Name: inhibition of aspergillus flavus growth and aflatoxin production in transgenic maize expressing the &#945;-amylase inhibitor from lablab purpureus l.
Uploaded: 2019-02-15T15:00:00
Description: Watch this Scientific Journal Video about Inhibition of Aspergillus flavus Growth and Aflatoxin Production in Transgenic Maize Expressing the Î±-amylase Inhibitor from Lablab purpureus L. at JoVE.co

We thank David Meints, University of Arkansas for his assistance in developing and analyzing the transgenic maize during the early generations. This work received the financial support of USDA-ARS CRIS project 6054-42000-025-00D. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. USDA-ARS&#8217; Equal Employment Opportunity (EEO) Policy mandates equal opportunity for all persons and prohibits discrimination in all aspects of the Agency&#8217;s personnel policies, practices, and operations.

1. Plasmid constructs and maize transformation
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	<li>PCR amplify Lablab AILP insert using the primers 5&#8217;-TATCTAGAACTAGTGATTACCATGGCTCC-3&#8217; and 5&#39;-ATACTGCAGGATTGCATGCAGAGTAGTACTG-3&#39;. The PCR conditions include an initial denaturation step at 98 &#176;C for 30 s (step 1), followed by denaturation at 98 &#176;C for 10 s (step 2), annealing at 55 &#176;C for 30 s (step 3), elongation at 72 &#176;C for 20 s (step 4), 31 cycles of step 2 to step 4, and a final elongation step at 72 &#176;C for...

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Yield losses in agricultural crops due to pathogens and pests is a global problem20. Currently, application of synthetic fungicides and pesticides is the predominant means for controlling plant pathogens and pests, but residual toxicity of these biochemicals in food and feed can pose serious threat to human and animal health21. Considering the economic importance of maize as a food and feed crop, reduction in or elimination of aflatoxin contamination is of utmost importance...

Mycotoxin contamination by the fungal genera, Aspergillus, Fusarium, Penicillium, and Alternaria is a major problem of food and feed crops grown worldwide1,2,3. Among these phytopathogenic fungi, Aspergillus has the highest adverse impact on crop value and human and animal health. Aspergillus flavus (A. flavus) is an opportunistic plant pathogen that infects oil rich crops such as maize, cottonseed and peanut and produces the potent carcinogens, aflatoxins, as well as numerous toxic secondary metabolites (SMs). Maize is an important food and feed crop grown worldwide and is highly susceptible to contamination by A. flavus. The economic impact of aflatoxin contamination on loses and reduced value in maize can be as much as $686.6 million/year in the U.S.2 With predicted changes in global climate, the impact of aflatoxins could result in greater economic losses in maize with estimates as high as $1.68 billion/year in the near future2. Given the adverse economic and health effects of aflatoxins in humans and livestock, pre-harvest aflatoxin control in maize might be the most efficient way to prevent aflatoxin contamination in food and feed products.
The major pre-harvest control approach for aflatoxin resistance in maize that has been used extensively in the last few decades is primarily through breeding, which requires a significant amount of time4. Recently, biocontrol has had some success in aflatoxin reduction in large scale field applications5,6. Besides biocontrol, application of cutting-edge molecular tools such as &#8216;Host Induced Gene Silencing&#8217; (HIGS) through RNAi and transgenic expression of resistance-associated proteins has had some success in reduction of A. flavus growth and aflatoxin production in small scale laboratory and field studies. These approaches are currently being optimized in addition to identifying new potential A. flavus gene targets for future manipulation.
Besides genes that are directly involved in mycotoxin production as potential targets of transgenic control strategies, fungal amylases have been shown to play a critical role in maintaining successful pathogenesis and mycotoxin production during early stages of host plant infection. A few examples include Pythium pleroticum (causal agent of ginger rhizome rot), Fusarium solani (causal agent of cauliflower wilt), where positive correlations between pathogenicity and &#945;-amylase expression and activity were observed7,8. Inhibition of &#945;-amylase activity either through gene knockout or knockdown approaches negatively affects fungal growth and toxin production. An &#945;-amylase knockout mutant of A. flavus was unable to produce aflatoxins when grown on starch substrate or degermed maize kernels9. Similarly, in Fusarium verticillioides an &#945;-amylase knockout strain failed to produce fumonisin B1 (mycotoxin) during infection of maize kernels10. In a more recent study, Gilbert et al. (2018) demonstrated that an RNAi-based knock down of A. flavus &#945;-amylase expression through HIGS significantly reduced A. flavus growth and aflatoxin production during maize kernel infection11.
Specific inhibitors of &#945;-amylase activity have also produced similar results as obtained from down-regulation of &#945;-amylase expression. The first report on the role of an &#945;-amylase inhibitor in fungal resistance came from the isolation and characterization of a 14-kDa trypsin-&#945;-amylase inhibitor from maize lines resistant to A. flavus12. Further screening of several hundreds of plant species by Fakhoury and Woloshuk led to the identification of a 36-kDa &#945;-amylase inhibitor-like protein (AILP) from the seeds of hyacinth beans, Lablab purpureus L.13. The peptide sequence of AILP resembled lectins belonging to the lectin&#8211;arcelin&#8211;&#945;-amylase inhibitor family reported in common bean14,15. Purified AILP does not exhibit any inhibitory activity towards mammalian trypsin and further in vitro characterization showed significant inhibition of A. flavus growth and conidial germination13. The reports presented here clearly shows &#945;-amylase can serve as a target in control approaches to restrict pathogens or pests that depend on starch mobilization (through &#945;-amylase activity) and acquisition of soluble sugars as an energy source during their pathogenic interaction with host plants.
Alpha-amylase is known to be critical in A. flavus pathogenicity9,10,11, and given the importance of AILP as a potent anti-A. flavus agent (&#945;-amylase inhibition/antigrowth)13, we generated transgenic maize plants expressing Lablab AILP gene under the constitutive CaMV 35S promoter. The goal was to investigate if heterologous expression of this &#945;-amylase inhibitor in maize is effective against A. flavus pathogenesis and aflatoxin production during maize kernel infection. Our results demonstrate that transgenic maize kernels expressing AILP significantly reduced A. flavus growth and aflatoxin production during kernel infection.

