No abstract

The emergence of resistant microbes threatens public health on our planet, and the emergence of resistant bacteria against the most commonly used antibiotics necessitates urgent alternative therapeutic options. One way to fight resistant microbes is to design new antimicrobial agents, however, this approach takes decades of research. An alternative or parallel approach is to target the virulence of bacteria with natural or synthetic agents. Active constituents from medicinal plants represent a wide library to screen for natural anti-virulence agents. Caraway is used as a traditional spice and in some medicinal applications such as carminative, antispasmodic, appetizer, and expectorant. Caraway essential oil is rich in terpenes that were previously reported to have antimicrobial activities. In our study, we tested the caraway essential oil in sub-inhibitory concentration as a virulence agent against the Gram-negative bacteria Pseudomonas aeruginosa. Caraway essential oil in sub-inhibitory concentration dramatically blocked protease activity, pyocyanin production, biofilm formation, and quorum sensing activity of P. aeruginosa. The gas chromatography–mass spectroscopy (GC-MS) profile of caraway fruit oil identified 13 compounds representing 85.4% of the total oil components with carvone and sylvestrene as the main constituents. In conclusion, caraway essential oil is a promising virulence-attenuating agent that can be used against topical infections caused by P. aeruginosa.

Two field experiments were carried out at a Private Farm located in Salaka village, El-Mansoura, Egypt, during two successive seasons of 2011/2012.These experiments aimed to study the effect of irrigation intervals and some foliar application treatments (salicylic acid and potassium) on common bean(Bronco cultivar) vegetative growth parameters (plant height, number of leaves ,fresh and dry weights and leaf area/plant) , yield (early yield and total yield) , Chemical constituents in leaves(chlorophyll a, b and total, N, P , K and proline content) and Chemical constituents in pods(protein, carbohydrates and sugar content).This study included 15 treatments, which were the combinations between three irrigation intervals (10, 13 and 16 days) and five foliar application treatments including control. These treatments were arranged in a split plot in a complete randomized block design with three replicates. The obtained results showed that the mean values of vegetative growth parameters ,yield and Chemical constituents in leaves and pods of common bean plants were reduced due to increasing irrigation intervals up to 16 days during both seasons of study, while proline content increased by increasing irrigation intervals up to 16 days. Generally, results showed that foliar application of Salicylic Acid at 15 and 30 ppm and foliar potassium at 1% and 2% improved all measured traits under both well watered and water stress conditions. The highest significant values of the aforementioned parameters were recorded with spraying plants with Salicylic Acid at 30 ppm and irrigation every 13 days (5 irrigations) followed with salicylic acid at 15 ppm and foliar potassium at 1% and 2% as compared with every 10 or 16 days (4 or 6 irrigations). However, the highest mean value of leaf`s proline content was obtained from the plants which irrigated every 16 days. Thus, results signify the role of SA and K in regulating drought response of plants and suggest that foliar salicylic acid and potassium could be used as a potential growth regulator, for improving common bean growth under water stress conditions.