RESUMO
An assay system has been developed based on automated radiometric quantification of 14CO2 produced through oxidation of [1-14C] fatty acids by mycobacteria. Two stains of M. tuberculosis (H37Rv and Erdman) and one of M. bovis (BCG) in 7H9 medium (ADC) with 1.0 microCi of one of the fatty acids (butyric, hexanoic, octanoic, decanoic, lauric, myristic, palmitic, stearic, oleic, linoleic and linolenic) were studied. Results previously published on M. lepraemurium (Hawaiian) were also included for comparison. Both strains of M. tuberculosis had maximum 14CO2 production from hexanoic acid. Oxidation of butyric and avid oxidation of lauric acids were also found with the H37Rv strain but not with Erdman. In contrast, 14CO2 production by M. bovis was greatest from lauric and somewhat less from decanoic acid. M. lepraemurium showed increasing oxidation rates from myristic, decanoic and lauric acids. Assimilation studies of M. tuberculosis H37Rv confirmed that most of the oxidized substrates were converted into by-products with no change in those from which no oxidation was found. These data suggest that the radiometric measurement of differential fatty acid metabolism may provide a basis of strain identification of the genus Mycobacterium.
Assuntos
Ácidos Graxos/metabolismo , Mycobacterium/metabolismo , Dióxido de Carbono/análise , Radioisótopos de Carbono , Meios de Cultura , Mycobacterium bovis/metabolismo , Mycobacterium lepraemurium/metabolismo , Mycobacterium tuberculosis/metabolismo , OxirreduçãoRESUMO
An assay system has been developed based on automated radiometric quantification of 14CO2 produced through oxidation of (1--14C) fatty acids by mycobacteria. With this system, the Hawaiian strain of M. lepraemurium was studied using the K-36 buffer as a suspending solution for the organisms along with 5.0 muCi of one of the following fatty acids: acetate, butyric, hexanoic, octanoic, decanoic, lauric, myristic, palmitic, stearic, oleic, linoleic, linolenic, and malonic. The 14CO2 production by this organism was greatest with lauric, decanoic, myristic, octanoic, stearic, oleic, linoleic, linolenic, and malonic. The 14CO2 production by this organism was greatest with lauric, decanoic, myristic, octanoic, and stearic acids, in decreasing order. Assimilation studies and radiochromatograms confirmed that most of the oxidized substrates were converted into by-products with no change in those from which no oxidation was found. These data suggest that the radiometric measurement of differential fatty acid metabolism may provide a basis of radiometric identification of M. lepraemurium and assessment of the growth requirements of this organism.
Assuntos
Ácidos Graxos/metabolismo , Mycobacterium lepraemurium/metabolismo , Radiometria/instrumentação , Dióxido de Carbono/metabolismo , Cromatografia em Papel , Cromatografia em Camada FinaRESUMO
A radiometric microbiologic assay has been developed for the determination of niacin in biologic fluids. Lactobacillus plantarum produced 14CO2 from L-[U-14C] hr malic acid in quantities proportional to the amount of niacin present. The assay is specific for the biologically active forms of niacin in humans. Thirty normal hemolysates were analyzed and the values ranged from 13.0 to 17.8 micrograms niacin/ml RBC (mean = 15.27 +/- 1.33 s.d.). Good recovery and reproducibility studies were obtained with this assay. On thirty blood samples, correlation was excellent between the radiometric and the conventional turbidimetric assays.
Assuntos
Bioensaio/métodos , Radioisótopos de Carbono , Ácidos Nicotínicos/sangue , Animais , Peso Corporal/efeitos dos fármacos , Dióxido de Carbono/metabolismo , Lactobacillus/crescimento & desenvolvimento , Lactobacillus/metabolismo , Malatos/metabolismo , Nefelometria e Turbidimetria , Ácidos Nicotínicos/análise , RatosRESUMO
A radiometric microbiologic assay for the determination of folic acid in human plasma and red blood cells is described. The assay is based upon the measurement of 14CO2 produced from the metabolism of [1-14C] gluconate by Lactobacillus casei. The 14CO2 evolved was shown to be proportional to the amount of added DL-N-5-methyltetrahydrofolage (DL-N-5-methyl FH4). A total of 26 normal plasma and 57 blood hemolysates were assayed in parallel by this radiometric and the standard (turbidimetric) microbiologic assay. The correlation coefficients for the two assays were r = 0.96 for plasma and r = 0.98 for red-cell folate. Lyophilization of L. casei was found to simplify this radiometric assay by eliminating routine maintenance and culture of this microorganism.
Assuntos
Eritrócitos/análise , Ácido Fólico/sangue , Lacticaseibacillus casei/metabolismo , Bioensaio , Dióxido de Carbono/metabolismo , Radioisótopos de Carbono , Ácido Fólico/análise , Gluconatos/metabolismo , Humanos , Radiometria , Tetra-Hidrofolatos/metabolismoRESUMO
A 48-hour radiometric test for determining the drug susceptibility of Mycobacterium tuberculosis has been developed. The test is based on the measurement of 14CO2 produced by the oxidation of formate labeled with carbon-14. The test system uses 5 X 10(7) organisms in 1 ml of Middlebrook 7H9 medium plus albumin-dextrose-catalase enrichment and 1 muCi of [14C]formate. The 14CO2 produced is measured in an ionization chamber at 24-, 48-, and 72-hour intervals, with and without the addition of antituberculous drugs. Isoniazid, streptomycin, rifampin, and ethambutol were each tested at 3 concentrations by the radiometric method and the reference (agar dilution) method. Six standard strains and 21 patient isolates were compared by both methods. Production of 14CO2 was quantitatively decreased in the presence of drugs that inhibit the organism. The radiometric method requires 2 days; the agar dilution, 14 to 21 days.