Thermostable alkaline protease produced by Bacillus thermoruber, a new species of Bacillus

\u2022 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\ub1800. the isoelectric point was 5.3; the optimum pH and temperature for proteolytic activity (on casein) was found to be pH 9 and 45\ub0C 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

Purification and properties of an endopolygalacturonase produced by Rhizopus stolonifer

A 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\ub0C, and a molecular weight of 57,000\ub1500 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

Enzymic modification of vegetable protein by a crude preparation from a strain of Bacillus licheniformis

Sunflower 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

Molecular analysis of artisanal Italian cheeses reveals Enterococcus italicus sp. nov.

The taxonomic positions of seven atypical Enterococcus strains, isolated from artisanal Italian cheeses, were investigated in a polyphasic study. By using 16S rRNA gene sequencing, DNA\u2013DNA hybridization and intergenic transcribed spacer analysis, as well as by examining the phenotypic properties, the novel isolates were shown to constitute a novel enterococcal species. Their closest relatives are Enterococcus sulfureus and Enterococcus saccharolyticus, having a 16S rRNA gene sequence similarity of 96?7%. This group of strains can be easily differentiated from the other Enterococcus species by DNA\u2013DNA hybridization and by their phenotypic characteristics: the strains do not grow in 6?5% NaCl, and they do not produce acid from L-arabinose, melezitose, melibiose, raffinose or ribose. The name Enterococcus italicus sp. nov. is proposed for this species, with strain DSM 15952T (=LMG 22039T) as the type strain