Granulicella paludicola gen. nov., sp. nov., Granulicella pectinivorans sp. nov., Granulicella aggregans sp. nov. and Granulicella rosea sp. nov., acidophilic, polymer-degrading acidobacteria from Sphagnum peat bogs

Abstract

Five strains of strictly aerobic, heterotrophic bacteria that form pink-red colonies and are capable of hydrolysing pectin, xylan, laminarin, lichenan and starch were isolated from acidic Sphagnum peat bogs and were designated OB1010(T), LCBR1, TPB6011(T), TPB6028(T) and TPO1014(T). Cells of these isolates were Gram-negative, non-motile rods that produced an amorphous extracellular polysaccharide-like substance. Old cultures contained spherical bodies of varying sizes, which represent starvation forms. Cells of all five strains were acidophilic and psychrotolerant, capable of growth at pH 3.0-7.5 (optimum pH 3.8-4.5) and at 2-33°C (optimum 15-22°C). The major fatty acids were iso-C(15 : 0), C(16 : 0) and summed feature 3 (C(16 : 1)ω7c and/or iso-C(15 : 0) 2-OH). The major menaquinone detected was MK-8. The pigments were carotenoids. The genomic DNA G+C contents were 57.3-59.3 mol%. The five isolates were found to be members of subdivision 1 of the phylum Acidobacteria and displayed 95.3-98.9 % 16S rRNA gene sequence similarity to each other. The closest described relatives to strains OB1010(T), LCBR1, TPB6011(T), TPB6028(T), and TPO1014(T) were members of the genera Terriglobus (94.6-95.8 % 16S rRNA gene sequence similarity) and Edaphobacter (94.2-95.4 %). Based on differences in cell morphology, phenotypic characteristics and hydrolytic capabilities, we propose a novel genus, Granulicella gen. nov., containing four novel species, Granulicella paludicola sp. nov. with type strain OB1010(T) (=DSM 22464(T) =LMG 25275(T)) and strain LCBR1, Granulicella pectinivorans sp. nov. with type strain TPB6011(T) (=VKM B-2509(T) =DSM 21001(T)), Granulicella rosea sp. nov. with type strain TPO1014(T) (=DSM 18704(T) =ATCC BAA-1396(T)) and Granulicella aggregans sp. nov. with type strain TPB6028(T) (=LMG 25274(T) =VKM B-2571(T)).