Fottea

Fottea 2022, 22(1):78-92 | DOI: 10.5507/fot.2021.017

Geosmin-producing Scytonema foetidum sp. nov. (Scytonemataceae, Cyanobacteria): morphology and molecular phylogeny

Wittaya Tawong^{1, 2*}, Pongsanat Pongcharoen^{1, 2}, Tomohiro Nishimura³

¹ Department of Agricultural Science, Faculty of Agricultural Natural Resources and Environment, Naresuan University, Phitsanulok 65000, Thailand; *Corresponding author e-mail: wittayat@nu.ac.th

² Center of Excellence in Research in Agricultural Biotechnology, Naresuan University, Phitsanulok 65000, Thailand

³ Cawthron Institute, Nelson 7010, New Zealand

A novel Scytonema species, Scytonema foetidum sp. nov. is described by combining morphological and genetic evidences. Two clonal strains of the new species were isolated from a wet soil sample taken from the Khek River in the lower northern part of Thailand. This species is morphologically similar to S. hofmanii, but can be differentiated by a small filament width, conically rounded apical cell, and sheath present throughout the whole trichome. The 16S ribosomal RNA (rRNA), rbcLX, and nifH phylogenetic trees indicated that S. foetidum clearly formed a unique cluster within the Scytonema sensu stricto clade and shared low 16S rRNA sequence similarity (<98.4%) with the phylogenetically related taxa, supporting separation at species level. The 16S-23S rRNA internal transcribed spacer (ITS) sequences of S. foetidum also possessed unique secondary structures in D1-D1', Box B, and V3 helices, differentiating this species from other known Scytonema species. Furthermore, S. foetidum could produce the odoriferous compound, geosmin.

Keywords: Cyanobacteria, Geosmin, 16S rRNA phylogeny, ITS secondary structure, Scytonema, Systematics, Taxonomy, Thailand

Received: May 28, 2021; Revised: August 4, 2021; Accepted: September 17, 2021; Prepublished online: January 10, 2022; Published: April 1, 2022  Show citation