Trends in biological degradation of cyanobacteria and toxins

Abstract

Cyanobacteria are known as blue-green algae, blue-green bacteria, and Cyanophyta. They are present in both toxic and non-toxic forms and it is actually the toxic form which proliferates in the aquatic environment. There are principally two types of toxins (neurotoxin and hepatotoxin) which lead to adverse environmental and human health impacts. Thus, the cyanobacteria and their cyanotoxins must be eliminated from fresh waters (lakes, river) to avoid contamination of drinking water and prevent other environmental adversities. Several treatment methods, such as physical and chemical treatment comprising chlorination, ozonation, photooxidation, activated carbon, and biological treatment including utilization of pure microorganisms such as bacteria, virus, fungi, protozoa, among others have been studied to ensure higher elimination of cyanobacteria. The physico-chemical treatment is the most prevalent and faster than biological treatment. However, this treatment causes the lysis of cyanobacterial cells and releases cyanotoxins and other carcinogenic and mutagenic substances in to the medium. In this context, the biological treatment is an eco-friendly option for removal of cyanobacteria and their toxins present in fresh waters. This mini-review is an attempt to explore different aspects of the research in the field of removal of cyanobacteria. The review presents the ecological aspects of cyanobacteria, physical-chemical treatment methodologies in short, biological treatment of cyanobacteria and cyanotoxins in details as latter are potentially more toxic.