Bacterial chromate reduction and product characterization

Conference · Sun Nov 01 00:00:00 EST 1992

OSTI ID:10130983

Mehlhorn, R J ^[1]; Buchanan, B B; Leighton, T ^[2]

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1. Lawrence Berkeley Lab., CA (United States)
2. California Univ., Berkeley, CA (United States)

Bacillus subtilis reduced hexavalent chromate to trivalent chromium under either aerobic or anaerobic conditions. Reduction of CR(VI) and appearance of extracellular Cr(III) were demonstrated by electron spin resonance and spectrophotometry. Chromate reduction was stimulated more than five-fold by freeze-thawing, indicating that intracellular reductases or chemical reductants reduce chromate more rapidly than do intact cells. Moderately concentrated cells (10% pellet volume after centrifugation) reduced approximately 40 {mu}M chromate/min (2 mg Cr/1-min) when exposed to 100 {mu}M chromate (5 mg Cr/1). Highly concentrated cells (70% pellet volume) reduced more than 99.8% of 2 mM chromate (100 mg Cr/1) within 15 min. This rate of chromate reduction was of the same order of magnitude as the rate of respiration in aerobic cells. A substantial fraction of the reduction product (ca. 75%) was extracellular Cr(M), which could readily be separated from the cells by centrifugation. At high chromate concentrations, some fraction of reduced CR(VI) appeared to be taken up by cells, consistent with a detection of intracellular paramagnetic products. At low chromate concentrations, undefined growth medium alone reduced Cr(VI), but at a slow rate, relative to cells. Under appropriate conditions, B. subtilis appears to be an organism of choice for detoxifying chromate-contaminated soil and water.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 10130983
• Report Number(s): LBL-33252; WSRC-MS-93-018; CONF-930482-4; ON: DE93007698; TRN: 93:006367
• Resource Relation: Conference: 2. international symposium on in situ and on-site bioreclamation,San Diego, CA (United States),5-8 Apr 1993; Other Information: PBD: Nov 1992
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
54 ENVIRONMENTAL SCIENCES
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
CHROMATES
REDUCTION
BIODEGRADATION
SOIL CHEMISTRY
LAND POLLUTION
BACILLUS SUBTILIS
REMEDIAL ACTION
OXIDOREDUCTASES
550500
320305
540220
053003
METABOLISM
INDUSTRIAL WASTE MANAGEMENT
CHEMICALS MONITORING AND TRANSPORT
CHEMICAL AND THERMAL EFFLUENTS