ALLORHIZOBIUM-UNDICOLA GEN. NOV., SP. NOV., NITROGEN-FIXING BACTERIA THAT EFFICIENTLY NODULATE NEPTUNIA-NATANS IN SENEGAL

A group of nodule isolates from Neptunia natans, an indigenous stem-no dulated tropical legume found in waterlogged areas of Senegal, was stu died. Polyphasic taxonomy was performed, including SDS-PAGE of total p roteins, auxanography using API galleries, host-plant specificity, PCR -RFLP of the internal transcribed spacer region between the 16S and th e 23S rRNA coding genes, 16S rRNA gene sequencing and DNA-DNA hybridiz ation. It was demonstrated that this group is phenotypically and phylo genetically separate from the known species of Rhizobium, Sinorhizobiu m, Mesorhizobium, Agrobacterium, Bradyrhizobium and Azorhizobium, Its closest phylogenetic neighbour, as deduced by 16S rRNA gene sequencing , is Agrobacterium vitis (96.2 % sequence homology). The name Allorhiz obium undicola gen, nov., sp. nov., is proposed for this group of bact eria, which are capable of efficient nitrogen-fixing symbiosis with Ne ptunia natans, and the type strain is ORS 992(T)(= LMC 11875(T)).