The effects of hydrolysis condition on antioxidant activity of protein hydrolyzate from quinoa

In the present study, quinoa protein hydrolyzate was prepared using alcalase and pepsin enzymes. Then, the effect of different temperatures (40, 45, 50, and 55°C), periods of time (60, 120, 150, 180, and 210 min), and the ratio of enzyme to substrate (30, 60, and 90 Anson unit/kg protein) on degree of hydrolysis were examined. Also, the antioxidant activity was assessed using DPPH radical scavenging test, and investigated using a completely randomized design. According to results, the optimum condition to produce hydrolyzates with the highest degree of hydrolysis (24.65%) was 55°C, 210 min, with ratio of enzyme to substrate of 60 Anson unit/kg protein, The highest antioxidant activity (35.44) of protein hydrolyzed was achieved at 150 min, 50°C, and the ratio of enzyme to substrate 60 (Anson unit/kg protein). Moreover, there was no significant (p > 0.05) between the level of hydrolysis and the antioxidant activity was among different time and temperatures. In conclusion, the peptide derived from quinoa protein showed a sufficient antioxidant activity to be incorporated in food products

High salt-tolerant protease from a potential biocontrol agent bacillus pumilus M3-16

In this paper, we investigate the characterization and evaluation of the antifungal protease activity from a halotolerant strain M3-16 of Bacillus pumilus, earlier isolated from a shallow salt lake in Tunisia. Protease enzyme was highly induced by the pathogen tested in vitro (27.4 U/ml). This is the first report on high salt-tolerant protease from B. pumilus, since it was active at high salinity (from 5 to 30% NaCl, w/v) as well as in the absence of salinity. This enzyme showed optimal activity at 60 °C and pH 8. At 80 °C and 30 min, the enzyme retained up to 91% and it showed stability over a wide pH range (from pH 5 to 11). The enzyme was found to be monomer with an estimated molecular mass of 31 kDa. The amino acid sequence showed high similarity (94%) to ATP-dependent protease from B. pumilus strain ATCC 7061. Thus, our alkaline thermostable and high salt-tolerant protease induced by a phytopathogenic fungus, could be useful for application in diverse areas such as biotechnology alimentary and agronomy industries

Rice bran as a substrate for proteolytic enzyme production

Rice bran was used as the substrate for screening nine strains of Rhizopus sp. for neutral protease production by solid-state fermentation. The best producer, Rhizopus microsporus NRRL 3671, was used for optimizing the process parameters for enzyme production. Fermentation carried out with 44.44 % initial moisture content at a temperature of 30 C for 72 h was found to be the optimum for enzyme secretion by the fermenting organism. While most of the carbon supplements favored enzyme production, addition of casein resulted in a marginal increase in protease yield. Fermentation was then carried out under optimized conditions to obtain the crude extract of the enzyme, which was partially purified by precipitation and dialysis. A 3-fold increase in the enzyme purity was achieved in this manner. The enzyme was found to be a metalloprotease, being activated by Mn2+, with maximal activity at a temperature of 60 C and pH 7.0.<br>Farelo de arroz foi utilizado como substrato para seleção de nove linhagens de Rhizopus sp. com vistas a produção de protease neutra. A linhagem que apresentou maior produtividade da enzima foi Rhizopus microsporus NRRL 3671, sendo utilizada na otimização dos parâmetros do processos e produção da enzima. As condições otimizadas para produção da enzima foram 44% de umidade inicial, temperatura de 30ºC e 72h de fermentação.A suplementação do farelo de arroz com uma fonte de carbono favoreceu a produção da enzima, porém a adição de caseína resultou em um aumento marginal do rendimento em protease. Condições otimizadas foram utilizadas para obtenção do extrato cru da enzima que foi parcialmente purificado por precipitação e diálise. A enzima purificada teve sua atividade incrementada 3 vezes. A enzima foi classificada como metalo-protease, sendo ativada pelo Mn2+ , sendo que sua atividade máxima foi obtida a temperatura de 60ºC e a pH 7.0