共查询到20条相似文献,搜索用时 62 毫秒
1.
H. Okada T. Sekiya K. Yokoyama H. Tohda H. Kumagai Y. Morikawa 《Applied microbiology and biotechnology》1998,49(3):301-308
A cbh2 cDNA encoding Trichoderma reesei QM9414 cellobiohydrolase II, located on the expression vector whose copy number is controlled by the level of gentamicin,
was successfully expressed under the control of a human cytomegalovirus promoter in the fission yeast, Schizosaccharomyces pombe. The 24-amino-acid leader peptide of the cbh2 gene was recognized by the yeast, enabling the efficient secretion of the heterologous cellobiohydrolase. The transformed
S. pombe strain produced over 115 μg cellobiohydrolase proteins/ml rich medium supplemented with malt extract and 100 μg/ml gentamicin.
The molecular masses of the recombinant cellobiohydrolases, secreted as two molecular species, were estimated to be 70 kDa
and 72 kDa by sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE). Deglycosylation treatments revealed that
the recombinant enzymes were overglycosylated and scarcely susceptible to α-mannosidase. The recombinant enzymes showed no
carboxymethylcellulase activity, but showed similar characteristics to those of a native enzyme purified from T. reesei in their optimum pH and temperature, pH and temperature stabilities, and V
max values toward phosphoric-acid-swollen cellulose as substrate, except that their K
m values were about fourfold higher than that of the native enzyme.
Received: 4 August 1997 / Received revision: 13 October 1997 / Accepted: 31 October 1997 相似文献
2.
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
3.
Production of (R)-3-pentyn-2-ol through stereoinversion of racemic 3-pentyn-2-ol by Nocardia fusca AKU 2123 总被引:1,自引:0,他引:1
Wet cells of Nocardia fusca AKU 2123 are good catalysts for the production of (R)-3-pentyn-2-ol (PYOH) from (RS)-PYOH through a stereoinversion reaction. Under optimal conditions (350 mM potassium phosphate buffer, pH 8.0, 30% (w/v)
wet cells, 0.12% NADPH, 10% glucose, and 30 U/ml glucose dehydrogenase) (R)-PYOH of high optical purity (98.7% e.e.) was produced from 2% (v/v) (RS)-PYOH with a yield of 70.4% by 140 h incubation.
Received: 22 January 1999 / Received revision: 23 April 1999 / Accepted: 1 May 1999 相似文献
4.
M. B. Cassidy K. W. Shaw H. Lee J. T. Trevors 《Applied microbiology and biotechnology》1997,47(2):108-113
A pentachlorophenol(PCP)-degrading Pseudomonas sp. strain UG30 was encapsulated in κ-carrageenan for use in PCP degradation. Free and encapsulated cells were compared for
their ability to dechlorinate and mineralize 100–800 μg/ml sodium pentachlorophenate in broth. Dechlorination was measured
with a chloride ion electrode, and mineralization was measured by 14CO2 evolution from radiolabelled [U-14C]PCP. Free and encapsulated Pseudomonas sp. UG30 cells mineralized up to 200 μg/ml and 600 μg/ml PCP, respectively, after 21 days. Encapsulation of UG30 cells provided
a protective effect, allowing dechlorination and mineralization of high levels of PCP to occur.
Received: 3 May 1996 / Received revision: 4 September 1996 / Accepted: 13 September 1996 相似文献
5.
A gene transfer system for Rhodococcus opacus PD630 based on electroporation was established and optimized employing the Escherichia coli-Rhodococcus shuttle vectors pNC9501 and pNC9503 as well as the E. coli-Corynebacterium glutamicum shuttle vector pJC1 as suitable cloning vectors for R. opacus PD630, resulting in transformation efficiencies up to 1.5 × 105 CFUs/μg plasmid DNA. Applying the optimized electroporation protocol to the pNC9501-derivatives pAK68 and pAK71 harboring
the entire PHB synthesis operon from Ralstonia eutropha and the PHA synthase gene phaC1 from Pseudomonas aeruginosa, respectively, recombinant PHA biosynthesis was established in R. opacus PD630 and the TAG-negative mutant ROM34. Plasmid pAK68 enabled synthesis and accumulation of poly(3HB) in R. opacus PD630 and ROM34 during cultivation under storage conditions from 1% (w/v) gluconate, of poly(3HB-co-3HV) from 0.2% (w/v) propionate and of poly(3HV) from 0.1% (w/v) valerate. Under storage conditions, recombinant strains
of PD630 and ROM34 harboring pAK71 were able to synthesize and accumulate PHA of the medium chain length hydroxyalkanoic acids
3HHx, 3HO, 3HD and 3HDD from 0.1% (w/v) hexadecane or octadecane and a copolyester composed of 3HHp, 3HN and 3HUD from 0.1%
(w/v) pentadecane or heptadecane. In the recombinant strains of PD630 and ROM34, the thiostrepton-induced overexpression of
a 20 kDa protein was observed with its N-terminus exhibiting a homology of 60% identical amino acids to TipA from Streptomyces lividans.
