title: Antibiotic effects on growth and heterocyst differentiation of the cyanobacterium Nostoc muscorum.
abstract: In a medium free of combined nitrogen, 1.0-6.0 micrograms/ml chloramphenicol gradually decreased the growth of the nitrogen-fixing cyanobacterium Nostoc muscorum; at 2.0 micrograms/ml the culture appeared yellowish, heterocyst frequency was not evident up to 3.0 micrograms/ml, whereas 4.0 micrograms/ml suppressed heterocyst differentiation. Lower concentrations (0.0125-0.75 microgram/ml) of rifampicin suppressed the growth but had no significant effect on heterocyst frequency in liquid medium, whereas on solid medium 0.02 micrograms/ml produced chains of heterocysts in filaments. The growth and heterocyst frequency declined gradually with increasing doses of puromycin and 6.0 micrograms/ml suppressed the heterocyst differentiation. Actinomycin-D did not affect significantly growth and heterocyst frequency even at 10.0 and 20.0 micrograms/ml.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002701:Chloramphenicol / Q000494:pharmacology; D000458:Cyanobacteria / Q000187:drug effects* / Q000254:growth & development; D003609:Dactinomycin / Q000494:pharmacology; D011691:Puromycin / Q000494:pharmacology; D012293:Rifampin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D003609:Dactinomycin; D011691:Puromycin; D002701:Chloramphenicol; D012293:Rifampin