DEVELOPMENT OF A NEW METHOD WHICH ALLOWS AVAILABILITY OF OXYGEN TO THE CELL MICROENVIRONMENT IN A BIOREACTOR. THIS AVOIDS GAS BUBBLING AND HIGH STIRRER SHEAR STRESSES WHICH ARE UNSUITABLE FOR MANY MODES OF IMMOBILIZATION. IT ALSO WILL IMPROVE OXYGEN SUPPLY TO IMMOBILIZED CELLS, WHOSE PRODUCTIVITY DEPENDS ON OXYGEN AVAILABILITY.
Microenvironmental factors are of major importance for reaction kinetics and productivity of immobilized biocatalysts. However, only little is known about the structure of the microenvironment and its controlled change to improve biocatalytic process. Thus, microenvironmental effects of oxygen were investigated, a definite factor of basic and industrial relevance. A defined microenvironment was created around microorganisms with regard to oxygen. The possiblity of oxygen supply to living cells by coimmobilization of the cells with catalase and addition of hydrogen peroxide as an oxygen donor was also examined. 2 examples were chosen: production of bacitracin by Bacillus licheniformis and formation of ergot alkaloids by Claviceps purpurea. The work involved detailed investigation of the constituents of the 2 complex systems and tests in different reactors in which the 2 biocatalysts were kept in the coimmobilized state. The microbial production of bacitracin and ergot alkaloids depended on oxygen available in the microenvironment of the screening organisms. The concept of influencing the microenvironment was found to be considerably affected by multiple interactions between microorganisms, enzymes, substrates and products. Complementarity of the biocatalysts was achieved and the feasibility of supply oxygen to microorganisms via hydrogen peroxide and catalase was demonstrated. However, the following limitations were found: operational instability of catalase and toxicity of peroxide in some of the configurations tested.
CREATION AROUND A MICROORGANISM OF A DEFINED MICROENVIRONMENT WITH REGARDS TO OXYGEN BY COIMMOBILISATION WITH A CATALASE IN ORDER TO ALLOW CONTROLLED ADDITION OF HYDROGEN PEROXIDE AS OXYGEN DONOR .
TWO SYSTEMS WILL BE INVESTIGATED :
1- PRODUCTION OF ALCALOIDS BY CLAVICEPS PURPUREA.
2- PRODUCTION OF BACITRACINE BY BACILLUS SP.
Funding SchemeCSC - Cost-sharing contracts