Industrial properties of SCFA-producers in herbivorous vertebrate targeted toward optimized PHA biosynthesis for sustainable bioplastic production: a review

Recently, significant attention has shifted to the overall benefits of short-chain fatty acids (SCFAs), which are released from anaerobic digestion of dietary fibers by the gut microflora, on human health. Interestingly, an alternate SCFA metabolic route has been implicated in the production of polyhydroxyalkanoates (PHAs) in some microorganisms with high storage capacities. PHAs are a new component of the bioplastic industry and present nontoxic biodegradable polymers with a thermoplastic nature. They are gradually becoming suitable replacements for their recalcitrant conventional counterparts obtained from fossil fuels, which are currently accumulating in alarming quantities both on land and in the ocean, thereby representing a serious global threat. The fermentation of dietary fibers by rumen microorganisms generates organic acid streams of acetic, butyric and propionic acids that can subsequently be routed through the central metabolite ‘pyruvate’ into other intermediates that are then polymerized via the microbial phaABC operon into PHA polymers with diverse mechanical properties. Thus, this review seeks to provide insight into the industrial properties of the abundant SCFA producers that reside in the gut of herbivorous vertebrates as important factors crucial in optimizing their PHA production potential. This will foster the development of cheaper and safer bioplastic production and ultimately promote sustainable development goals, especially those related to industry, innovation and infrastructure, affordable clean energy, and responsible consumption and production.