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1.
TheBacillus subtilis alkaline protease(aprA) gene was previously cloned on a pUBHO-derivative plasmid. High levels of expression and gene stability were demonstrated
whenB. subtilis cells were grown on the laboratory medium 2XSG.B. subtilis cells harboring the multicopyaprA gene were grown on basal medium, supplemented with 1 % chicken feather as a source of energy, carbon, and nitrogen. Proteolytic
and kera-tinolytic activities were monitored throughout the cultivation time. A high level of keratinolytic activity was obtained,
and this indicates that alkaline protease is acting as a keratinase. Furthermore, considerable amounts of soluble proteins
and free amino acids were obtained as a result of the enzymatic hydrolysis of feather. Biodegradation of feather waste using
these cells represents an alternative way to improve the nutritional value of feather, since feather waste is currently utilized
on a limited basis as a dietary protein supplement for animal feedstuffs. Moreover, the release of free amino acids from feather
and the secreted keratinase enzyme would promote industries based on feather waste. 相似文献
2.
Garcia-Kirchner O. Bautista-Ramirez Ma. E. Segura-Granados M. 《Applied biochemistry and biotechnology》1998,(1):277-284
Keratinases can be used for the production of potentially important hydrolyzed proteins and chemicals. This study investigated
the keratinolytic activity ofStreptomyces sp on keratinaceous materials like wool. High levels of proteolytic and keratinolytic activity were obtained after 96 h of
culture when two Streptomyces sp strains were grown on basal medium containing mineral salts and 3% (w/v) of defatted wool
as a source of energy, carbon, and nitrogen. The cell-free culture filtrates exhibited rapid proteolytic digestion of keratin
powder. Currently, the authors are testing whether the enzymatic activity obtained is in fact keratinolytic, and not only
an alkaline protease activity. 相似文献
3.
Palumbo A. V. Strong-Gunderson J. M. Carroll S. 《Applied biochemistry and biotechnology》1997,(1):789-796
To determine if compounds added during trichloroethylene (TCE) degradation could reduce the loss of enzyme activity or increase
enzyme recovery, different compounds serving as energy and carbon sources, pH buffers, or free radical scavengers were tested.
Formate and formic acid (reducing power and a carbon source), as well as ascorbic acid and citric acid (free radical scavengers)
were added during TCE degradation at a concentration of 2 mM. A saturated solution of calcium carbonate was also tested to
address pH concerns. In the presence of formate and methane, only calcium carbonate and formic acid had a beneficial effect
on enzyme recovery. The calcium carbonate and formic acid both reduced the loss of enzyme activity and resulted in the highest
levels of enzyme activity after recovery. 相似文献
4.
Soni B. K. Conrad John Kelley Robert L. Srivastava Vipul J. 《Applied biochemistry and biotechnology》1998,(1):729-738
Several methanotrophic microorganisms, i.e.,Methylococcus capsulatus (Bath),Methylomonas albus (BG-8),Methylosinus trichosporium OB3b, andMethylocystis parvus (OBBP), were evaluated for growth and methane utilization. The effect of temperature was examined in the range of 25 to 45°C
for growth and methane utilization. The temperature variations (25–35°C) had minimal effect on growth ofM. albus and M. parvus. Methane consumption varied at different temperatures with a maximum of 0.67 mol%/h and 0.53 mol%/h. at 30 and 35°C, respectively,
forM. albus and M. parvus. The growth and methane consumption was slower forM. trichosporium OB3b as a maximum methane consumption of 0.07 mol%/h was obtained at 25°C and growth was inhibited at 35°C.M. capsulatus grew the best at 37°C and growth was affected at higher temperature of 45°C. Of the different cultures examined,M. albus andM. capsulatus grew the best and were further evaluated for the effect of pressure in the range of 10–50 psi. The results obtained usingM. albus demonstrated an enhancement in methane consumption rate by fourfold and final cell concentration by 40% at a pressure of
20 psi by injecting a methane/oxygen mixture, however further increase in the pressure up to 50 psi inhibited the growth.
The inhibition was not seen with nitrogen incorporated mixture of oxygen and methane, which suggest that the high partial
pressure of methane and/or oxygen are inhibitory for the growth ofM. albus. M. capsulatus was more sensitive to pressure as evidenced by inhibition at the relatively low pressure of 10 psi 相似文献
5.
