Bryobacter aggregatus gen. nov., sp. nov. is proposed to accommodate three strains of slowly growing, chemo-organotrophic bacteria isolated from acidic Sphagnum peat bogs. These bacteria were strictly aerobic, Gram-negative, colourless, non-motile coccoids or short rods that multiplied by normal cell division and formed irregularly shaped cell aggregates. Strains MPL3T, MPL1011 and MOB76 were acidotolerant, mesophilic organisms capable of growth at pH 4.5–7.2 and between 4 and 33 °C (optimum growth at pH 5.5–6.5 and 22–28 °C). The preferred growth substrates were sugars, some heteropolysaccharides and galacturonic and glucuronic acids, which are released during decomposition of Sphagnum moss. The major fatty acids were iso-C15 : 0, C16 : 0 and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1 ω7c); the major quinones were MK-9 and MK-10. The DNA G+C content was 55.5–56.5 mol%. Strains MPL3T, MPL1011 and MOB76 possessed nearly identical 16S rRNA gene sequences and belonged to the phylum Acidobacteria. They represent the first taxonomically characterized members of acidobacterial subdivision 3 and display only 81.7–86.7 % 16S rRNA gene sequence similarity to other members of the Acidobacteria with validly published names. Therefore, strains MPL3T, MPL1011 and MOB76 are classified as representatives of a novel species in a new genus, for which the name Bryobacter aggregatus gen. nov., sp. nov. is proposed; strain MPL3T (=ATCC BAA-1390T =DSM 18758T) is the type strain of Bryobacter aggregatus.
A thermophilic bacterium, designated strain CR11T, was isolated from a filamentous sample collected from a terrestrial hot spring on the south-western foothills of the Rincón volcano in Costa Rica. The Gram-negative cells are approximately 2.4–3.9 μm long and 0.5–0.6 μm wide and are motile rods with polar flagella. Strain CR11T grows between 65 and 85 °C (optimum 75 °C, doubling time 4.5 h) and between pH 4.8 and 7.8 (optimum pH 5.9–6.5). The isolate grows chemolithotrophically with S0, or H2 as the electron donor and with O2 (up to 16 %, v/v) as the sole electron acceptor. The isolate can grow on mannose, glucose, maltose, succinate, peptone, Casamino acids, starch, citrate and yeast extract in the presence of oxygen (4 %) and S0. Growth occurs only at NaCl concentrations below 0.4 % (w/v). The G+C content of strain CR11T is 40.3 mol%. Phylogenetic analysis of the 16S rRNA gene sequence places the strain as a close relative of Thermocrinis ruber OC 1/4T (95.7 % sequence similarity). Based on phylogenetic and physiological characteristics, we propose the name Thermocrinis minervae sp. nov., with CR11T (=DSM 19557T =ATCC BAA-1533T) as the type strain.