SIMULTANEOUS SULFATE AND CHROMIUM REMOVAL BY Streptomyces sp. MC1.

BONILLA JO; CASTRO MF; DELFINI CD; AMOROSO MJ; VILLEGAS LB

San Luis

Congreso; Sociedad Biología de Cuyo; 2014

Sociedad Biología de Cuyo

In previous works, Streptomyces sp. MC1 showed the ability to Cr(VI) reduction, moreover the presence of 5 M of sulfate ion mitigated the inhibitory effect of Cr(VI) on bacterial growth, and increased their removal from culture supernatants. The main aim of this study was to investigate the influence of increased sulfate concentrations on the Cr(VI) reduction by Streptomyces sp. MC1 and the sulfate removal in absence and presence of Cr(VI). Cells of Streptomyces sp. MC1 were grown in liquid minimal medium supplemented with glucose and with or without 20 mg/L of Cr(VI) and Na2SO4 (ranging from 0 to 10 mM) for 96 h at 30 ºC in an orbital shaker. Biomass was determined by dry weight, Cr(VI) concentration in the medium by the colorimetric method of 1,5-diphenylcarbazide, total chromium by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and residual sulfate by Hach DR2800. In absence of Cr(VI), the growth of Streptomyces sp. MC1 was practically the same at 0 to 7,5 mM of sulfate concentration while at 10 mM the growth was inhibited markedly. In presence of Cr(VI) but in absence the sulfate ions, the bacteria no showed growth. Cr(VI) reduction was highest at 5 and 7,5 mM of sulfate, and the sulfate removal was lightly major in presence of Cr(VI). On the other hand, total chromium concentration in the supernatant decreased 40-50% in all assayed conditions. These results indicate that Streptomyces sp. MC1 can utilize chromate as an electron acceptor for sulfate reduction and hence both Cr(VI) and sulfates get removed from the broth.