RESUMEN
In a halotolerant fungus Aspergillus glaucus CCHA, several functional proteins with stress-tolerant activity have been studied, but no secretory enzymes have been identified yet. The unique GH5 cellulase candidate from A. glaucus, an endoglucanase termed as AgCMCase, was cloned, expressed in the Pichia pastoris system and the purified enzyme was characterized. A large amount of recombinant enzyme secreted by the P. pastoris GS115 strain was purified to homogeneity. The molecular weight of the purified endoglucanase is about 55.0 kDa. The AgCMCase exhibited optimum catalytic activity at pH 5.0 and 55 °C. However, it remained relatively stable at temperatures ranging from 45 to 80 °C and pH ranging from 4.0 to 9.0. In addition, it showed higher activity at extreme NaCl concentrations from 1.0 to 4.0 M, suggesting it is an enzyme highly stable under heat, acid, alkaline and saline conditions. To evaluate the catalytic activity of AgCMCase, the hydrolysis products of rice and corn straws were successfully studied. In conclusion, the AgCMCase is a thermostable and salt-tolerant cellulase with potential for industrial application.
Asunto(s)
Aspergillus/enzimología , Celulasa/metabolismo , Proteínas Fúngicas/metabolismo , Microbiología Industrial/métodos , Tolerancia a la Sal , Termotolerancia , Aspergillus/genética , Biotransformación , Celulasa/química , Celulasa/genética , Celulosa/metabolismo , Estabilidad de Enzimas , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Concentración de Iones de HidrógenoRESUMEN
Halotolerant fungus Cladosporium cladosporioides OUCMDZ-187 was isolated from the mangrove plant Rhizophora stylosa collected in Shankou, Guangxi Province of China. Three new fatty acid esters cladosporesters A-C (1-3) and 5 new fatty acids cladosporacids A-E (4-8) were isolated from the ethyl acetate extract of the fermentation broth of OUCMDZ-187 in a hypersaline (10% salt) medium. Their structures were elucidated by UV, IR, MS, specific rotation, and 1D and 2D NMR data.
Asunto(s)
Cladosporium/química , Ácidos Grasos/química , Rhizophoraceae/química , Células A549 , Antibacterianos/química , Antibacterianos/aislamiento & purificación , Antibacterianos/farmacología , Antifúngicos/química , Antifúngicos/aislamiento & purificación , Antifúngicos/farmacología , Antineoplásicos/química , Antineoplásicos/aislamiento & purificación , Antineoplásicos/farmacología , Supervivencia Celular/efectos de los fármacos , Ácidos Grasos/aislamiento & purificación , Ácidos Grasos/farmacología , Fermentación , Células HeLa , Humanos , Células K562 , Estructura Molecular , Relación Estructura-ActividadRESUMEN
Five new pyrazin-2(1H)-one derivatives, ochramides A-D (1-4) and ochralate A (5), as well as three known analogues (6-8) were isolated from the fermentation broth of the marine coral-derived halotolerant Aspergillus ochraceus LCJ11-102 in a nutrient-limited medium containing 10% NaI. Their chemical structures were determined by analyzing NMR and X-ray diffraction data. Compounds 2, 5 and 6 showed antimicrobial activities against Enterobacter aerogenes with the MIC values of 40.0, 18.9, and 20.1 µM, respectively.