco P. Díaz J. Martínez T. Vidal A. L. Torres F. I. J. Pastor 《Applied microbiology and biotechnology》1998,50(1):48-54
The gene celA, encoding an endoglucanase from the strain Bacillus sp. BP-23, was cloned and expressed in Escherichia coli. The nucleotide sequence of a 1867-bp DNA fragment containing the celA gene was determined, revealing an open reading frame of 1200 nucleotides that encodes a protein of 44 803 Da. The deduced
amino acid sequence of the encoded enzyme shows high homology to those of enzymes belonging to subtype 4 of the family-A cellulases.
The celA gene product synthesized in E. coli showed activity on carboxymethylcellulose and lichenan but no activity was found on Avicel. Activity was enhanced in the
presence of 10 mM Mg2+ and Ca2+ and showed its maximum at 40 °C and pH 4.0. Study of the performance of CelA on paper manufacture from agricultural fibres
showed that treatment with the enzyme improved the properties of the pulp and the quality of paper. CelA treatment enhanced
the physical properties (stretch and tensile index) of paper from wheat straw, while dewatering properties were slightly diminished.
Electron-microscope analysis showed that the surface of straw fibres was modified by CelA.
Received: 11 February 1998 / Received revision: 20 March 1998 / Accepted: 20 March 1998 相似文献
11.
N. T. Mlobeli N. A. Gutierrez I. S. Maddox 《Applied microbiology and biotechnology》1998,50(1):125-128
A strain of Bifidobacterium bifidum was grown on different sugars under pH-controlled conditions to estimate some kinetic parameters for growth and product formation.
Glucose was the preferred sugar in terms of growth rate and yield, sugar utilisation rate and acetate formation rate, while
lactose gave considerably lower values for these parameters. When present in a mixture with glucose, the rate of lactose utilisation
was lower than when present on its own.
Received: 24 February 1998 / Received revision: 15 April 1998 / Accepted: 19 April 1998 相似文献
12.
C. Förster S. Marienfeld F. Wendisch R. Krämer 《Applied microbiology and biotechnology》1998,50(2):219-226
Osmoadaption mechanisms of the biotechnologically important hemiascomycete Ashbya gossypii were investigated, thereby distinguishing between halo- and osmotolerance by exposure to NaCl and mannitol stress. We studied
the growth and ultrastructure of differently treated cells and quantified the intracellular contents of compatible solutes
and inorganic ions. Mannitol affected growth of A. gossypii at concentrations above 0.8 M, whereas NaCl inhibited growth at 0.2 M. NaCl-treated cells differed from control cells in
having smaller vacuoles, which occupied a smaller part of the cell volume. Glycerol was found to be the predominant compatible
solute in A. gossypii; accumulation of inorganic ions could not be detected. Measurement of glycerol uptake under isosmotic conditions as well
as upon hyperosmotic stress revealed the existence of a highly active glycerol-uptake system, which, however, was down-regulated
under hyperosmotic stress. Investigation of glycerol biosynthesis by measuring glycerol-3-phosphate dehydrogenase activity
under hyperosmotic conditions indicated that accumulation of glycerol in A. gossypii is almost solely due to biosynthesis.
Received: 13 January 1998 / Received revision: 7 April 1998 / Accepted: 13 April 1998 相似文献
13.
A plasmid (pYP17) containing a genomic DNA insert from Escherichia coli K-12 that confers the ability to hydrolyze carboxymethylcellulose (CMC) was isolated from a genomic library constructed in
the cosmid vector pLAFR3 in E. coli DH5α. A small 1.65-kb fragment, designated bcsC (pYP300), was sequenced and found to contain an ORF of 1,104 bp encoding a protein of 368 amino acid residues, with a calculated
molecular weight of 41,700 Da. BcsC carries a typical prokaryotic signal peptide of 21 amino acid residues. The predicted
amino acid sequence of the BcsC protein is similar to that of CelY of Erwinia chrysanthemi, CMCase of Cellulomonas uda, EngX of Acetobacter xylinum, and CelC of Agrobacterium tumefaciens. Based on these sequence similarities, we propose that the bcsC gene is a member of glycosyl hydrolase family 8. The apparent molecular mass of the protein, when expressed in E. coli, is approximately 40 kDa, and the CMCase activity is found mainly in the extracellular space. The enzyme is optimally active
at pH 7 and a temperature of 40° C.
Received: 6 February 1998 / Accepted: 6 November 1998 相似文献
14.
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
15.
G. M. Gübitz D. W. Stebbing C. I. Johansson J. N. Saddler 《Applied microbiology and biotechnology》1998,50(3):390-395
Mannan and xylan present in bleached softwood dissolving pulp were found to be partially resistant to hemicellulases even
after repeated enzyme treatment. Despite the additional effect of an endoglucanase from Gloeophyllum sepiarium, which increased the␣accessibility of mannan and xylan to a mannanase from Sclerotium rolfsii and to a xylanase from Thermomyces lanuginosus, the enzyme mixture solubilized only half of the hemicellulose present in the pulp. Half of the remaining hemicellulose present
in the pulp appeared to be entrapped within the cellulose matrix while the other half was associated with lignin-carbohydrate
complexes. The latter hemicellulose portion was isolated and characterized. Chromatography and spectroscopic techniques revealed
the presence of two types of lignin-carbohydrate complex, a galactoglucomannan-lignin complex (degree of polymerization DP
50–60) and a xylan-lignin complex (DP >200).
Received: 8 December 1997 / Received revision: 30 April 1998 / Accepted: 8 May 1998 相似文献
16.
