Microbial Strategies for Controlling Harmful Cyanobacterial Blooms

Abstract

Cyanobacteria are earth's oldest heterogeneous group of prokaryotes that are predominantly photosynthetic. The anthropogenic nutrient enrichment in aquatic system fuels the exponential cyanobacterial growth along with optimum environmental conditions leading to the propagation of harmful scums known as ``cyanoblooms''. The catastrophic effects of these cyanoblooms include prevalence of anoxic conditions, alteration of food webs, accumulation of organic materials, and adverse effects on animals, birds, and humans due to release of toxic secondary metabolites (cyanotoxins). The CyanoHABs (cyanobacterial harmful algal blooms) pose a serious threat to the usability and substantiality of freshwater resources. The applicability and feasibility of different control strategies depend upon the intensity, frequency, and magnitude of invasion of the cyanobacterial population along with other environmental limitations. Moreover, the insights about the type of ecostrategist, the area/zone inhabited, the type of aquatic system escalated, and the mechanism of formation of CyanoHABs are yet other critical factors. The physical (sonication, aeration) and chemical (algicide, oxidants) agents used for the modulation of CyanoHABs have proved to be transitory and spatially constricted to smaller eutrophying systems. Additionally, chemical agents have potential to exterminate aquatic biota and also require intermittent dosage for its utility. The effectiveness of future cyanobloom management approaches thus could be magnified by employing biocontrol strategies which include use of virus, bacteria, fungi, and protozoans and biomanipulation for impeding cyanobacterial growth.