Cyclodextrin-glucosyl-transferase (CGTase) is amongst the most important enzymes used in CD biosynthesis. However, the bioproduction of CDs still faces challenges in terms of optimization and process complexity. This study proposes a novel CD bioproduction system in a batch mode to increase yield and reduce costs. Two bacterial strains were selected: the alkalophilic Bacillus pseudofirmus DSM2517 strain and the neutrophilic Paenibacillus macerans DSM1574 strain. Three different culture media, two temperatures (30 °C and 37 °C), and three scales (shake flasks 20 mL and 100 mL, and bioreactor 3.2 L) were evaluated with respect to bacterial growth kinetics, protein production, and CGTase biosynthesis and activity for β-CD production. Bacterial growth was monitored by measuring optical density (OD600 nm), while CGTase activity was assessed by measuring β-CD production directly in the medium after filtration or in samples after concentration (using a Vivaspin 500® ultrafiltration spin column with a 10 kDa cut-off). β-CD quantification was performed using the phenolphthalein colorimetric method and HPLC. The best conditions for combined growth and protein production, for both microorganisms, in shake flasks were achieved with a medium containing 2% dextrin as the carbohydrate source. Scale-up to the bioreactor displayed improved growth kinetics for both bacteria and higher protein production and CGTase activity for Paenibacillus macerans.
Guedes, A.M.; Santos Alves, T.F.; Salústio, P.J.; Cabral-Marques, H.M.; Ribeiro, M.H.L. Design of a Cyclodextrin Bioproduction Process Using Bacillus pseudofirmus and Paenibacillus macerans. Future Pharmacol. 2023, 3, 568-584. https://doi.org/10.3390/futurepharmacol3030035