<table>
	<tbody>
		<tr>
			<td>Agar</td>
			<td>Caisson</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Amazing Marine Goop</td>
			<td>Eclectic Products</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>C1000 Touch CFX96 Real-Time System</td>
			<td>Bio-Rad</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Corning&#160;Falcon Tissue Culture Dishes, 60 mm</td>
			<td>Fisher Scientific</td>
			<td>08-772F</td>
			<td></td>
		</tr>
		<tr>
			<td>Eppendorf&#160;5424 Microcentrifuge</td>
			<td>Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Erlenmeyer flask with stopper, 50 mL</td>
			<td>Ace Glass</td>
			<td>6999-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FluoroQuant Afla</td>
			<td>Romer Labs</td>
			<td>COKFA1010</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluted Qualitative Filter Paper Circles, 15 cm</td>
			<td>Fisher Scientific</td>
			<td>09-790-14E</td>
			<td></td>
		</tr>
		<tr>
			<td>Force Air Oven</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FQ-Reader</td>
			<td>Romer Labs</td>
			<td>EQFFM3010</td>
			<td></td>
		</tr>
		<tr>
			<td>Geno/Grinder 2010</td>
			<td>OPS Diagnostics</td>
			<td>SP 2010-115</td>
			<td></td>
		</tr>
		<tr>
			<td>Innova 44 Incubator Shaker</td>
			<td>Brunswick Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>iScript cDNA Synthesis Kit</td>
			<td>Bio-Rad</td>
			<td>1708890</td>
			<td></td>
		</tr>
		<tr>
			<td>liquid Nitrogen</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Low Form Griffin Beakers, 100 mL</td>
			<td>DKW Life Sciences</td>
			<td>14000-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Methylene Chloride</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nexttec 1-step DNA Isolation Kit for Plants</td>
			<td>Nexttec</td>
			<td>47N</td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon Eclipse E600 microscope with Nikon DS-Qi1 camera</td>
			<td>Nikon</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon SMZ25 stereomicroscope with C-HGFI Episcopic Illuminator and Andor Zyla 4.2 sCMOS camera</td>
			<td>Nikon</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nunc Square BioAssay Dishes</td>
			<td>ThermoFisher Scientific</td>
			<td>240835</td>
			<td></td>
		</tr>
		<tr>
			<td>Phire Plant Direct PCR Kit</td>
			<td>ThermoFisher Scientific</td>
			<td>F130WH</td>
			<td></td>
		</tr>
		<tr>
			<td>Polycarbonate Vials, 15 ml</td>
			<td>OPS Diagnostics</td>
			<td>PCRV 15-100-23</td>
			<td></td>
		</tr>
		<tr>
			<td>Potato Dextrose Broth</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Snap Cap, 22 mm</td>
			<td>DKW Life Sciences</td>
			<td>242612</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Phosphate dibasic heptahydrate</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Phosphate monobasic</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrum Plant Total RNA Kit</td>
			<td>Sigma-Aldrich</td>
			<td>STRN50</td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless Steel Grinding Balls, 3/8&#39;&#39;</td>
			<td>OPS Diagnostics</td>
			<td>GBSS 375-1000-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Stir Plate</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Synergy 4 Fluorometer</td>
			<td>Biotek</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>T100 Thermal Cycler</td>
			<td>Bio-Rad</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich</td>
			<td>T-9284</td>
			<td></td>
		</tr>
		<tr>
			<td>V8 juice</td>
			<td>Campbell&#39;s</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Whatman Qualitative Grade Plain Sheets, Grade 3</td>
			<td>Fisher Scientific</td>
			<td>09-820P</td>
			<td></td>
		</tr>
		<tr>
			<td>Wrist-Action Shaker</td>
			<td>Burrell Scientific</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

