# Cyanobacteria as Chassis for Industrial Biotechnology: Progress and Prospects
###### Abstract  
Cyanobacteria hold significant potential as industrial biotechnology (IB) platforms for the production of a wide variety of bio-products ranging from biofuels such as hydrogen, alcohols and isoprenoids, to high-value bioactive and recombinant proteins. Underpinning this technology, are the recent advances in cyanobacterial \"omics\" research, the development of improved genetic engineering tools for key species, and the emerging field of cyanobacterial synthetic biology. These approaches enabled the development of elaborate metabolic engineering programs aimed at creating designer strains tailored for different IB applications. In this review, we provide an overview of the current status of the fields of cyanobacterial omics and genetic engineering with specific focus on the current molecular tools and technologies that have been developed in the past five years. The paper concludes by giving insights on future commercial applications of cyanobacteria and highlights the challenges that need to be addressed in order to make cyanobacterial industrial biotechnology more feasible in the near future. cyanobacteria; biotechnology; biofuels; bio-products; genetic engineering +
Footnote †: journal: J. Neurol. 0000-0002-0001-8880][PERSON] 0000-0002-0002-3330][PERSON] 0000-0002-0002-3333][PERSON]. [PERSON] 0000-0002-0002-3333][PERSON]. [PERSON] 0000-0002-0002-3333][PERSON] 0000-0002-0003-0003-3333][PERSON] 0000-0002-0002-3333][PERSON]. by genetic manipulation, make cyanobacterial-produced fuel molecules excellent options as future fungible fuels [6]. In a recent study, the combustion and emissions of terpen in a diesel engine were examined with a view to their biological production in cyanobacteria [19]. The study highlighted the potential of genetically engineering the isoprenoid pathway of _Synechocystis_ 6803 for the production of isoprenoid-derived fuels that can act as drop-in fuels in diesel engines [19]. Additionally, cyanobacteria are being optimised to overproduce numerous products of value [20]. For example, naturally occurring cyanobacterial phycobiliproteins are commonly used in fluorescent tagging applications in research [21] in conjugation with monoclonal and polyclonal antibodies to make fluorescent antibody reagents that are used for cell sorting [22]. Other natural products are used as food dyes or pigments in cosmetics [23]. Some cyanobacterial strains are used as vectors for the delivery of mosquitocidal toxins [21], while nitrogen-fixing strains are commonly used as natural fertilisers [23]. Chemical products such as fish growth hormones [21], polyhydroxyalkanoates (PHA's) [22; 24] and polyunsaturated fatty acids (PUFA) [25] have been produced from genetically engineered cyanobacteria. _Synechococcus_ has been genetically engineered for the heterologous expression of a single gene (_efe_) from _Pseudomonas syringae_ that led to the successful synthesis of ethylene [8], one of the most important building blocks in synthetic chemical industry [26]. Furthermore, acetone was recently produced by modified _Synechocystis_ 6803 with a reported yield of 36.0 mg/L [27]. A summary of some of the various cyanobacterial products can be found in Figure 1, and [28]. Although synthetic biology tools have contributed significantly to unlocking cyanobacteria's potential for these functions, these tools are still far behind those established for _S. cerevisiae_ and _E. coli_[29]. Nevertheless, in recent years, there have been significant advances in cyanobacterial strain improvement using genetic engineering and synthetic biology [30]. It is worth mentioning that most of the efforts for developing genetic engineering tools have been aimed at model or heavily studied cyanobacterial strains such as the filamentous, nitrogen-fixing _Anabena_ sp. strain PCC 7120 [31; 32; 33], and the naturally competent _Synechococcus_ 7942 [34; 35; 36; 37], _Synechococcus_ 7002 [38; 39; 40; 41; 42; 43] and _Synechocystis_ 6803 [45; 46; 47; 48; 49; 50; 51; 52].