Júlio Xandro Heck

Cellulase and xylanase productions by isolated Amazon Bacillus strains using soybean industrial residue based solid-state cultivation

In Brazil, a large amount of a fibrous residue is generated as result of soybean ( Glycine max) protein production. This material, which is rich in hemicellulose and cellulose, can be used in solid state cultivations for the production of valuable metabolites and enzymes. In this work, we studied the bioconversion of this residue by bacteria strains isolated from water and soil collected in the Amazon region. Five strains among 87 isolated bacteria selected for their ability to produce either celullases or xylanases were cultivated on the aforementioned residue. From strain BL62, identified as Bacillus subtilis, it was obtained a preparation showing the highest specific cellulase activity, 1.08 UI/mg protein within 24 hours of growth. Concerning xylanase, the isolate BL53, also identified as Bacillus subtilis, showed the highest specific activity for this enzyme, 5.19 UI/mg protein within 72 hours of cultivation. It has also been observed the production of proteases that were associated with the loss of cellulase and xylanase activities. These results indicated that the selected microorganisms, and the cultivation process, have great biotechnological potential.

Purification, immobilization, and characterization of a specific lipase from Staphylococcus warneri EX17 by enzyme fractionating via adsorption on different hydrophobic supports

Staphylococcus warneri strain EX17 produces three lipases with different molecular weights of 28, 30, and 45 kDa. The 45 kDa fraction (SWL‐45) has been purified from crude protein extracts by one chromatographic step based on the selective adsorption of this lipase by interfacial activation on different hydrophobic supports at low ionic strength. The adsorption of SWL‐45 on octyl‐Sepharose increased the enzyme activity by 60%, but the other lipases were also adsorbed on this support. Using butyl‐Toyopearl, which is a lesser hydrophobic support, the purification factor was close to 20, and the only protein band detected on the sodium dodecyl sulfate‐polyacrylamide electrophoresis analysis gel was that corresponding to the SWL‐45, which could be easily desorbed from the support by incubation with triton X‐100, producing a purified enzyme. SWL‐45 was immobilized under very mild conditions on cyanogen bromide Sepharose, showing similar activities and stability as for its soluble form but without intermolecular interaction. The effects of different detergents over the activity of the immobilized SWL‐45 were analyzed, which was hyperactivated by factors of 1.3 and 2.5 with 0.01% Tween 80 and 0.1% Triton X‐100, respectively, while ionic detergents produced detrimental effects on the enzyme activity even at very low concentrations. Optimal reaction conditions and the effect of other additives on the enzyme activity were also investigated.

Production of High-protein Hydrolysate from Poultry Industry Residue and their Molecular Profiles

The use of mechanically deboned poultry meat (MDPM) as a source of raw protein for the enzymatic preparation of hydrolysates was investigated using commercial proteases Alcalase and Flavourzyme. Hydrolysis conditions were optimized by response surface methodology, and the influence of temperature, pH, and enzyme concentration were evaluated to determine the hydrolysis index. For Alcalase, optimal values of temperature, pH, and enzyme concentration were found to be 50°C, 7.5%, and 2.5%, respectively, while for Flavourzyme the optimized variables were at 50°C, 6.0%, and 3.5%, respectively. Compared to raw MDPM, Alcalase produced a very high recovery of 89% of the nitrogen from the hydrolysates, while for Flavourzyme recovery was around 67%. Alcalase was used to produce a spray-dried hydrolysate containing 62% of total protein with molecular weights ranging from 5,807 to 12,000 Da, and had excellent microbiological quality.