Journal of Aridland Agriculture 2021, 7: 9-14 doi: 10.25081/jaa.2021.v7.6664 http://updatepublishing.com/journal/index.php/jaa J Aridland Agric • 2021 • Vol 7 9 INTRODUCTION Cyanobacterial harmful algae blooms have been recognized as a problem worldwide, resulting from the inherent detrimental effects, although the presence in the ecosystem is not widely recognized. Cyanobacteria, also known as blue-green algae (N. A. Herrera et al., 2015) are a group of bacteria characterized by numerous structural features (El Gamal, 2010). These microorganisms are autotrophic, which are primary producers in aquatic systems, hence categorized as algae (Picardo et al., 2019). Also, due to the chlorophyll a content and the presence of related compounds (El Gamal, 2010), cyanobacteria are able to perform photosynthesis, which is a process that provides the primary source of energy for most forms of life on Earth (Axmann et al., 2014; Bortoli et al., 2014; Kimambo et al., 2019). Furthermore, they are also highly adaptive, with the capacity to grow autotrophically (Picardo et al., 2019), heterotrophically (Atteia et al., 2013), or mixotrophically (Subashchandrabose et al., 2013). Morphologically, blue-green algae have been identified in diverse forms, including filamentous (Kurmayer et al., 2016), unicellular (Atteia et al., 2013), colony as well as multicellular, and they are taxonomically grouped under prokaryotes (Bortoli et al., 2014). These microorganisms are considered as gram-negative, despite the demonstration of both gram-negative and gram-positive properties using electron microscopy. Some strains have very rich chemistry and are capable of producing a wide range of bioactive compounds with varying properties (El Gamal, 2010; Picardo et al., 2019), of which some are beneficial and have been applied in many valuable products (Axmann et al., 2014). Meanwhile, other forms yield a variety of toxic and possibly harmful compounds, in the form of secondary metabolites, termed cyanotoxins, attributed as one of the most important groups of natural toxins (Picardo et al., 2019; Kimambo et al., 2019; EPA, 2015a; Griffith & Gobler, 2020). Therefore it is necessary to establish microcystin exposure pathways, which summarize several studies on the dangers, to enhance the ease of understanding. The complete characterization of cyanobacteria is the main study here, which is related to its presence in aquatic ecosystems; knowledge obtained from exposure pathways to microcystin; direct effects of toxins on human health; danger of low dose exposure for the ecosystem; the safety of food and food supplements made from cyanobacteria, given the tendency to accumulate in plants and animals; the best use of microcystin; and the use of cyanobacteria as processing and/or remediation of polluted environments. It is all based on recommendations from the previous research literature. ALGAL BLOOM Environmental Factors The continuous aging of water bodies has been attributed to natural and anthropogenic activities (Martins et al., 2017; Problems and use of cyanobacteria for environmental improvement – A Review Diana Indah Kusumawati, Sarwoko Mangkoedihardjo* Department of Environmental Engineering, Institut Teknologi Sepuluh Nopember (ITS), Surabaya, Indonesia ABSTRACT Cyanobacteria were considered harmful to other living organisms, due to their microcystin content. In addition, uncontrolled populations of cyanobacteria, also known as algal blooms, occur both naturally and as a result of human activity, leading to the development of more complex problems. These microorganisms are currently receiving a lot of attention, as several investigations have considered successful applications of reducing exposure to nature, causing reduced risks to ecosystems, and providing benefits to human life. This study aims to provide answers to current problems, by providing a different perspective on cyanobacteria. Furthermore, it is for the benefits of cyanobacteria for the environment in accordance with the recommendations in some of the literature on previous research results. KEY WORDS: Cyanobacteria, algae bloom, microcystin, harmful, utilization Copyright: © The authors. This article is open access and licensed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted, use, distribution and reproduction in any medium, or format for any purpose, even commercially provided the work is properly cited. Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. Review Article ISSN: 2455-9377 Received: December 19, 2020 Revised: January 31, 2020 Accepted: February 7, 2020 Published: February 16, 2020 *Corresponding Author: Sarwoko Mangkoedihardjo, E-mail: prosarwoko@gmail. com