Polyhydroxyalkanoates as matrices for enzyme immobilization: In vivo and In vitro approaches

Since polyhydroxyalkanoates (PHAs) are biodegradable, bioresourced and biocompatible, they are versatile biopolymers having huge applicability in food packaging, biomedicine, drug delivery systems, production of biofuels and many other fields. With the use of waste carbon sources or renewable feedstocks, their process of production can be made cost effective. Moreover, just by exploiting PHA synthesis enzymes, they can also be produced in vivo i.e., without employing microbial cell. Thanks to this adaptable PHA nanogranular technology, it also has become possible to immobilize a huge variety of enzymes, creating a novel and promising set of immobilization techniques. In comparison to soluble enzymes, immobilized enzymes have a number of significant benefits, like increased stability, higher catalytic activity, extended shelf life, recycling for repeated use and easier purification of the product, however, showing some limitations (like improper orientation, substrate diffusion and enzyme deactivate etc) as well. Due to directed display and a high surface area to volume ratio, the PHA based enzyme immobilization platform offers flexibility, stability and excellent functionality. The nano or micro beads of PHA produced in vitro, act as matrix for enzyme immobilization being both economically appealing and potentially applicable in a variety of process circumstances. The developments in synthetic biology and material science to produce more effective, adaptable PHA-enzyme systems for industrial and environmental applications, are future prospects for enzyme immobilization on PHA. It is important to optimize enzyme-PHA interactions for enhanced efficiency and cost effective industry level production processes. This review highlights the importance and great utility of PHA for enzyme immobilization. It mainly focuses on the in vivo and in vitro enzyme immobilization studies done so far, using latest technologies to enhance the properties of immobilized enzymes.