1,721,074 research outputs found
SITE-SPECIFIC RESTRICTION ENDONUCLEASES IN BACILLUS-LICHENIFORMIS
No full textWe systematically studied site-specific restriction endonucleases in Bacillus licheniformis strains and detected endonuclease activity in 25 of 217 strains tested. Three different activities were obtained. One of these activities detected in 21 strains was the most representative within the species and produced a banding pattern, after digestion of A DNA, identical to that seen with ClaI. Two other strains isolated from soil samples from China and USA were found to produce a DNA-cleaving enzyme with the same recognition sequence as BsaI. One producer strain, isolated from a Peruvian soil sample, showed to possess a mixture of two isoschizomers, ClaI and BsaI. Finally, one strain produced an endonuclease activity, not previously described in B. licheniformis, that showed the same recognition sites as Bsu361
Thermostable alkaline protease produced by Bacillus thermoruber, a new species of Bacillus
No full text• The proteolytic activity produced by a new species of Bacillus isolated in our laboratory was investigated. This enzyme was purified to homogeneity from cell-free culture liquids of B. thermoruber. The purification procedure included ion-exchange chromatography on DEAE-Sephadex A-50 and -casein agarose affinity chromatography. The protease consists of one polypeptide chain with a molecular weight of 39000±800. the isoelectric point was 5.3; the optimum pH and temperature for proteolytic activity (on casein) was found to be pH 9 and 45°C respectively. Enzyme activity was inhibited by PMSF and EDTA. The stability was considerably increased by addition of Ca2+, and the protease exhibited a relatively high thermal stability. The alkaline protease shows a preference for leucine in the carboxylic side of the peptide bond of the substrate. The K m value for benzyloxycarbonyl-Ala-Ala-Leu-p-nitroanilide was 2.5 mM
Solid state interaction of steroids with calixarenes. I. A preliminary FTIR and DSC study on 4-en-3-keto-steroids
No full textBoth DSC and FTIR studies indicate that co-grinding and co-precipitation cause steroids to interact with calixarenes. This interaction leads to breaking of the crystal lattice of the steroids, dispersion of the steroidal carbonyls in a hydrophobic environment and formation of hydrogen bonds between steroidal and calixarene hydroxyls. This interaction seems to be specific, depending on the structure of the calixarene and of the steroid involved. It is reasonable to assume that inclusion complexes are formed
Purification and properties of an endopolygalacturonase produced by Rhizopus stolonifer
No full textA polygalacturonase from culture filtrates of a strain of Rhizopus stolonifer was purified about 80 fold by ethanol precipitation, followed by ion exchange chromatography (CM-Sepharose 6B) and gel filtration (Sephadex G-100). The purified preparation was homogeneous when examined by PAGE. The enzyme is an endopolygalacturonase with an optimum catalytic activity at pH 5.0 and 45°C, and a molecular weight of 57,000±500 daltons. The activity was stimulated by Fe+++, Mg++, Co++, and inhibited by Mn++ and Zn++. The enzyme was stable in the pH range of 3.0 to 5.0. The purified enzyme was specific for nonmethoxylate polygalacturonic acid, with Km and Vmax values respectively of 0.19 mg/ml and 1.3 mol/ g/min. In addition, this enzymatic preparation degraded pectic substances in orange peel
Identification And Effect of Two Bacterial Contaminants on Apple Organogenesis
No full textShoots of the apple cultivar Golden Delicious clone B were maintained actively proliferating for several years and routinely used as source of leaves to regenerate adventitious shoots. Contamination appearing during proliferation did not affect the performances of axillary branching or shoot growth but was further related to a dramatic decrease of regenerative ability of the leaves. Two bacterial strains, C1 and C2, were isolated and identified on the basis of the 16S rRNA gene partial sequence analysis. C1 strain showed significant homology with Luteibacter, a gamma-proteobacterium isolated from the rhizosphere of Hordeum vulgare, while C2 showed the highest similarity with Staphylococcus pasteuri. Leaves artificially infected with either single C1 and C2 cells or both strains together recorded a significant drop in shoot regeneration ability and concealed the leaf morphogenic gradient. On the other hand, contaminated leaves produced more abundant callus that could result from the production of growth regulators by the bacterial strains
Enzymic modification of vegetable protein by a crude preparation from a strain of Bacillus licheniformis
No full textSunflower seed proteins are of interest for their functionality, and for their nutritional quality which arises from a balanced amino acid pattern and the absence of antinutritional factors (Jaya et a1 1981; Rossi et a1 1985). Furthermore, sunflower meal is readily available after the oil extraction process. This communication reports the results of a preliminary study carried out to evaluate the ability of a crude proteolytic enzyme preparation, obtained from a strain of Bacillus licheniformis isolated in this laboratory, to hydrolyse proteins of different source. In particular, sunflower protein concentrate was investigated. Factors affecting the extent of enzymic hydrolysis, such as substrate concentration, pH, temperature, and some characteristics of the hydrolysates obtained, were studied
Small rolling circle plasmids in Bacillus subtilis and related species: Organization, distribution, and their possible role in host physiology
No full textBacillus subtilis and related species (Bacillus licheniformis, Bacillus pumilus, Bacillus amyloliquefaciens, and Bacillus mojavensis) represent a group of bacteria largely studied and widely employed by industry. Small rolling circle replicating plasmids of this group of bacteria have been intensively studied as they represent a convenient model for genetic research and for the construction of molecular tools for the genetic modification of their hosts. Through the computational analysis of the available plasmid sequences to date, the first part of this review focuses on the main stages that the present model for rolling circle replication involves, citing the research data which helped to elucidate the mechanism by which these molecules replicate. Analysis of the distribution and phylogeny of the small RC plasmids inside the Bacillus genus is then considered, emphasizing the low level of diversity observed among these plasmids through the in silico analysis of their organization and the sequence divergence of their replication module. Finally, the parasitic vs. mutualistic nature of small rolling circle plasmids is briefly discussed
Pectic enzymes from Aureobasidium pullulans LV10
No full text• Aureobasidium pullulans LV 10 produced extracellular pectolytic activity when grown in a medium containing apple pectin as a carbon source. Maximum enzyme production (22 PGU ml−1 and 9 PLU ml−1) was obtained after 4 days of batch growth. Two pectin hydrolases and two pectin lyases by CM-Sepharose 6B, DEAE-cellulose, and Sephadex G-100 column chromatography were partially purified and characterized. Hydrolases I and II gave optimum activity at pH 5.5 and 4.5, respectively, at 50°C. For lyases I and II, the optimum occurred at pH 5.0 and 7.5, respectively, and 40°C
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