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1.
Dr. Concepción Calvo Ana García de la Paz Victoria Bejar Emilia Quesada Alberto Ramos-Cormenzana 《Current microbiology》1988,17(1):49-53
Thirty-eight strains ofDeleya halophila species were examined for production of phage after mitomycin C induction. Thirty-two of them were able to inhibit growth of some other strains. Phage F9-11, isolated fromD. halophila strain F9-11, showed an isometric head and a noncontractile tail. The effects of salt concentrations variation on the stability and replication of this phage were established. Its replication was possible at a wide range of marine salt concentrations, from 2.5% to 15% (wt/vol). Stability seems to be influenced by osmolarity of medium rather than by NaCl level. The euryhaline character showed by F9-11 phage is evoked as an important factor for the survival of this phage in its environment. 相似文献
2.
Two Yersinia enterocolitica strains were able to utilize the products of cephalothin degradation. The utilization of these products was shown by an increase of oxygen uptake by Y. enterocolitica with cephalothin as the only substrate, and by the growth of both strains with the hydrolysis products of cephalothin as sole energy and carbon sources. Nuclear magnetic resonance analysis of the cephalothin degradation reaction demonstrated the progressive disappearance of hydrolysis products. However, the products of benzylpenicillin degradation could not be utilized by Y. enterocolitica. 相似文献
3.
Lotfi Mellouli Raoudha Ghorbel Alya Kammoun Monia Mezghani Samir Bejar 《Biotechnology letters》1996,18(7):809-814
Summary A new thermophilic Streptomyces sp. TO1, isolated from Tunisian soil, produced a thermostable alpha-amylase and pullulanase. The gene encoding for the alpha-amylase activity was cloned into the multicopy cloning plasmid pLM1 using S. lividans ZX1 as host strain. The ZX1 / pLM1 strain has the same activity than the initial TO1 strain and about 25 fold higher activity than the ZX1 strain. This alpha-amylase has an optimum of pH and temperature at 6 and 70 °C respectively. 相似文献
4.
Valentina Ferrari Alison Tarke Hannah Fields Luca Ferrari Trevor Conley Franco Ferrari Zeynep Koşaloğlu-Yalçın Alessandro Sette Bjoern Peters Colin L. McCarthy Asad Bashey Dimitrios Tzachanis Edward D. Ball Tiffany N. Tanaka Rafael Bejar Thomas A. Lane Antonella Vitiello 《Cytotherapy》2021,23(4):320-328
Therapies that utilize immune checkpoint inhibition work by leveraging mutation-derived neoantigens and have shown greater clinical efficacy in tumors with higher mutational burden. Whether tumors with a low mutational burden are susceptible to neoantigen-targeted therapy has not been fully addressed. To examine the feasibility of neoantigen-specific adoptive T-cell therapy, the authors studied the T-cell response against somatic variants in five patients with myelodysplastic syndrome (MDS), a malignancy with a very low tumor mutational burden. DNA and RNA from tumor (CD34+) and normal (CD3+) cells isolated from the patients’ blood were sequenced to predict patient-specific MDS neopeptides. Neopeptides representing the somatic variants were used to induce and expand autologous T cells ex vivo, and these were systematically tested in killing assays to determine the proportion of neopeptides yielding neoantigen-specific T cells. The authors identified a total of 32 somatic variants (four to eight per patient) and found that 21 (66%) induced a peptide-specific T-cell response and 19 (59%) induced a T-cell response capable of killing autologous tumor cells. Of the 32 somatic variants, 11 (34%) induced a CD4+ response and 11 (34%) induced a CD8+ response that killed the tumor. These results indicate that in vitro induction of neoantigen-specific T cells is feasible for tumors with very low mutational burden and that this approach warrants investigation as a therapeutic option for such patients. 相似文献
5.
C Calvo F Martinez-Checa A Mota V Bejar E Quesada 《Journal of industrial microbiology & biotechnology》1998,20(3-4):205-209
The effects of monovalent and divalent cations on the rheological behavior of Halomonas eurihalina exopolysaccharide (EPS) were studied. Sodium, potassium, magnesium and calcium were added and the relative abilities to increase
viscosity were as follows: KCl > NaCl > MgCl2 > CaCl2. The highest viscosity value was measured in acidic 10−4 M KCl, in which a gel formed. A loss of sulfate content seemed to correlate with the increase of viscosity. H. eurihalina produced EPS in all growth media. Addition of hydrophobic substrates to culture media produced changes in chemical
composition and emulsifying activity of the EPS. Xylene was the most effectively emulsified substance and the EPS produced
on tetradecane and on corn oil the most active emulsifier.
Received 25 July 1997/ Accepted in revised form 30 January 1998 相似文献
6.
Lactobacillusdelbrueckii subsp. bulgaricus and Streptococcus thermophilus are used for the biotransformation of milk in yoghurt. During milk fermentation, these lactic acid bacteria (LAB) hydrolyze lactose producing a glucose moiety that is further metabolized and a galactose moiety that they are enable to metabolize. We investigated the ability of L. bulgaricus and S. thermophilus strains expressing a heterologous L-arabinose isomerase to convert residual D-galactose to D-tagatose. The Bacillus stearothermophilus US100l-arabinose isomerase (US100l-AI) was expressed in both LAB, using a new shuttle vector where the araA US100 gene is under the control of the strong and constitutive promoter of the L. bulgaricus ATCC 11842 hlbA gene. The production of L-AI by these LAB allowed the bioconversion of D-galactose to D-tagatose during fermentation in laboratory media and milk. We also established that the addition of L-AI to milk also allowed the conversion of D-galactose into D-tagatose during the fermentation process. 相似文献
7.
