AUTHOR=Rast Patrick , Glöckner Ines , Boedeker Christian , Jeske Olga , Wiegand Sandra , Reinhardt Richard , Schumann Peter , Rohde Manfred , Spring Stefan , Glöckner Frank O. , Jogler Christian , Jogler Mareike 

TITLE=Three Novel Species with Peptidoglycan Cell Walls form the New Genus Lacunisphaera gen. nov. in the Family Opitutaceae of the Verrucomicrobial Subdivision 4

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00202

DOI=10.3389/fmicb.2017.00202

ISSN=1664-302X

ABSTRACT=<p>The cell wall of free-living bacteria consists of peptidoglycan (PG) and is critical for maintenance of shape as dissolved solutes cause osmotic pressure and challenge cell integrity. Surprisingly, the subdivision 4 of the phylum Verrucomicrobia appears to be exceptional in this respect. Organisms of this subdivision are described to be devoid of muramic or diaminopimelic acid (DAP), usually found as components of PG in bacterial cell walls. Here we describe three novel bacterial strains from a freshwater lake, IG15<sup>T</sup>, IG16b<sup>T</sup>, and IG31<sup>T</sup>, belonging to a new genus in the subdivision 4 of Verrucomicrobia which we found to possess PG as part of their cell walls. Biochemical analysis revealed the presence of DAP not only in these novel strains, but also in <italic>Opitutus terrae</italic> PB90-1<sup>T</sup>, the closest described relative of strains IG15<sup>T</sup>, IG16b<sup>T</sup>, and IG31<sup>T</sup>. Furthermore, we found that nearly all genes necessary for peptidoglycan synthesis are present in genomes of subdivision 4 members, as well as in the complete genome sequence of strain IG16b<sup>T</sup>. In addition, we isolated and visualized PG-sacculi for strain IG16b<sup>T</sup>. Thus, our results challenge the concept of peptidoglycan-less free-living bacteria. Our polyphasic taxonomy approach places the novel strains in a new genus within the family <italic>Opitutaceae</italic>, for which the name <italic>Lacunisphaera</italic> gen. nov. is proposed. Strain designations for IG15<sup>T</sup>, IG16b<sup>T</sup> and IG31<sup>T</sup> are <italic>Lacunisphaera parvula</italic> sp. nov. (=DSM 26814 = LMG 29468), <italic>L. limnophila</italic> sp. nov. (=DSM 26815 = LMG 29469) and <italic>L. anatis</italic> sp. nov. (=DSM 103142 = LMG 29578) respectively, with <italic>L. limnophila</italic> IG16b<sup>T</sup> being the type species of the genus.</p>