Biomedical subjects

A D LARSON

Publications and source records attributed to A D LARSON.

10 recordsLinked to original sources

PubMed1965

VOLATILE FATTY ACID REQUIREMENT OF A STRAIN OF LISTERIA MONOCYTOGENES.

Larson, A. D. (Louisiana State University, Baton Rouge), L. V. Hattier, and C. S. McCleskey. Volatile fatty acid requirement of a strain of Listeria monocytogenes. J. Bacteriol. 89:819-824. 1965.-Listeria monocytogenes strain 2 requires either isobutyric or 2-methylbutyric acid for growth. Elucidation of this requirement began with characterization of the growth-enhancing substance in culture filtrates of Aerobacter aerogenes. A. aerogenes required tryptose, glucose, and aerobic conditions for excretion of active fatty acids into the medium. Commercial preparations of isobutyric, 2-methylbutyric, isovaleric, 3-methylvaleric, and n-valeric acid supported the growth of strain 2. Purification of these fatty acids by gas chromatography demonstrated that strain 2 responded significantly only to isobutyric and 2-methylbutyric acid. Amines, alcohols, and hydroxy fatty acids, which were structurally related to the active acids, did not satisfy the fatty acid requirement of L. monocytogenes strain 2. Only one isolate (strain 2) of 128 cultures of L. monocytogenes required volatile fatty acid for growth.

Alcohols↗

PubMed1965

DENITRIFICATION BY CORYNEBACTERIUM NEPHRIDII.

Hart, Lewis T. (Louisiana State University, Baton Rouge), A. D. Larson, and C. S. McCleskey. Denitrification by Cornyebacterium nephridii. J. Bacteriol. 89:1104-1108. 1965.-Corynebacterium nephridii was found to reduce nitrate (contrary to the original description) at a rapid rate. In the conventional 0.1% nitrate broth, neither nitrite nor nitrate was detected after 24 hr. There was no assimilation of nitrate nitrogen, and the final product of nitrate reduction was nitrous oxide. Manometric studies and growth experiments indicated that the organism is incapable of reducing nitrous oxide. C. nephridii is gram-negative, grows on bile salts (5%) agar, EMB Agar, and MacConkey Agar. It was proposed that this species be transferrrd to the genus Achromobacter and designated Achromobacter nephridii (Büsing, Döll, and Freytag) comb. nov.

Achromobacter↗

PubMed1964

CATALASE ACTIVITY IN LEPTOSPIRA.

Rao, P. J. (University of Illinois, Urbana), A. D. Larson, and C. D. Cox. Catalase activity in Leptospira. J. Bacteriol. 88:1045-1048. 1964.-A number of serotypes of Leptospira were found to possess catalase activity, although considerable variation in activity existed among various serotypes. Catalase activity of L. pomona was reduced by inhibitors commonly employed for arresting catalase activity in other biological systems. Catalase activity was increased three to five times by growing cultures under conditions of oxygen availability; however, aeration had no beneficial effect on total viable cell crop. The relationship of oxygen to metabolism and future studies on virulence of the leptospirae is discussed.

Azides↗

PubMed1964

BACTERIAL METABOLISM OF 2-METHYLALANINE.

Aaslestad, H. G. (Louisiana State University, Baton Rouge), and A. D. Larson. Bacterial metabolism of 2-methylalanine. J. Bacteriol. 88:1296-1303. 1964.-A bacterium isolated from soil was found to oxidize 2-methylalanine to 65% of the theoretical value by an adaptive enzyme system. Manometric experiments with whole cells indicated that acetone but not isopropylamine was an intermediate. Cellular extracts produced carbon dioxide from 2-methylalanine when pyruvate was added to the reaction mixture. Dialysis stimulated the 2-methylalanine metabolizing system, providing pyridoxal phosphate and pyruvate were supplied. A study of the stoichiometry of this pyridoxal phosphate-dependent reaction indicated that acetone and carbon dioxide were principal products. The formation of carbon dioxide from 2-methylalanine seemed dependent upon transfer of the amino group to pyridoxal phosphate. Other 2-methyl amino acids were found to be decarboxylated by this system, thus indicating a lack of absolute specificity.

Acetone↗

PubMed1959