Engineering of plant growth-promoting bacteria for sustainable nutrient management and agricultural sustainability

Nitrogen (N), phosphorus (P), and potassium (K) are plant growth and development nutrients with key functions in the life cycle of plants. However, the levels of these nutrients in soil are often insufficient for plant uptake, so they must be supplemented using chemical fertilizers. Excessive use of these fertilizers has polluted the soil, air, and groundwater, which is a serious threat to the sustainability of agriculture. Plant growth-promoting bacteria (PGPB) facilitate plant growth by improving nitrogen fixation, as well as phosphorus and potassium solubilization. These bacteria have the potential to partially or even entirely replace chemical fertilizers, an achievement that could improve soil fertility, boost crop production, and ensure sustainable agriculture. Even though many PGPB strains can be used instead of chemical fertilizers, they have been shown to exhibit limited activity in N fixation and P or K solubilization when plants are grown in the field. Recent advances in gene editing technologies now provide new avenues for enhancing these abilities in PGPB toward more efficient and consistent biofertilizer production. This review discusses the mechanisms whereby asymbiotic nitrogen-fixing bacteria (ANFB) as well as phosphorus- and potassium-solubilizing bacteria (PSB and KSB) enhance plant growth, and it outlines the recent advances in gene editing efforts for improving microbial function. We suggest creating a synthetic community (SynCom) comprised of genetically modified bacteria to enhance the PGP effects of engineered bacteria and promote efficient nutrient utilization.