Detailed characterization of the Arthrospira type species separating commercially grown taxa into the new genus Limnospira (Cyanobacteria)

Paulina Nowicka-Krawczyk,Radka Mühlsteinová,Tomáš Hauer

doi:10.1038/s41598-018-36831-0

Paulina Nowicka-Krawczyk, Radka Mühlsteinová + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-36831-0

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Abstract

The genus Arthrospira has a long history of being used as a food source in different parts of the world. Its mass cultivation for production of food supplements and additives has contributed to a more detailed study of several species of this genus. In contrast, the type species of the genus (A. jenneri), has scarcely been studied. This work adopts a polyphasic approach to thoroughly investigate environmental samples of A. jenneri, whose persistent bloom was noticed in an urban reservoir in Poland, Central Europe. The obtained results were compared with strains designated as A. platensis, A. maxima, and A. fusiformis from several culture collections and other Arthrospira records from GenBank. The comparison has shown that A. jenneri differs from popular species that are massively utilized commercially with regard to its cell morphology, ultrastructure and ecology, as well as its 16S rRNA gene sequence. Based on our findings, we propose the establishment of a new genus, Limnospira, which currently encompasses three species including the massively produced L. (A.) fusiformis and L. (A.) maxima with the type species Limnospira fusiformis.

Highlights

Among the simple trichal cyanobacteria, three genera possess helically-coiled trichomes as a prominent diacritical feature: Spirulina Turpin ex Gomont 1892, Halospirulina Nübel, Garcia-Pichel et Muyzer 2000, and Arthrospira Stizenberger ex Gomont 1892
Strains/organisms determined as A. maxima Setchell & Gardner, A. fusiformis (Voronichin) Komárek & Lund, and A. platensis Gomont have often been isolated from highly alkaline and saline inland habitats in tropical and subtropical climate zones[18,19]; this knowledge, combined with the lack of information on the type species incorrectly suggests that the preference for high pH and high salinity and/or electrical conductivity is a general feature shared by the entire genus[6]
Gomont[8], in the literature designated as a starting point for the nomenclature of simple filamentous cyanobacteria, accepts the genus and indicates that this species can be found in various pools and garden lakes in different parts of Europe

Summary

Introduction

Among the simple trichal cyanobacteria, three genera possess helically-coiled trichomes as a prominent diacritical feature: Spirulina Turpin ex Gomont 1892, Halospirulina Nübel, Garcia-Pichel et Muyzer 2000, and Arthrospira Stizenberger ex Gomont 1892. The latter is a widely-known taxon with long history of use as a food source, for example as dihé in Africa or tecuitlatl in Mexico[1,2,3]. A wide array of studies have confirmed that Arthrospira and Spirulina represent two independent genera, each classified in different orders, and apart from possessing helically-coiled trichomes, the two share a minimal morphological resemblance[11]. The presence of A. jenneri has been constant: in winter, it creates a visible benthic mat under the ice cover, while in summer, when the air temperature increases to 28 °C, it detaches from the bottom of the reservoir and large lobes of its mat float to the surface

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