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1.
Penna Thereza Christina Vessoni Ishii Marina Machoshvili Irene Alexeevna Marques Marcelo 《Applied biochemistry and biotechnology》2002,98(1-9):525-538
Paper strips inoculated with spores of Bacillus stearothermophilus ATCC 7953 were conventionally dried (lot 1) and lyophilized (lot 2); stored in defined environments of 32 and 86% relative
humidity at 10, 25 and 33°C for 210 d; and submitted to moist heat treatments at 121°C. A significant decrease in thermal
resistance from initial starting levels was found for lyophilized bioindicators stored at 86% relative humidity. The respective
average D
121°C values were 1.55 ± 0.05 and 1.37 ± 0.10 min for lyophilized bioindicators stored at 32 and 86% relative humidity; and 1.65±0.15min
and 1.57 ± 0.11 min for dried bioindicators stored in the same environments. 相似文献
2.
Thereza Christina Vessoni Penna Irene A. Machoshvili Marina Ishii 《Applied biochemistry and biotechnology》2003,106(1-3):287-294
The interference of eight components in the yield of sporulation and thermal resistance to moist heat (121°C) of Bacillus stearothermophilus spores suspended in 0.02 M calcium acetate solution and inoculated on paper strips previously treated with calcium acetate/calcium hydroxide was studied.
The spore yield of 1.0×108/mL was developed at 62°C in 17 media containing different concentrations of d-glucose, sodium chloride, l-glutamic acid, yeast extract, peptone, manganese sulfate, potassium phosphate, and ammonium phosphate. The combined effects
of yeast extract, peptone, and glucose contributed positively to the spore yield and to the stability of the thermal resistance
of both spores in suspension and on strips. 相似文献
3.
A cassava flour-processing effluent (manipueira) was evaluated as a substrate for surfactant production by two Bacillus subtilis strains. B. subtilis ATCC 21332 reduced the surface tension of the medium to 25.9 mN/m, producing a crude biosurfactant concentration of 2.2 g/L.
The wild-type strain, B. subtilis LB5a, reduced the surface tension of the medium to 26.6 mN/m, giving a crude biosurfactant concentration of 3.0 g/L. A decrease
in surfactant concentration observed for B. subtilis ATCC 21332 seemed to be related to an increase in protease activity. The biosurfactant produced on cassava effluent medium
by B. subtilis LB5a was similar to surfactin. 相似文献
4.
Tabbene O Ben Slimene I Bouabdallah F Mangoni ML Urdaci MC Limam F 《Applied biochemistry and biotechnology》2009,157(3):407-419
B38 bacterial strain, isolated from Tunisian soil showed a strong antimicrobial activity. Based on biochemical characterization
and 16S rDNA sequence analysis, B38 strain was identified as Bacillus subtilis. Cell culture supernatant showed antibacterial activity against clinical isolates of methicillin-resistant Staphylococcus species and several Gram-positive and Gram-negative bacteria. Antifungal activity against phytopathogenic fungi was also
observed. Antibacterial activity production started at early exponential growth phase, and maximum activity was reached at
the stationary phase. This antibacterial activity was neither affected by proteases, lipase, and organic solvents, nor by
surfactants. It was stable over a wide pH range and still active after autoclaving at 121 °C during 20 min. Thin layer chromatography
followed by bioautography assay allowed the detection of four active spots with R
f values of 0.30, 0.47, 0.70, and 0.82. The single spot with R
f 0.30 showed antifungal activity, whereas the spots with R
f values of 0.47, 0.70, and 0.82 exhibited antibacterial activity. 相似文献
5.
The high TC
superconducting phase Bi2Sr2Ca2Cu3Ox
(2223) in the Pb-BSCCO system has been produced by EDTA-gel processing
using nitrate solutions. The precursor has heated in two stages, at 300 and
800°C each for 2 h, to avoid the burning of the important species involved
in the final product. The effects of time (6 to 48 h) and temperature (845
and 855°C) on the formation of the 2223 phase have been studied by sintering
the samples in air. Thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning
electron microscopy (SEM) and a vibrating sample magnetometer (VSM) have been
employed to investigate the powder produced at different stages of decomposition,
oxidation and formation of sintered materials from the powders. The volume-fraction
of the 2223 phase at 845°C increases with time, the maximum value of the
2223 phase was obtained at 120 h. It has been observed that the formation
of the high TC phase
is remarkably enhanced at the temperature of the endothermic peak of the DTA
curve. The best result has been obtained in the sample sintered for 24 h at
the temperature 855°C (endothermic peak). This also indicated that at
855°C, the large volume-fraction of 2223 phase with TC
113 K grew in short time and as the sintering time increased, it decomposed
into the Bi2Sr2CaCu2Ox
(2212) phase and other phases. 相似文献
6.
