ABSTRACT. The use of probiotics and exogenous enzymes in fish feed is a promising alternative to improve animal performance. This study evaluated the feasibility of applying Bacillus sp. SMIA-2 and its enzymes as supplements in the diet for juvenile tilapia. The effect of adding different concentrations of Bacillus sp. SMIA-2 and its enzymes in food on zootechnical development, intestinal morphometry of animals was analyzed. The bacteria could be recovered from the intestines of animals, demonstrating its ability to survive gastric and bile acids. The comparative study of SMIA-2 with commercial products showed a significant effect on individual food intake, final weight and weight gain in all treatments. Gut length, villus height and intestinal coefficient were an advantage of SMIA-2 compared to commercial products and the control group. Therefore, the inclusion of Bacillus sp. SMIA-2 and its enzymes in fish feed may represent a viable alternative to improve animal development and significantly increase intestinal villi, contributing to nutrient absorption and animal health. ABSTRACT performance sp SMIA2 SMIA 2 SMIA- tilapia analyzed acids intake treatments length group Therefore villi health

Abstract This study assessed the effect of different concentrations of (Capsicum baccatum var. pendulum) on lipid oxidation, microbiological and sensorial characteristics of four different formulations of fresh pork sausage and smoked (control, F1, F2, F3), with the substitution of industrial antioxidant for the natural one. Lipid oxidation values (TBARS) did not display significant differences (P>0.05) among the treatments, and at different times of analysis (storage). The only significant differences were between the different types of sausages (fresh and smoked). The enumeration of all the microorganisms searched was below the standard required by Brazilian laws. F2 formula received the highest scores for acceptance but did not display significant difference (P>0.05) as it refers to taste, with the remaining formulations. The substitution of the synthetic antioxidant by the natural one displayed similar results, demonstrating that the natural extract from the balloon pepper does not affect the technological and sensorial properties of the sausages, which proves the viability of the product.

Abstract Microbial proteases, especially from Bacillus spp., have enormously been exploited for a broad variety of applications such as for physiological processes, food and feedstuff, detergents, as well as in the pharmaceutical and leather. In this work, proteases produced by the thermophilic Bacillus sp. SMIA-2 submerged cultures were spray-dried in an attempt to improve its stability for applications in industry. The enzymatic extract was dried using drying adjuvants, and optimal conditions for preserving enzymatic activity were studied following a statistical experimental design. The spray process factors studied were the drier air inlet temperature and the adjuvants concentrations. The responses analyzed were the enzymatic activity and mass recovered of the powder after spray drying. Additionally, the stability of the powder was assessed during 180 days at room temperature. The results revealed that satisfactory levels of enzymatic activity were obtained when 0.5% (w/v) carboxymethylcellulose and 1.0% (w/v) maltodextrin were incorporated to enzymes solutions and the spray drier inlet temperature was 110 ºC. Furthermore, this dried protease extracts showed potential for future commercial applications because of their stability at room temperature for 180 days.

Resumo: O objetivo deste trabalho foi avaliar tratamentos térmicos e químicos com Ca2+, no controle da atividade da poligalacturonase e de seus efeitos no rendimento de extração e no grau de esterificação da pectina do albedo da casca de maracujá-amarelo (Passiflora edulis). Utilizaram-se cascas de frutos com coloração verde-clara, as quais foram lavadas, sanitizadas, trituradas e deixadas em repouso em água, para suspensão do albedo. O albedo foi recolhido e submetido à temperatura de 90oC a 30, 60 e 120 min, ou a concentrações de cálcio de 0,01 e 1% durante 1 hora de agitação de 400 rpm, em temperatura ambiente. Realizou-se, também, o tratamento térmico do extrato enzimático bruto obtido do albedo a 65, 75 e 85°C. O tratamento térmico do albedo a 90°C não inativou a poligalacturonase após 120 min. A inativação da enzima extraída do albedo ocorreu após incubação a 65, 75 e 85°C por 30, 20 e 10 min, respectivamente. O tratamento com íons de cálcio a 1% promoveu o bloqueio enzimático e a redução no conteúdo de ácidos urônicos livres (AUL) da pectina. O tratamento do albedo de maracujá com solução de 1% de Ca2+ por 1 hora inibe a atividade da poligalacturonase e reduz o conteúdo de AUL.

