ABSTRACT
Permeabilized cells containing trehalose synthase from Meiothermus sp.CBS-01 was immobilized by the integration of entrapment in alginate beads with cross-linking and electrostatic self-assembly coating technique.Coating on alginate beads with diazo-resin and poly(styrene sulfonate) can protect the beads from degradation in phosphate buffer,whereas cross-linking with carbodiimide improves the thermostability of trehalose synthase entrapped in alginate beads.By co-immobilization of permeabilized cells using entrapment-cross-linking- coating method,the enzyme recovery was 32%,and the optimum temperature of the enzyme was still 60℃,but the optimum pH was shifted from 6.5 to 7.In batch manner,a maximum conversion yield of 60% trehalose from maltose could be reached by the immobilized cells.Within 4 times repeated use of the immobilized cells,and each time was operated at 50℃ for 24h,more than 50% conversion yield of trehalose could be maintained with less than 20% loss of the enzyme activity.
ABSTRACT
By using enrichment media NPC and CVP, 792 strains of Pseudomonas and 515 strains of Erwinia were isolated from the rhizosphere of Digitaria adscendens (H. B. K.) Hem and Setaria vindis (L.) Beanv. Following which, experiments of antimetabolic test with E. coli, seed emergence controlling of S. viridis, herbicidal activity and security with green grass were carried out to select the desired bacteria. As the result, the selected strain, S7, could wholly control the seed emergence of S. viridis without any harm to the two tested green grass. And more, S7 promoted the seed emergence of Festuca arundinacea slightly. In spite of the comparatively low corrected mortality (56. 7%) of S7 after emergence of S. viridis, Selecting of microbial herbicides from weed DRB is thought to be more prospective.
