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This study examined (1) the effect of the accelerated seed ageing on cucumber germination with treatments:Bacillus subtilisQST713 orPseudomonas fluorescensCA in 1% methylcellulose and fungicides difenoconazole, carboxin or pyraclostrobin in 5% polyvinyl alcohol, and (2) the impact on disease severity of gummy stem blight (GSB) caused byDidymella bryoniaeby the seed treatments and foliar spray application of methylcellulose-formulatedB. subtilisorP. fluorescens. Difenoconazole, pyraclostrobin and microorganisms suppressed growth ofD. bryoniaein a laboratory dual culture; carboxin had no effect onD. bryoniaegrowth. Germination of fungicide-treated seed was unaffected by accelerated seed ageing. Greenhouse: GSB disease severity with PVA and non-treated seed was 89% and 84%, respectively, whereas, difenoconazole, carboxin and pyraclostrobin, was significantly reduced, 56%, 53% and 40%, respectively. Germination ofBacillus-treated seed was unaffected by accelerated seed ageing, but was significantly reduced withPseudomonas-treated seed. GSB disease severity withB. subtilisorP. fluorescens-treated seed was inconsistent; however, foliar spray application ofB. subtilissignificantly reduced GSB. Accelerated seed ageing exposed a significant negative impact on seed germination withP. fluorescens. Based on the accelerated ageing test,P. fluorescens-treated cucumber seed is detrimental to seed survival and therefore, is not a candidate for biocontrol activities for cucumber requiring seed storage. [ABSTRACT FROM PUBLISHER]

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Pseudomonas fluorescens 6-8, a rhizosphere isolate previously shown to enhance root elongation of canola ( Brassica napus L.), was characterized for its ability to produce indole-3-acetic acid and cytokinins in pure culture and in the rhizosphere of canola under gnotobiotic conditions in comparison with the cytokinin-producing strain P. fluorescens G20-18 and its mutant CNT2. Strain 6-8 produced isopentenyl adenosine, zeatin riboside, and dihydroxyzeatin riboside at levels similar to those of G20-18, but only very low concentrations of indole-3-acetic acid. In a gnotobiotic assay canola inoculated with 6-8 and G20-18 had higher concentrations of isopentenyl adenosine and zeatin riboside in the rhizosphere and greater root length than the noninoculated control. The ability of strain 6-8 to colonize canola roots was assessed following transformation with the green fluorescent protein and inoculation onto canola seed in a gnotobiotic assay. Higher populations of strain 6-8 were observed on the proximal region of the root closest to the seed than on the mid and distal portions 9 days after seed inoculation. The ability of P. fluorescens 6-8 to produce cytokinins, colonize the roots of canola seedlings, and enhance root elongation may contribute to its ability to survive in the rhizosphere and may benefit seedling growth. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Serratia grimesii 4-9 and Serratia plymuthica 5-6, isolated from the rhizosphere of pea, Pisum sativum (L), were evaluated for their potential to suppress growth of Fusarium sambucinum in vitro and to reduce Fusarium dry rot in stored potatoes (Solanum tuberosum L). In vitro studies indicated that these bacterial isolates suppressed growth of F. sambucinum by 60% or more at both 15 and 25°C. In a potato tuber slice assay the number of infection sites in potato slices exposed to F. sambucinum and treated with S. grimesii 4-9 and S. plymuthica 5-6 was reduced by 96 and 97%, respectively, at 15°C. The diameter (mm) of the infection sites was reduced 91 and 96%, respectively, when compared to slices treated with F. sambucinum alone. Studies with Fusarium-infected whole potato tubers also showed significant reduction in dry rot formation following treatment with the bacterial isolates or the fungicide thiabendazole. When applied simultaneously with the pathogen, S. grimesii 4-9 and S. plymuthica 5-6 suppressed development of Fusarium dry rot by 60 and 77%, respectively, at 15°C and by 63 and 84%, respectively, at 25°C compared to tubers inoculated with the pathogen alone. Thiabendazole suppressed development of Fusarium dry rot by 66 and 81% at 15 and 25°C, respectively, compared to tubers inoculated with the pathogen alone. These studies demonstrate the potential of soil bacteria as biofungicides for managing post-harvest crop diseases. Due to the potential risks to human health associated with S. grimesii 4-9, S. plymuthica 5-6 is recommended for further study for biofungicide development. [ABSTRACT FROM AUTHOR]

This study was conducted to compare the performance of two densification processes, namely pelletization and granulation, on quality parameters (enzyme activity and density) of a beta-glucanase-rich biomass, processing time/material throughput, and power consumption. The pellet mill heating condition (dry heating and steam conditioning settings) had more effect on the product quality parameters than the storage temperature (ranging from -18ºC to 45ºC) of biomass during pelletization. In pelletization, the factor of heating source (dry and steam heating) was more effective than the factor of biomass initial temperature (ranged from -18ºC to 45ºC) on the quality parameters. In no-heat or dry-heat (temperatures of up to 55ºC) and low-flow steam conditioning, enzyme activities of over 90% were obtained. However, at the high-flow steam conditioning, a lower material throughput, higher power consumption, and a complete loss of enzyme activity was obtained. In granulation, the factor of moisture content (MC) was more important than binder inclusion, material residence, and extrusion direction in affecting product quality parameters. Compared to pelletization, granulation would be a preferable process resulting in a uniform and small-sized densified product. However, it has higher energy consumption and less efficiency in terms of product densification. [ABSTRACT FROM AUTHOR]