Abstract: The objective of this work was to evaluate the use of thermal and chemical treatments with Ca2+, in order to control the activity of polygalacturonase and its effects on extraction yield and degree of pectin esterification from albedo of yellow passion fruit (Passiflora edulis) rind. Rinds of fruit with light-green peel were washed, sanitized, grind, and left to stand in water for albedo suspension. Albedo was collected and subjected to a temperature of 90oC for 30, 60, and 120 min, or to calcium levels of 0.01 and 1% during 1 hour of stirring, at 400 rpm, at ambient temperature. Thermal treatment of the crude enzymatic extract obtained from the albedo at 65, 75, and 85oC was also performed. The thermal treatment of the albedo at 90oC did not inactivate polygalacturonase after 120 min. The inactivation of the enzyme extracted from the albedo occurred after incubation at 65, 75, and 85oC for 30, 20, and 10 min, respectively. The treatment with calcium ion solution at 1% promoted enzymatic inactivation and a decrease in the content of free carboxylic acids (FCA) of pectin. The treatment of passion fruit albedo with calcium Ca2+ solution at 1% for 1 hour inhibits the polygalacturonase activity and decreases the content of FCA.

Background This paper reports the production of cellulase by thermophilic Bacillus sp. SMIA-2 using sugarcane bagasse and corn steep liquor as substrates. Some biochemical properties of the enzyme were also assessed for the purposes of exploiting its potential in the detergent industry, as well as other suitable applications. Results Bacillus sp. produced cellulases when cultivated at 50°C in liquid cultures containing sugarcane bagasse and corn steep liquor. Maximum avicelase (0.83 U mL-1) and CMCase (0.29 U mL-1) activities were reached in 120 h and 168 h of culturing time, respectively. The avicelase and CMCase presented an optimum activity at pH of 7.5 and 8.0, respectively. The maximum stability of avicelase and CMCase was observed at a pH range between 6.5-8.0 and 7.0-9.0 respectively, where they retained more than 70% of their maximum activities after incubation at room temperature for 3 h. The optimum temperature of avicelase and CMCase was 70°C, and both enzymes remained 100% stable until the treatment at 60°C for 1 h. Bacillus sp. cultures also released proteases into the culture medium, but the cellulases were resistant to protease digestion. The compatibility of cellulases varied with each laundry detergent tested, being more stable in the presence of Ultra Biz® and less with Ariel®. In addition, the enzyme was stable in sodium dodecyl sulfate and RENEX-95, and was inhibited by TritonX-100 and H2O2. Conclusions The properties presented by Bacillus sp. SMIA-2 suggest that this organism might become a potential source of lignocellulose-degrading enzymes for industrial applications such as in the detergent industry.

This study aimed at evaluating the bacteriological effects of the treatment of sheep meat contaminated with total coliforms, coliforms at 45 °C and Salmonella spp. by using irradiation at doses of 3 kGy and 5 kGy. Thirty sheep meat samples were collected from animals located in Rio de Janeiro State, Brazil, and then grouped in three lots including 10 samples: non-irradiated (control); irradiated with 3 kGy; and irradiated with 5 kGy. Exposure to gamma radiation in a 137Cs source-driven irradiating facility was perfomed at the Nuclear Defense Section of the Brazilian Army Technological Center (CTEx) in Rio de Janeiro. The samples were kept under freezing temperature (-18 °C) until the analyses, which occurred in two and four months after irradiation. The results were interpreted by comparison with the standards of the current legislation and demonstrated that non-irradiated samples were outside the parameters established by law for all groups of bacteria studied. Gamma irradiation was effective in inactivating those microorganisms at both doses tested and the optimal dose was achieved at 3 kGy. The results have shown not only the need for sanitary conditions improvements in slaughter and processing of sheep meat but also the irradiation effectiveness to eliminate coliform bacteria and Salmonella spp.

