INIQUI   05448
INSTITUTO DE INVESTIGACIONES PARA LA INDUSTRIA QUIMICA
Unidad Ejecutora - UE
artículos
Título:
Quantification of the genetic expression of bgl-A, bgl, CspA and enzymatic characterization of β-glucosidases in Shewanella sp G5
Autor/es:
CARLOS ABATE; RAMIRO POMA; HECTOR ANTONIO CRISTÓBAL; VERONICA B RAJAL; CARLOS ABATE; RAMIRO POMA; HECTOR ANTONIO CRISTÓBAL; VERONICA B RAJAL
Revista:
MARINE BIOTECHNOLOGY
Editorial:
SPRINGER
Referencias:
Lugar: Berlin; Año: 2016 vol. 18 p. 396 - 408
ISSN:
1436-2228
Resumen:
Shewanella sp. G5, a psychrotolerant marine bacterium, has a cold-shock protein (CspA) and three β-glucosidases, two of which have been classified in glycosyl hydrolase families 1 and 3, encoded by bgl-A and bgl genes, respectively. Shewanella sp. G5 was cultured on rich (LB) and mineral (MMB) media with glucose and cellobiose, at various temperatures and pH 6 and 8. The relative quantification of the expression levels of all three genes was studied by means of real-time PCR with the comparative Ct method (2-ΔΔCt), using the gyrB housekeeping gene as a normalizer. The results showed that the genes had remarkably different genetic expression levels under the conditions considered, with increased expression in all genes being obtained on MMB with cellobiose at 30ºC. Different culture conditions were taken into account so as to determine specific growth rate and specific β-glucosidase activity. Shewanella sp. G5 was able to grow on both media at 4ºC, showing the maximum specific growth rate on LB with cellobiose at 37ºC. The specific β-glucosidase activity obtained on MMB with cellobiose at 30°C was 25 to 50% higher than under all the other conditions. At pH 8, relative activity was 34, 60, and 63% higher at 30ºC than at 10ºC, with three peaks at 10, 25, and 37ºC on both media. Enzyme activity increased by 61 and 47% in the presence of Ca2+ and 24 and 31% in the presence of Mg2+, on LB and MMB at 30°C, respectively, but it was totally inhibited by Hg2+, Cu2+, and EDTA. Moreover, this activity was slightly decreased by SDS, Zn2+ and DTT, all at 5 mM. Ethanol (14% v/v) and glucose (100 mM) also reduced the activity by 63 and 60%, respectively.