Isolation and characterization of a high salt-tolerant and glyphosate-degrading strain of Agrobacterium tumefaciens BZ8

ABSTRACT

In this study, a high salt-tolerant and glyphosate-degrading strain named BZ8 was isolated from activated sludge. According to 16S rDNA sequencing methods, morphological, physiological and biochemical analysis, strain BZ8 was identified as Agrobacterium tumefaciens. The growth and glyphosate-degrading capability of A. tumefaciens BZ8 were investigated and the results showed that the optimum conditions for glyphosate degradation under 6% of NaCl concentration were found as follows: inoculation size of 10% (v/v), incubation temperature 37℃ and initial pH of 5.0. Salt tolerance test showed that A. tumefaciens BZ8 grew well and could thoroughly degrade 2000 mg/L glyphosate in 36 h if the concentration of NaCl was lower than 6%, while the degradation rate decreased gradually with increasing NaCl concentration. But the glyphosate degradation rate could still reach 62% when the salt concentration was 8%. In addition, the kinetic parameters for A. tumefaciens BZ8 grown on 100-2800 mg/L glyphosate according to Haldane’s model could predict the cell growth tendency successfully. These results showed that A. tumefaciens BZ8 could be used to control glyphosate wastewater with high salt content. Therefore, it has potential application.

Keywords:
salt-tolerant; glyphosate-degrading strain; identification; growth kinetics