inhibition of aspergillus flavus growth and aflatoxin production in transgenic maize expressing the &#945;-amylase inhibitor from lablab purpureus l.

Aflatoxin contamination in food and feed crops is a major challenge worldwide. Aflatoxins, produced by the fungus Aspergillus flavus (A. flavus) are potent carcinogens that substantially reduce crop value in maize and other oil rich crops like peanut besides posing serious threat to human and animal health. Different approaches, including traditional breeding, transgenic expression of resistance associated proteins, and RNA interference (RNAi)-based host-induced gene silencing of critical A. flavus gene targets, are being evaluated to increase aflatoxin resistance in susceptible crops. Past studies have shown an important role of &#945;-amylase in A. flavus pathogenesis and aflatoxin production, suggesting this gene/enzyme is a potential target to reduce both A. flavus growth and aflatoxin production. In this regard, the current study was undertaken to evaluate heterologous expression (under control of the constitutive CaMV 35S promoter) of a Lablab purpureus L. &#945;-amylase inhibitor-like protein (AILP) in maize against A. flavus. AILP is a 36-kDa protein, which is a competitive inhibitor of A. flavus &#945;-amylase enzyme and belongs to the lectin&#8211;arcelin&#8211;&#945;-amylase inhibitor protein family in common bean. In vitro studies prior to the current work had demonstrated the role of AILP in inhibition of A. flavus &#945;-amylase activity and fungal growth. Fungal growth and aflatoxin production in mature kernels were monitored in real time using a GFP-expressing A. flavus strain. This kernel screening assay (KSA) is very simple to set up and provides reliable and reproducible data on infection and the extent of spread that could be quantified for evaluation of germplasm and transgenic lines. The fluorescence from the GFP strain is closely correlated to fungal growth and, by extension, it is well-correlated to aflatoxin values.&#160; The goal of the current work was to implement this previous knowledge in a commercially important crop like maize to increase aflatoxin resistance. Our results show a 35%&#8211;72% reduction in A. flavus growth in AILP-expressing transgenic maize kernels which, in turn, translated into a 62%&#8211;88% reduction in aflatoxin levels.

Maize transformation and molecular screening of transgenic plants
Immature embryos of maize Hi-II lines were transformed using Agrobacterium tumefaciens EHA101 strain containing the final plant destination vector expressing the Lablab purpureus AILP gene under the control of CaMV 35S promoter. Five independently transformed maize lines were advanced to the T6 generation for su...

Watch this Scientific Journal Video about Inhibition of Aspergillus flavus Growth and Aflatoxin Production in Transgenic Maize Expressing the Î±-amylase Inhibitor from Lablab purpureus L. at JoVE.co

Inhibition of Aspergillus flavus Growth and Aflatoxin Production in Transgenic Maize Expressing the &amp;#945;-amylase Inhibitor from Lablab purpureus L.

Here we present a protocol to analyze Aspergillus flavus growth and aflatoxin production in maize kernels expressing an antifungal protein.&#160; Using a GFP-expressing A. flavus strain we monitored the infection and spread of the fungus in mature kernels in real time. The assay is rapid, reliable, and reproducible.

Inhibition of Aspergillus flavus Growth and Aflatoxin Production in Transgenic Maize Expressing the &#945;-amylase Inhibitor from Lablab purpureus L.

Aflatoxin contamination in food and feed crops is a major challenge worldwide. Aflatoxins, produced by the fungus Aspergillus flavus (A. flavus) are ...

