Brian Weselowski

Complete Genome Sequence of Paenibacillus polymyxa CR1, a Plant Growth-Promoting Bacterium Isolated from the Corn Rhizosphere Exhibiting Potential for Biocontrol, Biomass Degradation, and Biofuel Production

ABSTRACT Here we report the complete genome sequence of the bacterium Paenibacillus polymyxa CR1 (accession no. CP006941), which consists of one circular chromosome of 6,024,666 bp with 5,283 coding sequences (CDS), 87 tRNAs, and 12 rRNA operons. Data presented will allow for further insights into the mechanisms underpinning agriculturally and industrially relevant processes.

Isolation, identification and characterization of Paenibacillus polymyxa CR1 with potentials for biopesticide, biofertilization, biomass degradation and biofuel production

BackgroundPaenibacillus polymyxa is a plant-growth promoting rhizobacterium that could be exploited as an environmentally friendlier alternative to chemical fertilizers and pesticides. Various strains have been isolated that can benefit agriculture through antimicrobial activity, nitrogen fixation, phosphate solubilization, plant hormone production, or lignocellulose degradation. However, no single strain has yet been identified in which all of these advantageous traits have been confirmed.ResultsP. polymyxa CR1 was isolated from degrading corn roots from southern Ontario, Canada. It was shown to possess in vitro antagonistic activities against the common plant pathogens Phytophthora sojae P6497 (oomycete), Rhizoctonia solani 1809 (basidiomycete fungus), Cylindrocarpon destructans 2062 (ascomycete fungus), Pseudomonas syringae DC3000 (bacterium), and Xanthomonas campestris 93-1 (bacterium), as well as Bacillus cereus (bacterium), an agent of food-borne illness. P. polymyxa CR1 enhanced growth of maize, potato, cucumber, Arabidopsis, and tomato plants; utilized atmospheric nitrogen and insoluble phosphorus; produced the phytohormone indole-3-acetic acid (IAA); and degraded and utilized the major components of lignocellulose (lignin, cellulose, and hemicellulose).ConclusionsP. polymyxa CR1 has multiple beneficial traits that are relevant to sustainable agriculture and the bio-economy. This strain could be developed for field application in order to control pathogens, promote plant growth, and degrade crop residues after harvest.

Effectiveness of AG3 phosphonate formulation in suppressing phytophthora blight in cucumber and bell pepper plants under growth room conditions

Abstract Phytophthora blight or crown or root rot (Phytophthora capsici Leonian) is an important disease of a wide range of plant species including peppers, tomatoes, cucumbers and other cucurbits in Canada and worldwide. We have previously demonstrated the effectiveness of a new liquid formulation of AG3 phosphonate (Calirus 150, Bromine Compounds Ltd., Beer Sheva, Israel) in suppressing pythium damping-off of cucumbers and clubroot of bok choy and cabbage. In this study, the effectiveness of AG3 phosphonate formulation to suppress phytophthora damping-off and root rot of cucumber (Cucumis sativus L.) seedlings or phytophthora blight of bell pepper (Capsicum annuum L.) plants was determined in a peat-based mix or sandy-loam soil artificially infested with soil inoculum of P. capsici under growth room conditions. In an infested peat-based mix, AG3 phosphonate preplanting amendment or postplanting drench treatments (0.05%, 0.1% and 0.2% a.i.) and a 10-min seed-soak treatment (10.45% a.i.) significantly increased the percentage of healthy cucumber seedlings and reduced damping-off and root rot severity. The seed-soak and 0.2% treatments were the most effective treatments that consistently suppressed damping-off and root rot of cucumber even in a peat-based mix infested with high inoculum levels of P. capsici. Disease severity on cucumber plants was also significantly less in the AG3 phosphonate treatments. The single drench applications of AG3 phosphonate (0.05%, 0.1% and 0.2% a.i.) significantly reduced the incidence and severity of phytophthora blight of bell pepper plants in an infested peat-based mix or a sandy-loam soil compared with the control plants receiving no treatment. The best control of phytophthora blight of bell pepper was achieved with the higher rate (0.2% a.i.) in both peat-based mix and soil with 90% of the plants remaining healthy compared with none in the control. The disease protection increased with increasing concentrations of AG3 phosphonate in both bell peppers and cucumbers without any phytotoxicity.

Complete Genome Sequence of Acinetobacter calcoaceticus CA16, a Bacterium Capable of Degrading Diesel and Lignin

ABSTRACT We report here the complete assembled genome sequence of Acinetobacter calcoaceticus CA16, which is capable of utilizing diesel and lignin as a sole carbon source. CA16 contains a 4,110,074-bp chromosome and a 5,920-bp plasmid. The assembled sequences will help elucidate potential metabolic pathways and mechanisms responsible for CA16’s hydrocarbon degradation ability.

Complete Genome Sequence of Arthrobacter sp. Strain LS16, Isolated from Agricultural Soils with Potential for Applications in Bioremediation and Bioproducts.

ABSTRACT Here we report the complete genomic sequence of the bacterium Arthrobacter sp. strain LS16, consisting of a single circular chromosome of 3.85 Mb with no identified plasmid. Data contained within will facilitate future genetic modification and engineering of the Arthrobacter sp. LS16 metabolic network to enhance traits relevant to bioremediation and bioproducts.

