Colin I. Mayfield

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In the past decade efforts have been made to reduce the formation of harmful disinfection byproducts during the treatment and distribution of drinking water. This has been accomplished in part by the introduction of processes that involve the deliberate encouragement of indigenous biofilm growth in filters. In a controlled environment, such as a filter,(More)
A simple modification of Gray's flagellar staining procedure is described. It can be used on air-dried smears or directly on wet mounts of motile bacteria. The stained bacterial flagella can be observed with phase-contrast or bright-field optics. No rigorous cleaning of slides, counterstains, or any washing procedures are required with the staining method,(More)
A psychrotrophic bacterium, originally isolated from a natural aquatic environment, was characterized and identified as Pseudomonas putida Q5 for use as a representative recipient for biodegradative genes from a mesophilic microorganism. The TOL plasmid pWWO of the mesophile P. putida PaW1 was successfully transferred by conjugation to the naturally(More)
Electron transport system (ETS) activity was measured in amended and nonamended soil by measuring the reduction of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to iodonitrotetrazolium formazan (INT-formazan), which can be easily extracted with methanol without interference from other compounds found in soil. A high correlation(More)
Several naturally occurring calcium-phosphate apatites which varied in crystalline structure and ionic composition were added as crystals of different particle size to P-free (<1μg/liter total P) nutrient media. Sufficient ortho-PO 4 3− was released by the partial dissolution of apatite crystals at limnetic pH levels (pH 7.8) to support growth of several(More)
A bioassay using Pseudomonas fluorescens was affected by the sequence of exposure to pentachlorophenol (PCP) and 2,3,4,5-tetrachlorophenol (TCP). Surviving cells from standardized cell suspensions initially treated with PCP at concentrations ranging from 10 to 75 micrograms/ml, followed by removal of the toxicant, were not affected by a second dose of PCP(More)
Small samples of soil amended with 2% (w/w) of glucose were preincubated either aerobically or anaerobically and then assayed (N2 15 and C2H2-C2H4) either aerobically or anaerobically for different time periods. One-hour C2H2-C2H4 assays showed greatest activity when anaerobic assay followed anaerobic preincubation. During the anaerobic preincubation a lag(More)
An improved method is proposed for the preparation of sediment elutriates which permits relatively realistic determination of bioavailable contaminants. It suggests the use of rotary tumbling in a cycle of 3–4 rpm to achieve sediment-water mixing. Experiments were undertaken to evaluate the mixing efficiency of the rotary tumbler as compared to that of the(More)
Exposure to endotoxins in treated drinking water can occur through ingestion, dermal abrasions, inhalation of water vapor, intravenous injection or during dialysis. While the risks associated with endotoxin ingestion and entry through dermal abrasions are not well quantified, adverse effects of intravenous injection and dialysis are well known and some(More)
Soil columns were exposed to balanced (low Na+) or unbalanced (high Na+) high-salt solutions for a period of 7 days followed by 7 days of stress reflief. Total numbers of bacteria released into the perfusates rose under both types of stress, but the proportion of displaced bacteria that were viable fell significantly. Relief from both types of stress(More)