Genome Sequence of Pseudomonas chlororaphis Strain 189.

Pseudomonas chlororaphis strain 189 is a potent inhibitor of the growth of the potato pathogen Phytophthora infestans We determined the complete, finished sequence of the 6.8-Mbp genome of this strain, consisting of a single contiguous molecule. Strain 189 is closely related to previously sequenced strains of P. chlororaphis.

High-Quality Draft Genome Sequence of Biocontrol Strain Pantoea sp. OXWO6B1.

Pantoea sp. strain OXWO6B1 inhibits the growth of the potato pathogen Phytophthora infestans We determined the 5.2-Mbp genome sequence of this strain, which featured at least 3 confirmed plasmids of up to 250 kbp. The genome sequence of OXWO6B1 is different from that of all previously sequenced strains of Pantoea.

High-Quality Draft Genome Sequence of Arthrobacter sp. OY3WO11, a Strain That Inhibits the Growth of Phytophthora infestans.

Arthrobacter sp. strain OY3WO11 inhibits the growth of the potato pathogen Phytophthora infestans in in vivo growth challenge assays. We determined the draft genome sequence of this strain, assembling it into 3 scaffolds of 4.2 Mbp total length. OY3WO11 may represent a novel species of Arthrobacter.

High-Quality Draft Genome Sequence of Bacillus subtilis Strain WAUSV36.

Bacillus subtilis strain WAUSV36 inhibits the growth of and decreases disease symptoms caused by the potato pathogen Phytophthora infestans We determined the sequence of the 4.7-Mbp genome of this strain. WAUSV36 shared very high nucleotide sequence identity with previously sequenced strains of B. subtilis.

Colonization and bioherbicidal activity on green foxtail by Pseudomonas fluorescens BRG100 in a pesta formulation.

Pseudomonas fluorescens BRG100 produces secondary metabolites with herbicidal activity on green foxtail ( Setaria viridis ), an important weed pest in Canadian agriculture. Five gfp transformants of P. fluorescens BRG100 were compared with the wild-type isolate for green foxtail root herbicide activity, i.e., root growth suppression, doubling time, carbon utilization, and colonization of green foxtail root (proximal and distal regions). The most revealing comparison between the wild type and its gfp transformants was herbicidal activity on green foxtail. Herbicidal activity of transformant gfp-7 was not significantly different from the uninoculated control, suggesting that insertion of the gfp gene may have interfered with a gene, or genes, vital to the bioherbicide process. Doubling time, carbon utilization, and colonization of green foxtail did not differ to a great extent between the wild type and the gfp transformants, indicating their suitability as conservatively tagged organisms for subsequent colonization-herbicidal activity studies. Accordingly, a pesta granule formulation delivered transformant gfp-2 to the seed coat and roots of green foxtail. Epifluorescent and confocal laser scanning microscopy revealed the transformant gfp-2 colonized the ventral portion of the seed coat, root hairs, and all areas of the root except the root cap region, where gfp-2 presumably exerted herbicidal effects. These results suggest that P. fluorescens BRG100 has considerable potential as a bioherbicide because of its successful colonization and suppressive activity on green foxtail root growth.

Characterization of the anti-fungal activity of a Bacillus spp. associated with sclerotia from Sclerotinia sclerotiorum.

Sclerotinia sclerotiorum fruiting bodies (sclerotia) were found to harbour bacteria that possess anti-fungal activity. Among 1,140 bacterial isolates collected, 32 were found to inhibit the growth of four common fungal pathogens of canola, S. sclerotiorum, Rhizoctonia solani, Alternaria brassicae and Leptosphaeria maculans. One of these broad-spectrum isolates, LEV-006, was found to be closely related to Bacillus subtilis based on 16S rRNA analysis. The anti-fungal activities were purified and found to be associated with a low molecular weight peptide complex consisting mostly of the cyclic lipopeptide fengycin A and B, as revealed by matrix-assisted laser desorption/ionization time-of-flight and post-source decay analysis, as well as two proteins of 20 and 55 kDa. Peptide mass fingerprinting revealed that the 55-kDa protein was similar to vegetative catalase 1; however, when the enzyme was expressed in Escherichia coli, it exhibited catalase but not anti-fungal activity. The sequences of several peptides from the 20-kDa protein were obtained and indicated that it was a unique anti-fungal protein.

Structure, chemistry, and biological activity of pseudophomins A and B, new cyclic lipodepsipeptides isolated from the biocontrol bacterium Pseudomonas fluorescens.

Pseudophomins A and B are cyclic lipodepsipeptides isolated from Pseudomonas fluorescens strain BRG100, a bacterium with potential application for biocontrol of plant pathogens and weeds. Their chemical structures were established by a combination of spectroscopic data, X-ray crystallography, and selective chemical degradation. This unique chemical degradation allowed the unambiguous determination of the absolute configuration of the amino acid residue Leu-1, due to gamma-lactam formation followed by selective cleavage of the adjacent N(8)-C(7) bond. To the best of our knowledge this is the first application of gamma-lactam formation to the determination of absolute configuration of an adjacent amino acid. Pseudophomin B showed higher antifungal activity against the phytopathogens Phoma lingam/Leptosphaeria maculans and Sclerotinia sclerotiorum than pseudophomin A, and is likely to be the main component responsible for the antifungal activity of EtOAc extracts of strain BRG100. By contrast, pseudophomin A showed stronger inhibition of green foxtail (Setaria viridis) root germination than pseudophomin B.

Pseudophomins A and B, a class of cyclic lipodepsipeptides isolated from a Pseudomonas species.

The crystal structures of pseudophomins A and B, with primary structures beta-hydroxydecanoyl-L-Leu-D-Glu-D-allo-Thr-D-Ile-D-Leu-D-Ser-L-Leu-D-Ser-L-Ile monohydrate, C(55)H(97)N(9)O(16).H(2)O, and beta-hydroxydodecanoyl-L-Leu-D-Glu-D-allo-Thr-D-Ile-D-Leu-D-Ser-L-Leu-D-Ser-L-Ile monohydrate, C(57)H(101)N(9)O(16).H(2)O, new cyclic lipodepsipeptides isolated from Pseudomonas fluorescens strain BRG100, have been solved. The absolute configuration of pseudophomin A has been determined from anomalous dispersion and the stereochemistry of the beta-hydroxy acid group is R.