4. Conclusion
Statistical nutrient optimization was implemented to enhance
c-PGA productivity by a newly isolated B. amyloliquefaciens LL3.
The orthogonal design showed sucrose was the most significantly
variable affecting c-PGA productivity. A 200 L fermentation provided
well-balanced changes in processing parameters and a relative
high c-PGA yield of 4.36 g/L. This study described for the
first time the cloning and expression of pgsBCA genes from glutamic
acid independent strain LL3, which produce 0.70 g/L cPGA
without glutamate. At present, much more statistical approaches
and genetically regulatory elements are being examined
to maximize the yields and to elucidate the mechanisms of c-PGA
synthesis.