Aggregatilinea lenta gen. nov., sp. nov., a slow-growing, facultatively anaerobic bacterium isolated from subseafloor sediment, and proposal of the new order Aggregatilineales ord. nov. within the class Anaerolineae of the phylum Chloroflexi

A novel slow-growing, facultatively anaerobic, filamentous bacterium, strain MO-CFX2(T), was isolated from a methanogenic microbial community in a continuous-flow bioreactor that was established from subseafloor sediment collected off the Shimokita Peninsula of Japan. Cells were multicellular filamentous, non-motile and Gram-stain-negative. The filaments were generally more than 20 mu m (up to approximately 200 mu m) long and 0.5-0.6 mu m wide. Cells possessed pili-like structures on the cell surface and a multilayer structure in the cytoplasm. Growth of the strain was observed at 20-37 degrees C (optimum, 30 degrees C), pH 5.5-8.0 (pH 6.5-7.0), and 0-30 g l(-1) NaCl (5 g l(-1) NaCl). Under optimum growth conditions, doubling time and maximum cell density were estimated to be approximately 19 days and similar to 10 5 cells ml(-1), respectively. Strain MO-CFX2(T) grew chemoorganotrophically on a limited range of organic substrates in anaerobic conditions. The major cellular fatty acids were saturated C-16:0 (47.9 %) and C-18:0 (36.9 %), and unsaturated C-18:1 omega 9c (6.0 %) and C-16: 1 omega 7 (5.1 %). The G+C content of genomic DNA was 63.2 mol%. 16S rRNA gene-based phylogenetic analysis showed that strain MO-CFX2(T) shares a notably low sequence identity with its closest relatives, which were Thermanaerothrix daxensis GNS-1( )(T)and Thermomarinilinea lacunifontana SW7(T) (both 85.8 % sequence identity). Based on these phenotypic and genomic properties, we propose the name Aggregatilinea lenta gen. nov., sp. nov. for strain MO-CFX2(T) (=KCTC 15625(T), =JCM 32065(T)). In addition, we also propose the associated family and order as Aggregatilineaceae fam. nov. and Aggregatilineales ord. nov., respectively.