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9. Factors influencing the toxicity of heavy metals in food.

Author

Huisingh, Donald and Huisingh, Joellen

Abstract

The level of heavy metals that man can tolerate in his diet is not simply determined. The absorption, transport, and biotransformations of cadmium, mercury, and lead by the plants and animals that are direct or indirect parts of man's food supply, and the effects these metals have upon man, depend upon many factors. Those discussed here include: influence of the form of the heavy metal on its toxicity; the capacity of several elements to modify the toxicity of heavy metals; the stage of development of the organism and its health status as it influences susceptibility to heavy metals. The provisionally tolerable weekly intake of cadmium, mercury, and lead is discussed in relation to the levels man is currently ingesting. The need for the establishment of a Standardized International Food Monitoring Network is discussed. The Food Monitoring Network would be responsible for obtaining much needed information on concentrations and forms of the heavy metals interacting in foods and would help to insure the wholesomeness of man's food supplies. [ABSTRACT FROM PUBLISHER]

Published
1974
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11. Sulfate Reduction by a DesulfovibrioSpecies Isolated from Sheep Rumen

Author

Huisingh, Joellen, McNeill, J. J., and Matrone, G.

Abstract

Several dissimilatory, sulfate-reducing bacteria were isolated from the rumen fluid of sheep fed purified diets containing sulfate. One isolate, strain D, was selected for characterization. This organism is a nonsporeforming, obligately anaerobic, mesophilic, nonmotile, gram-negative, straight rod. Cell-free extracts show absorption maxima for cytochrome c3and desulfoviridin, characteristic of Desulfovibrio. Carbohydrates, as a sole carbon source, will support growth. Lactate supports growth in the presence of sulfate, not in its absence, whereas glucose or pyruvate support growth either in the presence or absence of sulfate. The isolate has a deoxyribonucleic acid base composition of 61.2% guanine plus cytosine, which is similar to that of several other species of Desulfovibrio; however, it differs from previously described species in morphology, motility, and carbon source utilization. Cell-free extracts of this bacterium exhibit adenosine 5′-triphosphate-sulfurylase, adenosine-5′-phosphosulfate-reductase, and hydrogenase activity. After incubation of cell-free extracts with adenine 5′-triphosphate and 35SO42-, adenosine-5′-phosphosulfate rather than 3′-phosphoadenosine-5′-phosphosulfate was shown to be labeled, indicating that the pathway of sulfate reduction in this organism is similar to that of other dissimilatory sulfate reducers. This is the first report of a Desulfovibriosp. isolated from the rumen.Images

Published
1974
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12. Effect of Molybdate on Sulfide Production from Methionine and Sulfate by Ruminal Microorganisms of Sheep

Author

Huisingh, Joellen, Milholland, Dan C., and Matrone, Gennard

Abstract

Purified diets containing sodium sulfate and DL-methionine as sole dietary sources of sulfur were fed to fistulated sheep. The effect of dietary sodium molybdate (50 ppm Mo) on the capacity of the rumen microorganisms to produce sulfide from either sulfate or methionine was assayed in the two sulfur diets. Dietary molybdenum significantly inhibited the production of sulfide from sulfate but enhanced significantly the production of sulfide from methionine. The inhibitory effect of molybdenum on sulfide production in vitro and the number of sulfide-producing bacteria present in the rumen of these sheep are discussed in considering the mechanism of the molybdate effect on sulfide production.

Published
1975
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13. Copper-Molybdenum Interactions with the Sulfate-Reducing System in Rumen Microorganisms1

Author

Huisingh, Joellen and Matrone, G.

Abstract

Washed rumen microorganisms were investigated under conditions conducive to sulfate reduction, giving the following results: Molybdate inhibits the reduction of sulfate to hydrogen sulfide. Molybdate inhibition increases as the concentration of sulfate decreases. Molybdate has little effect on sulfite reduction. In the presence of copper, molybdate inhibition is markedly decreased.

Published
1972
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14. Sulfate Reduction by a Desulfovibrio Species Isolated from Sheep Rumen1

Author

Huisingh, Joellen, McNeill, J. J., and Matrone, G.

Subjects
DNA, Bacterial, Rumen, Sheep, Cell-Free System, Nucleotides, Sulfates, Sulfides, Sulfur Radioisotopes, Nucleotidyltransferases, Microscopy, Electron, Animals, Desulfovibrio, Electrophoresis, Paper, Anaerobiosis, Oxidoreductases, Oxidation-Reduction, Environmental Microbiology and Ecology
Abstract

Several dissimilatory, sulfate-reducing bacteria were isolated from the rumen fluid of sheep fed purified diets containing sulfate. One isolate, strain D, was selected for characterization. This organism is a nonsporeforming, obligately anaerobic, mesophilic, nonmotile, gram-negative, straight rod. Cell-free extracts show absorption maxima for cytochrome c(3) and desulfoviridin, characteristic of Desulfovibrio. Carbohydrates, as a sole carbon source, will support growth. Lactate supports growth in the presence of sulfate, not in its absence, whereas glucose or pyruvate support growth either in the presence or absence of sulfate. The isolate has a deoxyribonucleic acid base composition of 61.2% guanine plus cytosine, which is similar to that of several other species of Desulfovibrio; however, it differs from previously described species in morphology, motility, and carbon source utilization. Cell-free extracts of this bacterium exhibit adenosine 5'-triphosphate-sulfurylase, adenosine-5'-phosphosulfate-reductase, and hydrogenase activity. After incubation of cell-free extracts with adenine 5'-triphosphate and (35)SO(4) (2-), adenosine-5'-phosphosulfate rather than 3'-phosphoadenosine-5'-phosphosulfate was shown to be labeled, indicating that the pathway of sulfate reduction in this organism is similar to that of other dissimilatory sulfate reducers. This is the first report of a Desulfovibrio sp. isolated from the rumen.

Published
1974

48. Keynote Address

Author

Hunt, Vilma, Waters, Michael D., editor, Sandhu, Shahbeg S., editor, Huisingh, Joellen Lewtas, editor, Claxton, Larry, editor, and Nesnow, Stephen, editor

Published
1980
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