New insights into the biodiversity and applications of cyanobacteria (blue-green algae)-Prospects and challenges

Cyanobacteria (blue-green algae) are Gram-negative oxygenic photosynthetic prokaryotes with a long evolutionary history. They have potential applications in diverse areas, especially in agriculture, as nutrient supplements in agriculture and industry (as biofertilizer, plant growth promoting rhizobacteria and as biocontrol agents). Their role as food supplements/nutraceuticals and in bioremediation and wastewater treatment is an emerging area of interest. In addition, they are known to produce wide array of bioactive compounds (secondary metabolites) with diverse biological activities - including antiviral, antibacterial, antifungal, antimalarial, antitumoral and anti-inflammatory properties, having therapeutic, industrial and agricultural significance. One of the major problems has been regarding their classification being incongruent with the phylogeny, because the phenotype of cyanobacterial strains is known to be altered under different environmental/nutritional conditions. However, because of their simple growth needs, they are the favourite model organisms for deeper understanding of several metabolic processes and for the production of recombinant compounds of medicinal and commercial value. In recent years, cyanobacteria have gained interest for producing third generation biofuels (both biomass and H-2 production). With the recent advances in metabolic engineering techniques and availability of genome sequences, novel approaches are being explored for realising the potential of cyanobacteria. Our review provides an overview of the polyphasic approaches used in the analyses of cyanobacterial biodiversity and the potential of these organisms in providing viable solutions to global problems of food, energy and environmental degradation, which need further impetus through adoption of multidisciplinary collaborative programs. (C) 2013 Elsevier B.V. All rights reserved.