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Technological processes mediated by microorganisms and enzymes are promising alternatives for treatment of recalcitrant residues. Keratinases hydrolyze keratin, the primary component of some wastes generated in many industrial activities. The present study was designed to evaluate strategies for obtaining keratinases produced by fungi using submerged fermentation and two residues as substrates, chicken feathers and swine hair. Two fungi isolated from feather residues showed potential for keratinase production, Fusarium oxysporum and Aspergillus sp. These were subjected to submerged fermentation using chicken feathers and swine hair prepared in three conditions (microbial concentration reduction, sterilization and hydrogen peroxide). The residual mass was quantified and tested for keratinase production. The most potent enzymatic extract was used in the precipitation technique with salts and organic solvents. The best results of enzymatic activity were obtained using F. oxysporum, on the 6thday of fermentation, obtaining 243.25 U mL −1 using sterilized swine hair as the substrate. Aspergillus sp. showed the highest keratinolytic activity on the 9thday, 113.50 U mL −1 using feathers as the substrate. The highest degradation percentage was 59.20% (w/w) in swine hair and the precipitation technique, with relative activities close to 50%. The results are promising for the application of residues and microorganisms in biotechnological processes of economic and environmental interest.

This study aimed at evaluating the activity of peroxidases after ultrasound and microwave radiation exposure as an alternative to the wastewater treatment improvement. The results showed that after treatment with ultrasound using a power of 30% and a temperature of 55 °C was obtained an increase in relative activity, 129.5% in the enzyme from rice bran, 147.9% in the enzyme from soybean meal and 102.4% in the enzyme from horseradish. Using microwave radiation, the highest relative activity (107.4%) was observed for the peroxidase extracted from rice bran with 10 seconds of reaction time and a reaction temperature of about 50 °C. The data obtained in this study suggest that the ultrasonic bath and microwave are adequate for conducting reactions catalyzed by peroxidases because it was possible to increase their activity during the performed tests. Preliminary tests of enzyme application showed that the highest color removal occurred using 3 mL of the enzyme extract from rice bran and H 2 O 2 concentrations of 40 mg L -1 . This condition resulted in a color removal of about 40%.

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In this study, we evaluated the concentration of lipases from Aspergillus niger using efficient and low-cost methods aiming at application in the treatment of waste cooking oils. The change in ionic strength of the medium by the addition of salt and precipitation with ethanol increased the specific activity from 2.90 to 28.50 U/mg, resulting in a purification factor of 9.82-fold. The use of acetone resulted in a specific activity of 33.63 U/mg, resulting in a purification factor of 11.60-fold. After that, the concentrated lipase was used in the hydrolysis of waste cooking oil and 753.07 and 421.60 µmol/mL of free fatty acids were obtained for the enzyme precipitated with ethanol and acetone, respectively. The hydrolysis of waste cooking oil catalyzed by homemade purified lipase in ultrasonic media can be considered a pretreatment of oil by converting a significant amount of triglycerides into free fatty acids.

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The present study was designed to evaluate the scaling process used to obtain fungi and enzymes from Trichoderma koningiopsis to produce bioherbicides with low levels of genotoxicity using a stirred-tank bioreactor. We measured fungal biomass and activities of enzymes (amylase, cellulase, lipase and peroxidase). Fermentative products were applied to weeds (Bidens pilosa and Euphorbia heterophylla), and the bioherbicide effect was evaluated. We found greater elevations of peroxidase and lipase activity in the scaled-up models than in those at small scale (0.15 L), even with less biomass, suggesting that the scaling was cost-beneficial in terms of enzymatic yield. Bioherbicide activity tests showed up to 100-80% phytotoxic effects on weeds that were resistant to synthetic herbicide. A genotoxicity study of the fermented extract performed in Allium cepa meristem cells showed low genotoxicity and no DNA damage. Our findings point to new perspectives regarding bioherbicides derived from fungal fermentation and enzyme yield technology, aimed at sustainable and ecofriendly agriculture.

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