Microbiology of Salinispora tropica, Fermentation and Scale-up

The key to the initial success of yield improvement was the addition of solid resins to the production culture (step 1, Table 12.1). The inherent instability of the p-lactone ring of NPI-0052 in aqueous solution,36 such as in the submerged saline fermentation, was overcome by addition of solid resin to the fermentation in order to bind and capture NPI-0052. The addition of resin to the production culture led to an 18-fold increase in yield in a preliminary study (Table 12.1). Further investigation of the resin stabilisation effect on NPI-0052 using the production strain NPS21184 established the conditions for the large-scale resin addition process.37 

Media formulation studies (steps 3 and 5, Table 12.1) were successfully carried out to replace natural seawater and animal-derived media components 

Improvement step Improvement process Shake flask (mg/L) Fermenter ( mg/L) 

2 Optimisation of seed, production and resin addition cycles 120 120 

We successfully transferred the yield improvement conditions developed in shake flasks to lab fermenter as shown in Table 12.1. A NPI-0052 titre of 360mg/L was achieved in the 42L lab fermenter, which is lower than the maximum titre of 450 mg/L detected in shake flasks. The discrepancy in titres is due to the foaming problem that occurred in the fermenter (but not in shake flasks) when rich media containing high concentrations of starch and soy type products were used. Based on the potency of NPI-0052, a titre of 360 mg/L in fermenter scale is sufficient to support the clinical development of NPI-0052. 

---