Here we present a simple kernel screening assay to analyze Aspergillus flavus growth and Aflatoxin production in maize kernels expressing an antifungal protein. Using a green fluorescent protein expressing Aspergillus flavus strain, we monitor the infection and spread of the fungus in mature kernels in real-time. This simple assay provides a reliable means of evaluating the maize kernel's ability to resist Aspergillus flavus infection and Aflatoxin production.Results from this lab assay performed under controlled conditions on mature kernels correlates well with results from infection under field conditions. Demonstrating the procedure will be Dr.Rajtilak Majumdar, a postdoc from our laboratory, along with Christine Sickler and David Ambrosio, biological science technicians also from our lab. To begin, glue 20 two mm snap caps in a Petri dish to create KSA caps.Let the glue dry for 48 hours before using the caps. In a biological safety cabinet spray a square bioassay tray with 70%ethanol in water. Let the tray air dry.Add sterile chromatography paper to the dry tray. Spray nine of the KSA caps with 70%ethanol and let them air dry. Then place the caps on the bioassay tray.For each transgenic maize line being tested, select 20 undamaged kernels and place them into a 50 ml centrifuge tube. Using a tabletop stereo microscope select only undamaged kernels for the assay. Damaged kernels are more susceptible for Aspergillus attack and produce more Aflatoxin, thereby skewing the results and not representing the true antifungal or antimicrobial traits of the variety.Add 70%ethanol to each tube. Let the kernels sterilize for four minutes while occasionally gently shaking them. After this gently pour off the ethanol and gently rinse the kernels in sterile deionized water three times.Obtain a six day culture of Aspergillus flavus stain 70 expressing GFP grown on V8 medium. Add 20 ml of sterile 0.02%Triton X-100 in deionized water. And use a sterile loop to scrape off the spores.Pipette off the inoculum and transfer it to a 300 ml sterile beaker. Prepare a five-fold dilution with 0.02%Triton X-100 and use a hemocytometer to perform a spore count. Dilute again if necessary to obtain 100 ml with a concentration of four million spores per ml.Pour off the inoculum into an empty beaker. Place the kernels into a sterile 300 ml beaker with a stir bar and stir for three minutes. Using forceps transfer the kernels to the bioassay dish, making sure to only place one kernel into each cap.Add 30 ml of deionized water to the bottom of each bioassay tray. And incubate at 31 degrees Celsius for seven days. After seven days of inoculation with A.flavus, take pictures of four kernels that were designated for microscopic analysis and photography.Then use a soft tissue and deionized water to clean the exterior of kernels. Perform longitudinal sections of kernels and immediately take photographs under the fluorescent microscope. To prepare the kernels for analysis, clean the outside of the remaining kernels with a soft tissue and deionized water.Place four kernels, which constitute one rep, into a 15 ml screw cap polycarbonate vial containing two stainless steel balls. Immediately freeze the vials in liquid nitrogen and store at 80 degrees Celsius until ready to proceed with further processing and analysis. When ready, remove the kernels from the freezer and use a homogenizer to grind them at 1500 rpm for three minutes.Use the same ground materials for GFP analysis, Aflatoxin determination, and molecular analysis, so that all values are representative of the samples. While a minimum of three replicates are recommended, more is always better depending on the availability of good quality kernels. In this study immature embryos of maize HI-II lines are transformed using Agrobacterium tumefaciens EHA101 strain containing the final plant destination vector expressing the Lablab purpureus AILP gene under the control of the 35S promoter from the cauliflower mosaic virus.PCR amplification of the target AILP gene showed a 548 bp amplicon observed only in the transgenic maize lines. The AILP gene showed expression in the transgenic lines whereas no AILP expression was observed in the control plants. Early stage germinating spores are exposed to crude leaf extracts from young transgenic maize plants for 20 hours.High full length from spores exposed to transgenic leaf extracts show a 58 to 80%reduction compared to the negative control. The A.flavus strain used contains a GFP reporter which enables the monitoring and quantification of fungal growth in real-time. Significant reduction in GFP fluorescence is observed in transgenic AILP kernels compared to the isogenic negative control.A significant reduction is seen in fungal growth for AILP lines four and five, 69%and 72%respectively. The other lines show a reduction of 35 to 60%reduction in comparison to the control kernels. A reduction of 62 to 88%in Aflatoxin content was observed in the AILP kernels as compared to the control.Line four is seen to have the lowest Aflatoxin content at 486 ng per g, followed by other lines ranging which had contents ranging between 640 and 1498 ng per g in the kernels. Following this procedure, additional methods can be performed such as using a fluorometer to quantify GFP and as its fungal growth. Immunobased commercial kits or HPLC or EPLC can be used to perform Aflatoxin quantitation.The availability of KSA provides a quick and simple means of determining resistance to Aflatoxin contamination. The of different maize breeding lines can be assessed quickly using this technique. While the kernel screening assay is not hazardous, the operator should protect himself or herself from exposure to Aspergillus flavus spores, use proper protective equipment.

