306 research outputs found

    Co-culture of Yeast Antagonists of Fusarium Head Blight and their Effect on Disease Development in Wheat

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    Multistrain mixtures of biocontrol agents which can reduce plant disease to a greater extent than the individual strains of the mixture, commonly, are prepared by blending separately produced fermentation products. Co-cultivation of strains to equivalent biomass yields would provide mixture advantages without incurring the cost disadvantages of multiple fermentation and processing protocols. Fusariwn Head Blight (FHB) antagonists Cryptococcus flavescens OR 182.9 (NRRL Y-302l6), C. aureus OH 181.1 (NRRL Y-302l5) and C. aureus OR 181.1 (NRRL Y -30215), were grown in two- and three-strain co-cultures to assess the quality and efficacy of the fermentation end products produced. Final cell counts of component strains of all co-cultures produced were equivalent when plated on a medilllll that contained the trisaccharide melezitose as a sole carbon source and produced colonies of strain-distinguishable sizes. Co-cultures of C. flavescens OH 182.9 and C. aureus OH 71.4 significantly reduced FHB disease severity (32%, p = 0.05, Dunnett\u27s t-test) when averaged across four greenhouse studies. In wheat field trials, biomass from co-cultures of these two strains reduced FHB incidence in some cases but rarely other FHB disease parameters (p = 0.05, Bonferoni mean separation). Relative Performance Index (RPI) analysis of the overall effect of treatments at both field sites revealed that treatment with the OH 71.4 and OH 182.9 co-culture significantly reduced FHB, as evidence by a higher RPI value than for the control, while the individual strains did not. The potential for obtaining superior efficacy and cost benefits with multi-strain cultures of biocontrol agents justifies additional research effort

    Carbon-to-Nitrogen Ratio and Carbon Loading of Production Media Influence Freeze-Drying Survival and Biocontrol Efficacy of \u3ci\u3eCryptococcus nodaensis\u3c/i\u3e OH 182.9

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    Fusarium head blight (FHB), caused by Gibberella zeae, is a devastating disease of wheat worldwide. Cryptococcus nodaensis OH 182.9 is an effective biocontrol agent for this disease. Development of a dried product of OH 182.9 would have potential advantages of ease of handling, favorable economics, and acceptance by end users. Isolate OH 182.9 was grown for 48 and 72 h in semi-defined complete liquid (SDCL) medium with carbon-to-nitrogen (C/N) ratios of 6.5:1, 9:1, 11:1, 15:1, and 30:1, and in SDCL C/N 30:1 media with varied carbon loadings of 7, 14, 21, and 28 g/liter. Total biomass production and cell survival at 15 days after freeze-drying were evaluated. Biomass production of OH 182.9 (CFU per milliliter) was not different for all cultivation time by medium C/N or carbon loading combinations. In general, cells harvested at 48 h survived freeze-drying better than those harvested at 72 h. Survival of freeze-dried cells was greatest for cells grown for 48 h in C/N 30:1 medium. Cells produced in C/N 6.5:1 medium generally exhibited the poorest survival. For the C/N 30:1 media, cells from 7 g/liter carbon loading medium harvested after 48 h had the best survival after freezedrying. The difference in freeze-dried cell populations between superior and inferior treatments was typically 1 to 2 log units at 15 days after freeze-drying. The biomass of OH 182.9 produced in SDCL with varied C/N ratios and in SDCL C/N 30:1 media with differing carbon loadings was tested for biocontrol efficacy against FHB in greenhouse studies. The biomass harvested from SDCL C/N 9:1, 11:1, and 15:1 media after 48 h significantly reduced symptoms of FHB. None of the treatments with cells harvested at 72 h consistently reduced FHB severity (P ≤ 0.05). Cells grown in SDCL C/N 30:1 media with 7 and 14 g/liter carbon loading significantly reduced FHB disease severity. Cells harvested from SDCL C/N 9:1, 11:1, and 30:1 with 14 g/liter carbon increased the 100-kernel weight compared with the disease control. The potential of improving OH 182.9 product quality via management of the nutritional environment of the production medium is demonstrated in this study

    Carbon-to-Nitrogen Ratio and Carbon Loading of Production Media Influence Freeze-Drying Survival and Biocontrol Efficacy of \u3ci\u3eCryptococcus nodaensis\u3c/i\u3e OH 182.9

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    Fusarium head blight (FHB), caused by Gibberella zeae, is a devastating disease of wheat worldwide. Cryptococcus nodaensis OH 182.9 is an effective biocontrol agent for this disease. Development of a dried product of OH 182.9 would have potential advantages of ease of handling, favorable economics, and acceptance by end users. Isolate OH 182.9 was grown for 48 and 72 h in semi-defined complete liquid (SDCL) medium with carbon-to-nitrogen (C/N) ratios of 6.5:1, 9:1, 11:1, 15:1, and 30:1, and in SDCL C/N 30:1 media with varied carbon loadings of 7, 14, 21, and 28 g/liter. Total biomass production and cell survival at 15 days after freeze-drying were evaluated. Biomass production of OH 182.9 (CFU per milliliter) was not different for all cultivation time by medium C/N or carbon loading combinations. In general, cells harvested at 48 h survived freeze-drying better than those harvested at 72 h. Survival of freeze-dried cells was greatest for cells grown for 48 h in C/N 30:1 medium. Cells produced in C/N 6.5:1 medium generally exhibited the poorest survival. For the C/N 30:1 media, cells from 7 g/liter carbon loading medium harvested after 48 h had the best survival after freezedrying. The difference in freeze-dried cell populations between superior and inferior treatments was typically 1 to 2 log units at 15 days after freeze-drying. The biomass of OH 182.9 produced in SDCL with varied C/N ratios and in SDCL C/N 30:1 media with differing carbon loadings was tested for biocontrol efficacy against FHB in greenhouse studies. The biomass harvested from SDCL C/N 9:1, 11:1, and 15:1 media after 48 h significantly reduced symptoms of FHB. None of the treatments with cells harvested at 72 h consistently reduced FHB severity (P ≤ 0.05). Cells grown in SDCL C/N 30:1 media with 7 and 14 g/liter carbon loading significantly reduced FHB disease severity. Cells harvested from SDCL C/N 9:1, 11:1, and 30:1 with 14 g/liter carbon increased the 100-kernel weight compared with the disease control. The potential of improving OH 182.9 product quality via management of the nutritional environment of the production medium is demonstrated in this study