Characterization of Thermo-stable Endoinulinase from a New Strain <Emphasis Type="Italic">Bacillus Smithii</Emphasis> T7 总被引:1,自引:0,他引:1
A new thermophilic inulinase-producing strain, which grows optimally at 60 °C, was isolated from soil samples with medium
containing inulin as a sole carbon source. It was identified as a Bacillus smithii by analysis of 16s rDNA. Maximum inulinase yield of 135.2 IU/ml was achieved with medium pH7.0, containing inulin 2.0%, (NH4)H2PO4 0.5%, yeast extract 0.5%, at 50 °C 200 rpm shaker for 72-h incubation. The purified inulinase from the extracellular extract
of B. smithii T7 shows endoinulinolytic activity. The optimum pH for this endoinulinase is 4.5 and stable at pH range of 4.0–8.0. The optimum
temperature for enzyme activity was 70 °C, the half life of the endoinulinase is 9 h and 2.5 h at 70 °C and 80 °C respectively.
Comparatively lower Michaelis–Menten constant (4.17 mM) and higher maximum reaction velocity (833 IU/mg protein) demonstrate
the endoinulinase’s greater affinity for inulin substrate. These findings are significant for its potential industrial application. 相似文献
7.
G. V. Girichev V. V. Rybkin N. V. Tverdova S. A. Shlykov N. P. Kuzmina I. G. Zaitseva 《Journal of Structural Chemistry》2007,48(5):811-820
Simultaneous electron diffraction and mass spectrometry along with a quantum chemical (DFT/B3LYP) calculation are applied
to study the molecular structure of yttrium tris-hexafluoroacetylacetonate Y(hfa)3. The superheating of the vapor in a double two-temperature effusion cell shows that up to a temperature of ∼200°C ions containing
from one to three metal atoms are formed, and the most intensive ion has the stoichiometry of (Y2L5)+ at a temperature below ∼120°C. The monomer starts to noticeably decompose at temperatures above 330°C.The electron diffraction
patterns of monomers are obtained at T
exp = 208(5)°C. According to the results of theoretical and experimental investigations, Y(hfa)3 molecule has D
3-symmetry. The rotation angle of triangular O-O-O faces with respect to their position in the regular prism is equal to 14.4(1)°C.
The values of internuclear distances and valence angles (r
h1-geometry) are: r(Y-O) = 2.259(6) Å, r(C-O) = 1.263(6) Å, r(C-Cr) = 1.413(4) Å, r(C-CF) = 1.531(4) Å, r(C-F) = 1.344(3) Å, O-Y-O = 75.2(2)°, O-C-CF = 113.8(2)°, C-CF-F = 112.4(2)°. The results of quantum chemical calculations are well consistent with the experimental data.
Original Russian Text Copyright ? 2007 by G. V. Girichev, V. V. Rybkin, N. V. Tverdova, S. A. Shlykov, N. P. Kuz’mina, and
I. G. Zaitseva
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 5, pp. 871–879, September–October, 2007. 相似文献
8.
Yujie Wang Lifang Ruan Wai-Hung Lo Hong Chua Hoi-Fu Yu 《Applied biochemistry and biotechnology》2006,132(1-3):1015-1022
Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyalkanoates synthesized by numerous bacteria as intracellular carbon
and energy storage compounds and accumulated as granules in the cytoplasm of cells. In this work, we constructed two recombinant
plasmids, pBE2C1, and pBE2C1AB, containing one or two PHA synthse, genes, respectively. The two plasmids were inserted into
Bacillus subtilis DB104 to generate modified strains, B. subtilis/pBE2C1 and B. subtilis/pBE2C1AB. The two recombinants strains were subjected to fermentation and showed PHA accumulation, the first reported example
of mcl-PHA production in B. subtilis. Gas Chromatography analysis identified the compound produced by B. subtilis/pBE2C1 to be a hydroxydecanoate-co-hydroxydodecanoate (HD-co-HDD) polymer whereas that produced by B. subtilis/pBE2C1AB was a hydroxybutyrate-co-hydroxyde-canoate-co-hydroxydodecanoate (HB-HD-HDD) polymer. 相似文献
9.