Received: 13 March 1999 / Received revision: 18 May 1999 / Accepted: 21 May 1999 相似文献
6.
López-Contreras AM Claassen PA Mooibroek H De Vos WM 《Applied microbiology and biotechnology》2000,54(2):162-167
Domestic organic waste (DOW) collected in The Netherlands was analysed and used as substrate for acetone, butanol and ethanol
(ABE) production. Two different samples of DOW, referred to as fresh DOW and dried DOW, were treated by extrusion in order
to expand the polymer fibres present and to obtain a homogeneous mixture. The extruded material was analysed with respect
to solvent and hot water extractives, uronic acids, lignin, sugars and ash. The total sugar content in the polymeric fractions
of the materials varied from 27.7% to 39.3% (w/w), in which glucose represented the 18.4 and 25.1% of the materials, for fresh
and dried DOW, respectively. The extruded fresh DOW was used as substrate for the ABE fermentation by the solventogenic strain
Clostridium acetobutylicum ATCC 824. This strain was grown on a suspension of 10% (w/v) DOW in demineralised water without further nutrient supplement.
This strain produced 4 g ABE/100 g extruded DOW. When C. acetobutylicum ATCC 824 was grown on a suspension of 10% (w/v) DOW hydrolysed by a combination of commercial cellulases and β-glucosidases,
the yield of solvents increased to 7.5 g ABE/100 g extruded DOW. The utilisation of sugar polymers in both hydrolysed and
non-hydrolysed DOW was determined, showing that only a small proportion of the polymers had been consumed by the bacteria.
These results indicate that growth and ABE production on DOW is mainly supported by soluble saccharides in the medium.
Received: 5 November 1999 / Received revision: 21 February 2000 / Accepted: 25 February 2000 相似文献
7.
Thermomonospora curvata produced a thermostable β-xylosidase during growth on birch xylan. The enzyme, extracted by sonication of early stationary
phase mycelia, was purified by isoelectric focusing and size exclusion HPLC. The isoelectric point was pH 4.8. The molecular
weight was estimated to be 102 000 by size exclusion HPLC and 112 000 by SDS-PAGE. Maximal activity occurred at pH 6–7 and
60–68°C. K
m values for xylobiose and p-nitrophenyl-β -D-xylopyranoside were 4.0 M and 0.6 M respectively. The enzyme was sensitive to low levels of Hg2+ (50% inhibition at 0.2 μM), but was stimulated by Co2+ and Pb2+. Addition of the xylosidase to a xylanase reaction mixture increased the liberation of xylose equivalents from xylan and
decreased the proportion of xylobiose in the hydrolysate.
Received 14 April 1997/ Accepted in revised form 21 October 1997 相似文献
8.
Glycine-rich peptide toxin of cyanobacterium Scytonema MKU 106 was purified. UV spectral analysis showed an absorption maximum at 228 nm and the molecular mass was less than 12
kDa. The mortality rate of American boll worms (Helicoverpa armigera) was about 80% and 40% 84 h after treatment with 0.001% crude and purified peptide toxins respectively; 100% mortality was
observed after 108 h treatment with both purified and crude peptide toxins. The LC50 (lethal concentration to 50% of the population) for Heliothis larvae after 96 h was 8.3 μg/ml purified peptide toxin and 6.2 μg/ml crude peptide toxin. Observations also show that the
peptide toxin at 0.01% concentration acts as a biopesticide and at high (0.1%) concentrations it will act as an anti-feeding
compound for Stylepta derogata (leaf-roller) larvae of the cotton crop.
Received: 22 May 1996 / Accepted: 8 July 1996 相似文献
9.
