[Phylogenetic comparison between Spirulina and Arthrospira based on 16S rRNA and rpoC1 gene].

OBJECTIVE: Based on 16S rRNA and rpoC1 gene sequences, the phylogenetic relationship between Spirulina and Arthrospira were studied and compared. METHODS: We amplified, sequenced and analyzed 16S rRNA and rpoC1 of 84 strains. Then the phylogenetic trees were constructed and compared. RESULTS: The conserved sites percentage, average G+C content and sequence identity of rpoC1 were 49.7%, 47.7%, 76%-100% respectively, significantly lower than 79.4%, 55.6% and 91%-100% of 16S rRNA, and the heterogeneity degree was higher. The trees generated with two different genes showed similar topologies and thus inferred consistent phylogenetic relationships. Eighty-four experimental strains were divided into 3 groups belonging to 2 genera: F-35 1, F-904-2, F-1070 and TJBC14 were Spirulina and the rest were Arthrospira. Although morphospecies and geographical species could not be distinguished based on 16S rRNA and rpoC1 gene sequences, the bootstrap value of rpoC1 (100%) was higher than that of 16S rRNA (99%). Moreover, clustering effect of rpoC1 for Spirulina and Arthrospirai was better than 16S rRNA. CONCLUSION: Spirulina and Arthrospira were different genera, rpoC1 gene has more advantage to distinguish the strains in the same genus than that of 16S rRNA gene.