Xylanase from Bacillus pumilus strain MK001 was immobilized on different matrices following varied immobilization methods. Entrapment using gelatin (GE)
(40.0%), physical adsorption on chitin (CH) (35.0%), ionic binding with Q-sepharose (Q-S) (45.0%), and covalent binding with
HP-20 beads (42.0%) showed the maximum xylanase immobilization efficiency. The optimum pH of immobilized xylanase shifted
up to 1.0 unit (pH 7.0) as compared to free enzyme (pH 6.0). The immobilized xylanase exhibited higher pH stability (up to
28.0%) in the alkaline pH range (7.0–10.0) as compared to free enzyme. Optimum temperature of immobilized xylanase was observed
to be 8 °C higher (68.0 °C) than free enzyme (60.0 °C). The free xylanase retained 50.0% activity, whereas xylanase immobilized
on HP-20, Q-S, CH, and GE retained 68.0, 64.0, 58.0, and 57.0% residual activity, respectively, after 3 h of incubation at
80.0 °C. The immobilized xylanase registered marginal increase and decrease in K
m and V
max values, respectively, as compared to free enzyme. The immobilized xylanase retained up to 70.0% of its initial hydrolysis
activity after seven enzyme reaction cycles. The immobilized xylanase was found to produce higher levels of high-quality xylo-oligosaccharides
from birchwood xylan, indicating its potential in the nutraceutical industry. 相似文献
10.
Chitinase was purified from the culture medium of Bacillus licheniformis SK-1 by colloidal chitin affinity adsorption followed by diethylamino ethanol-cellulose column chromatography. The purified
enzyme showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The molecular size and pI of chitinase 72 (Chi72) were 72 kDa and 4.62 (Chi72) kDa, respectively. The purified chitinase revealed two activity optima
at pH 6 and 8 when colloidal chitin was used as substrate. The enzyme exhibited activity in broad temperature range, from
40 to 70°C, with optimum at 55°C. It was stable for 2 h at temperatures below 60°C and stable over a broad pH range of 4.0–9.0
for 24 h. The apparent K
m and V
max of Chi72 for colloidal chitin were 0.23 mg ml−1 and 7.03 U/mg, respectively. The chitinase activity was high on colloidal chitin, regenerated chitin, partially N-acetylated chitin, and chitosan. N-bromosuccinamide completely inhibited the enzyme activity. This enzyme should be a good candidate for applications in the
recycling of chitin waste. 相似文献
11.
Kastli D. Schaller Sandra L. Fox Debby F. Bruhn Karl S. Noah Gregory A. Bala 《Applied biochemistry and biotechnology》2004,115(1-3):827-836
Surfactin produced by Bacillus subtilis (ATCC 21332) was used to examine the effect of altering salt concentration, pH, and temperature on surfactin activity (as
measured by reductions in surface tension). These parameters are some of the conditions that define oil reservoir characteristics
and can affect the application of surfactants. The Biotechnology for Oilfield Operations research program at the Idaho National
Engineering and Environmental Laboratory (INEEL) has successfully produced surfactin from potato process effluents for possible
use as an economical alternative to chemical surfactants for improved oil recovery. Surfactants enhance the recovery of oil
through a reduction of the interfacial tension between the oil and water interfaces, or by mediating changes in the wettability
index of the system. We investigated changes in surfactin activity under a range of conditions by measuring surface tension.
Surface tension was determined using video image analysis of inverted pendant drops. Experimental variables included NaCl
(0–10%), pH (3.0–10.0), and temperature (21–70°C). Each of these parameters, as well as selected combinations, resulted in
discrete changes in surfactin activity. It is therefore important to consider the exploration of the studied surfactin as
an enhanced oil recovery agent. 相似文献
12.
