ABSTRACT
The aim of the present work was to select filamentous fungi isolated from diverse substrates to obtain the strains with potential to produce the hydrolytic enzymes. From a total of 215 strains, seven strains from the soils, six from the plants and one from sugarcane bagasse were selected and identified as belonging to the Trichoderma, Penicillium and Aspergillus genera. The best hydrolytic activities obtained by semi-solid fermentation using these strains were approximately: 35; 1; 160; 170 and 120 U/gdm (CMCase, FPase, β-glucosidase, xylanase and polygalacturonase, respectively), demonstrating their potential to synthesize the enzymes compared with the results reported in the literature.
ABSTRACT
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.
O objetivo deste trabalho foi produzir lipases por fermentação em estado sólido (FES) utilizando, como substrato, resíduo agroindustrial enriquecido com subprodutos do processo de refino do óleo de milho ou óleo de oliva. Para um conjunto de dez linhagens de fungos selecionadas nas primeiras etapas, a atividade lipásica obtida por FES variou de 7,7 a 58,6 U/g de substrato seco (gss). Dentre as linhagens avaliadas, o mutante Aspergillusniger 11T53A14 foi selecionado por apresentar a melhor produção enzimática.Para os testes de fermentação, dois substratos foram investigados: farelo de trigo e sabugo de milho, ambos enriquecidos com óleo de oliva. Nestes testes, os melhores resultados foram obtidos com farelo de trigo. Adicionalmente, três subprodutos industriais do refino do óleo de milho (borra, estearina e ácidos graxos) foram avaliados como substitutos do óleo de oliva na função de indutor para a produção de lipases. Dentre eles, borra e estearina demonstraram ser melhores indutores, enquanto ácidos graxos apresentaram um efeito inibidor. As mais altas atividades lipásicas utilizando borra, estearina e ácidos graxos foram 62,7 U/gss, 37,7 U/gss e 4,1 U/gss, respectivamente.