Table 1.

Comparison of four PGA synthesis methods.

Synthesis Methods	Purity	Productive	Cost	Pollution	Applications
Chemical synthesis	Low	Low	High	High	Occasionally laboratory study
Enzyme conversion	High	High	High	Low	Soil, plant regulators, etc.
Extraction	Low	Low	Low	Low	Early production methods of γ-PGA
Microbial fermentation	High	Relatively high	Relatively low	Low	Commonly used for large-scale production of γ-PGA and applied in cosmetics, food, pharmaceuticals, water treatment, and other fields