Phyllobacterium

Abstract: In this study we examined the taxonomic relationships of strains variously labeled Achromobacter species biotypes 1 and 2, Achromobacter group A, and Centers for Disease Control (CDC) groups Vd-1 and Vd-2. Previous studies of ribosomal ribonucleic acid cistron similarities placed these organisms on the Brucella ribosomal ribonucleic acid branch of ribosomal ribonucleic acid superfamily IV; their closest neighbors were Brucella, Phyllobacterium, and the Agrobacterium-Rhizobium complex. We performed a numerical taxonomic analysis of 284 phenotypic features (69 conventional tests, 147 API assimilation tests, 68 API ZYM tests) carried out on 95 strains. These organisms comprised 56 strains thought to correspond to CDC group Vd (including 3 strains originally labeled “Pseudomonas arsenoxydans”) and 39 strains (included for reference purposes) representing the genera Achromobacter, Agrobacterium, Alcaligenes, Brucella, Mycoplana, Phyllobacterium, and Rhizobium. A phenotypic analysis showed that group Vd bacteria are most similar to Phyllobacterium. However, strains of Group Vd were shown to be distinct by deoxyribonucleic acid (DNA)-DNA hybridization and by several phenotypic tests from Phyllobacterium and other related taxa. The CDC group Vd strains formed essentially a single taxon in the numerical taxonomic analysis of phenotypic characters and as determined by DNA-DNA hybridization. This taxon could be subdivided into three biotypes (biotypes A, C, and D), but none of these corresponded to the two biotypes originally described among the group Vd strains. For CDC group Vd we propose a new genus and new species, Ochrobactrum anthropi: The type strain is strain CIP 82.115 (= CIP 14970 = NCTC 12168 = LMG 3331). O. anthropi strains are rod shaped, aerobic, gram negative, nonpigmented, and motile by means of peritrichous flagella, produce acid from several carbohydrates, and reduce both nitrate and nitrite. The guanine-plus-cytosine contents of the DNAs of 29 strains ranged from 56 to 59 mol%. Almost all 56 group Vd strains were originally isolated from various human clinical specimens, commonly from blood cultures.

Abstract: Thirteen of the most abundant Gram-negative bacteria which are able to grow in N-depleted culture conditions were isolated from the rhizoplane and endorhizosphere of canola (Brassica napus) and identified by 16S rDNA sequence analysis. Eight of these bacteria induced a significant increase in root dry weight ranging from 11 to 52%. Phylogenetic positioning based on 16S rDNA sequences indicated that at least four genera are represented, Pseudomonas, Variovorax, Agrobacterium and Phyllobacterium. The most important direct plant growth-promoting-rhizobacteria effect was found with both isolates belonging to the Phyllobacterium.

Abstract: Inoculation of the oilseed halophyte Salicornia bigelovii Torr. with eight species of halotolerant bacteria, grown in seawater-irrigated pots under environmental conditions native to the plant's habitat, resulted in significant plant growth promotion by the end of the growing season, 8–11 months later. Statistical analysis demonstrated that inoculation with Azospirillum halopraeferens, a mixture of two Azospirillum brasilense strains, a mixture of Vibrio aestuarianus and Vibrio proteolyticus, or a mixture of Bacillus licheniformis and Phyllobacterium sp. significantly increased plant height and dry weight at the end of the season. Some of the bacterial strains also increased the number of side branches and the size of the spikes. The bacteria did not affect the number of seeds or their weight. Inoculation with the mangrove cyanobacterium Microcoleus chthonoplastes had no effect on plant foliage variables. At the end of the growing season, the N and protein content of the plant foliage was significantly reduced by bacterial inoculation; however, the N and protein content of seeds significantly increased. The P content in foliage increased significantly in plants treated with all the bacteria except M. chthonoplastes, whereas the total lipid content of foliage increased significantly only when plants were inoculated with a mixture of A. brasilense strains or with M. chthonoplastes. In three inoculation treatments palmitic acid in seeds significantly increased and linoleic acid significantly decreased. This study demonstrates the feasibility of using bacteria to promote the growth of halotolerant plants cultivated for forage and seed production in proposed seawater-irrigated agriculture.