Sonia Couri

Hydrolytic enzyme production in solid-state fermentation by Aspergillus niger 3T5B8

Abstract A mixture containing polygalacturonase, cellulase, xylanase and protease enzymes was produced using Aspergillus niger 3T5B8 on different agroindustrial residues by solid-state fermentation and tested for vegetable oil extraction. The enzymic activities were evaluated using second-order empirical models from experimental data as a function of fermentation time and cellobiose concentration in the fermentation medium. The use of wheat bran as substrate without cellobiose addition and 42 h of fermentation were the most favourable conditions for producing the mixture of hydrolytic enzymes (polygalacturonase 30.75 U/ml, xylanase 30.62 U/ml, protease 5.27 U/ml). Another favourable condition was obtained when mango peel was used as substrate in the presence of 0.2% cellobiose and 24 h of fermentation (FPCAse 3.5 U/ml, xylanase 20.33 U/ml). Enzymic formulations with suitable polygalacturonase and FPCAse activities were favourable to extract oil from the pulp of tropical fruits and oleaginous seeds.

Finding stable cellulase and xylanase: evaluation of the synergistic effect of pH and temperature

Ethanol from lignocellulosic biomass has been recognized as one of the most promising alternatives for the production of renewable and sustainable energy. However, one of the major bottlenecks holding back its commercialization is the high costs of the enzymes needed for biomass conversion. In this work, we studied the enzymes produced from a selected strain of Aspergillus niger under solid state fermentation. The cellulase and xylanase enzymatic cocktail was characterized in terms of pH and temperature by using response surface methodology. Thermostability and kinetic parameters were also determined. The statistical analysis of pH and temperature effects on enzymatic activity showed a synergistic interaction of these two variables, thus enabling to find a pH and temperature range in which the enzymes have a higher activity. The results obtained allowed the construction of mathematical models used to predict endoglucanase, β-glucosidase and xylanase activities under different pH and temperature conditions. Optimum temperature values for all three enzymes were found to be in the range between 35°C and 60°C, and the optimum pH range was found between 4 and 5.5. The methodology employed here was very effective in estimating enzyme behavior under different process conditions.

Cashew apple juice stabilization by microfiltration

Abstract Cashew apple is a tropical fruit that presents high vitamin C content, rich flavour and aroma. Brazilian market of cashew apple juice is about 40,000 ton/y and it presents a low consumption at the international market. This work had the objective of studying the shelf-life stability of cashew apple juice clarified by microfiltration associated with enzymes, supposedly to present a lower astringency and a better physical stability. Cashew apple pulp was used as raw material. It was first hydrolysed and then microfiltered in a 0.3-μm pore size tubular membrane. Permeate juice was collected in a sterilised closed system and stored at room (30°C) and refrigeration (4°C) temperatures for 2 months. Ascorbic acid and tannin contents, haze, pH, acidity, soluble solids of the juice as well as microbiological counting were determined each 15 d. Juice storage at the lower temperature was appropriate for consumption after a 2-month shelf life, still as a vitamin C source and without any haze.

Selection of tannase-producing Aspergillus niger strains

The aim of this work was to select strains of Aspergillus niger for tannase production. Growth of colonies in plates with tannic acid-containing medium indicated their ability to synthesize tannase. Tannase activity was also measured in solid-state fermentation. A. niger 11T25A5 was the best tannase producer (67.5 U.g-1/72 hours of fermentation).

UTILIZATION OF AGROINDUSTRIAL RESIDUES FOR LIPASE PRODUCTION BY SOLID-STATE FERMENTATION

The aim of this work was to produce lipases by solid-state fermentation (SSF) using, as substrate, agroindustrial residue supplemented with by-products from corn oil refining process or olive oil. For a group of ten fungi strains selected in the first steps, the lipase activity obtained by SSF varied from 7.7 to 58.6 U/g of dry substrate (gds). Among the evaluated strains, the Aspergillus niger mutant 11T53A14 was selected by presenting the best enzymatic production. For the fermentation tests, two substrates were also investigated: wheat bran and corn cob, both supplemented with olive oil. The best results were obtained with wheat bran. Additionally, three industrial by-products from corn oil refining (soapstock, stearin and fatty acids) were evaluated as substitutes to the olive oil in the function of lipases production inducer. Among them, soapstock and stearin were the best inducers, whereas fatty acids presented an inhibitor effect. The highest lipase activities using soapstock, stearin and fatty acids were 62.7 U/gds, 37.7 U/gds and 4.1 U/gds, respectively.

Correlation between Agar Plate Screening and Solid-State Fermentation for the Prediction of Cellulase Production by Trichoderma Strains

The viability of converting biomass into biofuels and chemicals still requires further development towards the reduction of the enzyme production costs. Thus, there is a growing demand for the development of efficient procedures for selection of cellulase-producing microorganisms. This work correlates qualitative screening using agar plate assays with quantitative measurements of cellulase production during cultivation under solid-state fermentation (SSF). The initial screening step consisted of observation of the growth of 78 preselected strains of the genus Trichoderma on plates, using microcrystalline cellulose as carbon source. The 49 strains that were able to grow on this substrate were then subjected to a second screening step using the Congo red test. From this test it was possible to select 10 strains that presented the highest enzymatic indices (EI), with values ranging from 1.51 to 1.90. SSF cultivations using sugarcane bagasse and wheat bran as substrates were performed using selected strains. The CG 104NH strain presented the highest EGase activity (25.93 UI·g−1). The EI results obtained in the screening procedure using plates were compared with cellulase production under SSF. A correlation coefficient (R 2) of 0.977 was obtained between the Congo red test and SSF, demonstrating that the two methodologies were in good agreement.

