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Copyright of American Journal of Potato Research is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The cationic amylose-hexadecylammonium chloride inclusion complex (Hex-Am) was found to be an effective antifungal treatment for Fusarium sambucinum (Fückel), a causal agent of potato dry rot. The Hex-Am treatment was effective against F. sambucinum in vitro and in situ, with an effective 50% inhibitory concentration of 400 μg/ml; active component concentration of 20 μg/ml. The amylose complex alone, and blended with polyvinyl alcohol (PVOH), was effective in controlling dry rot in five varieties of potatoes with up to a 99% reduction in damage to the potato tubers. The amylose complex showed no apparent signs of phytotoxicity, with wound periderm reforming within one week of storage at 15 °C and 90% RH. The Hex-Am treatments form an effective antimicrobial film at the wound site, significantly inhibiting fungal damage to the wounded tubers. [ABSTRACT FROM AUTHOR]

The production of microbial biomass in liquid media often represents an indispensable step in the research and development of bacterial and fungal strains. Costs of commercially prepared nutrient media or purified media components, however, can represent a significant hurdle to conducting research in locations where obtaining these products is difficult. A less expensive option for providing components essential to microbial growth in liquid culture is the use of extracts of fresh or dried plant products obtained by using hot water extraction techniques. A total of 13 plant extract-based media were prepared from a variety of plant fruits, pods or seeds of plant species including Allium cepa (red onion bulb), Phaseolus vulgaris (green bean pods), and Lens culinaris (lentil seeds). In shake flask tests, cell production by potato dry rot antagonist Pseudomonas fluorescens P22Y05 in plant extract-based media was generally statistically indistinguishable from that in commercially produced tryptic soy broth and nutrient broth as measured by optical density and colony forming units/ml produced ( P ≤ 0.05, Fisher's protected LSD). The efficacy of biomass produced in the best plant extract-based media or commercial media was equivalent in reducing Fusarium dry rot by 50-96 % compared to controls. In studies using a high-throughput microbioreactor, logarithmic growth of P22Y05 in plant extract-based media initiated in 3-5 h in most cases but specific growth rate and the time of maximum OD varied as did the maximum pH obtained in media. Nutrient analysis of selected media before and after cell growth indicated that nitrogen in the form of NH accumulated in culture supernatants, possibly due to unbalanced growth conditions brought on by a scarcity of simple sugars in the media tested. The potential of plant extract-based media to economically produce biomass of microbes active in reducing plant disease is considerable and deserves further research. [ABSTRACT FROM AUTHOR]

The objective of the study was to identify the lipopetides associated with three Bacillus subtilis strains. The strains are antagonists of Gibberella zeae, and have been shown to be effective in reducing Fusarium head blight in wheat. The lipopeptide profile of three B. subtilis strains (AS43.3, AS43.4, and OH131.1) was determined using mass spectroscopy. Strains AS43.3 and AS43.4 produced the anti-fungal lipopeptides from the iturin and fengycin family during the stationary growth phase. All three strains produced the lipopeptide surfactin at different growth times. Strain OH131.1 only produced surfactin under these conditions. The antifungal activity of the culture supernatant and individual lipopeptides was determined by the inhibition of G. zeae. Cell-free supernatant from strains AS43.3 and AS43.4 demonstrated strong antibiosis of G. zeae, while strain OH131.1 had no antibiosis activity. These results suggest a different mechanism of antagonism for strain OH131.1, relative to AS43.3 and AS43.4. [ABSTRACT FROM AUTHOR]

Copyright of American Journal of Potato Research is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lack of effective chemicals impedes control of Fusarium dry rot of stored potato tubers destined for processed and table stock use. Biological control of dry rot incited by Gibberella pulicaris (anamorph=Fusarium sambucinum) has been demonstrated in laboratory studies but not in commercial storage environments. Several Gram-negative bacterial strains that were efficacious and amenable to production in liquid culture in laboratory studies were selected for pilot studies in Idaho and for bin trials at commercial storage houses in Idaho and North Dakota. In the first year of pilot studies, Pseudomonas fluorescens S22:T:04 (≈1 x 108 cfu/ml) decreased dry rot caused by G. pulicaris by 19% when coinoculated with the pathogen compared to controls and to the fungicide thiabendazole (TBZ) applied at label rates. In second year pilot studies, P. fluorescens P22:Y:05 and Enterobacter cloacae S11:T:07 (≈4 x 108 cfu/ml) reduced the severity of disease incited by G. pulicaris (25% and 17% average disease decrease, respectively) when antagonists were applied after pathogen inoculum. Treatment effects on dry rot that developed from inoculation with Nectria haematococca (anamorph=Fusarium solani var. coeruleum) were variable and influenced by interactions between antagonists, a wetting agent, and TBZ. In commercial storage bin trials, E. cloacae S11:T:07 reduced naturally occurring levels of dry rot by an average of 21% compared to 14% for TBZ, demonstrating that this antagonist was effective when produced using a liquid culture medium and methodology that approximates commercial practices for producing biomass. [ABSTRACT FROM AUTHOR]

Copyright of American Potato Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)