AN OPTIMIZED ULTRASONICATION PROTOCOL FOR BACTERIAL-CELL DISRUPTION AND RECOVERY OF BETA-GALACTOSIDASE FUSION PROTEINS

In this work, we have developed and optimized an ultrasonication proto col for Escherichia coli recombinant cells, adapted to laboratory-scal e release of beta-galactosidase fusion proteins. After a single sonica tion treatment of 15 minutes, about 30% of recombinant protein present in the sample remains still associated to cellular debris, and it can not be removed by increasing the sonication time. After a clarificati on step a second sonication treatment of the resuspended cell debris a gain releases only a 70% of the remaining product. Therefore, the appl ication of two short, consecutive sonication treatments permits a glob al recovery yield of about 90%. The use of a new disruption buffer to stabilize beta-galactosidase allows the fusion proteins to maintain th e active form throughout the process.