Identification and characterization of Hg-resistant rhizobacteria isolated from petroleum sludge farm

DOI: 10.5176/2251-2489_BioTech13.39

Authors: N.I. Yatim, S.T. Chai, M.A. Ibrahim, and A. Hamzah

Abstract:

Two rhizobacterial isolates, Brevundimonas diminuta SF-S1-5 and Alcaligenes faecalis SF-S1-60, Gram-negative, rod-shaped bacteria, showed high tolerance towards mercury with minimum inhibitory concentration of 40 ppm. The growth of the isolates in minimal salt medium with 1 ppm Hg resulting in 7.08 x 108 CFU/mL for B. diminuta SF-S1-5, and 4.68 x 106 CFU/mL for A. faecalis SF-S1-60 with percentage of reduction of cells for both isolates was less than 50{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465}, compared with the growth in the control medium. Both isolates could grow in a wide range of pH from 5.0 to 9.0 and temperature from 25ºC to 40ºC and were also tolerant of other heavy metals such as Pb, As, Cd, Co, Zn, and Cu at concentrations from 200 ppm to 1400 ppm and resistant towards various antibiotics including ampicillin, penicillin and kanamycin. A mercury-resistant gene, merA, about ~876 bp and merT ~347 bp, had been isolated and amplified from B. diminuta SF-S1-5 and A. faecalis SF-S1-60.

Keywords: heavy metals; mercury; mer gene; rhizobacteria; resistant