John D. Wright Charles E. Wyman Karel Grohmann 《Applied biochemistry and biotechnology》1988,18(1):75-90
Simultaneous saccharification and fermentation (SSF) processes for producing ethanol from lignocellulose are capable of improved
hydrolysis rates, yields, and product concentrations compared to separate hydrolysis and fermentation (SHF) systems, because
the continuous removal of the sugars by the yeasts reduces the end-product inhibition of the enzyme complex. Recent experiments
using Genencor 150L cellulase and mixed yeast cultures have produced yields and concentrations of ethanol from cellulose of
80% and 4.5%, respectively. The mixed culture was employed because B.clausenii has the ability to ferment cellobiose (further reducing end-product inhibition), while the brewing yeastS. cerevisiae provides a robust ability to ferment the monomeric sugars. These experimental results are combined with a process model to
evaluate the economics of the process and to investigate the effect of alternative processes, conditions, and organisms. 相似文献
6.
Patricia M. G. Paiva Luana C. B. B. Coelho 《Applied biochemistry and biotechnology》1992,36(2):113-118
Two additional electrophoretically distinct molecular forms, isoforms (iso) 2 and 3, with lectin properties were isolated
fromCratylia mollis Mart, seeds (FABACEAE), by extraction with 0.15M NaCl and ammonium sulfate fractionation, followed by chromatography on Sephadex
G-75 and Bio-Gel P-200 (iso 2), as well as CM-Cellulose and Sephadex G-75 (iso 3). Both isoforms were human group nonspecific
and showed distinct specificity. Polyacrylamide gel electrophoresis resolved iso 2 and 3 in polypeptides of apparent mol wts
60 and 31 kDa, respectively; a distinct isoelectric focusing pattern was obtained for iso 2 and 3, under denaturing and reducing
conditions. 相似文献
7.
8.
A 1,4-β-d-glucan cellobiohydrolase (EC 3.2.1.91) and l,4-β-d-glucan glucanohydrolase (EC 3.2.1.4) were purified from the culture filtrates ofPenicillium funiculosum by using preparative isoelectric focusing. Both the enzymes were homogeneous on polyacrylamide gel with and without sodium
dodecyl sulphate. The mol wt of the cellobiohydrolase and endoglucanase were 14,400 and 25,000 respectively. The purified
enzymes were free of β-glucosidase activity. Acting in isolation, the cellobiohydrolase had little capacity for solubilizing
Avicel or Walseth cellulose, but showed increased rates of hydrolysis when combined with endoglucanase. Cellobiose inhibition
(50%) was observed in the initial rate of the hydrolysis of Walseth cellulose. It was also observed that cellobiohydrolase
initiates the attack on crystalline cellulose.
† NCL communication no. 3898. 相似文献
9.
Donnelly Mark I. Millard Cynthia Sanville Clark David P. Chen Michael J. Rathke Jerome W. 《Applied biochemistry and biotechnology》1998,(1):187-198
Escherichia coli strain NZN111, which is unable to grow fermentatively because of insertional inactivation of the genes encoding pyruvate:
formate lyase and the fermentative lactate dehydrogenase, gave rise spontaneously to a chromosomal mutation that restored
its ability to ferment glucose. The mutant strain, named AFP111, fermented glucose more slowly than did its wild-type ancestor,
strain W1485, and generated a very different spectrum of products. AFP111 produced succinic acid, acetic acid, and ethanol
in proportions of approx 2:1:1. Calculations of carbon and electron balances accounted fully for the observed products; 1
mol of glucose was converted to 1 mol of succinic acid and 0.5 mol each of acetic acid and ethanol. The data support the emergence
in E.coli of a novel succinic acid:acetic acid:ethanol fermentation pathway. 相似文献
10.
Guo Jian Liang Xl-xian Mo Pei-sheng Li Gao-xiang 《Applied biochemistry and biotechnology》1991,31(2):135-143
Bilirubin oxidase was purified from a culture filtrate of Myrothecium verrucaria Mv 2, 1089 by DEAE-cellulose and Sephadex G-100 column chromatographies. The purified enzyme had a specific activity of 30 U/mg protein and showed a single band on polyacrylamide gel electrophoresis. Some of the general properties of this bilirubin oxidase were as follows: the optimum pH for the enzyme reaction was 7.5 and the optimum temperature was 50 degrees C. The enzyme was stable at pH ranging from 9.0 to 9.5. The mol wt was calculated to be 61,900-62,700 by SDS-PAGE and gel-filtration technique. The apparent Km value of the bilirubin oxidase was calculated to be 9.4 x 10(-5) mol/L. The enzyme activity was greatly reduced by incubation of bilirubin oxidase with Fe2+, Hg+, NaN3, NH+4, and Zn2+. The enzyme reaction was inhibited in the presence of Ca2+, Hg+, Zn2+, Fe2+, and BSA. 相似文献
11.