Purification and properties of a novel raw starch degrading cyclomaltodextrin glucanotransferase from Bacillus firmus 总被引:3,自引:0,他引:3
B. N. Gawande A. Goel A. Y. Patkar S. N. Nene 《Applied microbiology and biotechnology》1999,51(4):504-509
A novel raw starch degrading cyclomaltodextrin glucanotransferase (CGTase; E.C. 2.4.1.19), produced by Bacillus firmus, was purified to homogeneity by ultrafiltration, affinity and gel filtration chromatography. The molecular weight of the
pure protein was estimated to be 78 000 and 82 000 Da, by SDS-PAGE and gel filtration, respectively. The pure enzyme had a
pH optimum in the range 5.5–8.5. It was stable over the pH range 7–11 at 10 °C, and at pH 7.0 at 60 °C. The optimum temperature
for enzyme activity was 65 °C. In the absence of substrate, the enzyme rapidly lost its activity above 30 °C. K
m and k
cat for the pure enzyme were 1.21 mg/ml and 145.17 μM/mg per minute respectively, with soluble starch as the substrate. For cyclodextrin
production, tapioca starch was the best substrate used when gelatinized, while wheat starch was the best substrate used when
raw. This CGTase could degrade raw wheat starch very efficiently; up to 50% conversion to cyclodextrins was obtained from
150 g/l starch without using any additives. The enzyme produced α-, β- and γ-cyclodextrins in the ratio of 0.2:9.2:0.6 and
0.2:8.6:1.2 from gelatinized tapioca starch and raw wheat starch with 150 g/l concentration respectively, after 18 h incubation.
Received: 25 September 1998 / Received revision: 15 December 1998 / Accepted: 21 December 1998 相似文献
10.
Bustard MT McEvoy EM Goodwin JA Burgess JG Wright PC 《Applied microbiology and biotechnology》2000,54(3):424-431
The aerobic biodegradation of high concentrations of 1-propanol and 2-propanol (IPA) by a mixed microbial consortium was
investigated. Solvent concentrations were one order of magnitude greater than any previously reported in the literature. The
consortium utilized these solvents as their sole carbon source to a maximum cell density of 2.4 × 109 cells ml−1. Enrichment experiments with propanol or IPA as carbon sources were carried out in batch culture and maximum specific growth
rates (μmax) calculated. At 20 °C, μ
max values were calculated to be 0.0305 h−1 and 0.1093 h−1 on 1% (v/v) IPA and 1-propanol, respectively. Growth on propanol and IPA was carried out between temperatures of 10 °C and
45 °C. Temperature shock responses by the microbial consortium at temperatures above 45 °C were demonstrated by considerable
cell flocculation. An increase in propanol substrate concentration from 1% (v/v) to 2% (v/v) decreased the μ
max from 0.1093 h−1 to 0.0715 h−1. Maximum achievable biodegradation rates of propanol and IPA were 6.11 × 10−3% (v/v) h−1 and 2.72 × 10−3% (v/v) h−1, respectively. Generation of acetone during IPA biodegradation commenced at 264 h and reached a maximum concentration of
0.4% (v/v). The results demonstrate the potential of mixed microbial consortia in the bioremediation of solvent-containing
waste streams.
Received: 14 December 1999 / Received revision: 3 April 2000 / Accepted: 7 April 2000 相似文献
11.
An expression system based on the Staphylococcus aureus protein A gene (spa) was developed to allow the production and export of proteins in Lactobacillus. Plasmid shuttle vectors were constructed that carried the eZZ gene, a synthetic gene based on the Protein A gene (spa) but lacking the carboxy-terminal membrane-anchoring region. A gene fusion was created between the eZZ gene and the VD4 region
of a chlamydial major outer-membrane protein gene. Expression studies demonstrated the recognition of the spa regulatory signals by several Lactobacillus, with the recombinant protein being expressed (from 0.1 μg of EZZVD4 fusion protein per ml in L. plantarum up to 10 μg of EZZ protein per ml in L. fermentum) and exported (levels up to 20% in L. fermentum) in several Lactobacillus strains.
Received: 27 August 1996 / Received revision: 27 November 1996 / Accepted: 29 November 1996 相似文献
12.
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
13.
