Anaerobic co-reduction of chromate and nitrate by bacterial cultures of Staphylococcus epidermidis L-02

Abstract

Industrial wastewater is often polluted by Cr(VI) compounds, presenting a serious environmental problem. This study addresses the removal of toxic, mutagenic Cr(VI) by means of microbial reduction to Cr(III), which can then be precipitated as oxides or hydroxides and extracted from the aquatic system. A strain of Staphylococcus epidermidis L-02 was isolated from a bacterial consortium used for the remediation of a chromate-contaminated constructed wetland system. This strain reduced Cr(VI) by using pyruvate as an electron donor under anaerobic conditions. The aims of the present study were to investigate the specific rate of Cr(VI) reduction by the strain L-02, the effects of chromate and nitrate (available as electron acceptors) on the strain, and the interference of chromate and nitrate reduction processes. The presence of Cr(VI) decreased the growth rate of the bacterium. Chromate and nitrate reduction did not occur under sterile conditions but was observed during tests with the strain L-02. The presence of nitrate increased both the specific Cr(VI) reduction rate and the cell number. Under denitrifying conditions, Cr(VI) reduction was not inhibited by nitrite, which was produced during nitrate reduction. The average specific rate of chromate reduction reached 4.4 micromol Cr 10(10 )cells(-1 )h(-1), but was only 2.0 micromol Cr 10(10 )cells(-1 )h(-1) at 20 degrees C. The maximum specific rate was as high as 8.8-9.8 micromol Cr 10(10 )cells(-1 )h(-1). The role of nitrate in chromate reduction is discussed.

Inhibition of Nitrate Reduction by Chromium(VI) in Anaerobic Soil Microcosms

“…3B). A similar relationship between Cr(VI) reduction and nitrate was reported with Staphylococcus epidermidis (45). Thus, nitrate-reducing bacteria and soil nitrate concentrations may accelerate the rate of anaerobic Cr(VI) reduction, which results in relief of Cr(VI) toxicity.…”

“…However, in other denitrifying bacteria (for example, Staphylococcus spp. ), no competitive interactions were reported (45).…”

Remediation of chromium contaminants using bacteria

“…Under denitrifying conditions, Cr(VI) reduction was not inhibited by nitrite. The maximum specific reduction rate was as high as 8.8-9.8 lM Cr 10 10 / cells/h (Vatsouria et al 2005). Intrasporangium sp.…”

Characterization of microbial communities in wetland mesocosms receiving caffeine-enriched wastewater

“…Bacillus, which is ubiquitously found in wetland substrate media and capable of high resistance to environmental insults due to its ability to form spores, has been extensively reported to have the potential for solubilizing phosphate (Dong and Reddy 2010), denitrification (Vymazal 2007), and pharmaceutical wastewater treatment in wetland systems (Chaturvedi et al 2008). Staphylococcus has been commonly used in bioremediation for the treatment of various wastewaters, including chromatecontaminated industrial wastewater (Vatsouria et al 2005), brewery wastewater (Zhang et al 2007), and textile dye wastewater (Elisangela et al 2009). Synergistaceae has been intensively found in the anaerobic processes for the treatment of various wastewaters like slaughterhouse wastewater (Palatsi et al 2011), rice straw fermentation liquor wastewater (Ducey and Hunt 2013), industrial oil recovery wastewater (Garcia-Mancha et al 2012), and swine wastewater (Ducey and Hunt 2013).…”