Cyanocohniella calida gen. et sp. nov. (Cyanobacteria: Aphanizomenonaceae) a new cyanobacterium from the thermal springs from Karlovy Vary, Czech Republic

Abstract

The thermal springs of Karlovy Vary (Carlsbad) is the locus classicus of the well-known thermal cyanobacterium Mastigocladus laminosus. In addition to the nominate variety, several other varieties and forms were described based on differences in morphology (true-branching versus non-branching) or ecology (thermal versus non-thermal). The cyanobacterial strain Kaštovský 1996/2, which was provisionally identified as M. laminosus f. nostocoides, was also isolated from this locality and discussed in previous work. Based on both morphological and molecular (SSU) analyses, this strain was found to not belong to Mastigocladus, but rather to an undescribed genus, presumably within the Nostocaceae. This strain was subsequently lost, and absence of type materials prevented the description of the genus. The species was successfully re-isolated in 2012. The new strain is identical in morphology, life cycle, and 16S rRNA sequence to the lost strain 1996/2. It is herein described as Cyanocohniella calida gen. et sp. nov. The genus differs from all other Nostocaceae and Aphanizomenonaceae by the unique combination of these characteristics: 1) thermal-tolerant ecology, 2) life cycle that includes Pseudanabaenaceae-like, Nostoc-like and Chlorogloeopsis-like stages, 3) absence of aerotopes, and 4) phylogenetic placement in the Aphanizomenonaceae. The sister taxa, based on 16S rRNA gene sequence phylogenetic analysis, are Cyanospira and Anabaenopsis, both spiral, planktonic, aerotope-bearing, tropical genera and species clearly distinct from C. calida.

Nunduva, a new marine genus of Rivulariaceae (Nostocales, Cyanobacteria) from marine rocky shores

“…Indeed, all 16S rRNA sequences of members of Rivulariaceae sensu stricto are above 94.5% similar, suggesting that this very morphologically and ecologically diverse group could all belong to the same genus if only this criterion was used. However, previous studies demonstrated that Nostocales are highly similar in the 16S rRNA gene sequence (Flechtner et al 2002;Lukešová et al 2009;Kaštovský et al 2014) and that genera in this order frequently are more similar than 98% to at least some other genera. According to Kaštovský et al (2014), to discriminate between genus and species, the similarity threshold in the 16S rRNA gene can be very close (<99% for species, and < 98% for genera).…”

“…However, previous studies demonstrated that Nostocales are highly similar in the 16S rRNA gene sequence (Flechtner et al 2002;Lukešová et al 2009;Kaštovský et al 2014) and that genera in this order frequently are more similar than 98% to at least some other genera. According to Kaštovský et al (2014), to discriminate between genus and species, the similarity threshold in the 16S rRNA gene can be very close (<99% for species, and < 98% for genera). We conclude that the 16S rRNA gene sequences were too similar to serve as a reliable or sole criterion for genus or species recognition in the Rivulariaceae.…”

Roholtiella, gen. nov. (Nostocales, Cyanobacteria)—a tapering and branching cyanobacteria of the family Nostocaceae

“…Ligation reaction was done right in the LMP gel using the Promega Easy-Vector Cloning kit (Promega Corp., Madison, WI, USA) for the Czech and Russian strains and Stratagene cloning kit for the USA strains according to the manufacturer's instructions. Five colonies were chosen at random and PCR amplified using primers T7 and SP6 and following conditions described by Kaštovský et al (2014). DNA sequencing was performed by the chain-termination method using Applied Biosystems BigDye™ Terminator Cycle Sequencing Kit v.3.1 (Life Technologies), according to the manufacturer's instructions.…”

“…Recently, a number of strains assigned to Tolypothrix, Calothrix, and Microchaete have been found to form a clade within the Nostocaceae (Kaštovský & Johansen 2008, Komárek et al 2014. Strains in this clade have recurrently appeared in phylogenetic analyses without taxonomic correction, including Nostoc Fin 152, Calothrix brevissima West 1907: 180 (AB074504), Tolypothrix IAM M-259, and Nostoc PCC 7120 (Rajaniemi et al 2005, Řeháková et al 2007, Kaštovský & Johansen 2008, Lukešová et al 2009 (as "mixed Nostocaceae"), Kaštovský et al 2014). We have long recognized that this group is problematic, but it is only recently (with the description of Calochaete cimrmanii Hauer et al 2013: 38) that taxonomic revision has come to any members of this group.…”

<italic>Violetonostoc minutum</italic> gen. et sp. nov. (Nostocales, Cyanobacteria) from a rocky substrate in China

“…Nostocaceae is among one of the most problematic group, and several genera in this family were arguably polyphyletic (Rajaniemi et al 2005a, Kozhevnikov and Kozhevnikova 2011, Zapomělová et al 2013, Komárek et al 2014, Choi et al 2018. Moreover, a number of strains assigned to Tolypothrix, Calothrix, and Microchaete have been found to form a clade within this family (Kaštovský and Johansen 2008, Kaštovský et al 2014, Komárek et al 2014). The genus Nostoc was morphologically defined as having unbranched uniseriate isopolar filaments with differentiated akinetes and terminal / intercalary heterocytes embedded in mucilaginous material-forming colonies.…”