Valquiria B. Damiano Richard Ward Eleni Gomes Heloiza Ferreira Alves-Prado Roberto Da Silva 《Applied biochemistry and biotechnology》2006,129(1-3):289-302
The alkalophilic bacteria Bacillus licheniformis 77-2 produces significant quantities of thermostable cellulase-free xylanases. The crude xylanase was purified to apparent
homogeneity by gel filtration (G-75) and ionic exchange chromatography (carboxymethyl sephadex, Q sepharose, and Mono Q),
resulting in the isolation of two xylanases. The molecular masses of the enzymes were estimated to be 17 kDa (X-I) and 40
kDa (X-II), as determined by SDS-PAGE. The K
m and V
max values were 1.8 mg/mL and 7.05 U/mg protein (X-I), and 1.05 mg/mL and 9.1 U/mg protein (X-II). The xylanases demonstrated
optimum activity at pH 7.0 and 8.0–10.0 for xylanase X-I and X-II, respectively, and, retained more than 75% of hydrolytic
activity up to pH 11.0. The purified enzymes were most active at 70 and 75°C for X-I and X-II, respectively, and, retained
more than 90% of hydrolytic activity after 1 h of heating at 50°C and 60°C for X-I and X-II, respectively. The predominant
products of xylan hydrolysates indicated that these enzymes were endoxylanases. 相似文献
13.
Danner H. Neureiter M. Madzingaidzo L. Gartner M. Braun R. 《Applied biochemistry and biotechnology》1998,(1):895-903
A process for the continuous production of high purityL-lactic acid in a membrane bioreactor at 65°C has been developed. Two differentBacillus stearothermophilus strains have been tested in batch experiments. Lactic acid yields are between 60 and more than 95% of theoretical yields.
The amounts of ethanol, acetate, and formate formed varied between 0 and 0.4, 0 and 0.1, and 0 and 0.5, respectively (mol/mol
glucose). All byproducts are valuable and may be separated easily by rectification of the fermentation broth. Complete cell
retention enables high volumetric productivity (5 g/Lh), and a minimum of growth supplements. The high temperature of 65°C
allows the autoselective fermentation without problems with contamination. 相似文献
14.
Purification and partial characterization of a lipase from Bacillus coagulans ZJU318 总被引:1,自引:0,他引:1
An extracellular lipase was purified from the fermentation broth of Bacillus coagulans ZJU318 by CM-Sepharose chromatography, followed by Sephacryl S-200 chromatography. The lipase was purified 14.7-fold with
18% recovery and a specific activity of 141.1 U/mg. The molecular weight of the homogeneous enzyme was (32 kDa), determined
by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The enzyme activity was maximum at pH 9.0 and was stable
over a pH range of 7.0–10.0, and the optimum temperature for the enzyme reaction was 45°C. Little activity loss (6.2%) was
observed after 1 h of incubation at 40°C. However, the stability of the lipase decreased sharply at 50 and 60°C. The enzyme
activity was strongly inhibited by Ag+ and Cu2+, whereas EDTA caused no inhibition. SDS, Brij 30, and Tween-80 inhibited lipase, whereas Triton X-100 did not significantly
inhibit lipase activity. 相似文献
15.
The vibrational spectra of C6D5PX
2, (C6D5)2PX (X=H, Cl), (C6D5)3P and of the Cyclophosphanes (PC6H5)
n
and (PC6D5)
n
(n=5, 6) are reported. The spectra of the phenylphosphorouscompound D (the structure beeing unknown) are given too. The C6H5/C6D5 isotopic shift data in the lower frequency-region (600–100 cm–1) (facilitating the recognition of vibrational coupling effects) are used for vibrational assignments. 相似文献
16.
