Kellie P. Burris

Composition and Bioactive Properties of Yerba Mate (llex paraguariensis A. St.-Hil.): A Review

Yerba mate es una infusion popular producida y consumida en Argentina, Brasil, Chile, Paraguay y Uruguay. Se procesa a partir de hojas y tallos de Ilex paraguariensis A. St.-Hil., un arbusto perenne de la familia Aquifoliaceae. El procesamiento ocurre en seis etapas: recoleccion de hojas maduras y tallos pequenos, tostado por fuego directo, secado por aire caliente, molienda, envejecimiento (dependiendo de los atributos sensoriales requeridos), y embalaje final. Si bien la yerba mate se ha cultivado y consumido por siglos en America del Sur, su popularidad en los Estados Unidos ha aumentando debido a la demanda por bebidas saludables y alimentos mas naturales y por los potenciales beneficios para la salud de la yerba mate (antioxidante, antimicrobiano, accion contra la obesidad y diabetes, digestivo, estimulante). La yerba mate tambien se ha investigado como agente de prevencion y causa de algunos tipos de cancer, causando controversia entre investigadores. Investigaciones recientes han ampliado el espectro de uso de la yerba mate como agente antimicrobiano, proteccion de cultivos y accion contra patogenos transmitidos por alimentos. Resultados prometedores para el uso de esta planta en la salud humana y animal han llevado a esta revision. Esta revision se centro en la composicion de la yerba mate, y el efecto que el cultivo y el procesamiento puede tener sobre sus propiedades.

Antimicrobial Activity of Yerba Mate (Ilex paraguariensis) Aqueous Extracts against Escherichia coli O157:H7 and Staphylococcus aureus

UNLABELLED Bioactive compounds from natural plant sources are becoming increasingly important to the food industry. Ilex paraguariensis is used in the preparation of a widely popular tea beverage (Yerba Mate) in the countries of Uruguay, Paraguay, Argentina, and Brazil. In this study, extracts of 4 brands of commercial tea, derived from the holly plant species, Ilex paraguariensis, were evaluated for their ability to inhibit or inactivate bacterial foodborne pathogens. The ultimate goal was to evaluate potential use of the extracts in commercial applications. Dialyzed aqueous extracts were screened for antimicrobial activity against Escherichia coli O157:H7 and Staphylococcus aureus. S. aureus was found to be the more sensitive to extracts than E. coli O157:H7. Minimum bactericidal concentrations (MBCs) were determined to be approximately 150 to 800 μg/mL and 25 to 50 μg/mL against E. coli O157:H7 and S. aureus, respectively. A Uruguayan brand had reduced activity against E. coli O157:H7 compared to the Argentinean brands tested. It was concluded that Yerba Mate could be used as a potential antimicrobial in foods and beverages against these pathogenic bacteria. PRACTICAL APPLICATION Soluble extracts from Yerba Mate are natural antimicrobials that can be incorporated into food products to achieve longer shelf life.

Optoelectronic Signatures of DNA-Based Hybrid Nanostructures

This paper presents a characterization of the vibrational modes of nanostructure-DNA complexes immobilized on substrates, such as silver-coated microspheres and silver nanostructure array DNA strands end terminated with titanium dioxide (TiO2) nanoparticles are used to study UV-induced cleaving of DNA molecules functionalized with indirect-bandgap semiconductors. In addition, conventional DNA-based molecular beacons were designed and applied in the detection of DNA of selected organisms. Micro-Raman (μRaman) measurements of DNA in water have proven to be a major challenge because of: 1) weak DNA signatures in solution; 2) changes in structural conformations of the DNA; and 3) environmental effects, such as temperature and pH of the solution in which DNA is suspended. We have studied optoelectronic properties of nanostructure-DNA complexes immobilized on silver nanosphere substrates as well as on Ag-coated micro- and nanostructures. In this research, self-assembled monolayers of DNA formed on these substrates were studied using μRaman techniques. These Raman spectra were used to identify prominent vibrational modes of DNA, and to characterize DNA Raman spectra for both B-DNA with a right-handed double helix, and Z-DNA with a left-handed double helix (S. C. Ha, K. Lowenhaupt, A. Rich, Y. Kim, and K. Kim, “Crystal structure of a junction between B-DNA and Z-DNA reveals two extruded bases,” Nature, Vol. 437, pp. 1183-1186, 2005). These Raman-based studies of the conformational states of DNA employ pH-changing trivalent salts, methylation of cytosine bases, and alternating GC bases. Moreover, DNA strands terminated with titanium dioxide (TiO2) nanoparticles were observed to undergo cleaving upon UV illumination.

Development of a rapid, low-cost protoplast transfection system for switchgrass (Panicum virgatum L.)

Key messageA switchgrass protoplast system was developed, achieving a cost reduction of ~1000-fold, a threefold increase in transformation efficiency, and a fourfold reduction in required DNA quantity compared to previous methods.AbstractIn recent years, there has been a resurgence in the use of protoplast systems for rapid screening of gene silencing and genome-editing targets for siRNA, miRNA, and CRISPR technologies. In the case of switchgrass (Panicum virgatum L.), to achieve economic feasibility for biofuel production, it is necessary to develop plants with decreased cell wall recalcitrance to reduce processing costs. To achieve this goal, transgenic plants have been generated with altered cell wall chemistry; however, with limited success owing to the complexity of cell walls. Because of the considerable cost, time, and effort required to screen transgenic plants, a protoplast system that can provide data at an early stage has potential to eliminate low performing candidate genes/targets prior to the creation of transgenic plants. Despite the advantages of protoplast systems, protoplast isolation in switchgrass has proven costly, requiring expensive lab-grade enzymes and high DNA quantities. In this paper, we describe a low-cost protoplast isolation system using a mesophyll culture approach and a cell suspension culture. Results from this work show a cost reduction of ~1000-fold compared to previous methods of protoplast isolation in switchgrass, with a cost of

