Effects of electron donor and acceptor conditions on reductive dehalogenation of tetrachloromethane by Shewanella putrefaciens 200

Journal Article · Sun Jan 01 04:00:00 EST 1995 · Applied and Environmental Microbiology

OSTI ID:75822

Picardal, F; Arnold, R G; Huey, B B ^[1]

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1. Univ. of Arizona, Tucson, AZ (United States)

Shewanella putrefaciens 200 is a nonfermentative bacterium that is capable of dehalogenating tetrachloromethane to chloroform and other, unidentified products under anaerobic conditions. Since S. putrefaciens 200 can respire anaerobically by using a variety of terminal electron acceptors, including NO{sub 3}{sup {minus}}, NO{sub 2}{sup {minus}}, and Fe(III), it provides a unique opportunity to study the competitive effects of different electron acceptors on dehalogenation in a single organism. The results of batch studies showed that dehalogenation of CT by S. putrefaciens 200 was inhibited by O{sub 2}, 10 mM NO{sub 3}{sup {minus}}, and 3 mM NO{sub 2}{sup {minus}}, but not by 15 mM Fe(III), 15 mM fumarate, or 15 mM trimethylamine oxide. Using measured O{sub 2}, Fe(III), NO{sub 2}{sup {minus}}, and NO{sub 3}{sup {minus}} reduction rates, we developed a speculative model of electron transport to explain inhibition patterns on the basis of (i) the kinetics of electron transfer at branch points in the electron transport chain, and (ii) possible direct inhibition by nitrogen oxides. In additional experiments in which we used 20 mM lactate, 20 mM glucose, 20 mM glycerol, 20 mM pyruvate, or 20 mM formate as the electron donor, dehalogenation rates were independent of the electron donor used. The results of other experiments suggested that sufficient quantities of endogenous substrates were present to support transformation of tetrachloromethane even in the absence of an exogenous electron donor. Our results should be significant for evaluating (i) the bioremediation potential at sites contaminated with both halogenated organic compounds and nitrogen oxides, and (ii) the bioremediation potential of iron-reducing bacteria at contaminated locations containing significant amounts of iron-bearing minerals. 22 refs., 4 figs., 1 tab.

• OSTI ID: 75822
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 1 Vol. 61; ISSN AEMIDF; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ANAEROBIC CONDITIONS
BACTERIA
BIODEGRADATION
DEHALOGENATION
ORGANIC HALOGEN COMPOUNDS