Production of Biomass-Degrading Multienzyme Complexes under Solid-State Fermentation of Soybean Meal Using a Bioreactor

Biomass-degrading enzymes are one of the most costly inputs affecting the economic viability of the biochemical route for biomass conversion into biofuels. This work evaluates the effects of operational conditions on biomass-degrading multienzyme production by a selected strain of Aspergillus niger. The fungus was cultivated under solid-state fermentation (SSF) of soybean meal, using an instrumented lab-scale bioreactor equipped with an on-line automated monitoring and control system. The effects of air flow rate, inlet air relative humidity, and initial substrate moisture content on multienzyme (FPase, endoglucanase, and xylanase) production were evaluated using a statistical design methodology. Highest production of FPase (0.55 IU/g), endoglucanase (35.1 IU/g), and xylanase (47.7 IU/g) was achieved using an initial substrate moisture content of 84%, an inlet air humidity of 70%, and a flow rate of 24 mL/min. The enzymatic complex was then used to hydrolyze a lignocellulosic biomass, releasing 4.4 g/L of glucose after 36 hours of saccharification of 50 g/L pretreated sugar cane bagasse. These results demonstrate the potential application of enzymes produced under SSF, thus contributing to generate the necessary technological advances to increase the efficiency of the use of biomass as a renewable energy source.

Composição em ácidos graxos do óleo da polpa de açaí extraído com enzimas e com hexano

Acai (Euterpe oleracea Martius) is a typical palm tree from the Amazon, growing spontaneously in states of Para, Amazonas, Amapa and Maranhao. It has been highlighted by the potential of its products, especially because of the economic importance for the regional fruit growing. The acai fruits are very appreciated by their pulp flavour. In the acai pulp, there is a significant amount of lipids, around 53%, in a dry basis, turning out to be an excellent source of essential fatty acids. The main purpose of the present work was to establish the fatty acid content in the lipid fraction of acai pulp using high resolution gaseous chromatography. The acai oil was obtained by enzymatic technology in water has been indicated as an alternative for vegetable oils extraction from pulp of fruits. A significant difference was not observed in the composition of the fatty acids present in acai oil obtained from either process. In both cases, the oil is high in monounsaturated fatty acids (68% to 71%) and in polyunsaturated fatty acids (7.8% to 10.6%).

Keratinase Production by Three Bacillus spp. Using Feather Meal and Whole Feather as Substrate in a Submerged Fermentation

Three Bacillus species (B. subtilis LFB-FIOCRUZ 1270, B. subtilis LFB-FIOCRUZ 1273, and B. licheniformis LFB-FIOCRUZ 1274), isolated from the poultry industry, were evaluated for keratinase production using feathers or feather meal as the sole carbon and nitrogen sources in a submerged fermentation. The three Bacillus spp. produced extracellular keratinases and peptidases after 7 days. Feather meal was the best substrate for keratinase and peptidase production in B. subtilis 1273, with 412 U/mL and 463 U/ml. The three strains were able to degrade feather meal (62–75%) and feather (40–95%) producing 3.9–4.4 mg/ml of soluble protein in feather meal medium and 1.9–3.3 mg/ml when feather medium was used. The three strains produced serine peptidases with keratinase and gelatinase activity. B. subtilis 1273 was the strain which exhibited the highest enzymatic activity.

Enzymatic technology to improve oil extraction from Caryocar brasiliense camb. (Pequi) Pulp.

O presente estudo tem como objetivo comparar o rendimento e a qualidade do oleo da polpa de pequi obtido por dois processos distintos: no primeiro, a secagem da polpa, conduzida em secador de bandeja a 60oC, foi combinada com tratamento enzimatico e prensagem para extracao de oleo, no segundo, um processo mai simples foi realizado combinando-se a secagem da polpa ao sol seguida da prensagem a frio. Neste estudo, frutos de pequi in natura foram coletados no estado do Mato Grosso, Brasil. Os frutos foram auto-clavados a 121o C e armazenados sob refrigeracao. Um extrato enzimatico com atividades pectinase e CMCase foi utilizado para a hidrolise da polpa de pequi antes da extracao do oleo. O processo de extracao foi realizado por prensagem hidraulica, com ou sem incubacao enzimatica. O teor de oleo na polpa do pequi (45% w/w) e as caracteristicas fisico-quimicas do oleo foram determinados de acordo com metodos analiticos oficiais. O teor de acidos graxos livres, os indices de peroxido, de iodo e de saponificacao foram respectivamente de 1,46 mgKOH/g, 2,98 meq/kg, 49,13 e 189,40. A acidez e os valores de peroxido foram inferiores aos valores obtidos em amostras comerciais de oleo vegetal, respectivamente, 2,48 mgKOH/g, 5,22 meq/kg. A extracao aquosa apresentou menor eficiencia e promoveu uma maior oxidacao dos acidos graxos insaturados. Por outro lado, a polpa de pequi prensada, apos secagem ao sol, produziu um oleo de melhor qualidade. No entanto, sua eficiencia ainda e menor do que no processo combinado onde se aplicou o tratamento aquoso enzimatico seguido da prensagem. O processo combinado promove a hidrolise da parede celular e a reducao da viscosidade da polpa, contribuindo com pelo menos 20% de aumento na produtividade da etapa de extracao do oleo por prensagem.