Este trabalho foi realizado com o objetivo de avaliar o efeito de atmosferas controladas contendo diferentes concentrações de oxigênio sobre a atividade das enzimas β-galactosidase e pectina metilesterase, e sobre a cor da casca e a firmeza da polpa de mamões 'Golden'. Os frutos foram mantidos por 36 dias, nas seguintes atmosferas controladas: 1% de O2 e 0,03% CO2 com adsorvedor de etileno, 3% de O2 e 0,03% de CO2 com adsorvedor de etileno, 5% O2 e 0,03% de CO2 com adsorvedor de etileno e atmosfera ambiente sem adsorvedor de etileno. A UR e a temperatura foram mantidas entre 85-95% e a 13º C, respectivamente. Os frutos estocados sob atmosfera de 1% de O2 e 0,03% CO2 apresentaram retardamento nas atividades das enzimas β-galactosidase e pectina metilesterase comparado com os frutos estocados nas outras atmosferas avaliadas. Os frutos armazenados sob atmosfera de 1% de O2 e 0,03% O2 também apresentaram atraso no desenvolvimento da cor da casca e amolecimento da polpa.

This study was carried out with the objective to evaluate the effect of controlled atmospheres containing different concentration of oxygen on the activity of β-galactosidase and pectinmethylesterase enzymes, on the skin color and pulp firmness in 'Golden' papaya. The fruits were kept for 36 days under the following controlled atmospheres: 1% of O2 and 0.03% CO2 with ethylene absorber, 3% of O2 and 0.03% of CO2 with ethylene absorber, 5% O2 and 0.03% of CO2 with ethylene absorber and environmental atmosphere without ethylene absorber. Relative humidity was set at the range 85-95% and temperature maintained at 13ºC. Fruit stored under atmospheres of 1% of O2 and 0.03% CO2 had a β-galactosidase and pectimethylesterase activities delayed compared with the fruits storage under the other atmospheres evaluated. There was also, a delay in the development of color and pulp softening in fruits stored under atmospheres of 1% of O2 and 0.03% O2.

As enzimas proteolíticas termoestáveis produzidas por microrganismos do gênero Bacillus possuem grande importância comercial, sendo sua aplicação predominante (35%) na indústria de detergentes. Neste trabalho, foi avaliada a produção de proteases pelo termofílico Bacillus sp. SMIA-2, utilizando-se substratos de baixo custo. A fim de verificar a utilidade da protease para aplicações industriais, a estabilidade e a atividade da enzima a diferentes valores de pH e temperatura foram também estudadas. A atividade da protease secretada por Bacillus sp. SMIA-2 em culturas submersas contendo 0,5% (m/v) de pectina de maçã, 0,1% (m/v) de proteínas do soro e 0,3% (m/v) de água de maceração de milho foi máxima após 24 h de incubação da cultura, com níveis de 54,3 U.mg-1 Proteína. A redução na concentração da pectina para 0,3% (m/v) e o aumento nos níveis das proteínas do soro para 0,3% (m/v) no meio de cultura aumentaram a produção da protease, que alcançou sua máxima atividade em 30 h, com níveis de 72,2 U.mg-1 Proteína. Estudos sobre a protease revelaram que as suas características mais importantes foram a alta temperatura ótima para atividade da enzima (70 °C) e a alta estabilidade em uma grande faixa de pH. A protease reteve em torno de 80% de sua atividade original quando incubada à temperatura ambiente por 2 h na faixa de pH entre 6,0 e 12,0. Essas propriedades constituem importantes vantagens para um possível uso da enzima em indústrias de detergentes.

