Butyric acid production with Clostridium tyrobutyricum immobilised to PVA gel

• Immobilisation of Clostridium tyrobutyricum to PVA gel.
• Remarkable stability of microorganism in repeated batches and continuous fermentations.
• Improvement of productivity of immobilised cell.
• Evaluation of entrapment and adsorption of biomass in/on PVA particles.

Clostridium tyrobutyricum was entrapped into lens-shaped polyvinyl alcohol particles (LentiKats®). Immobilised cells were propagated in series of repeated batches and reached average productivity of 1.74 g/L h and yield of 0.44 g/g during 31 repetitions with glucose as an initial substrate, which was 5 times higher productivity compared with a free cell system under the same conditions. Immobilised cells were successfully applied for more than 71 repeated batches and demonstrated remarkable process stability. Application of immobilised cells to a continuous system resulted in 5.8 times higher productivity compared with free cells, with 6.8 g/L of butyric acid and residual glucose of 5.8 g/L.

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