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Research

JoVE Journal

Environment

Mass Production of Genetically Modified Aedes aegypti for Field Releases in Brazil

New techniques and methods are being sought to try to win the battle against mosquitoes. Recent advances in molecular techniques have led to the development of new and innovative methods of mosquito control based around the Sterile Insect Technique (SIT)1-3. A control method known as RIDL&#160;(Release of Insects carrying a Dominant Lethal)4, is based around SIT, but uses genetic methods to remove the need for radiation-sterilization5-8. A RIDL&#160;strain of Ae. aegypti was successfully tested in the field in Grand Cayman9,10; further field use is planned or in progress in other countries around the world.
Mass rearing of insects has been established in several insect species and to levels of billions a week. However, in mosquitoes, rearing has generally been performed on a much smaller scale, with most large scale rearing being performed in the 1970s and 80s. For a RIDL&#160;program it is desirable to release as few females as possible as they bite and transmit disease. In a mass rearing program&#160;there are several stages to produce the males to be released: egg production, rearing eggs until pupation, and then sorting males from females before release. These males are then used for a RIDL&#160;control program,&#160;released as either pupae or adults11,12.
To suppress a mosquito population using RIDL&#160;a large number of high quality male adults need to be reared13,14. The following describes the methods for the mass rearing of OX513A, a RIDL&#160;strain of Ae. aegypti 8, for release and covers the techniques required for the production of eggs and mass rearing RIDL&#160;males for a control program.

Mass Production of Genetically Modified Aedes aegypti for Field Releases in Brazil

To achieve population suppression of Aedes aegypti using the RIDL&#174; (Release of Insects carrying a Dominant Lethal) system, large numbers of male mosquitoes need to be released. This requires the use of mass rearing techniques and technology to provide reliable systems to obtain the maximum number of high quality male mosquitoes.

New techniques and methods are being sought to try to win the battle against mosquitoes. Recent advances in molecular techniques have led to the ...

Determination of Microbial Extracellular Enzyme Activity in Waters, Soils, and Sediments using High Throughput Microplate Assays

Much of the nutrient cycling and carbon processing in natural environments occurs through the activity of extracellular enzymes released by microorganisms. Thus, measurement of the activity of these extracellular enzymes can give insights into the rates of ecosystem level processes, such as organic matter decomposition or nitrogen and phosphorus mineralization. Assays of extracellular enzyme activity in environmental samples typically involve exposing the samples to artificial colorimetric or fluorometric substrates and tracking the rate of substrate hydrolysis. Here we describe microplate based methods for these procedures that allow the analysis of large numbers of samples within a short time frame. Samples are allowed to react with artificial substrates within 96-well microplates or deep well microplate blocks, and enzyme activity is subsequently determined by absorption or fluorescence of the resulting end product using a typical microplate reader or fluorometer. Such high throughput procedures not only facilitate comparisons between spatially separate sites or ecosystems, but also substantially reduce the cost of such assays by reducing overall reagent volumes needed per sample.

Microplate based procedures are described for the colorimetric or fluorometric analysis of extracellular enzyme activity. These procedures allow for the rapid assay of such activity in large numbers of environmental samples within a manageable time frame.

Much of the nutrient cycling and carbon  processing in natural environments occurs through the activity of extracellular  enzymes released by ...

