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.

Yerba Mate is a popular tea beverage produced and consumed in the South American countries of Argentina, Brazil, Chile, Paraguay, and Uruguay, and is processed from the leaves and stems of Ilex paraguariensis A. St.-Hil., a perennial shrub from the Aquifoliaceae family. Production occurs in six stages: harvesting older leaves and small stems, roasting by direct fire, drying under hot air, milling to specified size, aging to acquire optimal sensory attributes, and final packaging. While grown and consumed for centuries in South America, its popularity is increasing in the United States because of demand by consumers for healthier, more natural foods, its filling a niche for a different type of tea beverage, and for Yerba Mate's potential health benefits-antimicrobial, antioxidant, antiobesity, anti-diabetic, digestive improvement, stimulant, and cardiovascular properties. Cultivation, production and processing may cause a variation in bioactive compounds biosynthesis and degradation. Recent research has been expanded to its potential use as an antimicrobial, protecting crops and foods against foodborne, human and plant pathogens. Promising results for the use of this botanical in human and animal health has prompted this review. This review focuses on the known chemical composition of Yerba Mate, the effect of cultivation, production and processing may have on composition, along with a specific discussion of those compounds found in Yerba Mate that have antimicrobial properties.

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 $0.003 (USD) per reaction for mesophyll protoplasts and $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.

Soluble extracts from Yerba Mate are natural antimicrobials that can be incorporated into food products to achieve longer shelf life.