Synthesis of Cyclodextrin Glucosyl Transferase byBacillus cereus for the production of cyclodextrins
R. Jamuna N. Saswathi R. Sheela S. V. Ramakrishna 《Applied biochemistry and biotechnology》1993,43(3):163-176
A potent indigenous bacillus isolate identified asBacillus cereus (RJ-30) was found to produce Cyclodextrin Glucosyl Transferase (CGTase) extracellularly. Process optimization of various
fermentation parameters has been established for optimal growth of bacillus and the maximum enzyme synthesis. The organism
had the highest specific growth rate (0.7μ) with a generation time of 1 h in glucose containing medium at the conditions of
pH 7.0, 37°C at 300 rpm, 1.5 vvm of agitation, and aeration. At these conditions, it exhibited the maximum activity of 54
U/mL at the synthesis rate of 2.7 U/L/h. CGTase was produced from the early exponential growth and peaked during the midsporulating
stage of about 16 h thereafter maintained at the same level of 50 U/mL. Saccharides containing media were better inducers
than starch, and the influence of carbohydrate substrates has shown that enzyme synthesis is promoted by xylose (65 U/mL)
and, more remarkably, by the supplementation of wheat bran extract in glucose medium (106 U/mL). This organism produced CGTase
stably in a chemostat culturing over a period of 400 h with a maximum productivity of 5.4 kU/L/h (threefold higher than obtained
in batch culturing [1.75 kU/L/h]). Comparatively, CGTase was produced by immobilized cells in a continuous fluidized bed reactor
for over approx 360 h, at a relatively high dilution rate of 0.88 h−1 resulting in the productivity of 23.0 kU/L/h. 相似文献
12.
Lamb pregastric lipase was purified from a commercial source using delipidation, solubilization with KSCN, acid-precipitation, pepsin-digestion, affinity chromatography with agarose-Cibacron Blue F3GA, gel filtration, and elution from a native 10% (w/v) polyacrylamide gel. The enzyme had a single subunit of 68,000 Da with maximum esterase activity when measured at pH 6.0 and 30 degrees C. The enzyme preferentially hydrolyzed short- and medium-chain (C4, C6, and C8) synthetic esters and short-chain (C4 and C6) monoacid triglycerides. The NH2-terminal sequence demonstrated high homology with gastric and lingual lipases. 相似文献
13.
Torres José L. Grethlein Hans E. Lynd Lee R. 《Applied biochemistry and biotechnology》1989,(1):621-633
High energy costs are associated with the recovery of ethanol from fermentation broths. This paper discusses a computer simulation
of the Dartmouth Process, which aims to reduce these costs by the use of IHOSR distillation, extensive heat integration, and
extractive distillation using a salt.
To resolve the uncertainty in modeling alcohol-water-salt vapor-liquid equilibrium, a new and more accurate activity coefficient
model was used. An Aspen™ model was used to generate capital and energy costs for a range of ethanol concentrations in the
feed. Simulation results show that the Dartmouth Process offers substantial economic advantages over benzene azeotropic distillation,
particularly at low feed concentrations. 相似文献
14.
Suyama Kyozo Fukazawa Yoshitaka Umetsu Yoshiyaki 《Applied biochemistry and biotechnology》1994,(1):871-879
The egg shell membrane (ESM) is an intricate lattice network of stable and water-insoluble fibers with high surface area.
ESM accumulates and eliminates various heavy metal ions from dilute aqueous solution with high affinity and in short contact
time, depending on pH and characteristics of the individual ion. Under certain conditions, the level of precious ions, Au,
Pt, and Pd accumulation approaches 55, 25, and 22% of dry wt of ESM, respectively. Also uranium uptake 30% of that of ESM.
Experiments suggested that ESM is promising to use for the purpose of removal/recovery of metals and water pollution control. 相似文献
15.
Peyton B. M. Skeen R. S. Hooker B. S. Lundman R. W. Cunningham A. B. 《Applied biochemistry and biotechnology》1995,(1):785-797
The ability of published biomass detachment rate expressions to describe experimental data obtained from porous media reactors
usingPseudomonas aeruginosa grown aerobically on glucose was evaluated. A first-order rate expression on attached biomass concentration best reflected
effluent substrate concentration for combined data sets. Detachment rate coefficientk
d1 was dependent on initial substrate concentration. Simulation of porous media reactor experiments indicated that responses
using higher influent substrate concentrations possessed greater sensitivity to variations ink
d1. Simulations of field bioremediation systems suggest the use of accurate biofilm development kinetics is important in the
prediction of well bore biofouling. 相似文献
16.
