Immobilization of Microbes for Biodegradation of Microcystins: A Mini Review

Abstract

Harmful cyanobacterial blooms (HCBs) frequently occur in eutrophic freshwater ecosystems worldwide. Microcystins (MCs) are considered to be the most prominent and toxic metabolites during HCBs. MCs may be harmful to human and animal health through drinking water and recreational water. Biodegradation is eco-friendly, cost-effective and one of the most effective methods to remove MCs. Many novel MC-degrading bacteria and their potential for MCs degradation have been documented. However, it is a challenge to apply the free MC-degrading bacterial cells in natural environments due to the long-term operational instability and difficult recycling. Immobilization is the process of restricting the mobility of bacteria using carriers, which has several advantages as biocatalysts compared to free bacterial cells. Biological water treatment systems with microbial immobilization technology can potentially be utilized to treat MC-polluted wastewater. In this review article, various types of supporting materials and methods for microbial immobilization and the application of bacterial immobilization technology for the treatment of MCs-contaminated water are discussed. This article may further broaden the application of microbial immobilization technology to the bioremediation of MC-polluted environments.

Keywords: biodegradation; microbial immobilization; microcystins (MCs).

Figure 1

General chemical structure of MCs. 1–7 signify seven amino acid residues. R1 and R2 in positions two and four are highly variable L-amino acids.

Figure 2

Types of immobilization. (a) Entrapment; (b) Encapsulation; (c) Adsorption and (d) Covalent binding.