    CHOLINE-UTILIZING MICROBLAL STRAINS FOR BIOLOGICALLY CONTROLLING FUSARIUM HEAD BLIGHT

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    Three choline utilizing strains of microorganisms isolated from the anthers of wheat, Aureobasidium pullulans strainAS 55.2, Arthrobacter species strain OH 221.3, and Pseudomonas species strain AS 64.4, are superior antagonists of F. graminearum. These microorganisms are effective for suppression and control of FHB in cereals, particularly in wheat and barley

    Draft Genome Sequence of the Yeast Pachysolen tannophilus CBS 4044/NRRL Y-2460

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    A draft genome sequence of the yeast Pachysolen tannophilus CBS 4044/NRRL Y-2460 is presented. The organism has the potential to be developed as a cell factory for biorefineries due to its ability to utilize waste feedstocks. The sequenced genome size was 12,238,196 bp, consisting of 34 scaffolds. A total of 4,463 genes from 5,346 predicted open reading frames were annotated with function

    Furfural induces reactive oxygen species accumulation and cellular damage in Saccharomyces cerevisiae

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    <p>Abstract</p> <p>Background</p> <p>Biofuels offer a viable alternative to petroleum-based fuel. However, current methods are not sufficient and the technology required in order to use lignocellulosic biomass as a fermentation substrate faces several challenges. One challenge is the need for a robust fermentative microorganism that can tolerate the inhibitors present during lignocellulosic fermentation. These inhibitors include the furan aldehyde, furfural, which is released as a byproduct of pentose dehydration during the weak acid pretreatment of lignocellulose. In order to survive in the presence of furfural, yeast cells need not only to reduce furfural to the less toxic furan methanol, but also to protect themselves and repair any damage caused by the furfural. Since furfural tolerance in yeast requires a functional pentose phosphate pathway (PPP), and the PPP is associated with reactive oxygen species (ROS) tolerance, we decided to investigate whether or not furfural induces ROS and its related cellular damage in yeast.</p> <p>Results</p> <p>We demonstrated that furfural induces the accumulation of ROS in <it>Saccharomyces cerevisiae</it>. In addition, furfural was shown to cause cellular damage that is consistent with ROS accumulation in cells which includes damage to mitochondria and vacuole membranes, the actin cytoskeleton and nuclear chromatin. The furfural-induced damage is less severe when yeast are grown in a furfural concentration (25 m<it>M</it>) that allows for eventual growth after an extended lag compared to a concentration of furfural (50 m<it>M</it>) that prevents growth.</p> <p>Conclusion</p> <p>These data suggest that when yeast cells encounter the inhibitor furfural, they not only need to reduce furfural into furan methanol but also to protect themselves from the cellular effects of furfural and repair any damage caused. The reduced cellular damage seen at 25 m<it>M </it>furfural compared to 50 m<it>M </it>furfural may be linked to the observation that at 25 m<it>M </it>furfural yeast were able to exit the furfural-induced lag phase and resume growth. Understanding the cellular effects of furfural will help direct future strain development to engineer strains capable of tolerating or remediating ROS and the effects of ROS.</p

    Bioconversion of Pelletized Big Bluestem, Switchgrass, and Low-Diversity Grass Mixtures Into Sugars and Bioethanol

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    Three crops of warm-season grasses are being developed for biomass production on northern rain-fed marginal farmland: big bluestem (BBS), switchgrass (SG), and a low diversity mixture of grasses (LDM). In this study, biomass harvested from established fields were compared for pelletization and subsequent conversion to sugars and ethanol. Each biomass was successfully pelletized to similar bulk densities without adding a binder at a commercial feed operation. Pelletizing increased the bulk density by 407% on average and was equally effective on all three biomass samples (528–554 kg/m3). Chemical analysis of the samples indicated that glucan and xylan contents were slightly reduced during pelletizing (by 23 and 16 g/kg, respectively), as well as theoretical ethanol yields, which are based upon total carbohydrate contents. Pellets and milled straws were pre-treated with either liquid hot-water or low-moisture ammonium hydroxide (LMA) and subsequently hydrolyzed with cellulases. Glucose and total sugar yields were similar for non-pellets and pellets using either pre-treatment; carbohydrates present in pellets were more efficiently recovered compared to non-pellets. LMA pretreated samples were separately hydrolyzed and fermented to ethanol using Scheffersomyces stipitis yeast. Hydrolysis recovered 69.7–76.8% of the glucose and 66.5–73.3% of the xylose across all samples. Glucose yields were 251–279 g/kg, db and were significantly lower for SG as compared to the other biomass samples. Recovered sugars were fermented to ethanol at 77.7–86.7% of theoretical yield. Final ethanol yields (245.9–275.5 L/Mg, db) were similar for all of the grasses and estimated to equate to production levels for BBS, LDM, and SG of 1,952, 2,586, and 2,636 l of ethanol per ha, respectively
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