Influence of foliar sprays of Bacillus subtilis QST 713 on development of early blight disease and yield of field tomatoes in Ontario

Abstract Early blight is an economically important foliar disease of processing and fresh market tomatoes. The aim of this multi-year field study was to investigate the impact of weekly foliar sprays of dried and aqueous formulations of Bacillus subtilis QST 713 (Serenade and Rhapsody), alone or as tank mixes with copper hydroxide, on early blight disease development and fruit yields of tomato. Field plots were established in London, Ontario during the 2008–2010 growing seasons and disease conditions were created artificially by inoculations with spore suspension of the early blight pathogen. The tank mixes of copper hydroxide and chlorothalonil were included as a standard spray treatment. Late blight also appeared naturally in the plots late in 2009 and 2010 field seasons and affected fruit in both years, but more severely in 2009. Spray treatments had variable effects on tomato early blight and fruit yields depending on the level of disease pressure in the inoculated plots. The weekly sprays of biofungicide alone did not consistently reduce disease severity on tomato foliage or incidence on fruit, but in a tank mix with copper hydroxide, both formulations consistently reduced foliar disease severity even when disease pressure was high in plots. Under high disease conditions, copper hydroxide alone or as a tank mix with chlorothalonil also consistently reduced disease severity on foliage. The mixture of two fungicides also consistently increased total fruit yields in all 3 years. Plots sprayed with copper hydroxide alone and in tank mixes with chlorothalonil and the dried formulation of biofungicide consistently had less late blight-infected fruit. The combined effects of biofungicides and copper hydroxide or other fungicides should be further investigated for consistent disease management and yield improvement.

Organic acids in condensed distiller's solubles: toxicity to soilborne plant pathogens and role in disease suppression.

Condensed distillers solubles (CDS), a coproduct of ethanol production from corn (Zea mays), has shown disease suppressing effects when added to pathogen-infested soils and peat-based substrate prior to planting. In this study, CDS amendment (1% and 3% w / w) to a sandy-loam soil displayed a low level of toxicity to microsclerotia of Verticillium dahliae and reduced their germination by 46% to 63% in 1 week in the laboratory soil microcosm tests. The analyses of CDS for the presence of any toxic substances revealed that it contains moderate levels (~144 mmol/L) of volatile (acetic and formic) and nonvolatile (glycolic) organic acids, and some of these are known toxicants. Glycolic, acetic, and formic acids contents were 77.1%, 17.7%, and 3.9%, respectively. Minor concentrations (0.2–0.7 mmol/L) of propionic, n -butyric, isobutyric, n -caproic, and n -valeric acids were also found in CDS. In solution assays, the viability of V. dahliae microsclerotia treated for 24 h in 1%, 2%, 5%, and 10% (v / v) CDS (pH 3.6–4.5) or a mixture of organic acids (pH 3.2–5.0) with the same percent composition as the CDS was reduced by 2%, 7%, 22%, and 48% or 6%, 32%, 53%, and 69%, respectively. A mixture of organic acids with the same volumetric ratios as 2% and 4% CDS completely inhibited the growth of Pythium ultimum after treatment of culture plugs for 24 h in solution assays. In growth room bioassays, addition of a mixture of organic as in 1% and 2% CDS (v / w) to a P. ultimum infested muck soil reduced damping-off severity by 45%–52% and increased the percentage of healthy seedlings by 164%–180% over the control. A pre-planting amendment of glycolic acid (0.075% and 0.15% w / w) to an infested muck soil significantly increased the percentage of healthy cucumber (Cucumis sativus) seedlings by 107% and 122%, respectively, and decreased the damping-off severity by 33% and 40%, respectively, over the control. This study suggests that organic acids from CDS have a role in disease suppression in sandy-loam and muck soils

Clavibacter michiganensis ssp. michiganensis: bacterial canker of tomato, molecular interactions and disease management: Clavibacter michiganensis ssp. michiganensis

Bacterial canker disease is considered to be one of the most destructive diseases of tomato (Solanum lycopersicum), and is caused by the seed-borne Gram-positive bacterium Clavibacter michiganensis ssp. michiganensis (Cmm). This vascular pathogen generally invades and proliferates in the xylem through natural openings or wounds, causing wilt and canker symptoms. The incidence of symptomless latent infections and the invasion of tomato seeds by Cmm are widespread. Pathogenicity is mediated by virulence factors and transcriptional regulators encoded by the chromosome and two natural plasmids. The virulence factors include serine proteases, cell wall-degrading enzymes (cellulases, xylanases, pectinases) and others. Mutational analyses of these genes and gene expression profiling (via quantitative reverse transcription-polymerase chain reaction, transcriptomics and proteomics) have begun to shed light on their roles in colonization and virulence, whereas the expression of tomato genes in response to Cmm infection suggests plant factors involved in the defence response. These findings may aid in the generation of target-specific bactericides or new resistant varieties of tomato. Meanwhile, various chemical and biological controls have been researched to control Cmm. This review presents a detailed investigation regarding the pathogen Cmm, bacterial canker infection, molecular interactions between Cmm and tomato, and current perspectives on improved disease management.