Natural killer (NK) cells are non-T, non-B cell lymphocytes that lyse a variety of tumor and virus-infected cells. In this
study, we demonstrated that phytohemagglutinin (PHA) rendered resistant autologous T cells extremely sensitive to natural-killer(NK)-cell-mediated
lysis. The sensitization was very rapid and concentration-dependent (0.01–1 μg/ml); 62% and 95% of autologous T cells were
lysed by interleukin-2-activated NK cells 5 min and 18 h respectively after treatment with PHA (1 μg/ml). The maximal decrease
in the level of MHC class I molecules observed on T cells was 22%. Induction of susceptibility to NK-mediated lysis was correlated
with the expression of activation markers on T cells treated for relatively long intervals (more than 18 h) with high concentrations
of PHA (more than 0.1 μg/ml). Sensitization of T cells required RNA and protein synthesis, although DNA synthesis was not
essential. We propose that this unique system is suitable for studying the mechanisms involved in recognition and killing
of target cells by NK cells.
Received: 11 February 1999 / Accepted: 28 July 1999 相似文献
14.
A. Brunella M. Graf M. Kittelmann K. Laumen O. Ghisalba 《Applied microbiology and biotechnology》1997,47(5):515-520
Rhodococcus equi Ac6 was found to express an inducible (S )-specific N-acetyl-1-phenylethylamine amidohydrolase. Optimal bacterial growth and amidohydrolase expression were both observed around
pH 6.5. Purification of the enzyme to a single band in a Coomassie-blue-stained sodium dodecyl sulfate/polyacrylamide gel
(SDS-PAGE) was achieved by ammonium sulfate precipitation of R. equi Ac6 crude extract and column chromatographies on Fractogel TSK Butyl-650(S) and Superose 12HR. At pH 7.0 and 30 °C the amidohydrolase
had a half-life of around 350 days; at 44 °C it was only 10 min. Except for Ni2+ and, to some extent, Zn2+ and Co2+, the enzyme was neither strongly influenced by metal cations nor by chelating agents, but was inhibited by 95% at 0.1 mM
phenylmethylsulfonyl fluoride. The molecular mass of the native enzyme was estimated to be 94 kDa by gel filtration and 50 kDa
by SDS-PAGE, suggesting a dimeric structure. Specificity experiments revealed a spectrum of related N-acetylated compounds being hydrolyzed with variable enantiomeric selectivities.
Received: 20 September 1996 / Received revision: 23 December 1996 / Accepted: 30 December 1996 相似文献
15.
Culture conditions for the fermentative production of β-poly(l-malate) (PMLA) by microplasmodia of Physarum polycephalum were investigated and optimized. Optimal production was achieved in the presence of CaCO3. For 1.5% (w/v) d-glucose, 1% bactotryptone and 1% CaCO3, a maximum of 1.7 g PMLA/l was secreted in 3 days. For 4.5% glucose and otherwise the same conditions, 2.7 g PMLA/l was produced
in 6 days. The contribution of carbonate was inhibited by avidin. PMLA and biomass production were not strictly coupled: PMLA
was also synthesized at the beginning of the stationary phase. At pH 5.5 PMLA production was twice that at pH 4.0, while biomass
was not changed. Optimal temperatures were 24–28 °C.
Received: 12 November 1998 / Received revision: 10 February 1999 / Accepted: 12 February 1999 相似文献
16.
P. Wahl P. Walser-Volken K. Laumen M. Kittelmann O. Ghisalba 《Applied microbiology and biotechnology》1999,53(1):12-18
Rhodococcus globerulus K1/1 was found to express an inducible (S)-specific N-acetyl-2-amino-1-phenyl-4-pentene amidohydrolase. Optimal bacterial growth and amidohydrolase expression were both observed
at about pH 6.5. Purification of the enzyme to a single band in a Coomassie blue-stained SDS-PAGE gel was achieved by nucleic
acid and ammonium sulfate precipitation of Rhodococcus globerulus K1/1 crude extract and column chromatography on TSK Butyl-650(S) Fractogel and Superose 12HR. The amidohydrolase was purified to a homogeneity leading to a tenfold increase of the specific
activity with a recovery rate of 65%. At pH 7.0 and 23 °C the enzyme showed no loss of activity after 30 days incubation.
The amidohydrolase was stable up to 55 °C. The enzyme was inhibited strongly only by 10 mM Zn2+ among the tested metal cations and was inhibited 100% by 0.01 mM phenylmethanesulfonyl fluoride. The molecular weight of
the native enzyme was estimated to be 92 kDa by gel filtration and 55 kDa by SDS-PAGE, suggesting a homodimeric structure.
Received: 8 February 1999 / Received revision: 3 May 1999 / Accepted: 7 May 1999 相似文献
17.