A. E. Cazemier J. C. Verdoes H. J. M. Op den Camp J. H. P. Hackstein A. J. J. van Ooyen 《Applied microbiology and biotechnology》1999,52(2):232-239
A gene library of Cellulomonas pachnodae was constructed in Escherichia coli and was screened for endoglucanase activity. Five endoglucanase-positive clones were isolated that carried identical DNA
fragments. The gene, designated cel6A, encoding an endoglucanase enzyme, belongs to the glycosyl hydrolase family 6 (cellulase family B). The recombinant Cel6A
had a molecular mass of 53 kDa, a pH optimum of 5.5, and a temperature optimum of 50–55 °C. The recombinant endoglucanase
Cel6A bound to crystalline cellulose and beech litter. Based on amino acid sequence similarity, a clear cellulose-binding
domain was not distinguished. However, the regions in the Cel6A amino acid sequence at the positions 262–319 and 448–473,
which did not show similarity to any of the known family-6 glycosyl hydrolases, may be involved in substrate binding.
Received: 14 January 1999 / Received revision: 29 March 1999 / Accepted: 6 April 1999 相似文献
17.
N. Kijima D. Goyal A. Takada M. Wachi K. Nagai 《Applied microbiology and biotechnology》1998,50(2):227-232
In order to characterize the cell-division mechanism of coryneform bacteria, we tried to isolate cell-division mutants from
Corynebacterium glutamicum after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis, such as Escherichia coli fts mutants, which form long filaments at the restrictive temperatures. At the non-permissive temperature, most of the mutants
formed club-shaped or dumbbell-shaped, elongated rod cells, but no filament formers were isolated. Then we examined the effects
of cell division inhibitors on this organism. Cephalexin and sparfloxacin, which are the inhibitors of septation and DNA synthesis
respectively, and are known to cause cell filamentation in E. coli, did not cause filamentation in C. glutamicum but induced morphological changes that were similar to those observed with the temperature-sensitive ts mutants of C.␣glutamicum. These results suggest that C. glutamicum has a unique regulation mechanism, that is, the inhibition of cell division leads to cessation of cell elongation.
Received: 5 February 1998 / Received revision: 6 April 1998 / Accepted: 27 April 1998 相似文献
18.
The majority of lignin-degrading basidiomycetes are able to depolymerize humic acids. In this presentation the relationship
and possible similarities between enzymes involved in lignin degradation and humic acid depolymerization were examined on
the genetic level. We have cloned fragments of the gene encoding the extracellular ligninolytic enzyme laccase from Clitocybula dusenii, Nematoloma frowardii and a fungal strain designated i63-2, and compared the three sequences with those of several other published laccase genes.
The sequenced fragments displayed a high homology both on the DNA (97%–77%) and amino acid (100%–85%) level. Furthermore,
the expression of this gene in the above-mentioned fungi was demonstrated by a nested polymerase chain reaction with cDNA
as template.
Received: 3 February 1998 / Received revision: 31 August 1998 / Accepted: 3 September 1998 相似文献
19.
P. Kontula J. Jaskari L. Nollet I. De Smet A. von Wright K. Poutanen T. Mattila-Sandholm 《Applied microbiology and biotechnology》1998,50(2):246-252
The effects of Lactobacillus-GG-fermented oat bran product on the microbiota and its metabolic activity in the human gut were investigated, using a simulator
of the human intestinal microbial ecosystem (SHIME), by analysing the bacterial population, short-chain fatty acids and gas
production. In addition, the effects of fermented oat bran supernatant and supernatant samples from reactors 4, 5 and 6 (large
intestine) on the growth of Escherichia coli IHE 13047, Enterococcus faecalis VTT E-93203, Lactobacillus rhamnosus VTT E-94522 (Lactobacillus GG) and Lactococcus lactis subsp. lactis VTT E-90414 were monitored to ascertain possible stimulatory/inhibitory effects by an in vitro turbidometric method. Our
experiments showed that Lactobacillus GG colonized the SHIME reactor and this colonization could be maintained for several weeks without extra supplementation.
Oat bran feeding also favoured the growth of bifidobacteria and caused an increase in the production of acetic, propionic
and butyric acid as well as CH4 and CO2. However, the effects of oat bran, either on bacterial populations or on their metabolic activity, were not directly dose-dependent.
In turbidometric measurements, the supernatant of fermented oat bran exerted an inhibitory effect of Lactobacillus GG, but stimulated the growth of enterococci.
Received: 19 January 1998 / Received revision: 6 April 1998 / Accepted: 13 April 1998 相似文献
20.
C. L. López-Fernández J. Rodríguez A. S. Ball J. L. Copa-Patiño M. I. Pérez-Leblic M. E. Arias 《Applied microbiology and biotechnology》1998,50(2):284-287
bstract The use of the insoluble polysaccharides Avicel and oat-spelt xylan for the binding and subsequent purification of active
xylanases from Streptomyces chattanoogensis was investigated. Maximum recovery of xylanases was achieved with oat-spelt xylan, using NaCl (2 M) to remove active protein.
The application of this technique to the purification of xylanases resulted in the purification of an endoxylanase (CM-2)
with high specific activity (729.5 U mg−1). The properties of the purified enzyme, exhibiting activity and stability between 40 °C and 60 °C and between pH 5 and 8,
suggest a potential role for both the enzyme and the rapid purification protocol in the removal of hemicelluloses from kraft
pulp prior to bleaching.
Received: 6 April 1998 / Accepted: 8 May 1998 相似文献