Investigating factors affecting the diversity and production of ‎secondary‏ ‏metabolites from mysterious genes of rhizosphere microbes

Plants with special compounds in their root exudates can strengthen a specific microbial community in the rhizosphere and prevent harmful microbial community from forming. The rhizosphere is a dynamic region around the plant root that is governed by the interaction between the plant and microorganisms. Plant root secretions can be influenced by plant species, plant growth stages and stress conditions and can be different; therefore, each microbial strain can regulate the expression of its genes at each stage of plant growth. Microbes are an unknown and huge source of secondary metabolites that play a very important role in the field of medicine and other industries. The present review focuses on factors inducing the production of new secondary metabolites from rhizosphere microbes. Each microbial strain has the potential to produce several compounds, but considering that the production of secondary metabolites is very costly for the cell, their synthesis is highly controlled by the cell. Studies have shown that changing the growth conditions of microbes, such as: temperature, salinity, co-cultivation (bacteria-bacteria, fungi-fungi, bacteria-fungi), change in oxygen concentration, aeration speed, addition of soil elements and rare metal ions, light radiation and also genetic engineering methods such as: insertion of strong inducible promoters, ribosome engineering, chromatin rearrangement, overexpression of pathway-specific regulatory genes and small molecules and chemical stimuli can help to discover new compounds. In this study, the above cases are explained in detail.