M. Watanabe K. Sasaki Y. Nakashimada T. Kakizono N. Noparatnaraporn N. Nishio 《Applied microbiology and biotechnology》1998,50(6):682-691
A marine photosynthetic bacterium (PS88), identified as Rhodovulum sp., with flocculating ability was isolated from the sea sediment mud of a shrimp cultivation farm in Thailand. This bacterium
flocculated in glutamate/malate medium during aerobic dark or anaerobic light cultivation. The flocculating ability was enhanced
with the increase of NaCl concentration to 6% (w/v). When PS88 was grown in glutamate/malate medium containing 3.5% NaCl,
protein, RNA and DNA were produced exocellularly and there was flocculation. The yields of DNA, RNA and protein were 8.3,
62.5 and 48.5 mg/g dry cell, respectively. The flocculated cells were deflocculated by treatment with a nucleolytic enzyme
such as RNase or DNase, while amylase, protease, trypsin, cellulase and pectinase had no deflocculating effect. These results
suggest that the exocellular nucleic acids are active in flocculation.
Received: 10 April 1998 / Received revision: 14 July 1998 / Accepted: 8 August 1998 相似文献
18.
Resting cells of a locally isolated strain of Aspergillus niger caused the bioconversion of alpha pinene to verbenone. The formation of verbenone was raised from trace amounts (under screening
conditions) to 3.28 mg/100 ml (equivalent to a molar yield of 16.5% conversion of the substrate) by amending the cultivation
medium for the fungus. The optimal conditions were: 6 g/100 ml for the glucose concentration, a pH of 7.0, an alpha pinene
concentration of 20 mg/100 ml, and a 6-h incubation period for the reaction.
Received: 9 August 1999 / Received revision: 24 September 1999 / Accepted: 24 September 1999 相似文献
19.
M. E. Sosa-Morales F. Guevara-Lara V. M. Martínez-Juárez O. Paredes-López 《Applied microbiology and biotechnology》1997,48(6):726-729
Production of indole-3-acetic acid (IAA) by four strains of the maize pathogen Ustilago maydis was analyzed. The fungus induces gall formation on its host plant and IAA production by U. maydis may be required as a pathogenicity or virulence factor. The study included the FB2 wild-type strain and the 103, 130FZ and
130FT mutants. Results show that treatment with clofibric acid, alone or in combination with UV light, can be used to obtain U. maydis strains with defective IAA production in vitro, as quantified with the Salkowski reagent and by HPLC. The strain with the
lowest production was 130FT, and its peak IAA level represented only 16% of the highest value obtained for the FB2 wild-type
strain (124 μg/ml).
Received: 11 April 1996 / Received last revision: 5 September 1997 / Accepted: 11 September 1997 相似文献
20.
Polymer production by two newly isolated extremely halophilic archaea: application of a novel corrosion-resistant bioreactor 总被引:3,自引:0,他引:3
Hezayen FF Rehm BH Eberhardt R Steinbüchel A 《Applied microbiology and biotechnology》2000,54(3):319-325
A novel corrosion-resistant bioreactor composed of polyetherether ketone (PEEK), tech glass and silicium nitrite ceramics
was constructed and applied for the cultivation of two newly isolated, extremely halophilic archaea producing poly(γ-glutamic
acid) (PGA), or poly(β-hydroxy butyric acid) (PHB), respectively. These bacteria were isolated from hypersaline soil close
to Aswan (Egypt). The isolate strain 40, which is related to the genus Natrialba, produced large amounts of PGA when cultivated on solid medium. Culture conditions were optimised applying the corrosion-resistant
bioreactor. PGA production was dependent on NaCl concentration and occurred about at 20% (w/v) NaCl in the medium. A maximum
cell density of about 1.6 g cell dry matter/l was obtained when the bioreactor was stirred and aerated in a batch fermentation
process using proteose-peptone medium. The supernatant was monitored with respect to PGA formation, and after 90 h a maximum
of 470 mg/l culture volume was detected by HPLC analysis. Culture conditions were optimized for the isolate 56, which accumulated
PHB as intracellular granules. Batch fermentations in the stirred and aerated bioreactor applying acetate and n-butyric acid as carbon sources led to cell density of 2.28 g cell dry matter/l and a maximum PHB accumulation contributing
to about 53% of cellular dry weight. About 4.6 g PHB were isolated from 10.6 g dried cells of strain 56, which exhibited a
weight average molar mass of 2.3 × 105 g mol−1 and a polydispersity of about 1.4.
Received: 3 December 1999 / Received revision: 22 February 2000 / Accepted: 25 February 2000 相似文献