Biomedical subjects

R A Mah

Publications and source records attributed to R A Mah.

40 records · Page 3Linked to original sources

PubMed1968

Microbiology of anaerobic sludge fermentation. I. Enumeration of the nonmethanogenic anaerobic bacteria.

An anaerobic medium containing sludge supernatant fluid and glucose was used for enumeration of bacteria from the sludge fermentation. Comparison of viable counts from several separate samples consistently showed 10 to 100 times more anaerobic than aerobic bacteria. However, viable counts of the various samples differed by as much as 10 times; this variation probably reflects a change in the natural environment or sampling errors, or a combination of the two. Direct microscopic counts yielded values of about 10(10)/ml. The discrepancy between viable (10(8) to 10(9)/ml) and direct counts may be due to large numbers of dead cells. Random isolates of representative colonies from high dilutions exhibited the ability to ferment sugars and are not likely to be methane bacteria.

Bacteria↗

PubMed1967

Microtiter hemagglutination-inhibition assay for staphylococcal enterotoxin B.

The rapid microtiter technique was investigated as a means of facilitating the detection of staphylococcal enterotoxin B. With this technique, many samples were assayed simultaneously, and readable results were obtained in 3 hr. Other advantages of this method, in addition to speed, were the small quantity of reactants used, ease of reading, and reproducibility.

Enterotoxins↗

PubMed1967

Nutritional requirements of Staphylococcus aureus S-6.

A synthetic medium was devised for growth of Staphylococcus aureus strain S-6. The growth yield in synthetic medium was compared to that in complex medium containing an equivalent amount of protein hydrolysate. Enterotoxin B formation in the two media was also compared. The defined medium was composed of inorganic salts, 11 amino acids (glycine, valine, leucine, threonine, phenylalanine, tyrosine, cysteine, methionine, proline, arginine, and histidine), and three vitamins (thiamine, nicotinic acid, and biotin). Biotin was a growth factor requirement of S-6 when glutamic acid but not glucose was used as a carbon source. The quantity of enterotoxin B produced in the defined medium was about one-seventh of that produced in complex medium, even though the growth yields were similar.

Amino Acids↗

PubMed1966

Kinetics of acetate metabolism during sludge digestion.

The quantitative contribution of acetic acid to methane production was studied by use of C(14)-labeled acetic acid. Samples of domestic sewage sludge were incubated anaerobically in Warburg vessels. The rate of methane production in the vessels was 0.033 mumoles per ml per min. C(14)-labeled acetic acid was added, and the turnover rate was calculated. The pool size of acetic acid in the sludge was 4.7 mumoles/ml. The turnover rate was 0.0052 min(-1), giving a rate of formation of acetic acid of 0.024 mumoles per ml per min. Under these conditions, acetic acid would account for approximately 73% of the methane produced by the sludge. Acetic acid was found to exist primarily in an extracellular pool. The turnover rate of the extracellular pool was rapid, and it was concluded that most of the acetic acid must be metabolized to methane by a specialized microflora not involved in the formation of acetic acid.

Acetates↗