Orbus hercynius gen. nov., sp. nov., isolated from faeces of wild boar, is most closely related to members of the orders ‘Enterobacteriales’ and Pasteurellales

Abstract

A novel gammaproteobacterium, strain CN3T, was isolated from the faeces of wild boar. Strain CN3T was facultatively anaerobic and appeared coccoid or rod-shaped. The partial 16S rRNA gene sequence determined for strain CN3T suggested a distant relationship with members of the orders ‘Enterobacteriales’ and Pasteurellales. The gene sequence showed highest similarity (90.3 %) with Obesumbacterium proteus DSM 2777T, a member of the family Enterobacteriaceae. The closest relatives outside the order ‘Enterobacteriales’ according to 16S rRNA gene sequence analysis were members of the order Pasteurellales with 88.7 % similarity (Mannheimia haemolytica NCTC 9380T and Actinobacillus lignieresii NCTC 4189T). In contrast to most members of the order ‘Enterobacteriales’, strain CN3T was oxidase-positive. The pattern of fatty acids, in particular the high relative abundance of C18 : 1 ω7c (38.5 %), was clearly distinct from the conserved pattern found for members of the order Pasteurellales. EcoRI ribotyping of strain CN3T yielded no significant similarity to existing database entries. The major ubiquinone of strain CN3T was Q-8. The DNA G+C content was 36.4 mol%. Strain CN3T hosted a phage and secreted considerable amounts of three proteins into the culture supernatant. A spontaneous mutant of strain CN3T was isolated which formed long filaments. Microscopic studies revealed the presence of a capsule that the mutant strain was unable to partition after cell division. Strain CN3T thus represents a novel species within a new genus, for which the name Orbus hercynius gen. nov., sp. nov. is proposed. The type strain of the type species is CN3T (=DSM 22228T=CCUG 57622T). Classification of the novel species to the family and order level will require further investigations.