**6. Capability of microorganisms to formulate phosphate-related nanoparticles**

Nanotechnology is a state-of-the-art technique of using particles between 1 to 100 nm, which originated as both organic and inorganic forms [67–69]. Nano minerals are currently used as plant fertilisers due to their Nano size, high surface area, and higher solubility in different solvents and penetrative capacity than conventional mineral fertilisers. Reduction of the particle size is directed to an increment of the surface area of particle and the number of particles per unit in fertiliser, which facilitate higher nutrient utilising efficacy. Nanoparticles enter into plants through nano and microscale openings, which are most commonly available in roots and leaves [70, 71]. Generally, root tips, rhizodermis, lateral root junctions and wounding of roots are the entering pathways to nanoparticles. Enhanced bioavailability of nano fertilisers than conventional fertilisers cause to prevent loss of nutrients from leaching, denitrification, volatilisation, and fixation in the soil to confirm the sustainable utilisation of minerals [70].

Microorganisms including bacteria, fungi, actinobacteria and viruses have the ability to synthesise phosphorus-related nanoparticles with well-defined chemical composition, morphology and size either intra-or extracellularly [71–73]. But no in-depth study or work has been done so far [74]. Enzymes [75, 76] such as phytase, phosphatases [75], extracellular polymeric substances (EPS) [76] and proteins [75] are the key potential materials to synthesise phosphorus-related nanoparticles which are produced by microorganisms. In addition, proteins act as capping agents to stabilise the produced nanoparticles [75]. This is a new arising area in nano formulations [74]. Therefore, limited research has been conducted on synthesising phosphorusrelated nanoparticles by using microorganisms, as mentioned in **Table 3**.


**Table 3.**

*Microbial synthesis of phosphorus-related nanoparticles.*
