The biodegradation of microcystins in temperate freshwater bodies with previous cyanobacterial history

Insight Into the Molecular Mechanisms for Microcystin Biodegradation in Lake Erie and Lake Taihu

“…The mlr pathway is currently the only characterized mechanism for MC biodegradation, however, there are many gaps regarding the diversity and ubiquity of this pathway especially in the natural environment. Many studies only use PCR approaches to determine if mlr is present in either isolates, sand filters or environmental samples (as examples, Yang et al, 2014a;Lezcano et al, 2016;Dziga et al, 2017;Thees et al, 2018). One limitation to PCR-based approaches for detecting mlr genes is that more diverse sequences may be missed due to mismatch of primers.…”

“…Despite these challenges, microorganisms that span multiple phyla and even domains are reported to degrade MCs ( Supplementary Table S1). Further, experiments assessing the biodegradation of MCs which employ natural microbial communities from lakes (Christoffersen et al, 2002;Edwards et al, 2008;Eleuterio and Batista, 2010;Mou et al, 2013;Dziga et al, 2017;Lezcano et al, 2018), drinking water reservoirs (Cousins et al, 1996;Ho et al, 2012), estuary and sea water (Lemes et al, 2008), water treatment facilities (Lam et al, 1995;Saito et al, 2003b;Ma et al, 2014), soil (Miller and Fallowfield, 2001;Bibo et al, 2008;Cao et al, 2018;Redouane et al, 2019), lake sediments (Rapala et al, 1994;Cousins et al, 1996;Chen X. et al, 2010;Song et al, 2014;Li et al, 2016;Zhu et al, 2019) and biofilters (Grützmacher et al, 2002;Ho et al, 2006;Lee et al, 2006;Ho et al, 2007;Hoefel et al, 2009;Ho et al, 2012;Kumar et al, 2019) have demonstrated that biodegradation capacity is seemingly ubiquitous across a wide range of environments and occurs under a variety of conditions (Li et al, 2017). For these reasons, the current literature often refers to biodegradation as the most important route for the disappearance of MCs in nature (Christoffersen et al, 2002;Holst et al, 2003;Chen et al, 2008;Grützmacher et al, 2009;Bukowska et al, 2018).…”

Source Community and Assembly Processes Affect the Efficiency of Microbial Microcystin Degradation on Drinking Water Filtration Membranes

“…This gene encodes for three enzymes (MlrA, MlrB, and MlrC) that are responsible for the degradation process: first the cyclic peptide is linearized by cleavage of the Adda-Arg bond, and subsequently the MlrB and MlrC enzymes hydrolyze the linear peptide into smaller ones (Bourne et al, 2001; Dziga et al, 2013). Additional degradation pathways have been suggested based on the discovery of novel intermediates and degradation semi-products (Amé et al, 2006; Edwards et al, 2008; Hashimoto et al, 2009; Zhang et al, 2010; Dziga et al, 2017). Moreover, other, hypothetical mechanisms for MC degradation have also been proposed, e.g., alkaline proteases or glutathione S-transferases (Takenaka and Watanabe, 1997; Mou et al, 2013), and the observation of MC degradation under anoxic conditions (Holst et al, 2003; Chen and Chen, 2010; Chen X. et al, 2010) strongly speaks for alternative metabolic strategies.…”

Further Understanding of Degradation Pathways of Microcystin-LR by an Indigenous Sphingopyxis sp. in Environmentally Relevant Pollution Concentrations

“…(CBA4) can demethylate microcystin RR (MC-RR), and the intermediate was degraded finally [28]. Dziga et al detected four products of dmMC-LR, including cyclic dmMC-LR, two cyclic dmMC-LR with different modifications in the Arg-Asp-Leu region, and the tetrapeptide in temperate freshwater bodies [29]. Zhang et al found that Sphingopyxis sp.…”