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41.
Laila Manni Kemel Jellouli Olfa Ghorbel-Bellaaj Rym Agrebi Anissa Haddar Alya Sellami-Kamoun Moncef Nasri 《Applied biochemistry and biotechnology》2010,160(8):2308-2321
The current increase in amount of shrimp wastes produced by the shrimp industry has led to the need in finding new methods
for shrimp wastes disposal. In this study, an extracellular organic solvent- and oxidant-stable metalloprotease was produced
by Bacillus cereus SV1. Maximum protease activity (5,900 U/mL) was obtained when the strain was grown in medium containing 40 g/L shrimp wastes
powder as a sole carbon source. The optimum pH, optimum temperature, pH stability, and thermal stability of the crude enzyme
preparation were pH 8.0, 60 °C, pH 6–9.5, and <55 °C, respectively. The crude protease was extremely stable toward several
organic solvents. No loss of activity was observed even after 60 days of incubation at 30 °C in the presence of 50% (v/v) dimethyl sulfoxide and ethyl ether; the enzyme retained more than 70% of its original activity in the presence of ethanol
and N,N-dimethylformamide. The protease showed high stability toward anionic (SDS) and non-ionic (Tween 80, Tween 20, and Triton
X-100) surfactants. Interestingly, the activity of the enzyme was significantly enhanced by oxidizing agents. In addition,
the enzyme showed excellent compatibility with some commercial liquid detergents. The protease of B. cereus SV1, produced under the optimal culture conditions, was tested for shrimp waste deproteinization in the preparation of chitin.
The protein removal with a ratio E/S of 20 was about 88%. The novelties of the SV1 protease include its high stability to organic solvents and surfactants. These
unique properties make it an ideal choice for application in detergent formulations and enzymatic peptide synthesis. In addition,
the enzyme may find potential applications in the deproteinization of shrimp wastes to produce chitin. 相似文献
42.
Noomen Hmidet Hana Maalej Anissa Haddar Moncef Nasri 《Applied biochemistry and biotechnology》2010,162(4):1018-1030
α-Amylase from Bacillus mojavensis A21 (BMA.2) was purified to homogeneity by ultrafiltration, Sephadex G-75 gel filtration and Sepharose mono Q anion exchange chromatography, with a 15.3-fold increase in specific activity and 11% recovery. The molecular weight of the BMA.2 enzyme was estimated to be 58 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration. The optimum temperature and pH were 80?°C and 6.5, respectively. BMA.2 belonged to the EDTA-sensitive α-amylase, but its activity was not stimulated by the presence of Ca2+ ions. The major end-products of starch hydrolysis were maltohexaose, maltopentaose and maltotriose. The N-terminal amino acid sequence of the first ten amino acids of the purified α-amylase was ASVNGTLMQY. Compared to sequences of other amylases, the ten amino acid sequence contains Val at position 3, while amylases from Bacillus licheniformis NH1 and Bacillus sp. SG-1 have Leu and Thr at position 3, respectively. 相似文献
43.
Rym Agrebi Noomen Hmidet Mohamed Hajji Nawrez Ktari Anissa Haddar Nahed Fakhfakh-Zouari Moncef Nasri 《Applied biochemistry and biotechnology》2010,162(1):75-88
In this study, Mirabilis jalapa tuber powder (MJTP) was used as a new complex organic substrate for the growth and production of fibrinolytic enzymes by
a newly isolated Bacillus amyloliquefaciens An6. Maximum protease activity (1,057 U/ml) with casein as a substrate was obtained when the strain was grown in medium containing
(grams per liter) MJTP 30, yeast extract 6, CaCl2 1, K2HPO4 0.1, and K2HPO4 0.1. The strain was also found to grow and produce extracellular proteases in a medium containing only MJTP, indicating that
it can obtain its carbon, nitrogen, and salts requirements directly from MJTP. The B. amyloliquefaciens An6 fibrinase (BAF1) was partially purified, and fibrinolytic activity was assayed in a test tube with an artificial fibrin
clot. The molecular weight of the partially purified BAF1 fibrinolytic protease was estimated to be 30 kDa by sodium dodecyl
sulfate polyacrylamide gel electrophoresis and gel filtration. The optimum temperature and pH for the caseinolytic activity
were 60 °C and 9.0, respectively. The enzyme was highly stable from pH 6.0 to 11.0 and retained 62% of its initial activity
after 1 h incubation at 50 °C. However, the enzyme was inactivated at higher temperatures. The activity of the enzyme was
totally lost in the presence of phenylmethylsulfonyl fluoride, suggesting that BAF1 is a serine protease. 相似文献
44.
Moufida Romdhani-Younes Ines Gara Amine Mezni Mohamed Moncef Chaabouni 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1074-1081
Abstract The β,β′-dihydroxydithioethers, derived from oxirane, have been converted into dithioethers dithiols in good yields. A colloidal solution of gold nanoparticles (AuNPs) with 5,8-dithiadodecane-3,10-dithiol was prepared and showed a good stability from tight binding offered by the thiol group on the Au surfaces. 相似文献
45.
