Plant‐Growth‐Promoting Rhizobacteria and Their Metabolites

Abstract

Soil contamination by heavy metals due to mining, industrialization, and excessive use of agrochemicals is a very worrying global environmental problem that negatively affects human health. Due to higher metal content, higher pH, less availability of essential nutrients, lower organic matter content, and inadequate soil structure, heavy metals are more difficult to extract from contaminated soils. The use of plant growth-promoting rhizobacteria (PGPR) is an innovative and effective clean and green approach in the elimination of heavy metals and the mitigation of their negative effects. PGPR are naturally occurring soil bacteria that colonize plant roots. They benefit plants by a wide variety of mechanisms like nutrient solubilization, nitrogen fixation, siderophore synthesis, phytohormone production, induction of systemic resistance, exhibiting antimicrobial and insecticidal activities, etc. The application of PGPR is steadily increased as it may offer new hope in sustainable agriculture, and it is an attractive way to replace chemical fertilizers. This chapter reviews the scientific literature related to current studies about PGPR and their biofertilization, biostimulation, biocontrol, and bioremediation potentialities with special emphasis on heavy metal bioremediation trait.