caa a22 4500 465790682 CHVBK 20180323112023.0 cr unu---uuuuu 170327e19901201xx s 000 0 eng 10.1007/BF02543883 doi (NATIONALLICENCE)springer-10.1007/BF02543883 Anomalies in the enumeration of starved bacteria on culture media containing nalidic acid and tetracycline [Elektronische Daten] [Fred Genthner, Janeshwar Upadhyay, Robert Campbell, Barbara Genthner] Culturable counts of antibiotic resistant, genetically engineeredPseudomonas fluorescens were determined on antibiotic-containing plate count agar during starvation in water. Prior to starvation, colony counts obtained on all media separated into two groups. The mean of the colony counts on plate count agar with or without tetracycline (4.9 × 106 ml−1) was significantly higher than the mean colony counts on plate count agar containing either nalidixic acid or nalidixic acid plus tetraclycline (2.5×106 ml−1). After 20 days of starvation the highest mean colony counts continued to be obtained on plate count agar (7.2 × 106 ml−1) with slightly, but significantly, lower counts obtained on plate count agar containing either nalidixic acid (5.6 × 106 ml−1) or tetraclycline (1.5×106 ml−1). A combination of nalidixic acid and tetracycline in plate count agar, however, dramatically reduced colony counts (8.3 × 102 ml−1) after this starvation period. The addition of catalase to plate count agar containing nalidixic acid and tetracycline negated the effect caused by this combination of antibiotics. When colony counts obtained over the entire 20 day incubation were considered, the addition of MgSO4 to plate count agar containing nalidixic acid and tetracycline resulted in a significant increase in colony counts. Other combinations of antibiotics, nalidixic acid+carbenicillin, nalidixic acid+kanamycin, streptomycin+tetracycline, streptomycin+carbenicillin, rifampicin+tetracycline, rifampicin+carbenicillin, and rifampicin+kanamycin, did not inhibit colony formation of starved cells. Antibiotic resistant strains ofP. putida andEscherichia coli also displayed sensitivity to the combination of nalidixic acid and tetracycline in plate count agar after starvation. Springer-Verlag New York Inc., 1990 Genthner Fred Microbial Ecology and Biotechnology Branch, 32561, Gulf Breeze, Florida, USA aut Upadhyay Janeshwar Virginia State University, 32561, Gulf Breeze, Florida, USA aut Campbell Robert Environmental Research Laboratory, Technical Resources Inc., U.S. Environmental Protection Agency, 32561, Gulf Breeze, Florida, USA aut Genthner Barbara Environmental Research Laboratory, Technical Resources Inc., U.S. Environmental Protection Agency, 32561, Gulf Breeze, Florida, USA aut Microbial Ecology Springer-Verlag 20/1(1990-12-01), 283-288 0095-3628 20:1<283 1990 20 248 https://doi.org/10.1007/BF02543883 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02543883 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Genthner Fred Microbial Ecology and Biotechnology Branch, 32561, Gulf Breeze, Florida, USA aut NATIONALLICENCE 700 1- Upadhyay Janeshwar Virginia State University, 32561, Gulf Breeze, Florida, USA aut NATIONALLICENCE 700 1- Campbell Robert Environmental Research Laboratory, Technical Resources Inc., U.S. Environmental Protection Agency, 32561, Gulf Breeze, Florida, USA aut NATIONALLICENCE 700 1- Genthner Barbara Environmental Research Laboratory, Technical Resources Inc., U.S. Environmental Protection Agency, 32561, Gulf Breeze, Florida, USA aut NATIONALLICENCE 773 0- Microbial Ecology Springer-Verlag 20/1(1990-12-01), 283-288 0095-3628 20:1<283 1990 20 248 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer