Symphyonema bifilamentata sp. nov., the Right Fischerella ambigua 108b: Half a Decade of Research on Taxonomy and Bioactive Compounds in New Light

Abstract

Since 1965 a cyanobacterial strain termed ‘Fischerella ambigua 108b’ was the object of several studies investigating its potential as a resource for new bioactive compounds in several European institutes. Over decades these investigations uncovered several unique small molecules and their respective biosynthetic pathways, including the polychlorinated triphenyls of the ambigol family and the tjipanazoles. However, the true taxonomic character of the producing strain remained concealed until now. Applying a polyphasic approach considering the phylogenetic position based on the 16S rRNA and the protein coding gene rbcLX, secondary structures and morphological features, we present the strain ‘Fischerella ambigua 108b’ as Symphyonema bifilamentata sp. nov. 97.28. Although there is the type species (holotype) S. sinense C.-C. Jao 1944 there is no authentic living strain or material for genetic analyses for the genus Symphyonema available. Thus we suggest and provide an epitypification of S. bifilamentata sp. nov. 97.28 as a valid reference for the genus Symphyonema. Its affiliation to the family Symphyonemataceae sheds not only new light on this rare taxon but also on the classes of bioactive metabolites of these heterocytous and true-branching cyanobacteria which we report here. We show conclusively that the literature on the isolation of bioactive products from this organism provides further support for a clear distinction between the secondary metabolism of Symphyonema bifilamentata sp. nov. 97.28 compared to related and other taxa, pointing to the assignment of this organism into a separate genus.

cblaster: a remote search tool for rapid identification and visualization of homologous gene clusters

“…In summary, cblaster can uncover homologous gene clusters and evolutionary relationships at a pace that far exceeds other available software and has become an indispensable tool in both our own research into the BGCs of fungi and bacteria ( Lacey et al , 2019 ; Li et al , 2019 , 2020 , 2021 ; Morshed et al , 2021 ) and in others ( Jung et al , 2021 ; Williams et al , 2021 ). We foresee cblaster being used to uncover novel variants of known pathways, or to prospect for new combinations of biological parts for use in synthetic biology ( Gilchrist et al , 2018 ; Sun et al , 2015 ; Wang et al , 2013 ).…”

Highlights of biosynthetic enzymes and natural products from symbiotic cyanobacteria

“…77 Structurally, PBDEs consist of hydroxy-or methoxy-substituted aromatic portions, biaryl ether bonds, and bromine substituents, 64 but are structurally distinct from the polychlorinated triphenyl ambigols, produced by the free-living cyanobacterium Symphyonema bilamentata 97.28 (formerly Fischerella ambigua 108b). 78,79 While PBDEs containing biaryl bonds have been reported, those of Lamellodysidea are exclusively composed of biaryl ethers.…”

Rare earths stick to rare cyanobacteria: Future potential for bioremediation and recovery of rare earth elements

“…from aquatic habitats, often cannot be used during biotechnological processes that involve heat or desiccation, while others, such as terrestrial strains, are better candidates and vice versa. In addition, it happens quite often that results are not linked to strain identifiers or to wrongly identified taxa what can lead to an incorrect comparison and interpretation of data-a mistake that can remain uncorrected over decades (e.g., Jung et al, 2021b). For these reasons we respected the ecology of the strains used in this study and depicted the phylogenetic placement of the strains.…”

“…92.1 were included in the study in order to complement the setup of heterocytous, branching cyanobacteria. The strain 97.28 was treated as Fisherella ambigua for the last 50 years of biotechnological research on secondary metabolites but was recently re-assigned as the type strain of the genus Symphyonema (Jung et al, 2021b). This strain has great biotechnological potential, because it grows fast and produces a diverse set of secondary metabolites, such as various ambigols (summarized in (Jung et al, 2021b)).…”

“…The strain 97.28 was treated as Fisherella ambigua for the last 50 years of biotechnological research on secondary metabolites but was recently re-assigned as the type strain of the genus Symphyonema (Jung et al, 2021b). This strain has great biotechnological potential, because it grows fast and produces a diverse set of secondary metabolites, such as various ambigols (summarized in (Jung et al, 2021b)). The strain 92.1 was formerly treated as Nostochopsis lobatus, but doubts about this assignment arose because N. lobatus is only known from aquatic habitats.…”