Synergistic Impacts of Plant-Growth-Promoting Bacteria and Selenium Nanoparticles on Improving the Nutritional Value and Biological Activities of Three Cultivars of Brassica Sprouts

Due to the growing world population and increasing environmentalstress, improving the production, nutritional quality, and pharmaceuticalapplications of plants have become an urgent need. Therefore, currentresearch was designed to investigate the impact of seed priming usingplant-growth-promoting bacteria (PGPB) along with selenium nanoparticles(SeNPs) treatment on chemical and biological properties of three Brassica oleracea cultivars [Southern star (VA1),Prominence (VA2), Monotop (VA3)]. With this aim, one out of five morphologicallydifferent strains of bacteria, namely, JM18, which was further identifiedvia 16S rRNA gene sequencing as a Nocardiopsis specieswith strong plant-growth-promoting traits, isolated from soil, wasused. To explore the growth-promoting potential of Nocardiopsis species, seeds of three varieties of B. oleracea were primed with JM18 individually or in combination with SeNP treatment.Seed treatments increased sprout growth (fresh and dry weights) andglucosinolate accumulation. The activity of myrosinase was significantlyincreased through brassica sprouts and consequently enhanced the amino-acid-derivedglucosinolate induction. Notably, a reduction in effective sulforaphanenitrile was detected, being positively correlated with a decreasein epithiospecifier protein (EP). Consequently, the antioxidant activitiesof VA2 and VA3, determined by the ferric reducing antioxidant power(FRAP) assay, were increased by 74 and 79%, respectively. Additionally,the antibacterial activities of JM18-treated cultivars were improved.However, a decrease was observed in SeNP- and JM18 + SeNP-treatedVA2 and VA3 against Serratia marcescens and Candida glabrata and VA1 against S. marcescens. In conclusion, seed priming with theJM18 extract is a promising method to enhance the health-promotingactivities of B. oleracea sprouts.