RESUMO
A soil isolate, Penicillium janthinellum sw09 has been found to produce significant amounts of an extracellular pectinase subsequently characterized as exo-polygalacturonase (exo-PG). By optimizing growth conditions, P. janthinellum sw09 produced high amount of exo-PG (16.54 units/mL). The crude enzyme was purified by gel filtration chromatography and two exo-PG activity peaks (designated as PGI and PGII) were revealed. On SDS-PAGE analysis, purified PGII using DEAE-Sepharose FF column, was found to be a single band with a molecular mass of 66.2 kDa. The purified PGII exhibited maximal activity at the temperature of 45 oC and pH 5.0. The stability profiles show that PGII is more stable in the pH range of 4.0-8.0 and below 60 oC. The Km and Vmax for the enzyme was 1.74 mg/mL and 18.08 µmol/ (mLâ¢min), respectively. Due to this enzymatic characterization, this pectinase is an attractive candidate for applications in degradation of pectin.
Assuntos
Penicillium/enzimologia , Poligalacturonase/biossíntese , Eletroforese em Gel de Poliacrilamida , Concentração de Íons de Hidrogênio , Penicillium/crescimento & desenvolvimento , Poligalacturonase/química , Poligalacturonase/isolamento & purificação , TemperaturaRESUMO
The aim of the study was to investigate the effect of cigarette smoke on the production and characterization of exopolysaccharides (EPSs) produced by Bifidobacterium. Cigarettes of Shanhua brand (nicotine: 1.1 mg, tar: 11 mg) were utilized to prepare a cigarette smoke condensate (CSC). The standard strain of Bifidobacterium animalis was cultured in MRS media under anaerobic addition of CSC. The results showed that CSC significantly decreased the growth of B. animalis as well as EPSs and acetic acid production. Furthermore, two EPSs fractions (Fr-I and Fr-II) were isolated and purified for chemical and molecular determination. By comparison with control, CSC was found to be of great impact on EPSs carbohydrate composition. The molecular weight mass of Fr-I changed from 3.33 × 10(5) g/mol (without CSC) to 2.99 × 10(5) (with CSC). In conclusion, in vitro studies revealed that CSC was directly able to affect the production of metabolites for B. animalis, which could be an essential factor in certain pathological disorders.