α-L- rhamnosidases Produced under Solid State Fermentation by Few Aspergillus Strains

The production of α-L-rhamnosidase from Aspergillus ochraceous MTCC -1810, A. wentii MTCC- 1901, A. sydowii MTCC- 635, A. foetidus MTCC-508 under solid- state fermentation using easily available agro- industrial residues such as corn cob, rice bran, sugarcane bagasse, wheat bran and citrus peel as substrate. Among these, sugarcane bagasse in combination with naringin and sucrose were found to be the best substrate. The α-L-rhamnosidase production was highest after the 4th day of incubation at 30ºC and a substrate to moisture ratio of 1:1 w/v. Supplementation of the medium with 10% naringin caused the maximum production of the enzyme. The temperature optima and pH optima of α-L-rhamnosidases were determined in the range of 50-60ºC and 4.0-5.0 respectively. The α-L-rhamnosidases secreted from the above fungal strains is suitable for the debittering of orange fruit juice.

Escherichia coli expressing endoglucanase gene from Thai higher termite bacteria for enzymatic and microbial hydrolysis of cellulosic materials

Background: Endoglucanase plays a major role in initiating cellulose hydrolysis. Various wild-type strains were searched to produce this enzyme, but mostly low extracellular enzyme activities were obtained. To improve extracellular enzyme production for potential industrial applications, the endoglucanase gene of Bacillus subtilis M015, isolated from Thai higher termite, was expressed in a periplasmic-leaky Escherichia coli. Then, the crude recombinant endoglucanase (EglS) along with a commercial cellulase (Cel) was used for hydrolyzing celluloses and microbial hydrolysis using whole bacterial cells. Results: E. coli Glu5 expressing endoglucanase at high levels was successfully constructed. It produced EglS (55 kDa) with extracellular activity of 18.56 U/mg total protein at optimal hydrolytic conditions (pH 4.8 and 50°C). EglS was highly stable (over 80% activity retained) at 40­50°C after 100 h. The addition of EglS significantly improved the initial sugar production rates of Cel on the hydrolysis of carboxymethyl cellulose (CMC), microcrystalline cellulose, and corncob about 5.2-, 1.7-, and 4.0-folds, respectively, compared to those with Cel alone. E. coli Glu5 could secrete EglS with high activity in the presence of glucose (1% w/v) and Tween 80 (5% w/v) with low glucose consumption. Microbial hydrolysis of CMC using E. coli Glu5 yielded 26 mg reducing sugar/g CMC at pH 7.0 and 37°C after 48 h. Conclusions: The recombinant endoglucanase activity improved by 17 times compared with that of the native strain and could greatly enhance the enzymatic hydrolysis of all studied celluloses when combined with a commercial cellulase.

Descoloração de azul de bromofenol utilizando peroxidase imobilizada em pó de sabugo de milho altamente ativado / Bromofhenol blue discoloration using peroxidase immobilized on highly activated corncob powder

The aim of the present study was to evaluate the efficacy of peroxidase immobilized on corncob powder for the discoloration of dye. Peroxidase was extracted from soybean seed coat, followed by amination of the surface of the tertiary structure. The aminated peroxidase was immobilized on highly activated corncob powder and employed for the discoloration of bromophenol blue. Amination was performed with 10 or 50 mmol.L-1 carbodiimide and 1 mol.L-1 ethylenediamine. The amount of protein in the extract was 0.235 ± 0.011 mg.mL-1 and specific peroxidase activity was 86.06 ± 1.52 μmol min-1. mg -1 , using 1 mmol.L-1 ABTS as substrate. Ten mmol.L-1 and 50 mmol.L-1 aminated peroxidase retained 88 and 100% of the initial activity. Following covalent immobilization on a corncob powder-glyoxyl support, 10 and 50 mmol.L-1 aminated peroxidase retained 74 and 86% of activity, respectively. Derivatives were used for the discoloration of 0.02 mmol.L-1 bromophenol blue solution. After 30 min, 93 and 89% discoloration was achieved with the 10 mmol.L-1 and 50 mmol.L-1 derivatives, respectively. Moreover, these derivatives retained 60% of the catalytic properties when used three times. Peroxidase extracted from soybean seed coat immobilized on a low-cost corncob powder support exhibited improved thermal stability.

Nesta pesquisa a enzima peroxidase foi extraída do tegumento de sementes de soja, e a superfície da estrutura terciária foi aminada. A peroxidase aminada foi imobilizada em suporte pó de sabugo de milho altamente ativado e utilizado na descoloração de azul de bromofenol. A aminação da peroxidase foi realizada com carbodiimida em concentrações de 10 e 50 mmol.L-1 , e 1 mol.L-1 de etilenodiamina. A quantidade de proteínas no extrato foi de 0,235 ± 0,011 mg.mL-1 , e a atividade específica da peroxidase foi 86,06 ± 1,52 μmol min-1 .mg-1, usando 1 mmol.L-1 de ABTS como substrato. A peroxidase aminada a 10 mmol.L-1 reteve 88% e a aminada a 50 mmol.L-1 reteve 100% da atividade inicial. As peroxidases aminadas a 10 ou 50 mmol.L-1 foram covalentemente imobilizadas em suporte glioxil-pó de sabugo de milho com atividade recuperada de 74% e 86%, respectivamente. Os derivados obtidos foram utilizados na descoloração de solução de azul de bromofenol 0,02 mmol.L-1 . Após 30 min 93% de descoloração foram alcançados com o derivado glioxil-pó de sabugo de milho com a peroxidase aminada 10 mmol.L-1 e 89% com a aminada 50 mmol.L-1 . Estes derivados mantiveram 60% das propriedades catalíticas, quando utilizado por três vezes. A peroxidase extraída do tegumento da semente de soja imobilizada em suporte de baixo custo pó de sabugo de milho apresentou melhoria na estabilidade térmica da enzima.

Study on Adsorption Efficiency of Corncob for Nickel in Water / 环境与健康杂志

Objective To study the adsorption capability of corncob for Ni2+ in water. Methods The tests were conducted on the factors including pH value, the initial concentration of Ni2+, adsorption time, temperature and absorbent dosage influencing the adsorption effect, and the adsorption capability of the desorbing corncob for Ni2+ in water compared with the fresh corncob. Results In the condition of 35 ℃, 0.1 g of corncobs, 20 ml of 10 mg/L Ni2+ solution, pH=6 and contact time of 2.5 h, the adsorption capacity of Ni2+ could be up to 1.6 mg/g. The adsorption data fit the Freundlich adsorption isotherm and the Langmuir adsorption isotherm. HCl could be used to desorb corncobs ladening Ni2+, the desorbed corncob had the same adsorption capacity and rate of the desorbing as the fresh corncob. Conclusion The corncob can effectively remove Ni2+ in water, and the desorbed corncob can be reused.