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Notable microbiologist: Donald Reasoner

By Tim Sandle
Posted Sep 7, 2012 in Science
Microbiologist Donald Reasoner, co-creator of the low nutrient R2A agar (along with Ed Geldreich) commonly used for the assessment of Water-for-Injection and purified water, passed away in May 2012.
I have reproduced his obituary notice below.
"Donald J., loving husband of Linda Reasoner (nee Garver), beloved father of Jeffrey Reasoner (Tammy) and David Reasoner (Paula), devoted grandfather of Ben and Claire, dear brother of Stan Reasoner of Portland, Oregon. Don, a resident of Pierce Township, passed away May 8, 2012 at the age of 71. Don was a research microbiologist for the U.S. EPA for 35 years and a Boy Scout leader of Troop 281. He was also a member of EAA Chapter 174. "
Here is the abstract from the paper relating to the R2A agar research
"Plate count agar is presently the recommended medium for the standard bacterial plate count (35 degrees C, 48-h incubation) of water and wastewater. However, plate count agar does not permit the growth of many bacteria that may be present in treated potable water supplies. A new medium was developed for use in heterotrophic plate count analyses and for subculture of bacteria isolated from potable water samples. The new medium, designated R2A, contains 0.5 g of yeast extract, 0.5 g of Difco Proteose Peptone no. 3 (Difco Laboratories), 0.5 g of Casamino Acids (Difco), 0.5 g of glucose, 0.5 g of soluble starch, 0.3 g of K2HPO4, 0.05 g of MgSO4 X 7H2O, 0.3 g of sodium pyruvate, and 15 g of agar per liter of laboratory quality water. Adjust the pH to 7.2 with crystalline K2HPO4 or KH2PO4 and sterilize at 121 degrees C for 15 min. Results from parallel studies with spread, membrane filter, and pour plate procedures showed that R2A medium yielded significantly higher bacterial counts than did plate count agar. Studies of the effect of incubation temperature showed that the magnitude of the count was inversely proportional to the incubation temperature. Longer incubation time, up to 14 days, yielded higher counts and increased detection of pigmented bacteria. Maximal bacterial counts were obtained after incubation at 20 degrees C for 14 days. As a tool to monitor heterotrophic bacterial populations in water treatment processes and in treated distribution water, R2A spread or membrane filter plates incubated at 28 degrees C for 5 to 7 days is recommended."

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