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A F GAUDY

Publications and source records attributed to A F GAUDY.

6 recordsLinked to original sources
PubMed1965

SEQUENTIAL SUBSTRATE REMOVAL IN A DILUTE SYSTEM BY HETEROGENEOUS MICROBIAL POPULATIONS.

The sequential metabolism of substrates by heterogeneous bacterial populations has been previously reported from this laboratory in studies with high substrate concentrations. This phenomenon has now been shown to occur at very dilute substrate concentrations, i.e., 5 mg/liter of glucose plus 5 mg/liter of sorbitol, in studies conducted under the conditions of the standard biochemical oxygen demand (BOD) test. Sequential metabolism of these substrates resulted in a diphasic curve of accumulated oxygen uptake wherein the two phases were separated by a discernible plateau. These findings illustrate one possible explanation for the generation of discontinuity in the kinetic course of carbonaceous BOD exertion.

Bacteria↗
PubMed1964

USE OF CHEMICAL OXYGEN DEMAND VALUES OF BACTERIAL CELLS IN WASTE-WATER PURIFICATION.

Four methods for determining substrate recoveries in studies concerned with the partition of substrate between sludge synthesis and respiration were investigated. An energy balance comparing chemical oxygen demand (COD) removed with the summation of oxygen uptake and the COD of the cells produced yielded average recoveries closer to 100% than any of the other three methods tested. The standard COD test was shown to yield highly reproducible values when used to determine the COD of activated sludge. Although the protein and carbohydrate content of the cells varied with cell age, a concomitant variation in cell COD was not noted.

Bacteria↗
PubMed1964

SEQUENTIAL SUBSTRATE REMOVAL IN RESPONSE TO QUALITATIVE SHOCK LOADING OF ACTIVATED SLUDGE SYSTEMS.

Heterogeneous populations acclimated to sorbitol or mannitol were subjected to shock loading with glucose during growth on the sugar alcohol. Under these severe shock-loading conditions, glucose caused immediate cessation of sorbitol or mannitol removal. Metabolism of these compounds was renewed subsequent to glucose exhaustion. Under similar shock-loading conditions, with the use of cells operationally defined as "old," the sugar alcohols were removed concurrently with glucose. In the absence of a nitrogen source with old cells, the added glucose was removed slowly in the presence of sorbitol and not at all in the mannitol-acclimated system. These results indicate the potential variability in purification efficiency attributable to substrate interaction.

Bacteria↗
PubMed1963

Multicomponent substrate utilization by natural populations and a pure culture of Escherichia coli.

A heterogeneous population, typical of activated sludge, and a prototrophic strain of Escherichia coli were used to test for sequential substrate removal in a glucose-sorbitol medium. Each culture was preacclimated to sorbitol and was studied in the two-component medium under growing and nonproliferating conditions. In all four systems, glucose blocked sorbitol removal. Since large initial inocula were used, the suppression of sorbitol metabolism could not be totally due to repression of enzyme synthesis. The results indicate that glucose may affect the functioning of an existing enzyme system in addition to its established effect on enzyme synthesis. From an applied standpoint, the results indicate that an activated sludge may be completely and immediately prevented from eliminating a waste constituent to which it is acclimated.

Bacteria↗
PubMed1963

Statistical study of the spot-plate technique for viable-cell counts.

A statistical study of the spot-plate technique was made for the purpose of establishing an acceptable counting range. The organism used in these studies was Micrococcus lysodeikticus. Standard deviations and coefficients of variation were computed for counts ranging from 20 to 440. The lower and upper limits for acceptable counts, based on coefficients of variation of 10 and 5.8, respectively, were chosen as 100 and 300.

Bacteriological Techniques↗