title: Auxotrophic mutant of the cyanobacterium Nostoc muscorum showing absolute requirement of Cs+ or Rb+ for diazotrophy and autotrophy.
abstract: Caesium-resistant (Cs(+)-R) mutant clones of the cyanobacterium Nostoc muscorum were characterized for diazotrophic growth in a medium devoid of Cs(+) or Rb(+) or both. Cs(+)-R phenotype suffered severe genetic damage of a pleiotropic nature affecting diazotrophic growth, chlorophyll a content, nitrogenase activity and photosynthetic O(2) evolution. Mutation leading to development of Cs(+)-R phenotype could be overcome by availability of Cs(+)/Rb(+). Parent and mutant strains were similar with respect to their Cs(+)/Rb(+) uptake. Available data suggests operation of an efficient coupling of the two incompatible reactions viz. oxygenic photosynthesis and oxygen sensitive N(2) fixation in this cyanobacterium.
authors.affiliation: Department of Botany, Swami Vivekanand Government College, Raisen 464551 (M.P.), India. santoshbhargava@hotmail.com
authors.forename: Santosh
authors.initials: S
authors.lastname: Bhargava
authors.forename: Rajendra
authors.initials: R
authors.lastname: Chauhan
authors.forename: Pramod K
authors.initials: PK
authors.lastname: Patil
authors.forename: Sarva Daman
authors.initials: SD
authors.lastname: Singh
mesh_terms: D002586:Cesium / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D009154:Mutation; D009586:Nitrogen Fixation / Q000502:physiology; D009591:Nitrogenase / Q000378:metabolism; D050502:Nostoc muscorum / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology; D012413:Rubidium / Q000378:metabolism*
chemical_list: D002734:Chlorophyll; D002586:Cesium; D009591:Nitrogenase; D005974:Glutamate-Ammonia Ligase; D012413:Rubidium; D000077194:Chlorophyll A