Cyclodextrin glucanotransferase, produced by Bacillus megaterium, was characterized, and the biochemical properties of the purified enzyme were determined. The substrate specificity of the
enzyme was tested with different α-1,4-glucans. Cyclodextrin glucanotransferase displayed maximum activity in the case of
soluble starch, with a K
m value of 3.4 g/L. The optimal pH and temperature values for the cyclization reaction were 7.2 and 60 °C, respectively. The
enzyme was stable at pH 6.0–10.5 and 30 °C. The enzyme activity was activated by Sr2+, Mg2+, Co2+, Mn2+, and Cu2+, and it was inhibited by Zn2+and Ag+. The molecular mass of cyclodextrin glucanotransferase was established to be 73,400 Da by sodium dodecyl sulfate–polyacrylamide
gel electrophoresis, 68,200 Da by gel chromatography, and 75,000 Da by mass spectrometry. The monomer form of the enzyme was
confirmed by the analysis of the N-terminal amino acid sequence. Cyclodextrin glucanotransferase formed all three types of
cyclodextrins, but the predominant product was β-cyclodextrin. 相似文献
17.
Summary The application of capillary zone electrophoresis to the study of interactions betweenBacillus subtilis tryptophanyl-tRNA synthetase (TrpRS) and tRNATrp is described. Significant changes in peak shape of tRNATrp incubated with TrpRS indicated the occurrence of interactions between TrpRS and tRNATrp in pH 8.0 Tris-HCl buffer containing 0.1 mmol L−1 EDTA and 1 mmol L−1−5 mmol L−1 mgCl2. Addition of Mg2+ decreased the electrophoretic mobility of tRNATrp, which illustrated that conformation of tRNATrp depended on Mg2+. The dissociation constant of the TrpRS-tRNATrp complex was estimated to be 0.63 μmol L−1 at 25°C in buffer solution. 相似文献
18.
To evaluate the commercial potential of new microbial feed additive, Issatchenkia orientalis Y266 and Bacillus subtilis B266 from commercial fermented rice bran were tested for their tolerance or resistance to pH, bile, oxgall, and temperature.
It was found that the strains grew very well up to pH 3.0 and resistant to relatively high concentrations of bile salt and
oxgall. I. orientalis and B. subtilis are extremely tolerant in range of 70–90°C in solid medium. B. subtilis B266 also has excellent tolerant property up to 90°C in liquid medium. The health indexes (the microflora in the small intestines
and the antibody titer to Newcastle disease virus) of chicks were significantly improved in the fermented rice bran with these
strains (0.25% addition to diet) in comparison with the Avilamycin (20 mg/kg diet)-fed group (p < 0.05). The fermented rice bran-fed group showed a better microbial flora in the small intestines. Accordingly, it would
appear that the fermented rice bran with these strains may be a potential candidate for an alternative microbial feed additive. 相似文献
19.
B. Choudhury Preetika Aggarwal R. K. Gothwal Rahul Mantri M. K. Mohan P. Ghosh 《Applied biochemistry and biotechnology》2006,128(2):159-169
The efficiency of xylanase of Bacillus brevis BISR-062 as a prebleaching agent was evaluated on three nonwoody pulps at two different pH values (7.0 and 8.5). Crude xylanase
was found to have an optimum temperature and pH of 65–70°C and 7.0, respectively. The stability of the enzyme was determined
at two pH values (7.0 and 8.0), and it lost approx 50% of its activity at both values within 2 h at 50°C. However, the enzyme
was found to be effective as a prebleaching agent only with rice straw pulp. A maximum brightness gain of 6 points was obtained
with this pulp at pH 7.0. The strength properties of the rice straw pulp at pH 7.0 also improved as the result of enzyme treatment. 相似文献
20.
Daniela A. Bocchini Valquiria B. Damiano Eleni Gomes Roberto Da Silva 《Applied biochemistry and biotechnology》2003,106(1-3):393-401
The alkalophilic Bacillus circulans D1 was isolated from decayed wood. It produced high levels of extracellular cellulase-free xylanase. The enzyme was thermally
stable up to 60°C, with an optimal hydrolysis temperature of 70°C. It was stable over a wide pH range (5.5—10.5), with an
optimum pH at 5.5 and 80% of its activity at pH 9.0. This cellulase-free xylanase preparation was used to biobleach kraft
pulp. Enzymatic treatment of kraft pulp decreased chlorine dioxide use by 23 and 37% to obtain the same kappa number (κ number)
and brightness, respectively. Separation on Sephadex G-50 isolated three fractions with xylanase activity with distinct molecular
weights. 相似文献