Resumo
The ability of four Aspergillus strains for biosynthesis of kojic acid was evaluated among which Aspergillus terreus represented the highest level (2.21 g/L) of kojic acid production. Improvement kojic acid production ability of A. terreus by random mutagenesis using different exposure time to ultraviolet light (540 min) was then performed to obtain a suitable mutant of kojic acid production (designated as C5-10, 7.63 g/L). Thereafter, design of experiment protocol was employed to find medium components (glucose, yeast extract, KH2PO4 (NH4)2SO4, and pH) influences on kojic acid production by the C5-10 mutant. A 25-1 fractional factorial design augmented to central composite design showed that glucose, yeast extract, and KH2PO4 were the most considerable factors within the tested levels (p < 0.05). The optimum medium composition for the kojic acid production by the C5-10 mutant was found to be glucose, 98.4 g/L; yeast extract, 1.0 g/L; and KH2PO4, 10.3 mM which was theoretically able to produce 120.2 g/L of kojic acid based on the obtained response surface model for medium optimization. Using these medium compositions an experimental maximum Kojic acid production (109.0 ± 10 g/L) was acquired which verified the efficiency of the applied method.(AU)
Resumo
To optimize the medium for high zofimarin production, sucrose maltose, glucose, tryptone and peptone were used in an orthogonal array design experiment, where the highest value of zofimarin produced was 25.6 µg/mL. This value was about 3 times higher than that obtained with Czapek yeast extract (CzYE) culture medium. A study with Plackett-Burman design showed that sucrose, maltose, glucose and NaNO3 were significant factors in zofimarin production. Further studies using central composite design (CCD) showed the significance of glucose and the interactions of these critical components affecting zofimarin production. Multiple regression analysis of the data yielded a poor fit as shown by the mismatch of the model with these variable factors. When a polynomial equation was applied, the maximum zofimarin production was predicted to be 201.9 µg/mL. Experimental verification yielded a much lower amount of zofimarin, at around 70 µg/mL. Reconsideration of the CCD data and repetition of some runs with high zofimarin production resulted in reproducible zofimarin yield at 79.7 µ/mL. Even though the amount was lower than the predicted value, the medium optimization study was considered to be quite successful as the yield increased to around 8 times that obtained with the original CzYE culture medium.(AU)
Assuntos
Antifúngicos/metabolismo , Meios de Cultura/química , Endófitos/metabolismo , Xylariales/metabolismo , Indenos/metabolismoResumo
The present work was aimed at optimizing a culture medium for biomass production and phenolic compounds by using Ganoderma lucidum. The culture was optimized in two stages; a Plackett-Burman design was used in the first one for identifying key components in the medium and a central composite design was used in the second one for optimizing their concentration. Both responses (biomass and phenolic compounds) were simultaneously optimized by the latter methodology regarding desirability, and the optimal concentrations obtained were 50.00 g/L sucrose, 13.29 g/L yeast extract and 2.99 g/L olive oil. Maximum biomass production identified in these optimal conditions was 9.5 g/L and that for phenolic compounds was 0.0452 g/L, this being 100% better than that obtained in the media usually used in the laboratory. Similar patterns regarding chemical characterization and biological activity towards Aspergillus sp., from both fruiting body and mycelium-derived secondary metabolites and extracts obtained in the proposed medium were observed. It was shown that such statistical methodologies are useful for optimizing fermentation and, in the specific case of G. lucidum, optimizing processes for its production and its metabolites in submerged culture as an alternative to traditional culture.(AU)
Assuntos
Otimização de Processos/métodos , /análise , Fenol/química , Aspergillus/ultraestrutura , Ganoderma/ultraestruturaResumo
The use of the filamentous fungus, Ashbya gossypii, to improve riboflavin production at an industrial scale is described in this paper. A riboflavin overproducing strain was isolated by ultraviolet irradiation. Ten minutes after spore suspensions of A. gossypii were irradiated by ultraviolet light, a survival rate of 5.5% spores was observed, with 10% of the surviving spores giving rise to riboflavin-overproducing mutants. At this time point, a stable mutant of the wild strain was isolated. Riboflavin production of the mutant was two fold higher than that of the wild strain in flask culture. When the mutant was growing on the optimized medium, maximum riboflavin production could reach 6.38 g/l. It has even greater promise to increase its riboflavin production through dynamic analysis of its growth phase parameters, and riboflavin production could reach 8.12 g/l with pH was adjusted to the range of 6.0-7.0 using KH2PO4 in the later growth phase. This mutant has the potential to be used for industrial scale riboflavin production.
