Advances in Microbiology, 2016, 6, 391-397 Published Online April 2016 in SciRes. http://www.scirp.org/journal/aim http://dx.doi.org/10.4236/aim.2016.65038 How to cite this paper: Gemma, S., Molteni, M. and Rossetti, C. (2016) Lipopolysaccharides in Cyanobacteria: A Brief Over- view. Advances in Microbiology, 6, 391-397. http://dx.doi.org/10.4236/aim.2016.65038 Lipopolysaccharides in Cyanobacteria: A Brief Overview Sabrina Gemma, Monica Molteni, Carlo Rossetti Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell’Insubria, Varese, Italy Received 24 February 2016; accepted 26 April 2016; published 29 April 2016 Copyright © 2016 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Cyanobacteria are an interesting group of photosynthetic prokaryotes with a great potential in drug discovery and scientific research. Due to their high degree of diversification, they have been able to adapt to almost all ecological niches. Similarly to Gram-negative bacteria, cyanobacterial cell wall contains Lipopolysaccharides (LPSs) in the outer membrane layer. LPSs are molecules that possess the ability to elicit an innate immune response via Toll-like receptor 4 (TLR-4) acti- vation. Cyanobacterial LPSs have been studied to a minor extent compared to Gram-negative bac- terial LPSs. However, available data revealed important differences between the LPSs of these two groups of organisms, both in term of structure and biological activity. This review summarizes the current knowledge about cyanobacterial LPSs, highlighting their peculiarity and their potentiality compared to more characterized bacterial LPSs. Keywords Cyanobacteria, Lipopolysaccharide (LPS), Lipid A 1. Introduction Cyanobacteria are among the oldest and most successful living organisms on earth. They are a highly diversified group of photosynthetic prokaryotes and can adapt to almost all ecological niches. They can be found in terre- strial, aerial, glaciers and aquatic environments, including extreme habitats like saline, hot springs and deserts [1]-[3]. Cyanobacteria are a huge source of bioactive compounds that can find applications in different markets including food, nutraceutical, pharmaceutical and cosmetic ones. Several cyanobacterial molecules have shown to possess pharmacologically interesting activities, like antiviral, antibacterial, antifungal, antimalarial, antitu- mor, immunosuppressant and many others [1]. Hence, cyanobacteria represent a great opportunity for drug dis- covery and scientific research. On the other hand, cyanobacterial metabolites include also toxins potentially