Valorization of waste foods using pullulan hydrolase from Thermococcus kodakarensis

Abstract

The starchy foods including staled or leftover bread, insect infested or damaged cereal grains and bakery wastes are usually discarded, which is a threat to public health due to extensive fungal growth. In the present study we have utilized them as raw materials for synthesis of maltose and glucose syrups using pullulan hydrolase from Thermococcus kodakarensis (TK-PUL). The novelty of the process was that whole process was completed: (i) in the absence of any liquefying amylase; (ii) without pre-gelatinization of starch; and (iii) using undisrupted E. coli cells, expressing TK-PUL gene, as a source of extremely thermostable TK-PUL protein. Since glucose and maltose can serve as precursors for a variety of biotechnological products, it is therefore anticipated that hydrolysis of starchy food wastes by TK-PUL would be highly beneficial. It will serve as cost effective measure not only to extract valuables from rubbish but also lower the level of environmental pollutants.