An Overview of Recent Advancements in Microbial Polyhydroxyalkanoates (PHA) Production from Dark Fermentation Acidogenic Effluents: A Path to an Integrated Bio-Refinery

Abstract

Global energy consumption has been increasing in tandem with economic growth motivating researchers to focus on renewable energy sources. Dark fermentative hydrogen synthesis utilizing various biomass resources is a promising, less costly, and less energy-intensive bioprocess relative to other biohydrogen production routes. The generated acidogenic dark fermentative effluent [e.g., volatile fatty acids (VFAs)] has potential as a reliable and sustainable carbon substrate for polyhydroxyalkanoate (PHA) synthesis. PHA, an important alternative to petrochemical based polymers has attracted interest recently, owing to its biodegradability and biocompatibility. This review illustrates methods for the conversion of acidogenic effluents (VFAs), such as acetate, butyrate, propionate, lactate, valerate, and mixtures of VFAs, into the value-added compound PHA. In addition, the review provides a comprehensive update on research progress of VFAs to PHA conversion and related enhancement techniques including optimization of operational parameters, fermentation strategies, and genetic engineering approaches. Finally, potential bottlenecks and future directions for the conversion of VFAs to PHA are outlined. This review offers insights to researchers on an integrated biorefinery route for sustainable and cost-effective bioplastics production.

Sustainable value methodology to compare the performance of conversion technologies for the production of electricity and heat, energy vectors and biofuels from waste biomass

“…This is the case of dark fermentation for hydrogen production and the possibility to valorise all the generated streams besides the gas, e.g. the liquid fraction that is rich in volatile fatty acids for the production of polyhydroxyalkanoates (Saratale et al, 2021). Another example is the co-recovery of the biochar fraction from thermochemical decomposition of waste biomass, for use in the production of biocomposites or for soil amendment (Bartoli et al, 2022;Paneque et al, 2019).…”

Application of Immersed Membrane Bioreactor for Semi-Continuous Production of Polyhydroxyalkanoates from Organic Waste-Based Volatile Fatty Acids

“…Additionally, recalcitrant and inhibitory materials could be released during the pretreatment processes, which potentially pose a number of negative impacts on PHA production [ 5 ]. In this regard, acidogenic fermentation is a promising approach to handling complex organic waste, producing fermentable compounds such as volatile fatty acids (VFAs) for the cultivation of PHA-bearing microorganisms [ 6 , 7 , 8 ].…”

“…VFAs have been known as important intermediates in anaerobic digestion for the production of biogas. However, due to the low profit of biogas, attention has been focused on VFAs, which can be used as precursors for further production of high-value biomaterials [ 6 , 8 , 9 , 10 ]. Recently, VFAs have emerged as economical feedstock for the production of PHAs [ 11 ].…”

Unveiling Polyhydroxyalkanoates Producing Bacteria Isolated from Mangalore Environment: An Unearthing Study

“…As the demand for petroleum-based polymer substitutes rises, attention is shifting towards bio-based alternatives as a potential solution for balancing environmental and industrial needs. (Saratale et al 2021;Thirumala et al 2022;Miu et al 2022). Polyhydroxybutyrate (PHB), one among PHA family is regarded as a major biodegradable polymer and the best alternative to synthetic plastics.…”