Building a Cell House from Cellulose: The Case of the Soil Acidobacterium SBC82.

SBC82 is a recently described representative of the phylum from lichen-covered tundra soil. Cells of this bacterium occur within unusual saccular chambers, with the chamber envelope formed by tightly packed fibrils. These extracellular structures were most pronounced in old cultures of strain SBC82 and were organized in cluster-like aggregates. The latter were efficiently destroyed by incubating cell suspensions with cellulase, thus suggesting that they were composed of cellulose. The diffraction pattern obtained for 45-day-old cultures of strain SBC82 by using small angle X-ray scattering was similar to those reported earlier for mature wood samples. The genome analysis revealed the presence of a cellulose biosynthesis locus . Cellulose synthase key subunits A and B were encoded by the gene whose close homologs are found in genomes of many members of the order . More distant homologs of the acidobacterial occurred in representatives of the . A unique feature of locus in strain SBC82 was the non-orthologous displacement of the gene, which encodes the GH8 family glycosidase with a GH5 family gene. Presumably, these cellulose-made extracellular structures produced by have a protective function and ensure the survival of this acidobacterium in habitats with harsh environmental conditions.