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We determined the nucleotide sequence of the entire genome of a diazotrophic endophyte, Azospirillum sp. B510. Strain B510 is an endophytic bacterium isolated from stems of rice plants (Oryza sativa cv. Nipponbare). The genome of B510 consisted of a single chromosome (3,311,395 bp) and six plasmids, designated as pAB510a (1,455,109 bp), pAB510b (723,779 bp), pAB510c (681,723 bp), pAB510d (628,837 bp), pAB510e (537,299 bp), and pAB510f (261,596 bp). The chromosome bears 2893 potential protein-encoding genes, two sets of rRNA gene clusters (rrns), and 45 tRNA genes representing 37 tRNA species. The genomes of the six plasmids contained a total of 3416 protein-encoding genes, seven sets of rrns, and 34 tRNAs representing 19 tRNA species. Eight genes for plasmid-specific tRNA species are located on either pAB510a or pAB510d. Two out of eight genomic islands are inserted in the plasmids, pAB510b and pAB510e, and one of the islands is inserted into trnfM-CAU in the rrn located on pAB510e. Genes other than the nif gene cluster that are involved in N(2) fixation and are homologues of Bradyrhizobium japonicum USDA110 include fixABCX, fixNOQP, fixHIS, fixG, and fixLJK. Three putative plant hormone-related genes encoding tryptophan 2-monooxytenase (iaaM) and indole-3-acetaldehyde hydrolase (iaaH), which are involved in IAA biosynthesis, and ACC deaminase (acdS), which reduces ethylene levels, were identified. Multiple gene-clusters for tripartite ATP-independent periplasmic-transport systems and a diverse set of malic enzymes were identified, suggesting that B510 utilizes C(4)-dicarboxylate during its symbiotic relationship with the host plant.

Candida antarctica lipase (Novozym 435) showed good to high enantioselectivity in the acylation of aliphatic and aromatic secondary alcohols ( E = 38−166), and higher enantioselectivity in the hydrolysis of their corresponding acetates than other lipases tested, including lipases AY and MY ( Candida sp.) and lipases PS, AK and LIP ( Pseudomonas sp.).

The symbiotic plasmid (pSym) of Rhizobium leguminosarum bv. trifolii 4S5, which carries Tn5-mob, was successfully transferred into Agrobacterium tumefaciens A136 by using a conjugation method. The resulting transconjugants induced the development of ineffective nitrogen-fixing nodules on the roots of white clover seedlings. Depending on the manner in which the pSym was retained, the transconjugants were divided into two groups of strains, Afp and Afcs. pSym was retained as a plasmid in the Afp strains but was integrated into the int gene encoding a phage-related integrase on the linear chromosome of A. tumefaciens A136 in strain Afcs1 (one of the Afcs strains) to form a symbiosis island. Conjugation was performed between strain Afcs1 and R. leguminosarum bv. trifolii H1 (a pSym-cured derivative of wild-type strain 4S), and the Rhizobium H1tr strains were screened as transconjugants. Eighteen of the H1tr strains induced effective nitrogen-fixing nodules on the roots of the host plants. pSym was transferred into all of the transconjugants, except for strain H1tr1, at the same size as pSym of strain 4S5. In strain H1tr1, pSym was integrated into the chromosome as a symbiosis island. These data suggest that pSym can exist among Rhizobium and Agrobacterium strains both as a plasmid and as a symbiosis island with transposon mediation.