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TWO MORPHOLOGICAL FORMS OF CYLINDROSPERMOPSIS RACIBORSKII (CYANOBACTERIA) ISOLATED FROM SOLOMON DAM, PALM ISLAND, QUEENSLAND
Author(s) -
Saker Martin L.,
Neilan Brett A.,
Griffiths Dilwyn J.
Publication year - 1999
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.1999.3530599.x
Subject(s) - biology , cylindrospermopsis raciborskii , trichome , botany , cyanobacteria , 16s ribosomal rna , genus , bacteria , genetics
Cylindrospermopsis raciborskii Woloszynska is a prominent constituent of a number of water bodies in northern Australia. In Solomon Dam, this species occurs as two distinct morphological forms, one with straight trichomes and one with coiled trichomes. Isolates of the two forms have been grown in pure culture and have been shown to maintain their respective characteristic form over successive generations. Both forms were similar with respect to cylindrospermopsin content expressed as a percentage of freeze‐dried culture material, ranging from 0.14% to 0.20%, depending on the N source provided in the medium. A morphological comparison between natural populations of the two forms showed significant differences in vegetative, heterocyst, and akinete cell dimensions. These characteristics are the primary taxonomic criteria at the species level in this genus. In culture, the coiled form grew slightly faster than the straight form over the range of conditions investigated in this study. The coiled form was better suited to growth under low‐light conditions. These clear and consistent morphological and physiological differences contrast with the 99.8% similarity between the two forms in their 16S rRNA gene nucleotide sequences. It is concluded that although taxonomic separation of the two forms at the species level might not be warranted, the two strains investigated are clearly distinct morphotypes, and it is recommended that they be so recorded in monitoring programs.