Pyruvate and Ethanol as Electron Donors for Nitrite Reduction by Escherichia coli K12

Abstract

Pyruvate and ethanol were both effective electron donors for nitrite reduction by Escherichia coli K12. The pyruvate-dependent rate decreased by approximately 50% when either a cysG mutation, which results in loss of NADH-dependent nitrite reductase activity (EC 1.6.6.4), or a chl mutation, which results in loss of the formate-nitrite oxidoreductase activity, was introduced into the prototrophic parental strain CGSC4315. A double mutant deficient in both of these previously described activities retained only 2% of the rate of nitrite reduction of the parental strain after growth on glucose or 5% after growth on pyruvate. We conclude that any third pathway for nitrite reduction contributes little to the in vivo rate of nitrite reduction by wild-type strains.

Role of the Escherichia coli nitrate transport protein, NarU, in survival during severe nutrient starvation and slow growth

“…Optical density readings were measured using 1 cm light path cuvettes and a Camspec M501 spectrophotometer. The defined medium was the minimal salts medium described by Pope & Cole (1984). Media were supplemented where appropriate with the following antibiotics: ampicillin, 100 mg ml 21 ; spectinomycin, 100 mg ml 21 ; kanamycin, 50 mg ml 21 ; chloramphenicol, 34 mg ml 21 ; or tetracycline, 15 mg ml 21 .…”

Involvement of products of the nrfEFG genes in the covalent attachment of haem c to a novel cysteine–lysine motif in the cytochrome c552 nitrite reductase from Escherichia coli

“…¹1 , determined as described in Pope and Cole (1984) except that ferricyanide replaced nitrite as the oxidant. c. This was shown by SDS-PAGE to be the 16 kDa NapB cytochrome, cytochrome c 550 .…”

The NapF protein of the Escherichia coli periplasmic nitrate reductase system: demonstration of a cytoplasmic location and interaction with the catalytic subunit, NapA

“…Anaerobic growth of these strains in minimal medium in the presence of a non-fermentable carbon source such as glycerol requires a reducible electron acceptor, so growth with nitrate is Nap-dependent (Brondijk et al, 2002). Bacteria were grown aerobically in LB (10 g tryptone l 21 , 5 g yeast extract l 21 and 5 g NaCl l 21 ) or anaerobically in MS medium [4?5 g KH 2 PO 4 l 21 , 10?5 g K 2 HPO 4 l 21 , 1 g NH 4 SO 4 l 21 , 0?05 g MgCl 2 l 21 , 2?5 g nutrient broth (NB) base l 21 , 10 mM sodium molybdate, 10 mM sodium selenate and 1 ml l 21 of E. coli sulphur-free salts (Pope & Cole, 1984) supplemented with 20 mM NaNO 3 and 0?4 % (v/v) glycerol or 0?4 % (w/v) D-glucose]. When appropriate 100 mg ampicillin ml 21 and/or 50 mg kanamycin ml 21 were added.…”

“…A nitrate electrode was used to measure rates of nitrate reduction by washed bacterial suspensions incubated with 1?2 mM nitrate and the physiological substrates glucose, glycerol or formate (Pope & Cole, 1984). Nitrate reductase activities of permeabilized bacteria incubated with 1 mM nitrate and reduced methylviologen were determined as described previously .…”

“…Aerobic and anaerobic cultures were grown and assayed for b-galactosidase activity as described previously (Jayaraman et al, 1987). Nitrite concentrations were measured according to Pope & Cole (1984). Protein concentrations were determined by the Lowry method.…”