The thermostable proteolytic enzymes produced by the genus Bacillus are commercially very important, being predominantly applied (35%) in detergents. In this work the production of proteases by a thermophilic Bacillus sp. SMIA-2 using low-cost substrates was evaluated. In order to assess the use of the protease for industrial use, the stability of the enzyme activity at different pH values and temperatures was also studied. The protease activity secreted by Bacillus sp. SMIA-2 in submerged cultures containing 0.5% (w/v) apple pectin, 0.1% (w/v) whey protein concentrate and 0.3% (w/v) corn steep liquor reached a maximum after 24 h, with levels of 54.3 U.mg-1 protein. A reduction in the pectin concentration to 0.3% (w/v) and increase in the whey protein levels to 0.3% (w/v) in the culture medium improved the protease production, which reached a maximum after 30 h, with levels of 72.2 U.mg-1 protein. Studies on the characterization of the protein revealed that the most important kinetic properties of the enzyme were the high optimal temperature (70 °C) and high stability in a very broad pH range. The protease retained about 80% of its original activity when incubated at room temperature for 2 h in a pH range between 6.0 - 12.0. These properties represent important advantages for the possible use of the enzyme in detergent industries.

A produção de proteases e α-amilase pelo termofílico Bacillus sp. cepa SMIA-2 cultivado em culturas líquidas contendo 0,25% (w/v) de amido como fonte de carbono alcançou o máximo em 18 horas (47 U.mg-1 Proteína) e 36 horas (325 U.mg-1 Proteína), respectivamente. A suplementação do meio de cultura com proteínas do soro de leite (0,1%, w/v) e água de maceração de milho (0,3%, w/v) não apenas aumentou a atividade de ambas as enzimas como tornou possível a produção simultânea das mesmas. Nestas condições, as maiores atividades da α-amilase e das proteases ocorreu após 18 horas de fermentação, com níveis de 401 U.mg-1 proteína e 78 U.mg-1 proteína, respectivamente. A compatibilidade das enzimas produzidas com detergentes comerciais foi investigada. Na presença do detergente Campeiro® a atividade da α-amilase aumentou, enquanto a atividade da protease decresceu em torno de 27%. Estas enzimas melhoraram o poder de lavagem do detergente Campeiro®. Elas removeram manchas de gema de ovo e de molho de tomate, quando utilizadas juntas com este detergente.

Protease and α-amylase production by a thermophilic Bacillus sp. SMIA-2 cultivated in liquid cultures containing 0.25% (w/v) starch as a carbon source reached a maximum at 18 hours (47 U.mg-1 Protein) and 36 hours (325 U.mg-1 Protein), respectively. Culture medium supplementation with whey protein concentrate (0.1%, w/v) and corn steep liquor (0.3%, w/v) not only improved the production of both enzymes but also enabled them to be produced simultaneously. Under these conditions, α-amylase and protease production reached a maximum in 18 hours with levels of 401 U.mg-1 protein and 78 U.mg-1 protein, respectively. The compatibility of the enzymes produced with commercial laundry detergent was investigated. In the presence of Campeiro® detergent, α-amylase activity increased while protease activity decreased by about 27%. These enzymes improved the cleaning power of Campeiro® detergent since they were able to remove egg yolk and tomato sauce stains when used in this detergent.

Este trabalho foi realizado com o objetivo de investigar o comportamento das enzimas pectina metilesterase (PME) e β-galactosidase (β-Gal) durante o amadurecimento do mamão cv.'Golden'. Mamões com 15% de cor amarela foram estocados em câmara de refrigeração a 20ºC e 85-95 % UR, por um período de 11 dias. Durante este período de estocagem, foi determinada a cor da casca, firmeza e pH da polpa dos frutos, bem como a atividade das enzimas PME e β-Gal. A atividade da PME, observada ao longo do amadurecimento do mamão, indicou que esta enzima participou do processo de hidrólise da parede celular, principalmente no início do amadurecimento dos frutos. Já a atividade da β-Gal aumentou, de maneira não gradual, do primeiro dia até o final do armazenamento, quando alcançou seu valor máximo. Uma redução drástica na firmeza e no pH da polpa ocorreu nos três primeiros dias de armazenamento. Neste período, os frutos apresentaram coloração com valores do ângulo hue próximos de 80, a qual corresponde a uma coloração amarela. Verificou-se que a PME atua de modo efetivo no amadurecimento do mamão, mas a redução precoce em sua atividade indica que a β-Gal tem também um papel fundamental na rápida perda de firmeza pelo mamão cv. Golden.

