Industrial Production of Poly-β-hydroxybutyrate from CO2: Can Cyanobacteria Meet this Challenge?

Abstract

The increasing impact of plastic materials on the environment is a growing global concern. In regards to this circumstance, it is a major challenge to find new sources for the production of bioplastics. Poly-β-hydroxybutyrate (PHB) is characterized by interesting features that draw attention for research and commercial ventures. Indeed, PHB is eco-friendly, biodegradable, and biocompatible. Bacterial fermentation processes are a known route to produce PHB. However, the production of PHB through the chemoheterotrophic bacterial system is very expensive due to the high costs of the carbon source for the growth of the organism. On the contrary, the production of PHB through the photoautotrophic cyanobacterium system is considered an attractive alternative for a low-cost PHB production because of the inexpensive feedstock (CO2 and light). This paper regards the evaluation of four independent strategies to improve the PHB production by cyanobacteria: (i) the design of the medium; (ii) the genetic engineering to improve the PHB accumulation; (iii) the development of robust models as a tool to identify the bottleneck(s) of the PHB production to maximize the production; and (iv) the continuous operation mode in a photobioreactor for PHB production. The synergic effect of these strategies could address the design of the optimal PHB production process by cyanobacteria. A further limitation for the commercial production of PHB via the biotechnological route are the high costs related to the recovery of PHB granules. Therefore, a further challenge is to select a low-cost and environmentally friendly process to recover PHB from cyanobacteria.

Microbial Production of Biodegradable Lactate-Based Polymers and Oligomeric Building Blocks From Renewable and Waste Resources

“…Currently, more than 150 different 3-, 4-, 5-, and 6-hydroxy fatty acid monomer constituents ( Figure 1 ) containing straight, branched, saturated, unsaturated, and aromatic structures ( R -side chain) in PHA have been documented in more than 90 genera of microbial species ( Anjum et al, 2016 ; Meng and Chen, 2018 ; Raza et al, 2018 ). Based on carbon chain length of the monomeric unit ( R ), PHAs have been classified into three classes ( Carpine et al, 2020 );…”

Industrial Applications of Cyanobacteria

“…Although the potential for biopolymer production from cyanobacteria exists, commercialization on an industrial scale is yet to be achieved. Research is currently geared towards optimization of cultivation and genetic modification approaches for enhanced biopolymer production [23,30,31].…”

Microalgae as Contributors to Produce Biopolymers

“…Thanks to the properties of PHAs, researchers and manufacturers intend to utilize these species of biopolymers in packaging, printing inks, coatings, laminations, waxes, binders, and adhesives [ 27 ]. Thus, and considering, for example, the high biocompatibility and sustainability associated with P(3HB), the number of companies producing these biopolymers is not surprising, namely the P(3HB) Industrial (Serrana, Brazil), Tianan (Ningbo, China), CJ CheilJedang (Dongho-ro, Korea)), Kaneka (Minato, Japan), and Biomer (Schwalbach am Taunus, Germany) [ 29 ]. The copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)), is known to be more flexible than P(3HB) [ 22 ] and, therefore, is much more interesting from the commercial point of view.…”

“…Companies in the PHA bioplastic business are widespread in North America, Europe, and Asia-Pacific. Companies such as CJ CheilJedang (Dongho-ro, Korea)., Ecomann Biotechnology Co. Ltd. (Shenzhen, China), Tianjin GreenBio Materials Co. Ltd. (Tianjin, China), Danimer Scientific (Bainbridge, USA), Mango Materials (Albany, USA), Newlight (Huntington Beach, USA), and Biomer (Schwalbach am Taunus, Germany) are considered the main PHA producers [ 29 ]. Industrially, PHAs are usually produced in large fermenters by heterotrophic bacteria fed with large amounts of organic carbon sources, which corresponds to 50% of the total production costs [ 22 ].…”