In this study solid and liquid wastes from the olive oil processing industry were evaluated as substrates for Yarrowia lipolytica growth with the aim of lipase production. Olive mill wastewater and olive oil cake seemed to provide necessary nutrients and physical support for the yeast to grow and produce enzyme. The highest lipolytic activity of 850 IU dm-3 was achieved after 4 days of submerged cultivation in supplemented olive mill wastewater. In addition, olive oil cake appeared to be a convenient substrate for lipase production under solid state fermentation mode. Lipase production was further improved by media supplementation and/or change in physical settings of the experiment. However, the most significant improvement of lipase production under solid state fermentation was achieved by an alkaline treatment of the substrate (more than 10-fold) when the amount of produced lipase reached up to ~40 IU g-1 of substrate. [Projekat Ministarstva nauke Republike Srbije, br. E!6750 i br. III 46010

The objectives of this study were to examine the effect of sonication and high-pressure carbon dioxide processing on proteolytic hydrolysis of egg white proteins and antioxidant activity of the obtained hydrolysates. It appeared that the ultrasound pretreatment resulted in an increase in the degree of hydrolysis of the enzymatic reaction while the high-pressure carbon dioxide processing showed an inhibition effect on the enzymatic hydrolysis of egg white proteins to some extent. The antioxidant activity of the obtained hydrolysates was improved by ultrasound pretreatment of egg white proteins at the pH 8.3. Thus, the combination of ultrasound pretreatment at the pH 8.3 and subsequent enzymatic hydrolysis with alcalase at 50°C and pH 8.0 could offer a new approach to the improvement of the functional properties of egg white proteins and their biological activity. [Projekat Ministarstva nauke Republike Srbije, br. E!6750

The production of bioactive peptides from egg white proteins (EWPs) and their separation are emerging areas with many new applications. The objective of this study was to compare antioxidant activity of three distinct EWP hydrolysates and their peptide fractions prepared by membrane ultrafiltration using membranes with 30, 10 and 1 kDa molecular weight cutoff. The hydrolysates were obtained by thermal and ultrasound pretreated EWPs hydrolyzed with a bacterial protease, Alcalase. It appeared that the pretreatment significantly affected peptide profiles and antioxidant activity of the hydrolysates measured by ABTS, DPPH and FRAP methods. The hydrolysate prepared using alcalase and ultrasound pretreatment at 40 kHz-15 min has shown to be the most effective in scavenging both DPPH and ABTS radicals (28.10±1.38 and 79.44±2.31%, respectively). It has been noticed that this hydrolysate had a nutritionally more adequate peptide profile than the other hydrolysates with a much lower amount of peptides <1 kDa (11.19±0.53%) and the greatest content of the peptide fraction in the molecular weight (MW) range of 1-10 kDa (28.80±0.07%). This peptide fraction has shown the highest DPPH and ABTS antioxidant activity compared to all other fractions having a potential to be used as a functional food ingredient.

Pseudomonas aeruginosa was repeatedly reported as powerful producer of rhamnolipid biosurfactants as well as producer of hydrolytic enzymes. In this study effects of four fermentation factors were evaluated using response surface methodology and experiments were performed in accordance with a four-factor and five-level central composite experimental design. Investigated factors were: fermentation temperature, time of fermentation, concentration of sunflower oil and concentration of Tween® 80. The most important finding was that regression coefficients of the highest values were those that describe interactions between factors and that they differ for lipase and rhamnolipid production, which were both investigated in this study. Production of both metabolites was optimized and response equations were obtained, making it possible to predict rhamnolipid concentration or lipase activity from known values of the four factors. The highest achieved rhamnolipid concentration and lipase activity were 138 mg dm-3 (sunflower oil concentration 0.8 %, Tween® 80 concentration 0.05 %, temperature 30°C, and fermentation time 72 h) and 11111 IU dm-3(sunflower concentration of 0.4 %, Tween® 80 concentration of 0.05 %, temperature of 30°C, and fermentation time of 120 h), respectively. [Projekat Ministarstva nauke Republike Srbije, br. E!6750 and br. III 46010

Finding a sustainable and ecofriendly methods for recalcitrant synthetic dyes removal is a researchers` major challenge. A carrier-free technique for commercial HRP immobilization is a focus of the present study. The immobilized biocatalyst, HRP-CLEAs with 580 U g-1 of the activity was obtained under the following immobilization conditions: precipitation reagent 80% ammonium sulphate, cross-linking reagent 1% of glutaraldehyde and protein-fedder, bovine serum albumin (BSA) concentration 5 mg ml-1. The obtained HRP-CLEAs showed great affinity towards model anthraquinone dye, C. I. Acid Violet 109. 88.4% of the dye was oxidized under the reaction conditions: pH 4, dye concentration 40 mg l-1 , H 2 O 2 concentration 1 mM and 0.1 U of HRP-CLEAs. The possibility of the immobilized biocatalyst application in five and eight oxidation cycles of the dye and pyrogallol (retained activity ~ 80%), respectively, indicates that HRP-CLEAs is an efficient and environmentally friendly biocatalyst with great potential in aromatic compounds removal from wastewater. This paper is a continuation of our earlier research related to HRP from horseradish extract immobilization in the form of CLEAs and the application in the wastewater colored with a synthetic anthraquinone dye treatment.