This work was carried out with the objective to investigate the behavior of the enzymes pectinmethylesterase (PME) and β-galactosidase (β-Gal) during the ripening of the papaya 'Golden'. The fruits with 15% of yellow peel color were stored in a cold chamber at 20ºC and 85-95 % RH for 11 days. During this stored period it was determined the skin color, pulp firmness and pH. The PME activity observed during the papaya storage showed that this enzyme participated in the hydrolyze process of the cell wall mainly at the beginning of the ripening. The β-Gal activity increased from the 1th day to the end of stored period where reached the maximum activity, although this increase was not gradual. A decrease in the pulp firmness and pH occurred until the 3th day of storage. In this same period, the fruits showed peel color with hue angle values around 80, which corresponds to yellow color. It was verified that the PME acts effectively in the ripening of papaya, however, the decrease in the activity of this enzyme in early periods of storage indicates that the β-Gal has an important role in the firmness loss of papaya cv. Golden.

A produção de poligalacturonase pelo termofílico Bacillus sp. SMIA-2 cultivado em culturas líquidas contendo 0,5% (p/v) de pectina de maçã e suplementado com 0,3% (p/v) de água de maceração de milho foi máxima em 36 horas com níveis de 39 U.mL-1. O aumento da concentração da pectina de maçã e da água de maceração de milho no meio de cultura de 0,5 e 0,3%, respectivamente, para 0,65%, afetou de maneira marcante a produção da poligalacturonase, cuja atividade aumentou cerca de quatro vezes, atingindo o valor máximo de 150,3 U.mL-1. Estudos sobre a caracterização da poligalacturonase revelaram que a temperatura para atividade ótima desta enzima foi entre 60-70 °C. Em relação à termoestabilidade da enzima, a poligalacturonase manteve sua atividade em torno de 82 e 63% a 60 e 70 °C, respectivamente, após 2 horas de incubação. O pH para atividade ótima da enzima foi 10,0. Após a incubação da solução enzimática bruta a pH 8,0 por 2 horas à temperatura ambiente, foi observado um decréscimo em torno de 29% de sua atividade original. À pH 10,0 o decréscimo na atividade foi de 25%.

Polygalacturonase production by the thermophilic Bacillus sp. SMIA-2 cultivated in liquid cultures containing 0.5% (w/v) apple pectin and supplemented with 0.3% (w/v) corn steep liquor, reached its maximum after 36 hours with levels of 39 U.mL-1. The increase in apple pectin and corn steep liquor concentrations in the medium from 0.5 and 0.3%, respectively, to 0.65%, markedly affected the production of polygalacturonase, whose activity increased four times, reaching a maximum of 150.3 U.mL-1. Studies on polygalacturonase characterization revealed that the optimum temperature of this enzyme was between 60-70 °C. Thermostability profile indicated that the enzyme retained about 82 and 63% of its activity at 60 and 70 °C, respectively, after 2 hours of incubation. The optimum pH of the enzyme was found to be 10.0. After incubation of crude enzyme solution at room temperature for 2 hours at pH 8.0, a decrease of about 29% on its original activity was observed. At pH 10.0, the decrease was 25%.

Thermophilic Bacillus sp. SMIA-2, produced protease when grown on apple pectic, whey protein and corn step liquor medium, whose concentration was varied from 3 to 10 gL-1, according to the central composite design 2³. The experiments were conducted in shaker, at 50 °C, 150 rpm and initial pH 6.5. The results revealed that the culture medium affected both, cell growth and enzyme production. After graphical and numerical optimization procedure, the enzyme production reached its maximum value at 30 h fermentation, reaching, approximately, 70 U protein mg-1, suggesting that this process was partially associated to the growth.