Optimize Flue Gas Settings to Promote Microalgae Growth in Photobioreactors via Computer Simulations

Flue gas from power plants can promote algal cultivation and reduce greenhouse gas emissions1. Microalgae not only capture solar energy more efficiently than plants3, but also synthesize advanced biofuels2-4. Generally, atmospheric CO2 is not a sufficient source for supporting maximal algal growth5. On the other hand, the high concentrations of CO2 in industrial exhaust gases have adverse effects on algal physiology. Consequently, both cultivation conditions (such as nutrients and light) and the control of the flue gas flow into the photo-bioreactors are important to develop an efficient &ldquo;flue gas to algae&rdquo; system. Researchers have proposed different photobioreactor configurations4,6 and cultivation strategies7,8 with flue gas. Here, we present a protocol that demonstrates how to use models to predict the microalgal growth in response to flue gas settings. We perform both experimental illustration and model simulations to determine the favorable conditions for algal growth with flue gas. We develop a Monod-based model coupled with mass transfer and light intensity equations to simulate the microalgal growth in a homogenous photo-bioreactor. The model simulation compares algal growth and flue gas consumptions under different flue-gas settings. The model illustrates: 1) how algal growth is influenced by different volumetric mass transfer coefficients of CO2; 2) how we can find optimal CO2 concentration for algal growth via the dynamic optimization approach (DOA); 3) how we can design a rectangular on-off flue gas pulse to promote algal biomass growth and to reduce the usage of flue gas. On the experimental side, we present a protocol for growing Chlorella under the flue gas (generated by natural gas combustion). The experimental results qualitatively validate the model predictions that the high frequency flue gas pulses can significantly improve algal cultivation.

Flue gas from power plants is a cheap CO2 source for algal growth. We have built prototype &#34;flue gas to algal cultivation&#34; systems and described how to scale up the algal cultivation process. We have demonstrated the use of a mass-transfer bio-reaction model to simulate and to design the optimal operation of flue gas for the growth of Chlorella sp. in algal photo-bioreactors.

Flue gas from power plants can promote algal cultivation and reduce greenhouse gas emissions1. Microalgae not only capture solar energy more efficiently ...

Methods for Facilitating Microbial Growth on Pulp Mill Waste Streams and Characterization of the Biodegradation Potential of Cultured Microbes

The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high quality paper. Black liquor is a pulping waste generated by the kraft process that has potential for downstream bioconversion. However, the recalcitrant nature of the lignocellulose resources, its chemical derivatives that constitute the majority of available organic carbon within black liquor, and its basic pH present challenges to microbial biodegradation of this waste material. Methods for the collection and modification of black liquor for microbial growth are aimed at utilization of this pulp waste to convert the lignin, organic acids, and polysaccharide degradation byproducts into valuable chemicals. The lignocellulose extraction techniques presented provide a reproducible method for preparation of lignocellulose growth substrates for understanding metabolic capacities of cultured microorganisms. Use of gas chromatography-mass spectrometry enables the identification and quantification of the fermentation products resulting from the growth of microorganisms on pulping waste. These methods when used together can facilitate the determination of the metabolic activity of microorganisms with potential to produce fermentation products that would provide greater value to the pulping system and reduce effluent waste, thereby increasing potential paper milling profits and offering additional uses for black liquor.

Industrial wastes can be collected and modified to analyze microbial growth. Lignocellulose extraction techniques provide components to analyze specific biodegradation ability. Gas chromatography-mass spectrometry identifies fermentation products of microorganisms grown on pulping waste. These methods determine the metabolic capacity of microorganisms to degrade pulping waste.

The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high ...

RNAi-mediated Control of Aflatoxins in Peanut: Method to Analyze Mycotoxin Production and Transgene Expression in the Peanut/Aspergillus Pathosystem

The Food and Agriculture Organization of the United Nations estimates that 25% of the food crops in the world are contaminated with aflatoxins. That represents 100 million tons of food being destroyed or diverted to non-human consumption each year. Aflatoxins are powerful carcinogens normally accumulated by the fungi Aspergillus flavus and A. parasiticus in cereals, nuts, root crops and other agricultural products. Silencing of five aflatoxin-synthesis genes by RNA interference (RNAi) in peanut plants was used to control aflatoxin accumulation following inoculation with A. flavus. Previously, no method existed to analyze the effectiveness of RNAi in individual peanut transgenic events, as these usually produce few seeds, and traditional methods of large field experiments under aflatoxin-conducive conditions were not an option. In the field, the probability of finding naturally contaminated seeds is often 1/100 to 1/1,000. In addition, aflatoxin contamination is not uniformly distributed. Our method uses few seeds per transgenic event, with small pieces processed for real-time PCR (RT-PCR) or small RNA sequencing, and for analysis of aflatoxin accumulation by ultra-performance liquid chromatography (UPLC). RNAi-expressing peanut lines 288-72 and 288-74, showed up to 100% reduction (p&#8804;0.01) in aflatoxin B1 and B2 compared to the control that accumulated up to 14,000 ng.g-1 of aflatoxin B1 when inoculated with aflatoxigenic A. flavus. As reference, the maximum total of aflatoxins allowable for human consumption in the United States is 20 ng.g-1. This protocol describes the application of RNAi-mediated control of aflatoxins in transgenic peanut seeds and methods for its evaluation. We believe that its application in breeding of peanut and other crops will bring rapid advancement in this important area of science, medicine and human nutrition, and will significantly contribute to the international effort to control aflatoxins, and potentially other mycotoxins in major food crops.