Gilbert Michel Breuil Colette Yaguchi Makoto Saddler J. N. 《Applied biochemistry and biotechnology》1992,(1):247-259
Thielavia terrestris 255B, a thermophilic ascomycete, produced two major forms of xylanase with pIs of 4.6 (xylanase I) and 6.1 (xylanase II).
The latter enzyme could be purified to > 99% homogeneity using anion-exchange chromatography and gel filtration. Xylanase
II had a mol wt of 25.7 kDa (SDS-PAGE) and a pH and a temperature optimum of 3.6–4.0 and 60–65°C, respectively. The ratio
of the enzyme’s activity against xylan and carboxymethylcellulose was 500–1000 to 1, indicating a possible application of
this enzyme in biobleaching processes. The amino acid sequence of this protein is being determined, and initial data suggest
that the enzyme belongs to a group of low-mol wt xylanases that have been isolated from both bacteria and fungi. 相似文献
17.
Beker M. J. Shvinka J. E. Pankova L. M. Laivenieks M. G. Mezhbarde I. N. 《Applied biochemistry and biotechnology》1990,(1):265-274
Two biotechnological systems were developed for sucrose conversion into levan and ethanol withZymomonas mobilis, ensuring a 66.7% transfer of substrate carbon in a batch and 61% carbon transfer in a continuous culture. The effect of
glucose, ethanol, and medium pH on sucrose conversion byZ. mobilis was studied. The addition of ethanol to the fermentation medium, in the final conc. of 100 g/L, uncoupled levan synthesis
from ethanol fermentation. For a continuous culture, the most efficient conversion of substrate carbon into levan was reached
at pH 4.8, giving 64.2 g/L levan, with the levan yield of 0.22 g/g and the productivity of 3.2 g/L/h. 相似文献
18.
Urease has been purified from the seeds of Cajanus Cajan. The purification process involves three solvent extraction steps followed by DEAE-cellulose column chromatography. The specific activity of the purified enzyme is found to be 1920 U/mg with the recovery of 8%. The application of the purified enzyme in a biosensor construction is discussed. 相似文献
19.
Aspen wood substrates with varying degrees of deacetylation, xylan, and lignin removal have been prepared and submitted to
enzymatic hydrolysis with a cellulase/hemicellulase preparation for an extended constant period of hydrolysis. Controlled
deacetylation has been achieved by treating wood with various alkali metal hydroxide solutions, at various alkali/wood ratios.
It has been found that samples with the same extent of deacetylation produce the same sugar yields upon enzymatic hydrolysis.
Increased degree of deacetylation increases the yield of sugars obtained from enzymatic hydrolysis, all other compositional
parameters held constant. The acetyl group removal is proportional to the stoichiometric relation between added base and wood
acetyl content, i.e., the same number of milliequivalents of base/weight of wood remove the same extent of acetyl groups,
regardless of the concentration of the base solution. No cation effects are found among Li, Na, and K alkali hydroxide solutions,
suggesting that swelling is not as important a parameter as is the removal of the acetyl groups from the xylan backbone in
determining the extent of hydrolyzability of the resulting sample. 相似文献
20.
Acetate kinase (EC 2.7.2.1) is involved in the wasteful production of acetate during conversion of cellulose to ethanol byClostridium thermocellum. The properties of this enzyme activity inC. thermocellum cell extracts were determined. Optimum enzyme activity was at 60 degrees C and between pH 7.5 and 9.0. In the presence of air, acetate kinase was stable to temperatures up to 60 degrees C, retaining 90% activity after 2 h, and was inactivated rapidly at higher temperatures. The enzyme exhibited a wide range of stability to pH (5.0-9.0) when incubated at 50 degrees C for 2 h. As with other acetate kinases, a divalent cation, such as Mg(2+), was required for enzyme activity. Optimum activity was observed at 20mM MgCl(2) when ATP was held constant at 10 mM. Acetate kinase activity was adversely affected by KCl, a salt commonly used in ion-exchange or affinity chromatography, with 0.3M KCl inhibiting by 50%. These results will be important in optimizing the direct microbial conversion process of cellulose to ethanol usingC. thermocellum in coculture withClostridium thermosaccharolyticum. 相似文献