A produção de poligalacturonase pelo termofílico Bacillus sp. SMIA-2, cultivado em meio líquido contendo pectina cítrica como única fonte de carbono, alcançou a sua máxima atividade enzimática em 30 horas, com níveis de 42 IU.mL-1. Entre as várias fontes orgânicas e inorgânicas de nitrogênio testadas, o sulfato de amônio foi a que proporcionou maior atividade da poligalacturonase. O aumento da concentração da pectina cítrica, no meio de cultura, acima de 0,5% não proporcionou um aumento da atividade da enzima. O microrganismo foi capaz de utilizar uma variedade de fontes de carbono, mas a atividade da poligalacturonase variou com cada fonte. Pectina de maçã foi a melhor fonte de carbono para a secreção da poligalacturonase (56 IU.mL-1), enquanto frutose e maltose não foram muito efetivas. Galactose, rafinose e glicose inibiram a síntese da enzima. Estudos sobre a caracterização da poligalacturonase revelaram que a temperatura ótima dessa enzima foi 70 ºC e que ela manteve 62 e 58% de sua atividade máxima quando incubada por 2 horas a 40 e 90 ºC, respectivamente. O pH ótimo para atividade da enzima foi 7,0. A enzima manteve 90 e 75% de sua atividade máxima quando incubada a pH 8,0 e 8,5, respectivamente, por 24 horas, à temperatura ambiente. A atividade enzimática foi estimulada pelos íons Mg2+ e Zn2+. Por outro lado, foi inibida pelos íons Cs+2, Hg+2, Li+2 e Sr+2.

Polygalacturonase production by thermophilic Bacillus sp strain SMIA-2 cultivated in liquid media containing citrus pectin as a carbon source reached the maximum activity at 30 hour with levels of 42 IU.mL-1. Among the various organic and inorganic nitrogen sources, ammonium sulphate was found to be the best for the enzyme secretion. An increase in the citrus pectin concentration in the medium of more than 0.5% did not enhance enzyme synthesis. The microorganism was capable of utilizing a wide range of carbon sources, but the activity of poligalacturonase varied depending on the carbon source. Apple's pectin was the best carbon source in the present study for polygalacturonase secretion (56 IU.mL-1) while fructose and maltose were not very effective. Rafinose and glucose inhibited the enzyme synthesis. Studies on the polygalacturonase characterization revealed that the optimum temperature of this enzyme was 70 ºC and that it maintained 62 and 58% of its activity when incubated at 40 ºC and 90 ºC for 2 hour, respectively. The optimum pH of the enzyme was found to be 7.0. The enzyme maintained 90% and 75% of its maximal activity when incubated at pH 8.0 and 8.5 for 24 hour at room temperature, respectively. The enzyme activity was enhanced in the presence of Mg2+ and Zn2+. On the other hand, the activity was inhibited in the presence of Cs+2, Hg+2, Li+2 and Sr+2.

Este trabalho foi realizado com o objetivo de avaliar a utilização da variável condutividade elétrica do meio desgomante como um indicador dos procedimentos de manejo do café despolpado durante a desgomagem do grão. Os experimentos foram conduzidos em três propriedades cafeeiras da região sudoeste da Bahia, utilizando Coffea arabica L., variedade Catuai Amarelo, para estudar o efeito de dois manejos de água do meio desgomante, dois manejos de revolvimento da solução desgomante e seis períodos de tempo em esquema fatorial. Um aumento da condutividade elétrica foi observado durante a desgomagem do grão, principalmente, no tratamento com revolvimento do meio. A troca de água do meio desgomante mostrou ser necessária, pois, ao longo da desgomagem, ocorreu um equilíbrio eletroquímico no meio, impedindo que a mucilagem continuasse a ser liberada do grão para o meio. Portanto, por meio da condutividade elétrica do meio, é possível indicar o momento em que se deve realizar a troca de água do tanque de desgomagem.

