Cyanobacteria passage through drinking water filters during perturbation episodes as a function of cell morphology, coagulant and initial filter loading rate

Eight pilot-scale in-line filtration trials were performed to evaluate the passage of cyanobacterial cells through drinking water filters after sudden increases in hydraulic loading rates. Trials were performed at 30 °C using two coagulant combinations (aluminum sulfate and cationic polymer or ferric chloride and cationic polymer), two initial filter loading rates (7 or 10 m/h) and two species of morphologically different cyanobacteria (Microcystis aeruginosa or Anabaena flos aquae). The filter was perturbed by instantaneously increasing the hydraulic loading rate by 50%. Filter influent and effluent water qualities were characterized by measuring turbidity, particles and chlorophyll a. The observed post-perturbation filter effluent chlorophyll a peaks were 1.6–48 times greater than the pre-perturbation averages. Chlorophyll a peaks were larger for M. aeruginosa than for A. flos aquae. Chlorophyll a peaks were also larger for the higher (10 m/h) than for the lower (7 m/h) initial filter loading rate. The post-perturbation effluent turbidity peaks were 1.4–7.2 times greater than the pre-perturbation averages. The post-perturbation effluent particle peaks were 6.5–25 times greater than the pre-perturbation averages. These results indicate that particles were a more sensitive indicator of cyanobacterial passage than turbidity.     

Interaction between the Effects of Inside and Outside Na and K on Bullfrog Skin Potential

The composition of the solution bathing one border of the isolated frog skin affects the response of the potential across the skin to changes in the composition of the solution bathing the opposite border. Increasing the K concentration of the inside (corium) bathing solution decreased the sensitivity of the potential to a change in outside Na concentration. Decreasing the outside Na concentration decreased the sensitivity of the potential to a change in inside K concentration. Increasing the total ionic strength of the outside bathing solution or of both bathing solutions decreased the sensitivity of the potential to a change in outside Na concentration.     

Evidence for catalytic site cysteine and histidine by chemical modification of beta-hydroxy-beta-methylglutaryl-coenzyme A reductase

S-(4-Bromo-2,3-dioxobutyl)-coenzyme A inactivates both yeast and rat liver beta-hydroxy-beta-methylglutaryl-coenzyme A reductase. The inactivation is irreversible, complete in 15 s, and proportional to the concentration of the reagent. beta-Hydroxy-beta-methylglutaryl-CoA provides protection against inactivation, whereas NADPH does not. Inactivation is attributed to reaction with an essential cysteine at the beta-hydroxy-beta-methylglutaryl-CoA binding site. Experiments with other active site-directed reagents confirm the involvement of a cysteine and support the presence of an active-site histidine, but rule out the participation of arginine or serine.     

Activity of Microorganisms in Acid Mine Water I. Influence of Acid Water on Aerobic Heterotrophs of a Normal Stream

Comparison of microbial content of acid-contaminated and nonacid-contaminated streams from the same geographical area indicated that nonacid streams contained relatively low numbers of acid-tolerant heterotrophic microorganisms. The acid-tolerant aerobes survived when acid entered the stream and actually increased in number to about 2 × 10³ per ml until the pH approached 3.0. The organisms then represented the heterotrophic aerobic microflora of the streams comprised of a mixture of mine drainage and nonacid water. A stream which was entirely acid drainage did not have a similar microflora. Most gram-positive aerobic and anaerobic bacteria died out very rapidly in acidic water, and they comprised a very small percentage of the microbial population of the streams examined. Iron- and sulfur-oxidizing autotrophic bacteria were present wherever mine water entered a stream system. The sulfur-oxidizing bacteria predominated over iron oxidizers. Ecological data from the field were verified by laboratory experiments designed to simulate stream conditions.     

Leakage of cellular material from Thiobacillus ferrooxidans in the presence of organic acids.

Thiobacillus ferroodixans cells released varying amounts of iron, phosphate, sugar, ribonucleic acid, deoxyribonucleic acid, and substances that absorbed light at both 260 and 280 nm, when exposed to 10(-2) to 10(-1) M concentrations of these organic acids: propionic, butyric, valeric, hexanoic, and oxalacetic. These acids also retarded iron oxidation by the cells. Electron microscope observation of cells after exposure to the organic acids showed varying degrees of cell envelope disruption, suggesting that the mode of inhibition of autotrophic iron oxidation in the cell involves interference with the function of the cell envelope, possibly the cell membrane.     

Exospore formation in Methylosinus trichosporium.

Formation of exospores in Methylosinus trichosporium was examined by electron microscopy; serial sectioning was used to visualize the shape and location of the developing exospore in relation to the vegetative cell. The initial stage was the formation of a budlike enlargement on one end of the vegetative cell. The enlargement was surrounded by the exospore capsule, and the cell wall was continuous around both the cell and the developing exospore. A constriction occurred in the area where the budlike structure was attached to the vegetative cell, and the constriction continued to form until the immature exospore was detached from the vegetative cell. The cup-shaped immature exospore was surrounded by the exospore capsule, which appeared to hold the exospore close to the vegetative cell. After separation from the vegetative cell, the immature exospore developed further by forming the exospore wall and by becoming spherical.     

Identification of the protein responsible for hepatic system N amino acid transport activity.

In the liver, glutamine utilization may be limited by the rate of transport across the plasma membrane by the System N carrier. System N-mediated transport activity has been solubilized from rat liver plasma membrane, partially purified, and then reconstituted into proteoliposomes. To identify the System N carrier protein, monoclonal antibodies were generated against the protein fraction enriched for System N activity. Two antibodies , 3E1-2 and 1E7-3, inhibited System N activity in hepatocytes. These antibodies also immunoprecipitated System N activity from a mixture of solubilized proteins and were specific for antigen recognition in that neither immunoprecipitated System A activity. The antibody recognized a single protein of molecular size 100 kDa by immunoblot analysis. Recognition of this protein by the antibody increased in parallel with the enrichment of System N activity in solubilized membrane fractions. These data suggest that a 100-kDa plasma membrane protein mediates System N transport activity in rat hepatocytes.     

Detection of Thiobacillus ferrooxidans in acid mine environments by indirect fluorescent antibody staining.

An indirect fluorescent antibody (FA) staining technique was developed for the rapid detection of Thiobacillus ferrooxidans. The specificity of the FA stain for T. ferrooxidans was demonstrated with both laboratory and environmental samples. Coal refuse examined by scanning electron microscopy exhibited a rough, porous surface, which was characteristically covered by water-soluble crystals. Significant numbers of T. ferrooxidans were detected in the refuse pores. A positive correlation between numbers of T. ferrooxidans and acid production in coal refuse in the laboratory was demonstrated with the FA technique.     

Whole-cell and membrane lipids of the methylotrophic bacterium Methylosinus trichosporium.

The lipid composition of the methylotrophic bacterium Methylosinus trichosporium was examined. Whole-cell lipid distribution was 39.1% neutral lipids, 34.5% polar lipids, and 26.4% poly-beta-hydroxybutyric acid. Membrane lipids were 83% phospholipids, with phosphatidylethanolamine and phosphatidylglycerol accounting for over 94% of the total. All the phospholipids had similar fatty acid compositions, with 18:1 accounting for about 87% of the total and most of the rest consisting of 16:1. Similarities between the lipid composition of this bacterium and other bacteria are discussed.