Biochemical processes of rhizobacteria and their application in biotechnology

Abstract

The rhizosphere is a multiple interface between soils, plant roots, microbes and fauna, where different biological components interact strongly. Rhizosphere interactions are based on complex exchanges that take place around plant roots. Beneficial, detrimental and neutral relationships between plant roots and microorganisms are all regulated by complex molecular signalling. Plants exude a variety of organic compounds (e.g. carbohydrates, carboxylic acids, phenolics, amino acids, flavonoids) as well as inorganic ions (protons and other ions) into the rhizosphere which change the chemistry and biology of the root microenvironment. All chemical compounds secreted by plants are collectively named rhizodepositions. In the rhizosphere, bacteria that exert beneficial effects on plant development are referred to as plant growth-promoting rhizobacteria (PGPR) because their application is often associated with increased rates of plant growth. On the other hand, although many technologies have been used in the improvement of stress tolerance in plants, fewer reports have been published on how PGPR can exert tolerance to salt, drought or heavy metals. In addition, the industrial use and technological application of compounds from plants and rhizobacteria are required to be successful in attaining sustainable microbial-based agrotechnologies. Among crops, legumes are a good source of starch, dietary fibre, protein and minerals. It has long been recognized that legumes are functional foods that promote good health and have therapeutic properties. This chapter shows the significance of some biochemical and biological compounds derived from legumes and rhizobacteria with potential in biotechnology.