This research was carried out with the aim to evaluate the use of electric conductivity of the degumming medium as an indicator for management procedures of depulped coffee during degummming of the grain. The experiment was performed in three coffee properties in the Southwest region of Bahia, Brazil, using Coffea arabica L., Yellow Catuai variety. It was studied the effect of two water management of the degumming medium, two management of rummaging of the degumming solution, six time periods in factorial design. An increase on the electrical conductivity values was observed during degumming of coffee grain. Mainly in the treatment where the medium was rummaged. The water change of the degumming medium showed to be necessary since along the degumming process an electro-chemical equilibrium of the medium was achieved, avoiding that the mucilage was liberated from the grain to the medium. Therefore, the electrical conductivity was possible to indicate when the water change from the degumming tank must be done.

A otimização das condições de cultivo para a produção de α-amilase por um termofílico Bacillus sp. cepa SMIA-2 foi realizada. Além disso, a hidrólise enzimática do amido, proveniente de várias fontes tais como batata, mandioca e milho, foi também investigada. A produção de α-amilase por Bacillus sp. SMIA-2, cultivado em meio líquido contendo amido (5 g.L-1) como fonte de carbono e suplementado com 0,5 g.L-1 de proteínas do soro de leite e 2 g.L-1 de peptona, alcançou o máximo em 32 horas com níveis de 37 U.mL-1. O microrganismo foi capaz de utilizar diversas fontes de carbono, porém a atividade da amilase variou com cada fonte. O amido foi a melhor fonte de carbono para a secreção da amilase, enquanto a sacarose, lactose, maltose, galactose e glicose não foram muito efetivas. Uma redução na concentração de amido de até 2,5 g.L-1 no meio de cultura melhorou o crescimento do organismo e a atividade enzimática. Em altas concentrações de amido, a produção da enzima foi comparativamente menor. Em relação às fontes de nitrogênio orgânico e inorgânico, a peptona (2 g.L-1) foi considerada a melhor. Considerando a quantidade de proteínas do soro de leite no meio de cultivo, a concentração de 0,25 g.L-1 foi considerada a mais efetiva para a secreção da α-amilase pelo microrganismo. A produção máxima da atividade enzimática foi observada a 50 °C e pH 8,5. A enzima foi capaz de degradar todos os amidos testados. A hidrólise do amido de batata resultou num alto rendimento de açúcares redutores em comparação às outras fontes de amido. Amido solúvel e amido de mandioca ocuparam, respectivamente, a segunda e terceira posição em relação à liberação dos açúcares redutores, enquanto que a amilase estudada mostrou apenas uma ligeira afinidade pelo amido de milho. Com o aumento da temperatura da reação para 70 °C, a hidrólise dos substratos, com exceção do amido solúvel, resultou em maiores quantidades de açúcares redutores.

The optimization of culture conditions for the production of α-amylase by the thermophilic Bacillus sp strain SMIA-2 was carried out. In addition, the enzymatic hydrolysis of starch from several sources, such as potato, cassava and corn was investigated. Alpha-amylase production by Bacillus sp SMIA-2 cultivated in liquid cultures containing starch as carbon source and supplemented with 0.5 g.L-1 whey protein and 2.0 g.L-1 peptone reached a maximum of 37 U.mL-1 at 32 hours. The microorganism was capable of utilizing several carbon sources, but amylase activity varied with each source. Starch was the best carbon source for amylase secretion, while lactose, maltose, sucrose, galactose, and glucose were not very effective. Decreasing starch concentration in the medium to 2.5 g.L-1 improved organism growth and enzyme activity. At higher starch concentrations, enzyme production was comparatively lower. Among the various organic and inorganic nitrogen sources, peptone (2.0 g.L-1) was found to be the best. Regarding the amount of whey protein in the medium, the concentration of 0.25 g.L-1 was considered the most effective for amylase secretion by the organism. Maximum amylase activity was observed at 50 °C and pH 8.5. The enzyme was able to degrade all the starches tested. Potato starch hydrolysis resulted in a higher yield of reducing sugars in comparison to the other starches. Soluble and cassava starch were, respectively, in second and third positions regarding the liberation of reducing sugars, while the amylase studied showed a slightly lower affinity for corn starch. Increasing the reaction temperature to 70 °C resulted in higher levels of reducing sugars after the hydrolysis of the substrates, except for soluble starch.