**7. Conclusions**

Optimisation of critical factors and nutrient sources is an essential step for metabolite, recombinant proteins before pilot fermentation. In this chapter, strategies, conventional, advanced process design are reviewed and detailed. DOE approaches with statistical evaluation are critical for process development are essential for saving experimentation time. The strategies and examples shared in this review have been analysed for ease of implementation, time consumption. The conditions and media designed needs to be further tested under realistic conditions, full scale process with replication to production setup.

Overall, this chapter detailed need of critical factors identification, their significant contribution in enhancing process of metabolite production. Also, recently, cofermentation of glycerol and glucose in engineered *E. coli* increased production of 1, 3 propanediol [1]. Similarly, O-acetylhomoserine production is increased by suitable designs for fermentation and modification of glycerol-Oxidative pathway [3]. Production of recombinant protein in one study response surface methodology was utilised for production of repletase and improved yield to 188 mg L1 of fermentation [15]. The approaches discussed in this chapter have several advantages for improving the yield and reduction of resource utilisation. These approaches are efficient for achieving the access for biotechnologically produced products to reach the larger population across the globe.

#### **Acknowledgements**

Puneet Kumar Gupta acknowledges financial support from Grace Lifetech Pvt. Ltd. for the study. Jyotheeswara Reddy Edula acknowledges support from the Tata Institute of Genomics and Society (TIGS).
