**4. Potential of cyanobacterial secondary metabolites in industrial biotechnology**

Sustainability in industry is increasingly important due to global warming and the depletion of fossil fuels. A considerable amount of research has been conducted to find new sources of industrially important compounds to reduce the carbon footprint and increase sustainability.

Cyanobacteria has received much interest in becoming a promising alternative due to their diversity, simple growth needs and simple genetic background, which are easily manipulated to form cell factories [34].

Some strains of cyanobacteria are already being used in industry, examples include the edible *Arthrospira* (*Spirulina*) and *Nostoc*, which have been used as a food source for thousands of years [35].

*Spirulina* has been well researched for its application within industry. It is used as a health food due to its extensive source of proteins, polyunsaturated fatty acids (γ-linoleic acid, GLA), antioxidants (phycocyanin and carotenoids) and vitamins [36].

A challenge remains in assessing and understanding the ability of cyanobacteria to produce target metabolites in sufficient quantities to be of use under standard and repeatable conditions. This will be easier moving into the future as 'omic' studies enable improved understanding on metabolite pathways using a whole systems approach.

#### **4.1. Pharmaceuticals and cosmetics**

apparatus. One mechanism is the non-photochemical quenching (NPQ) of excitation energy *via* photosystem II using the carotenoid zeaxanthin. They also produce enzymatic antioxidants such as; superoxide dismutases (SOD), catalases and peroxidases) as well as nonenzymatic antioxidants such as; carotenoids, phycobiliproteins, tocopherols and ascorbic

**MAA Molecular structure λmax (nm), ε** 

30 Secondary Metabolites - Sources and Applications

Mycosporine-glycine 310, 28,800 *Nostoc commune*

Shinorine 334, 44,668 *Anabaena* sp.

Asterina-330 330, 43,800 *Gloeocapsa* sp.

Porphyra-334 334, 42,300 *Nodularina baltica*

**(l·mol−1·cm−1)**

**Species of cyanobacteria**

Carotenoids absorbs light in the region of 400–500 nm and have several roles including sunscreening, singlet oxygen quenching, releasing excessive light as heat through the xantho-

Another group of antioxidants are the phycobiliproteins (PBP). These are present only in cyanobacteria and are primarily used as major light harvesting antennae but also have antioxidant

acid [31].

phyll cycle and radical scavenging [30].

**Table 3.** Example of MAAs [27, 28].

Natural products have been used to treat disease for thousands of years and are a useful source of bioactive compounds used in the pharmaceutical industry as leading compounds in drug discovery. They can be used as templates for synthesis of new drugs to treat complex diseases. Cyanobacteria have been widely researched for their applications in this field. They have found to possess a wide range of potential antimicrobial, anticancer, antiviral and antiinflammatory activities [37]. Some known bioactives are listed below (**Table 4**) [11].

Chemotherapies currently used in the treatment of cancer cause serious side effects; naturally derived alternatives give opportunities for synthesising new highly potent drugs with fewer side effects [15, 42]. Cytotoxic metabolites produced by cyanobacteria usually target tubulin or actin filaments in eukaryotic cells, which make them promising anticancer agents. Dolastatins found within *Leptolyngbya* and *Simploca* sp. are synthesised by NRPS-PKS enzymes and are able to disrupt microtubule formation. Other cyanobacterial metabolites act as proteases inhibitors such as the lyngbyastatins, which are cyclic depsipeptide derivatives, which are


there is still a large selection of species, which have yet to be sequenced and investigated with

Secondary Metabolites in Cyanobacteria http://dx.doi.org/10.5772/intechopen.75648 33

With thanks to Swansea University and the Department of Biosciences. Funding from the

[1] Lau N-S, Matsui M, Abdullah AA. Cyanobacteria: Photoautotrophic microbial factories for the sustainable synthesis of industrial products. BioMed Research International.

[2] Gupta V, Ratha SK, Sood A, Chaudhary V, Prasanna R. New insights into the biodiversity and applications of cyanobacteria (blue-green algae)-prospects and challenges.

[3] Meireles dos Santos A, Vieira KR, Basso Sartori R, Meireles dos Santos A, Queiroz MI, Queiroz Zepka L, et al. Heterotrophic cultivation of cyanobacteria: Study of effect of exogenous sources of organic carbon, absolute amount of nutrients, and stirring speed on biomass and lipid productivity. Frontiers in Bioengineering and Biotechnology.

[4] Singh SP, Montgomery BL. Determining cell shape: Adaptive regulation of cyanobacterial cellular differentiation and morphology. Trends in Microbiology. 2011;**19**:278-285.

[5] Stanier RY, Deruelles J, Rippka R, Herdman M, Waterbury JB. Generic assignments, strain histories and properties of pure cultures of cyanobacteria. Microbiology. 1979;**111**:1-61.

many potentially important secondary metabolites yet to be discovered.

UK-Biological Sciences Research Council (BBSRC).

Bethan Kultschar and Carole Llewellyn\*

2015;**2015**. DOI: 10.1155/2015/754934

2017;**5**:1-7. DOI: 10.3389/fbioe.2017.00012

DOI: 10.1016/j.tim.2011.03.001

DOI: 10.1099/00221287-111-1-1

\*Address all correspondence to: c.a.llewellyn@swansea.ac.uk

Department of Biosciences, Swansea University, Swansea, Wales, UK

Algal Research. 2013;**2**:79-97. DOI: 10.1016/j.algal.2013.01.006

**Acknowledgements**

**Conflict of interest**

No conflict of interest.

**Author details**

**References**

**Table 4.** Potential applications of cyanobacterial natural products in pharmaceutical and cosmetics industry.

thought to be elastase inhibitors. Apratoxins such as Apratoxin-a from *Lyngbya majuscule* is another metabolites biosynthesized from a hybrid NRPS-PKS pathway. It is cytotoxic due its ability to induce G1-phase cell cycle arrest and apoptosis [42].

Antibacterial metabolites produced by cyanobacteria are effective against gram negative and gram positive bacteria. In the age of antibacterial resistance, new drugs are essential to combat bacterial infections. The hapalindole-type class of indole alkaloids has been found to possess antimicrobial (bacteria, fungi) and antialgal activity [16].

Secondary metabolites can be used as natural ingredients in the cosmetics industry. Uses include the photoprotective MAAs in sunscreens to protect the skin from harmful UVR. Pigments such as carotenoids and phycobiliproteins could be used as natural colourants but also as antioxidants to protect the skin from damage caused by UV exposure [11].

Other potential uses for cyanobacterial secondary metabolites include their use in the nutraceutical and agricultural industry [11, 43].
