Charakterisierung und biologische Evaluierung eines klebtechnisch hergestellten RAMOS-Kolbens

Abstract:
The RAMOS device enables an online monitoring of oxygen transfer rate, of carbon dioxide transfer rate and of respiratory quotient in shaken bioreactors. Thus, very useful information can already be achieved during first steps of screening. But the previously used RAMOS flask made by melting shows a bad geometric reproducibility, a high need for material. Aside from this, an industrial serial production is not possible. Therefore, a new flask was developed that is manufactured by an autoclavable glass bonding technique. A volume reduction of 18 % leads to a shortening of the length of rinsing and measuring phases. Now the measuring phase takes only 8 minutes and the rinsing phase 17 minutes. So 5 minutes can be saved every measuring interval which means a total reduction of 20 %. Unfortunately, the aim of an improved reproducibilty regarding to its capacity could not be achieved. The deviation of medial flask volume exceeds with 7.8 % its production tolerance of 5 %. Nonetheless, it was managed to manufacture the structural elements of the flask in a reproducible manner. The imperviousness of connection was tested successfully, so that the flask meets the requirements of sterility and needs of the OTR measurement. In addition to that, the oxygen transfer capacity of the bonded flask is similar to that one of the melted flask. Comparative cultivations of Escherichia coli K 12, of Corynebacterium glutamicum DM 1730 and of Hansenula polymorpha wt were carried out in both types of RAMOS flasks for biological evaluation. The measurements in bonded flasks were performed with adjusted aeration rates (measuring phase = 8 min, rinsing phase = 17 min, high-flow = 1,3 min). Because same results were achieved in both flasks, the bonded ones are suitable for OTR measurements in the RAMOS device. The bonded flask is comparable with the melted flask regarding its efficiency and has the advantage of a shorter measuring interval. Therefore, the new bonded flask can replace the former melted one.

Keywords:
autoclavable glass adhesion technique, RAMOS flask, Escherichia coli K12, Corynebacterium glutamicum DM 1730, Hansenula polymorpha wt