Biomedical subjects

P L Wichlacz

Publications and source records attributed to P L Wichlacz.

4 recordsLinked to original sources

PubMed1988

Selenate reduction by bacteria from a selenium-rich environment.

Samples collected from Kesterson Reservoir were screened for bacterial presence and selenate reduction capability. Selenate concentrations of 100 mg/liter were not toxic to indigenous bacteria. Of the 44 samples collected, 20 possessed microbial populations capable of reducing selenate. Reduction was observed in 4% of the water samples, 92% of the sediment samples, and 100% of the soil samples. Microbial reduction of 100 mg of selenate per liter was complete within 1 week of incubation. Up to 75 mg of selenate per liter was reduced beyond selenite to an insoluble red precipitate. Data collected indicate that indigenous bacteria have a significant role in the biogeochemical cycling of selenium.

Bacteria↗

PubMed1985

Growth kinetics of attached iron-oxidizing bacteria.

A model of growth and substrate utilization for ferrous-iron-oxidizing bacteria attached to the disks of a rotating biological contactor was developed and tested. The model describes attached bacterial growth as a saturation function in which the rate of substrate utilization is determined by a maximum substrate oxidation rate constant (P), a half-saturation constant (K(s)), and the concentration of substrate within the rotating biological contactor (S(1)). The maximum oxidation rate constant was proportional to flow rate, and the substrate concentration in the reactor varied with influent substrate concentration (S(0)). The model allowed the prediction of metabolic constants and included terms for both constant and growth-rate-dependent maintenance energies. Estimates for metabolic constants of the attached population of acidophilic, chemolithotrophic, iron-oxidizing bacteria limited by ferrous iron were: maximum specific growth rate (mu(max)), 1.14 h; half-saturation constant (K(s)) for ferrous iron, 54.9 mg/liter; constant maintenance energy coefficient (m(1)), 0.154 h; growth-rate-dependent maintenance energy coefficient (m'), 0.07 h; maximum yield (Y(g)), 0.063 mg of organic nitrogen per mg of Fe(II) oxidized.

Journal Article↗

PubMed1985

Glucose catabolism in strains of acidophilic, heterotrophic bacteria.

Pathways of glucose catabolism, potentially operational in six strains of obligately aerobic, acidophilic bacteria, including Acidiphilium cryptum strain Lhet2, were investigated by short-term radiorespirometry and enzyme assays. Short-term radiorespirometry was conducted at pH 3.0 with specifically labeled [C]glucose. The high rate and yield of C-1 oxidized to CO(2) indicated that the Entner-Doudoroff, pentose phosphate, or both pathways were operational in all strains. Apparent nonequivalent yields of CO(2) from C-1 and estimated CO(2) from C-4 (C-1 > C-4) were suggestive of simultaneous glucose catabolism by both pathways in all strains tested. Variation in the relative contribution of the two pathways of glucose catabolism appears to account for observed strain differences. Calculation of the actual percent pathway participation was not feasible. Enzyme assays were completed with crude extracts of glucose-grown cells to substantiate the results obtained by radiorespirometry. The key enzymes of the pentose phosphate pathway (6-phosphogluconate dehydrogenase) and the Entner-Doudoroff pathway (2-keto-3-deoxy-6-phosphogluconate aldolase and 6-phosphogluconate dehydrase) were present in all strains examined (PW2, Lhet2, KLB, OP, and QBP). However, none of the strains exhibited detectable levels of the key enzyme of the Embden-Meyerhof-Parnas pathway, 6-phosphofructokinase. All strains contained glucose-6-phosphate dehydrogenase and fructose bisphosphate aldolase. The results of the enzyme study supported the contention that the pentose phosphate and Entner-Doudoroff pathways are operational for glucose catabolism in the acidophilic heterotrophs, and that the Embden-Meyerhof-Parnas pathway is apparently absent.

Journal Article↗

PubMed1981

Acidophilic, heterotrophic bacteria of acidic mine waters.

Obligately acidophilic, heterotrophic bacteria were isolated both from enrichment cultures developed with acidic mine water and from natural mine drainage. The bacteria were grouped by the ability to utilize a number of organic acids as sole carbon sources. None of the strains were capable of chemolithotrophic growth on inorganic reduced iron and sulfur compounds. All bacteria were rod shaped, gram negative, nonencapsulated, motile, capable of growth at pH 2.6 but not at pH 6.0, catalase and oxidase positive, strictly aerobic, and capable of growth on citric acid. The bacteria were cultivatable on solid nutrient media only if agarose was employed as the hardening agent. Bacterial densities in natural mine waters ranged from approximately 20 to 250 cells per ml, depending upon source and culture medium. Ferric hydrates and stream vegetation contained from 1,500 to over 7 x 10 cells per g.

Journal Article↗