A bioreactor that combines the steps of recombinant expression and separation of a biological product by binding the secreted biological product with a resin, discarding the nutrient medium and eluting the biological product as a concentrated solution, eliminating the steps of sterile filtration and volume reduction. The method also allows loading of resin for column-purification, eliminating all steps of perfusion process and maintaining a sink condition of a toxic product in nutrient medium to optimize productivity of host cells. The instant invention also allows harvesting of solubilized inclusion bodies after the cells have been lysed and refolding of proteins inside the bioreactor.