An Arabidopsis thaliana ABC transporter that confers kanamycin resistance in transgenic plants does not endow resistance to Escherichia coli

0.003 (USD) per reaction for mesophyll protoplasts and

The Potential of Systems Biology to Discover Antibacterial Mechanisms of Plant Phenolics

0.018 for axenic cell culture-derived protoplasts. Further, the efficiency of protoplast transformation was optimized threefold over previous methods, despite a fourfold reduction in DNA quantity. The methods developed in this work remove the cost barrier previously limiting high-throughput screening of genome-editing and gene silencing targets in switchgrass, paving the way for more efficient development of transgenic plants.

Origin of a novel regulatory module by duplication and degeneration of an ancient plant transcription factor.

Concerns have been raised about potential horizontal gene transfer (HGT) of antibiotic resistance markers (ARMs) from transgenic plants to bacteria of medical and environmental importance. All ARMs used in transgenic plants have been bacterial in origin, but it has been recently shown that an Arabidopsis thaliana ABC transporter, Atwbc19, confers kanamycin resistance when overexpressed in transgenic plants. Atwbc19 was evaluated for its ability to transfer kanamycin resistance to Escherichia coli, a kanamycin‐sensitive model bacterium, under simulated HGT, staged by subcloning Atwbc19 under the control of a bacterial promoter, genetically transforming to kanamycin‐sensitive bacteria, and assessing if resistance was conferred as compared with bacteria harbouring nptII, the standard kanamycin resistance gene used to produce transgenic plants. NptII provided much greater resistance than Atwbc19 and was significantly different from the no‐plasmid control at low concentrations. Atwbc19 was not significantly different from the no‐plasmid control at higher concentrations. Even though HGT risks are considered low with nptII, Atwbc19 should have even lower risks, as its encoded protein is possibly mistargeted in bacteria.

Computational Ranking of Yerba Mate Small Molecules Based on Their Predicted Contribution to Antibacterial Activity against Methicillin-Resistant Staphylococcus aureus.

Drug resistance of bacterial pathogens is a growing problem that can be addressed through the discovery of compounds with novel mechanisms of antibacterial activity. Natural products, including plant phenolic compounds, are one source of diverse chemical structures that could inhibit bacteria through novel mechanisms. However, evaluating novel antibacterial mechanisms of action can be difficult and is uncommon in assessments of plant phenolic compounds. With systems biology approaches, though, antibacterial mechanisms can be assessed without the bias of target-directed bioassays to enable the discovery of novel mechanism(s) of action against drug resistant microorganisms. This review article summarizes the current knowledge of antibacterial mechanisms of action of plant phenolic compounds and discusses relevant methodology.

Metabolomic analysis of the mechanism of action of yerba mate aqueous extract on Salmonella enterica serovar Typhimurium

It is commonly believed that gene duplications provide the raw material for morphological evolution. Both the number of genes and size of gene families have increased during the diversification of land plants. Several small proteins that regulate transcription factors have recently been identified in plants, including the LITTLE ZIPPER (ZPR) proteins. ZPRs are post-translational negative regulators, via heterodimerization, of class III Homeodomain Leucine Zipper (C3HDZ) proteins that play a key role in directing plant form and growth. We show that ZPR genes originated as a duplication of a C3HDZ transcription factor paralog in the common ancestor of euphyllophytes (ferns and seed plants). The ZPRs evolved by degenerative mutations resulting in loss all of the C3HDZ functional domains, except the leucine zipper that modulates dimerization. ZPRs represent a novel regulatory module of the C3HDZ network unique to the euphyllophyte lineage, and their origin correlates to a period of rapid morphological changes and increased complexity in land plants. The origin of the ZPRs illustrates the significance of gene duplications in creating developmental complexity during land plant evolution that likely led to morphological evolution.

Mega-Nano Detection of Foodborne Pathogens and Transgenes Using Molecular Beacon and Semiconductor Quantum Dot Technologies

The aqueous extract of yerba mate, a South American tea beverage made from Ilex paraguariensis leaves, has demonstrated bactericidal and inhibitory activity against bacterial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). The gas chromatography-mass spectrometry (GC-MS) analysis of two unique fractions of yerba mate aqueous extract revealed 8 identifiable small molecules in those fractions with antimicrobial activity. For a more comprehensive analysis, a data analysis pipeline was assembled to prioritize compounds for antimicrobial testing against both MRSA and methicillin-sensitive S. aureus using forty-two unique fractions of the tea extract that were generated in duplicate, assayed for activity, and analyzed with GC-MS. As validation of our automated analysis, we checked our predicted active compounds for activity in literature references and used authentic standards to test for antimicrobial activity. 3,4-dihydroxybenzaldehyde showed the most antibacterial activity against MRSA at low concentrations in our bioassays. In addition, quinic acid and quercetin were identified using random forests analysis and 5-hydroxy pipecolic acid was identified using linear discriminant analysis. We also generated a ranked list of unidentified compounds that may contribute to the antimicrobial activity of yerba mate against MRSA. Here we utilized GC-MS data to implement an automated analysis that resulted in a ranked list of compounds that likely contribute to the antimicrobial activity of aqueous yerba mate extract against MRSA.