Biomedical subjects

Elba P S Bon

Publications and source records attributed to Elba P S Bon.

7 recordsLinked to original sources

PubMed2005

Production and partial characterization of extracellular proteinases from Streptomyces malaysiensis, isolated from a Brazilian cerrado soil.

Streptomyces malaysiensis AMT-3, isolated from a Brazilian cerrado soil, showed proteolytic activities detected by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The optimum proteinase production was obtained when using 2.5% wheat bran and 0.1% yeast extract in the culture medium, after 5 days incubation at 30 degrees C. The enzymatic complex degraded gelatin optimally at pH 7.0, and under these conditions eight proteolytic bands (four serine-proteinases and four metaloproteinases), ranging from 20 to 212 kDa, were detected on the culture supernatant filtrates. In addition, a 35-kDa proteinase was thermostable at 60 degrees C for 120 min. These results point out to the applicability of gelatin zymograms in the characterization of crude enzymatic complexes. According to our results, this enzymatic complex could be used for biotechnological applications.

Brazil↗

PubMed2005

High-yield Bacillus subtilis protease production by solid-state fermentation.

A Bacillus subtilis isolate was shown to be able to produce extracellular protease in solid-state fermentations (SSF) using soy cake as culture medium. A significant effect of inoculum concentration and physiological age on pro tease production was observed. Maximum activities were obtained for inocula consisting of exponentially growing cells at inoculum concentrations in the range of 0.7-2.0 mg g(-1). A comparative study on the influence of cultivation temperature and initial medium pH on protease production in SSF and in submerged fermentation (SF) revealed that in SSF a broader pH range (5-10), but the same optimum temperature (37 degrees C), is obtained when compared to SF. A kinetic study showed that enzyme production is associated with bacterial growth and that enzyme inactivation begins before biomass reaches a maximum level for both SF and SSF. Maximum protease activity and productivity were 960 U g(-1) and 15.4 U g-1 h-1 for SSF, and 12 U mL-1 and 1.3 U mL-1 h-1 for SF. When SSF protease activity was expressed by volume of enzyme extract, the enzyme level was 10-fold higher and the enzyme productivity 45% higher than in SF. These results indicate that this bacterial strain shows a high biotechnological potential for protease production in solid-state fermentation.

Bacillus subtilis↗

PubMed2004

Kinetics of asparaginase II fermentation in Saccharomyces cerevisiae ure2dal80 mutant: effect of nitrogen nutrition and pH.

Although the quality of nitrogen source affects fermentation product formation, it has been managed empirically, to a large extent, in industrial scale. Laboratory-scale experiments successfully use the high-cost proline as a nonrepressive source. We evaluated urea as a substitute for proline in Saccharomyces cerevisiae ure2dal80 fermentations for asparaginase II production as a model system for nitrogen-regulated external enzymes. Maximum asparaginase II levels of 265 IU/L were observed in early stationary-phase cells grown on either proline or urea, whereas in ammonium cells, the maximum enzyme level was 157 IU/L. In all cases, enzyme stability was higher in buffered cultures with an initial pH of 6.5.

Asparaginase↗

PubMed2003

The role of the GATA factors Gln3p, Nil1p, Dal80p and the Ure2p on ASP3 regulation in Saccharomyces cerevisiae.

The role of Gln3p, Nil1p, Dal80p and Ure2p in the nitrogen regulation of ASP3, which codes for the periplasmic Saccharomyces cerevisiae asparaginase II, was investigated. Analysis of enzyme levels and mRNA(ASP3) in two wild-type strains and gln3, nil1, gln3nil1, gln3ure2, nil1ure2, nil1dal80, ure2, dal80 and ure2dal80 mutant cells allowed the study of the qualitative and quantitative regulatory role of the GATA factors and Ure2p on ASP3 expression. The simultaneous presence of Gln3p and Nil1p is a required condition for full gene transcription. Enzyme activity doubled upon nitrogen starvation of either ammonium-grown (possibly due to Nil2p/Deh1p derepression) or proline-grown (due to Dal80p derepression) cells. The ure2 mutation increased enzyme levels five-fold in fresh ammonium-grown cells and ten-fold in fresh proline-grown cells. The combined effects of the ure2 mutation and nitrogen starvation on ammonium- or proline-grown cells resulted in an overall 10-20-fold enzyme activity increase, respectively, in comparison with the wild-type cells.

Asparaginase↗

PubMed2003

Effect of aeration on lignin peroxidase production by Streptomyces viridosporus T7A.

The effect of aeration on lignin peroxidase production by Streptomyces viridosporus T7A was studied in a bench-scale bioreactor using a previously optimized growth medium (0.65% yeast extract and 0.1% corn oil, pH 7.0) at 37 degrees C and natural pH. Airflow rates of 0.3, 1.0, and 1.5 vvm and a fixed agitation of 200 rpm were initially studied followed by 1.0 vvm and 200, 300, 400, and 500 rpm. The use of 1.0 vvm and 400 rpm increased enzyme concentration 1.8-fold (100-180 U/L) and process productivity 4.8-fold (1.4-6.7 U/[L h]) in comparison with the use of 200 rpm and 0.3 vvm. The inexpensive corn oil, used as carbon source, besides its antifoam properties, proved to be nonrepressive for enzyme production.

Aerobiosis↗

PubMed2002

4-chlorophenol degradation by chloroperoxidase from Caldariomyces fumago: formation of insoluble products.

This study investigated the degradation of 4-chlorophenol (4-CP) by Caldariomyces fumago chloroperoxidase (CPO). Enzymatic oxidations were studied in reaction mixtures at pH 3.0, 4.0, and 6.0 in the presence and absence of Cl- containing 3.5 IU of CPO and 4-CP and hydrogen peroxide concentrations within the range of 0.5-50 and 0.005-50 mM, respectively. Distinct patterns of products regarding color, concentration, and solubility were observed. Reaction mixtures at pH 6.0 containing 3.5 IU of CPO and 5.0 mM 4-CP and H2O2 (1:1 stoichiometry) showed the highest 4-CP removal of 95% and the highest formation of a dark precipitate.

Archaea↗

PubMed2002

Use of steam explosion liquor from sugar cane bagasse for lignin peroxidase production by Phanerochaete chrysosporium.

The possibility of using two by-products of the sugar cane industry, molasses and bagasse steam explosion liquor (SEL), for lignin peroxidase (LiP) production by Phanerochaete chrysosporium was investigated. For comparison, the fungus was initially cultivated in synthetic media containing either glucose, sucrose, xylose, or xylan as sole carbon sources. The effect of veratryl alcohol (VA) was also investigated in relation to the enzyme activity levels. Results showed that sucrose was not metabolized by this fungus, which precluded the use of molasses as a carbon source. Glucose, xylose, and xylan promoted equivalent cell growth. Enzyme levels in the absence of VA were lower than 28 UI/L and in the presence of VA reached 109 IU/L with glucose and 85 IU/L with xylose or xylan. SEL was adequate for P. chrysosporium LiP production as LiP activity reached 90 IU/L. When VA was added to this medium, enzyme concentration increased to 155 IU/L.

Cellulose↗