Rim Nasri Mourad Jridi Imen Lassoued Ines Jemil Rabeb Ben Slama-Ben Salem Moncef Nasri Maha Karra-Châabouni 《Applied biochemistry and biotechnology》2014,173(5):1121-1134
Antioxidant properties and angiotensin-converting enzyme (ACE) inhibitory activities of protein hydrolysates from goby (Zosterisessor ophiocephalus) muscle, with different degrees of hydrolysis (DH) from 5 to 25 %, prepared by treatment with crude proteases extract from smooth hound intestines, were investigated. Goby protein hydrolysates (GPHs) are rich in Gly and Thr, which accounted for 14.1–15 % and 11.6–13.2 % of the total amino acids, respectively. The antioxidant activities of GPHs were investigated by using several in vitro assay systems. All GPHs exhibited significant metal chelating activity and DPPH free radical-scavenging activity, and inhibited linoleic acid peroxidation. For the ACE-inhibitory activity, as the DH increased, the activity of GPHs increased. The obtained results revealed that antioxidant and ACE-inhibitory activities of GPHs were influenced by the degree of hydrolysis. A medium degree of enzymatic hydrolysis was appropriate to obtain GPHs with good antioxidant activity, while small peptides were essential to obtain high ACE inhibitory activity. 相似文献
46.
Variable electrical and thermal conductivity in the theory of generalized thermoelastic diffusion 总被引:3,自引:0,他引:3
Moncef Aouadi 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2006,57(2):350-366
This paper deals with the problem of a thermoelastic half-space with a permeating substance in contact with the bounding plane
in the context of the theory of generalized thermoelastic diffusion with one relaxation time and with variable electrical
and thermal conductivity. The bounding surface of the half-space is taken to be traction free and subjected to a time dependent
thermal shock. The solution is obtained in the Laplace transform domain by a direct approach. A numerical technique is employed
to obtain the solution in the physical domain. It is found that there exist two coupled waves, one of which is elastic and
the other is thermal, and a third wave affects diffusion mainly. A comparison is made with the results obtained in a thermoelastic
medium with and without diffusion in the following cases : (a) the electrical and thermal conductivities have constant values,
(b) the presence of magnetic field and (c) the generalized theory in thermoelasticity.
Received: June 1, 2005 相似文献
47.
Bechir Mrabet Aymen Mejbri Samia Mahouche Sarra Gam‐Derouich Mireille Turmine Mourad Mechouet Philippe Lang Hilaire Bakala Moncef Ladjimi Amina Bakhrouf Sven Tougaard Mohamed M. Chehimi 《Surface and interface analysis : SIA》2011,43(11):1436-1443
Poly(oligoethylene glycol methacrylate), POEGMA, brushes were prepared by surface‐initiated atom transfer radical polymerization (SI‐ATRP) on gold‐coated silicon wafers. Prior to ATRP, the substrates were grafted by brominated aryl initiators via the electrochemical reduction of a noncommercial parent diazonium salt of the formula BF4?, +N2‐C6H4‐CH(CH3)Br. The diazonium‐modified gold plates (Au‐Br) served as macroinitiators for ATRP of OEGMA which resulted in hydrophilic surfaces (Au‐POEGMA) that could be used for two distinct objectives: (i) resistance to fouling by Salmonella Typhimurium; (ii) specific recognition of the same bacteria provided that the POEGMA grafts are activated by anti‐Salmonella. The Au‐POEGMA plates were characterized by XPS, polarization modulation‐infrared reflection‐absorption spectroscopy (PM‐IRRAS) and contact angle measurements. Both Beer‐Lambert equation and Tougaard's QUASES software indicated a POEGMA thickness that exceeds the critical ~10 nm value necessary for obtaining a hydrophilic polymer with effective resistance to cell adhesion. The Au‐POEGMA slides were further activated by trichlorotriazine (TCT) in order to covalently bind anti‐Salmonella antibodies (AS). The antibody‐modified Au‐POEGMA specimens were found to specifically attach Salmonella Typhimurium bacteria. This work is another example of the diazonium salt/ATRP process to provide biomedical polymer surfaces. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
48.
Moncef Aouadi 《Applicable analysis》2013,92(12):2169-2187
In this article, we investigate the asymptotic behaviour of solutions to the one-dimensional initial-boundary value problem in the linear theory of thermoelastic diffusion mixtures recently developed by Aouadi [M. Aouadi, Qualitative results in the theory of thermoelastic diffusion mixtures, J. Thermal Stresses 33 (2010), pp. 595–615]. Our main result is to establish the necessary and sufficient conditions over the coefficients of the system to get the exponential stability of the corresponding semigroup. 相似文献
49.
In this paper, we prove exact observability, boundary and internal exact controllability results for a nonsimple elastic rod. By the spectral analysis method, it is shown that the considered problem has a sequence of eigenfunctions, which forms a Riesz basis for the state space. The exact observability is proved by application of a modified version of Ingham’s Theorem. Then, via the Hilbert Uniqueness method, we prove a boundary controllability result with only one controller and an internal controllability result. 相似文献
50.
On the light of a previous work and its recommendations by Matoba et al. [J. Phys. B 41, 145205 (2008)], this paper proposes to look at the mobility of ground and metastable-excited states of C+ ions moving into a helium buffer gas. The calculations, based on the three-temperature theory for solving the Boltzmann kinetic equation, are accomplished with quantum-mechanical transport cross sections at the low temperatures 4.3 and 77?K. The obtained mobility results are contrasted with the available theoretical data and experimental measurements, which show acceptable agreements. 相似文献