Bioprocessing of corn rind using continuous multiphase-multistage bioreactor for downstream applications

Corn rind is a major agricultural residue which is often problematic for disposal. However, it is a rich lignocellulose source useful for many downstream industrial applications. The technique commonly used in the bioconversion of organic waste is a static two-stage fermentation system; in the first stage, corn rind is converted to simple sugars, and at the second stage, reduced sugars are used to produce commercial products. The stage one is a resource-consuming process as the product removal is not dynamic, and hence, the bioconversion process comes to an equilibrium due to product accumulation. Therefore, a novel concept of continuous multiphase-multistage bioreactor was introduced, in which the sugars formed are continuously removed to enhance the bioconversion efficiency. A lab-scale model with three digestion modules, each with 2000-ml working capacity, is developed for degradation of corn rind to partially optimize the process parameters that eventually improve corn rind degradation. The multiphase in each stage contributes cumulatively in achieving better degradation of corn rind. In the first stage, out of 150-g feed-stock introduced, a total of 2353 mg of free reducing sugar was released on completion of five phases (1st phase; 431 mg, 2nd phase; 690 mg, 3rd phase; 523 mg, 4th phase; 374 mg, 5th phase; 335 mg) which accounts for 44% of the yield potential. The lab-scale prototype showed promising trend of progressive degradation of corn rind that requires further process optimization to achieve maximum productivity. The reducing sugars thus obtained could be used for subsequent bioconversion processes by using suitable microorganisms.