title: Detection, with a pH indicator, of bacterial mutants unable to denitrify.
abstract: In order to facilitate isolation of mutants with alterations in the denitrification pathway, a new screening procedure using phenol red incorporated into agar overlay has been defined. Alkalinization in the neighbourhood of denitrifying colonies respiring nitrate or nitrite gives rise to a red circular halo. Antimycin blocked these colour changes, which suggests their association with the periplasmic reduction of nitrite. Inhibition of nitrous oxide reductase by acetylene had no significant effect on alkalinization elicited by nitrate or nitrite. Several mutants negative by the phenol red staining test were generated by transposon Tn5 mutagenesis of Paracoccus denitrificans. All these mutants were defective in the activities of nitrite and nitric oxide reductases while the other denitrification activities were present at the wild-type level.
authors.affiliation: Department of Biochemistry, Faculty of Science, Masaryk University, Kotlárská 2, CZ-61137 Brno, Czech Republic.
authors.forename: Jirí
authors.initials: J
authors.lastname: Mazoch
authors.forename: Igor
authors.initials: I
authors.lastname: Kucera
mesh_terms: D000114:Acetylene / Q000494:pharmacology; D000968:Antimycin A / Q000031:analogs & derivatives* / Q000494:pharmacology; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000737:chemistry; D016296:Mutagenesis / Q000235:genetics; D009566:Nitrates / Q000032:analysis* / Q000378:metabolism; D009573:Nitrites / Q000032:analysis* / Q000378:metabolism; D010088:Oxidoreductases / Q000037:antagonists & inhibitors; D010231:Paracoccus denitrificans / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D010637:Phenolsulfonphthalein / Q000737:chemistry*
chemical_list: D004251:DNA Transposable Elements; D007202:Indicators and Reagents; D009566:Nitrates; D009573:Nitrites; C032456:antimycin; D000968:Antimycin A; D010088:Oxidoreductases; C022763:nitrous oxide reductase; D010637:Phenolsulfonphthalein; D000114:Acetylene