RNAi-mediated Control of Aflatoxins in Peanut: Method to Analyze Mycotoxin Production and Transgene Expression in the Peanut/Aspergillus Pathosystem

We demonstrate a method for the analysis of aflatoxins and transgene expression in peanut seeds that contain RNA-interference signals for silencing aflatoxin-synthesis genes in the fungus Aspergillus flavus. RNAi-mediated control of mycotoxins in plants has not been reported previously.

The Food and Agriculture Organization of the United Nations estimates that 25% of the food crops in the world are contaminated with aflatoxins. That ...

Extraction and Analysis of Microbial Phospholipid Fatty Acids in Soils

Phospholipid fatty acids (PLFAs) are key components of microbial cell membranes. The analysis of PLFAs extracted from soils can provide information about the overall structure of terrestrial microbial communities. PLFA profiling has been extensively used in a range of ecosystems as a biological index of overall soil quality, and as a quantitative indicator of soil response to land management and other environmental stressors.
The standard method presented here outlines four key steps: 1. lipid extraction from soil samples with a single-phase chloroform mixture, 2. fractionation using solid phase extraction columns to isolate phospholipids from other extracted lipids, 3. methanolysis of phospholipids to produce fatty acid methyl esters (FAMEs), and 4. FAME analysis by capillary gas chromatography using a flame ionization detector (GC-FID). Two standards are used, including 1,2-dinonadecanoyl-sn-glycero-3-phosphocholine (PC(19:0/19:0)) to assess the overall recovery of the extraction method, and methyl decanoate (MeC10:0) as an internal standard (ISTD) for the GC analysis.

Phospholipid fatty acids provide information about the structure of soil microbial communities. We present methods for extraction from soil samples with a single-phase chloroform mixture, fractionation of extracted lipids using solid phase extraction columns, and methanolysis to produce fatty acid methyl esters, which are analyzed by capillary gas chromatography.

Phospholipid fatty acids (PLFAs) are key components of microbial cell membranes. The analysis of PLFAs extracted from soils can provide information about ...

A Gusseted Thermogradient Table to Control Soil Temperatures for Evaluating Plant Growth and Monitoring Soil Processes

Thermogradient tables were first developed in the 1950s primarily to test seed germination over a range of temperatures simultaneously without using a series of incubators. A temperature gradient is passively established across the surface of the table between the heated and cooled ends and is lost quickly at distances above the surface. Since temperature is only controlled on the table surface, experiments are restricted to shallow containers, such as Petri dishes, placed on the table. Welding continuous aluminum vertical strips or gussets perpendicular to the surface of a table enables temperature control in depth via convective heat flow. Soil in the channels between gussets was maintained across a gradient of temperatures allowing a greater diversity of experimentation. The gusseted design was evaluated by germinating oat, lettuce, tomato, and melon seeds. Soil temperatures were monitored using individual, battery-powered dataloggers positioned across the table. LED lights installed in the lids or along the sides of the gradient table create a controlled temperature chamber where seedlings can be grown over a range of temperatures. The gusseted design enabled accurate determination of optimum temperatures for fastest germination rate and the highest percentage germination for each species. Germination information from gradient table experiments can help predict seed germination and seedling growth under the adverse soil conditions often encountered during field crop production. Temperature effects on seed germination, seedling growth, and soil ecology can be tested under controlled conditions in a laboratory using a gusseted thermogradient table.

Traditional thermogradient tables create a range of temperatures across the surface. Welding gussets perpendicular to the surface of a thermogradient table will control temperature in depth increasing possible research applications.

Thermogradient tables were first developed in the 1950s primarily to test seed germination over a range of temperatures simultaneously without using a ...

