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C G Harfoot

Publications and source records attributed to C G Harfoot.

16 recordsLinked to original sources
PubMed1997

Reductive dehalogenation of halocarboxylic acids by the phototrophic genera Rhodospirillum and Rhodopseudomonas.

Type strains of the purple nonsulfur species Rhodospirillum rubrum, Rhodospirillum photometricum, and Rhodopseudomonas palustris grew phototrophically on a number of two- and three-carbon halocarboxylic acids in the presence of CO2, by reductive dehalogenation and assimilation of the resulting acid. Strains of each of these species were able to grow on chloroacetic, 2-bromopropionic, 2-chloropropionic, and 3-chloropropionic acids at a concentration of 2 mM. Only R. palustris DSM 123 was able to grow on bromoacetic acid and then only at a reduced concentration of 1 mM. R. palustris ATCC 33872 (formerly R. rutila) was unable to grow on any of the substrates tested. The ability of these organisms to utilize halocarboxylic acids indicates that they may have a significant role to play in the removal of these environmental pollutants from illuminated anaerobic habitats such as lakes, waste lagoons, sediments of ditches and ponds, mud, and moist soil.

Acetates↗
PubMed1996

Sodium-dependent succinate decarboxylation by a new anaerobic bacterium belonging to the genus Peptostreptococcus.

An anaerobic bacterium was isolated from a polluted sediment, with succinate and yeast extract as carbon and energy sources. The new strain was Gram-positive, the cells were coccal shaped, the mol% G+G content of the genomic DNA was 29, and the peptidoglycan was of the L-ornithine-D-glutamic acid type. Comparative sequence analysis of the 16S rRNA gene showed the new strain to belong to the genus Peptostreptococcus. Succinate, fumarate, pyruvate, 3-hydroxybutyrate and lysine supported growth. Succinate was degraded to propionate and presumably CO2, with a stoichiometric cell yield. Key enzymes of the methylmalonyl-CoA decarboxylase pathway were present. The methylmalonyl-CoA decarboxylase activity was avidin-sensitive and sodium dependent, and about 5 mM Na+ was required for maximal activity. Whole cells, however, required at least 50 mM sodium for maximal succinate decarboxylation activity and to support the maximum growth rate. Sodium-dependent energy conservation coupled to succinate decarboxylation is shown for the first time to occur in a bacterium belonging to the group of Gram-positive bacteria containing the peptostreptococci and their relatives.

Bacteria, Anaerobic↗
PubMed1995

Fly ash, basic slag and Glenbrook slag toxicity in cattle.

In case studies of two herds of dairy cattle, a herd of 270 Friesian cows and heifers and a herd of 256 Jersey cows and heifers experienced high death rates and a protracted course of illness when fly ash was broadcast as a fertiliser over the farms at a rate of about 1 tonne per hectare. The onset of weakness, lassitude and diarrhoea in the cattle first appeared within 4-5 days and both fertility and milk fat production fell off dramatically. In the following 7 months, 51 animals died in the Friesian herd and a similar death rate and performance losses occurred in the Jersey herd. Emaciation and hepatic fibrosis were consistently reported from autopsies. Heavy metal poisoning was eliminated from the possible diagnosis. The slags and fly ash used as fertiliser had several features in common. They contained 29-40% calcium as calcium oxide, 15-35 grams of iron per kg, they were all extremely alkaline and concentrations of lead and arsenic were low. The effect of adding fly ash to rumen contents in vitro was to raise the pH to greater than 7.2, at which point fermentation was markedly-reduced.

Journal Article↗
PubMed1995

Lactosphaera gen. nov., a new genus of lactic acid bacteria, and transfer of Ruminococcus pasteurii Schink 1984 to Lactosphaera pasteurii comb. nov.

The phylogenetic position and physiology of strain KoTa2T (T = type strain), which was previously classified as a Ruminococcus pasteurii strain, were studied. A determination of the 16S ribosomal DNA sequence of this taxon revealed its position within the radiation of the gram-positive lactic acid bacteria having low DNA G+C contents and that it is closely related to the genus Carnobacterium. L-Lactic acid was produced from glucose by a fructose-1,6-bisphosphate-activated lactate dehydrogenase, and oxygen tolerance was observed, characteristics which are consistent with assignment to this group. On the basis of its phenotypic characteristics and unique signature nucleotides, we propose that strain KoTa2 (= DSM 2381 = ATCC 35945) should be transferred to a new genus, Lactosphaera gen. nov., as the type strain of the species Lactosphaera pasteurii comb. nov.

Anaerobiosis↗
PubMed1992

Anaerobic malonate decarboxylation by Citrobacter diversus. Growth and metabolic studies, and evidence of ATP formation.

