Microbial production of α-amylase from agro-waste: An approach towards biorefinery and bio-economy

Economic utilization of waste in the generation of value-added products is the primary prerequisite of a circular economy. Agro-waste is one waste that is enormous on one hand and is rich in nutrients and bioproducts on the other hand. Microbial fermentation is an easy technology that can work following the nature of the waste substrate. Development of such a process is very much possible however it faces the initial challenge of diversity in substrates, microorganisms, enzymes, and bioproducts. It would be thus ideal to make an axis of one waste to one value-added product and then optimize around this axis. Here we explore the potential of a widely industrially used enzyme α-amylase as one terminal of the axis. The other axis would be starch-rich agro-waste like cereal waste. The connection between these two axis terminals would be an α-amylase producing microorganism. A lot of products e.g. nutraceuticals, biofuels, other enzymes, fertilizers, nanoparticles, etc. are possible around this axis. This review explores the suitability of α-amylase to serve as such an axis. We discuss the agro-waste that has the potential for α-amylase production, the industrial applicability of α-amylase, microorganisms known and bioengineered to produce α-amylase, and the optimization of this production process.