Production and Measurement of Organic Particulate Matter in the Harvard Environmental Chamber

The production and the evolution of atmospheric organic particulate matter (PM) are insufficiently understood for accurate simulations of atmospheric chemistry and climate. The complex production mechanisms and reaction pathways make this a challenging research topic. To address these issues, an environmental chamber, providing enough residence time and close-to-ambient concentrations of precursors for secondary organic materials, is needed. The Harvard Environmental Chamber (HEC) was built to serve this need, simulating the production of gas and particle phase species from volatile organic compounds (VOCs). The HEC has a volume of 4.7 m3 and a mean residence time of 3.4 h under typical operating conditions. It is operated as a completely mixed flow reactor (CMFR), providing the possibility of indefinite steady-state operation across days for sample collection and data analysis. The operation procedures are described in detail in this article. Several types of instrumentation are used to characterize the produced gas and particles. A High-Resolution Time-of-Fight Aerosol Mass Spectrometer (HR-ToF-AMS) is used to characterize particles. A Proton-Transfer-Reaction Mass Spectrometer (PTR-MS) is used for gaseous analysis. Example results are presented to show the use of the environmental chamber in a wide variety of applications related to the physicochemical properties and reaction mechanisms of organic atmospheric particulate matter.

This paper describes operation procedures for the Harvard Environmental Chamber (HEC) and related instrumentation for measuring gaseous and particle species. The environmental chamber is used to produce and study secondary organic species produced from the organic precursors, especially related to atmospheric organic particulate matter.

The production and the evolution of atmospheric organic particulate matter (PM) are insufficiently understood for accurate simulations of atmospheric ...

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current measures to combat such pathogens have proved too conservative and, thus, not sufficiently effective, and they can potentially pose environmental risks. Therefore, it is extremely necessary to identify host-resistance factors to assist in controlling plant diseases naturally through the identification of resistant germplasm, the isolation and characterization of resistance genes, and the molecular breeding of resistant cultivars. In this regard, there is need to establish an accurate, rapid, and large-scale inoculation method to breed and develop plant resistance genes. The rice blast fungal pathogen Magnaporthe grisea causes severe disease symptoms and yield losses. Recently, M. grisea has emerged as a model organism for studying the mechanisms of plant-fungal pathogen interactions. Hence, we report the development of a plant virulence test method that is specific for M. grisea. This method provides for both spray inoculation with a conidial suspension and wounding inoculation with mycelium cubes or droplets of conidial suspension. The key step of the wounding inoculation method for detached rice leaves is to make wounds on plant leaves, which avoids any interference caused by host penetration resistance. This spray/wounding protocol contributes to the rapid, accurate, and large-scale screening of the pathotypes of M. grisea isolates. This integrated and systematic plant infection method will serve as an excellent starting point for gaining a broad perspective of issues in plant pathology.

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Here, we present a protocol to test plant virulence with the plant pathogen Magnaporthe grisea. This report will contribute to the large-scale screening of the pathotypes of fungi isolates and serve as an excellent starting point for understanding the resistant mechanisms of plants during molecular breeding.

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current ...

High-throughput, Microscale Protocol for the Analysis of Processing Parameters and Nutritional Qualities in Maize (Zea mays L.)

Maize is an important grain crop in the United States and worldwide. However, maize grain must be processed prior to human consumption. Furthermore, whole grain composition and processing characteristics vary among maize hybrids and can impact the quality of the final processed product. Therefore, in order to produce healthier processed food products from maize, it is necessary to know how to optimize processing parameters for particular sets of germplasm to account for these differences in grain composition and processing characteristics. This includes a better understanding of how current processing techniques impact the nutritional quality of the final processed food product. Here, we describe a microscale protocol that both simulates the processing pipeline to produce cornflakes from large flaking grits and allows for the processing of multiple grain samples simultaneously. The flaking grits, the intermediate processed products, or final processed product, as well as the corn grain itself, can be analyzed for nutritional content as part of a high-throughput analytical pipeline. This procedure was developed specifically for incorporation into a maize breeding research program, and it can be modified for other grain crops. We provide an example of the analysis of insoluble-bound ferulic acid and p-coumaric acid content in maize. Samples were taken at five different processing stages. We demonstrate that sampling can take place at multiple stages during microscale processing, that the processing technique can be utilized in the context of a specialized maize breeding program, and that, in our example, most of the nutritional content was lost during food product processing.

High-throughput, Microscale Protocol for the Analysis of Processing Parameters and Nutritional Qualities in Maize Zea mays L.

Here, we present a microscale protocol for processing grain samples and for incorporating this microscale approach into a high-throughput analytical pipeline. This is a higher throughput adaptation of currently available protocols.

Maize is an important grain crop in the United States and worldwide. However, maize grain must be processed prior to human consumption. Furthermore, whole ...