Ines Hammami Bassem Jaouadi Abir Ben Bacha Ahmed Rebai Samir Bejar Xavier Nesme Ali Rhouma 《Biotechnology and Bioprocess Engineering》2012,17(1):41-49
Bacillus subtilis strain 14B was used to produce a novel antimicrobial peptide (bacteriocin) called Bac 14B. Pure bacteriocin was obtained
after heat and acidic treatments (80°C and pH 4), precipitation by ammonium sulfate, and chromatography on Sephadex G-50 and
Mono Q Sepharose columns. Based on MALDI-TOF mass spectrometry analysis, purified Bac 14B is a monomer protein with a molecular
mass of 20110.13 Da. N-terminal sequencing allowed for the straightforward identification of its first 12 residues, which
were of a pure bacteriocin. It also revealed that this bacteriocin contained a unique sequence, namely M-L-K-A-N-L-Q-N-P-L-N-A,
suggesting the identification of a novel compound. Bac 14B was stable for 1 h at temperatures up to 80°C and pH of 4 ∼ 8.
It also proved sensitive to various proteases, which demonstrated its protein nature. Bac 14B displayed a bacteriolytical
mode of action and a broad range of inhibitory spectra toward Gram-positive and -negative pathogens. Interestingly, based
on conventional agronomic seed vigor parameters, the application of Bac 14B (500 activity units/mL) to various crops revealed
that this bacteriocin was a potent exogenous enhancer of growth that stimulated the seedling vigor of tomatoes and muskmelons.
Compared to those of the control, the germination percentage, shoot weight, shoot height, and root length were all significantly
enhanced in Bac 14B-treated plant seeds. Bac 14B also exhibited effective disinfectant properties against a wide range of
seedborne diseases and significant effects on the control of damping off diseases, particularly at the pregermination stage.
It also proved to be effective against root rot diseases caused by Alternaria solani and other bacterial seedborne pathogens such as wilt diseases. The findings indicate that Bac 14B is the first B. subtilis-produced bacteriocin ever reported to exhibit such promising biological properties. 相似文献
8.
Mounira Ben Farhat Ameny Farhat Wacim Bejar Radhouan Kammoun Kameleddine Bouchaala Amin Fourati Hani Antoun Samir Bejar Hichem Chouayekh 《Archives of microbiology》2009,191(11):815-824
The mineral phosphate solubilizing (MPS) ability of a Serratia marcescens strain, namely CTM 50650, isolated from the phosphate mine of Gafsa, was characterized on a chemically defined medium (NBRIP
broth). Various insoluble inorganic phosphates, including rock phosphate (RP), calcium phosphate (CaHPO4), tri-calcium phosphate (Ca3(PO4)2) and hydroxyapatite were tested as sole sources of phosphate for bacterial growth. Solubilization of these phosphates by
S. marcescens CTM 50650 was very efficient. Indeed, under optimal conditions, the soluble phosphorus (P) concentration it produced reached
967, 500, 595 and 326 mg/l from CaHPO4, Ca3(PO4)2, hydroxyapatite and RP, respectively. Study of the mechanisms involved in the MPS activity of CTM 50650, showed that phosphate
solubilization was concomitant with significant drop in pH. HPLC-analysis of culture supernatants revealed the secretion of
gluconic acid (GA) resulting from direct oxidation pathway of glucose when the CTM 50650 cells were grown on NBRIP containing
glucose as unique carbon source. This was correlated with the simultaneous detection by PCR for the first time in a S. marcescens strain producing GA, of a gene encoding glucose dehydrogenase responsible for GA production, as well as the genes pqqA, B, C and E involved in biosynthesis of its PQQ cofactor. This study is expected to lead to the development of an environmental-friendly
process for fertilizer production considering the capacity of S. marcescens CTM 50650 to achieve yields of P extraction up to 75% from the Gafsa RP. 相似文献
9.
Monia Mezghani Mohamed Ali Borgi Radhouane Kammoun Hedi Aouissaoui Samir Bejar 《Enzyme and microbial technology》2005,37(7):735-738
In order to over express the xylA gene of Streptomyces sp. SK strain, it was cloned under the control of the constitutive ermE-up promoter. This construct was integrated through site-specific recombination process into the chromosome of a Streptomyces violaceoniger glucose isomerase deficient strain using the non-replicative vector pTS55. The resulting CBS4 strain shows a perfect stability in the absence of selection pressure. Its glucose isomerase activity was about four and nine-fold greater, than that obtained from Streptomyces sp. SK, respectively fully induced or not by xylose. 相似文献
10.
Mabrouk SB Messaoud EB Ayadi D Jemli S Roy A Mezghani M Bejar S 《Molecular biotechnology》2008,38(3):211-219
A gene encoding maltogenic amylase from acidic Bacillus sp. US149 (maUS149) was cloned, sequenced and over-expressed in Escherichia coli. The nucleotide sequence analysis revealed an open reading frame (ORF) of 1749 bp encoding a protein of 582 residues. The
alignment of deduced amino acid sequence revealed a relatively low homology with the already reported maltogenic amylases.
In fact, its highest identity, of only 60%, was found with the maltogenic amylase of Thermus sp. IM6501. The recombinant enzyme (MAUS149) was found to be intracellular and was purified to homogeneity from the cell
crude extract with a yield of 23%. According to PAGE analysis, under reducing and non-reducing conditions, the recombinant
enzyme has an apparent molecular weight of 135 kDa and is composed of two identical subunits of 67.5 kDa each. The maximum
activity was obtained at 40°C and pH 6.5. MAUS149 could be classified as a maltogenic amylase since it produces mainly maltose
from starch, maltose and glucose from β-cyclodextrin, and panose from pullulan. 相似文献