Ronen-Tarazi, M., Department of Plant Sciences, Avron-Everani Moshe Shilo Minerva C., Hebrew University of Jerusalem, 91904 Jerusalem, Israel
Bonfil, D.J., Department of Plant Sciences, Avron-Everani Moshe Shilo Minerva C., Hebrew University of Jerusalem, 91904 Jerusalem, Israel
Schatz, D., Department of Plant Sciences, Avron-Everani Moshe Shilo Minerva C., Hebrew University of Jerusalem, 91904 Jerusalem, Israel
Kaplan, A., Department of Plant Sciences, Avron-Everani Moshe Shilo Minerva C., Hebrew University of Jerusalem, 91904 Jerusalem, Israel

An inactivation library consisting of genomic fragments ligated within a modified bluescript vector was used to isolate several new high CO2 requiring mutants of Synechococcus PCC7942. The mutants described here were impaired in the ability to accumulate C(i) internally when supplied with HCO3 -. The relevant genomic regions bearing novel genes involved in the ability to transport and to accumulate C(i) within the cells and thus to grow under low-CO2 conditions are presented. Some of the mutants were also impaired in ability to adjust to an elevated pH in their medium. We show that the use of inactivation libraries enabled cloning of genes encoding membrane-located proteins; we point to mutations introduced by the single cross-recombination events resulting in the formation of some of these mutants. Possible artifacts that may result in incorrect identification of genes, the inactivation of which could have led to the observed phenotype, are discussed.