Citrobacter diversus ATCC 27156 was able to grow by decarboxylation of malonate to acetate under strictly anaerobic conditions, in the presence of yeast extract. The growth yield, corrected for growth on yeast extract, was 2.03 g cell dry mass per mol malonate. The addition of malonate to ATP-depleted cell suspensions (less than 0.2 nmol ATP/mg cell protein) resulted in a rapid increase in cellular ATP levels to between 4.5 and 6.0 nmol/mg cell protein. Intact cells decarboxylated malonate at rates of up to 1.5 mumol/min.mg protein. Enzyme assays on malonate-grown cells indicated activation of malonate by an ATP-dependent ligase reaction and by CoA transfer from acetyl-CoA, followed by decarboxylation of malonyl-CoA to acetyl-CoA with subsequent recovery of the invested ATP by substrate level phosphorylation through the activity of acetate kinase. Net ATP synthesis is postulated to be mediated by gradient formation coupled to the decarboxylation of malonyl-CoA. The protonophore CCCP and H(+)-ATPase inhibitor DCCD significantly reduced cellular ATP levels, suggesting a role for proton gradients in the energy metabolism of this strain when growing an malonate. Inhibitors of sodium metabolism or ommission of sodium had no effect on ATP levels or malonate decarboxylation.

Adenosine Triphosphate↗
PubMed1992

A comparison of the sensitivity of wound-infecting species of bacteria to the antibacterial activity of manuka honey and other honey.

Both honey and sugar are used with good effect as dressings for wounds and ulcers. The good control of infection is attributed to the high osmolarity, but honey can have additional antibacterial activity because of its content of hydrogen peroxide and unidentified substances from certain floral sources. Manuka honey is known to have a high level of the latter. Seven major wound-infecting species of bacteria were studied to compare their sensitivity to the non-peroxide antibacterial activity of manuka honey and to a honey in which the antibacterial activity was primarily due to hydrogen peroxide. Honeys with activity in the middle of the normal range were used. A comparison of the median response of the various species of bacteria showed no significant difference between the two types of activity overall, but marked differences between the two types of activity in the rank order of sensitivity of the seven bacterial species. The non-peroxide antibacterial activity of manuka honey at a honey concentration of 1.8% (v/v) completely inhibited the growth of Staphylococcus aureus during incubation for 8 h. The growth of all seven species was completely inhibited by both types of honey at concentrations below 11% (v/v).

Bacteria↗
PubMed1990

Isolation of a Citrobacter species able to grow on malonate under strictly anaerobic conditions.

An anaerobic enrichment from lake mud yielded a pure culture of a facultatively anaerobic bacterium able to grow on malonate under strictly anaerobic conditions. Strain 16mal1 was identified as a member of the family Enterobacteriaceae, and assigned to the genus Citrobacter on the basis of morphological, metabolic and biochemical characteristics. Malonate was fermented under strictly anaerobic (sulphide-reduced) conditions to acetate and CO2 concomitant with growth. A maximum growth rate of 1.88 generations h-1 (mu = 1.30 h-1) was measured. The dry weight yield of cells from malonate was estimated at 2.5 g mol-1. Yeast extract was required for growth on malonate: other additives, or a vitamin solution, could not replace this requirement. Other dicarboxylic acids were not degraded in the absence or presence of malonate. Malonate was degraded under anaerobic, but not aerobic conditions. Malonate-decarboxylating activity was inducible by malonate under both anaerobic and aerobic conditions, and was not expressed in glucose- or citrate-grown anaerobic cultures. Monensin had no effect on malonate degradation, while 2,4-dinitrophenol decreased the rate of malonate degradation. This, with the lack of a sodium requirement for anaerobic growth on malonate, suggested that ATP generation may not be mediated by a sodium-pumping mechanism.

Anaerobiosis↗
PubMed1976

Factors affecting the uptake and metabolism of soluble carbohydrates by the rumen ciliate Dasytricha ruminantium isolated from ovine rumen contents by filtration.

A filtration technique is described whereby metabolically-active suspensions of Dasytricha ruminantium can be isolated from rumen contents with negligible contamination by bacteria or other protozoa. The effects of environmental factors and of the diurnal cycle of the rumen on the uptake and metabolism of soluble carbohydrates by these isolated cells were examined. The principal contribution of the protozoan metabolic end-products to the host ruminant is the supply of lactic, acetic and butyric acids during periods when soluble sugars are in excess.

Acetates↗
PubMed1975

The role of plant particles, bacteria and cell-free supernatant fractions of rumen contents in the hydrolysis of trilinolein and the subsequent hydrogenation of linoleic acid.

The role of different fractions of rumen contents in the hydrolysis of trilinolein and the subsequent hydrogenation of the linoleic acid has been investigated by a series of in vitro incubations. Hydrolysis of the trilinolein to free linoleic acid occurs almost wholly in the cell-free supernatant; the liberated linoleic acid in the supernatant can be rapidly adsorbed onto food particles where it is hydrogenated to stearic acid via the C18 trans-11 monoene. Some 25% of the trilinolein added as substrate was taken up by the bacteria and of this a small percentage appeared to be hydrolysed and the free linoleic acid hydrogenated to stearic acid intracellularly. No conclusive evidence was obtained to suggest that this intracellular hydrogenation proceeded by a route other than that which took place on the food particles.

Animals↗
PubMed1973

Food particles as a site for biohydrogenation of unsaturated fatty acids in the rumen.

On incubation of linoleic acid with strained rumen contents from sheep, it was observed that conversion of linoleic acid into C(18:1)trans-11 monoenoic acid and subsequently into stearic acid was largely associated with the food-particle fraction. The bacteria, protozoa and cell-free supernatant together contributed less than 30% to the overall change in the added C(18:2) fatty acid.

Animals↗