Improving polyhydroxyalkanoate production from inexpensive carbon sources by genetic approaches: a review

Abstract

Polyhydroxyalkanoates (PHAs) are a family of biodegradable intracellular polyesters that a number of Eubacteria and Archaea can accumulate for energy and carbon storage. Most of the genetic modifications to the producing bacterial species have been accomplished to clarify basic biochemical, genetic, and metabolic aspects of PHA metabolism. However, due to its plastic‐like properties and complete biodegradability, this bio‐based polymer has attracted the attention of a variety of manufacturers. A number of genetic approaches have therefore been reported, aimed at improving the performance of the microorganisms with a potential for use in a production process. Indeed, genetic tools may find useful applications in all the phases of the PHA production chain, from the isolation and characterization of new microbial strains through all the production steps until they reach the downstream processes. The substrates generally used for PHA production are expensive, so the search for low‐cost feedstock is necessary. These materials, possibly deriving from agri‐food processes, are unfortunately not easily degraded or converted directly into PHAs. Thus, the development of engineered microbes is in progress to process waste streams and covert them to valuable polymers. This review will summarize the most relevant results obtained through genetic engineering tools for the production of PHAs from cheap carbon sources in view of possible industrial applications. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

Novel Yeast Strains for the Efficient Saccharification and Fermentation of Starchy By-Products to Bioethanol

“…Before being processed to any added-valued compounds, solid waste streams have to be carefully managed through the promotion of safe practices and effective technologies, such as source separation, biological treatment and supply chain development to ensure the overall economic feasibility of the process. A wide variety of waste organic materials, like residues from agricultural, forest and industrial processing as well as the organic fraction of municipal solid waste, actually contains considerable amounts of fermentable glucose, as monomers or polymers (i.e., starch, cellulose), that have been used for biofuels, biopolymers and enzymes production [14][15][16][17][18][19][20].…”

What Has Been Trending in the Research of Polyhydroxyalkanoates? A Systematic Review

“…In publications making up this trend, various E. coli strain modifications are examined to improve and optimize both the fermentation process and the final product itself. In the majority of the studies, stress is put on the modification of bacteria for processing cheap and readily available carbon sources such as substrates deriving from biomass (Nikel et al, 2006;Park et al, 2012;Yang et al, 2014;Favaro et al, 2019). The first reports of E. coli targeted recombination date back to 1999 when the first attempt of modification of metabolic network on PHB biosynthesis in recombinant E. coli was performed.…”

Switching from petro-plastics to microbial polyhydroxyalkanoates (PHA): the biotechnological escape route of choice out of the plastic predicament?

“…From the economic point of view, the development of engineered microbes able to convert inexpensive substrates (waste streams) into PHA is of particular significance (75). As a matter of fact, many natural microorganisms can synthesize PHAs with wide-ranging monomeric composition, which impacts the material properties of PHA.…”