Transformation in Agmenellum quadruplicatum.

A DNA-mediated transformation system for the blue-green alga Agmenellum quadruplicatum, strain PR-6, is described and characterized for DNA concentration dependence, dependence on time of exposure to DNA, phenotypic expression, sensitivity to various enzymes, and competence. The stability of the transformants has been investigated, and genetic backcross and selfing experiments have been performed. This system fulfills all of the criteria established for the well-characterized transformation systems in heterotrophic bacteria and demonstrates significant similarities to at least one of these systems for all characteristics examined. The efficiency of transformation is high. This system fills a need for a well-characterized genetic system in an oxygen-evolving photoautotroph. We have used it to transform a strain with a mutational lesion in assimilatory nitrogen metabolism to a wild-type genotype.