Resumo
The present study reports statistical medial optimization for chitinase production by a novel bacterial strain isolated from soil recently, which the name Chitinolyticbacter meiyuanensis SYBC-H1 is proposed. A sequential statistical methodology comprising of Plackett-Burman and response surface methodology (RSM) was applied to enhance the fermentative production of chitinase, in which inulin was firstly used as an effective carbon source. As a result, maximum chitinase activity of 5.17 U/mL was obtained in the optimized medium, which was 15.5-fold higher than that in the basal medium. The triplicate verification experiments were performed under the optimized nutrients levels which indicated that it well agreed with the predicted value.
Resumo
Cellulosimicrobium cellulans is one of the microorganisms that produces a wide variety of yeast cell wall-degrading enzymes, -1,3-glucanase, protease and chitinase. Dried cells of Saccharomyces cerevisiae were used as carbon and nitrogen source for cell growth and protease production. The medium components KH2PO4, KOH and dried yeast cells showed a significant effect (p 0.05) on the factorial fractional design. A second design was prepared using two factors: pH and percentage of dried yeast cells. The results showed that the culture medium for the maximum production of protease was 0.2 g/l of MgSO4.7H2O, 2.0 g/l of (NH4)2SO4 and 8% of dried yeast cells in 0.15M phosphate buffer at pH 8.0. The maximum alkaline protease production was 7.0 ± 0.27 U/ml over the center point. Crude protease showed best activity at 50°C and pH 7.0-8.0, and was stable at 50°C.
Cellulosimicrobium cellulans é um microrganismo que produz uma variedade de enzimas que hidrolisam a parede celular de leveduras: -1,3-glucanase, protease e quitinase. Células desidratadas de Saccharomyces cerevisiae foram usadas como fonte de carbono e nitrogênio para o crescimento celular e produção de protease. Os componentes do meio de cultura: KH2PO4, KOH e células de levedura desidratadas mostraram efeitos significativos (p 0,05) no planejamento experimental fracionário. Um segundo planejamento foi preparado usando dois fatores: pH e porcentagem de células de levedura desidratadas. Os resultados mostraram que o meio de cultura para a produção máxima de protease foi 0,2 g/L de MgSO4.7H2O; 2,0 g/L de (NH4)2SO4 e 8% de células de levedura desidratadas em tampão fosfato 0,15M e pH 8,0. A produção máxima de protease alcalina foi 7,0 ± 0,27 U/mL no ponto central. A protease bruta apresentou atividade ótima a 50 °C e pH 7,0-8,0; e foi estável a 50°C.
Resumo
In recent years, xylanases have expanded their use in many processing industries, such as pulp and paper, food and textile. Thermomyces lanuginosus IOC-4145 was able to produce a very high level of cellulase-free xylanase in shaken cultures using corncob as substrate (500 U/mL). An optimization of the medium composition in submerged fermentation was carried out aiming at a low cost medium composition for enzyme production. Statistical experiment design was employed for this purpose, pointing out corncob as the most important parameter, which affects enzyme production. Additionally, the influence of several chemicals on xylanase activity was investigated in the crude extract. A slight stimulation of the enzyme (5-15%) was achieved with NaCl and urea, both at 3 and 5 mM of concentration. On the other hand, dithiothreitol and beta-mercaptoethanol at a molarity of 5mM have caused a strong stimulation of the enzyme (40-53%). The crude xylanase displayed appreciable thermostability, retaining almost 50% of activity during 24 hours of incubation at 50ºC; about 50% of activity was present at 60ºC even after 4 hours of incubation. The enzyme also exhibited good storage stability at -20ºC without any stabilizing agent.
Nos últimos anos tem crescido o uso de xilanases em muitas indústrias, tais como polpa e papel, alimentos e têxtil. Thermomyces lanuginosus IOC-4145 foi capaz de produzir um alto nível de xilanase livre de celulase em culturas agitadas usando sabugo de milho como substrato (500 U/mL). Procedeu-se, inicialmente, à otimização da composição do meio de produção em fermentação submersa, com o intuito de alcançar uma composição de meio de produção de baixo custo para produção da enzima. Para este propósito, utilizou-se planejamento estatístico de experimentos. O sabugo de milho revelou-se como a mais importante variável que afeta a produção enzimática. Adicionalmente, a influência de vários reagentes na atividade xilanásica foi investigada no extrato bruto. Um pequeno estímulo na atividade enzimática (5-15%) foi observado para NaCl e uréia, ambos nas concentrações de 3 e 5 mM. Por outro lado, ditiotreitol e beta-mercaptoetanol 5mM causaram um grande estímulo na atividade xilanásica (40-53%). A xilanase produzida apresentou apreciável termoestabilidade, retendo quase 50% da atividade inicial durante 24 horas de incubação a 50ºC e, aproximadamente, 50% da atividade foram mantidos a 60ºC, mesmo após 4 horas de incubação. A enzima também exibiu boa estabilidade à estocagem a -20ºC na ausência de qualquer agente estabilizante.