Biological Treatment for the Destruction of Cyanotoxins

Degradation of Multiple Peptides by Microcystin-Degrader Paucibacter toxinivorans (2C20)

“…Although P. toxinivorans lacks the mlr enzymatic pathway, it has been previously described as MC-LR degrader [ 37 ] including studies where P. toxinivorans 2C20 was used as positive control for the MC-LR biodegradation process [ 28 , 29 , 41 ]. Recently, authors have suggested bacteria possess other biodegradation pathways than mlr from the identifying different patterns of amino acids breaks in degradation-resulting products, besides the absence of mlr genes in MC-degrader bacteria [ 19 , 21 , 27 , 28 , 29 , 30 , 41 ]. Nevertheless, other findings have shown that a microbe should not necessarily have an exclusive enzymatic pathway to degrade a specific compound, and a single microorganism might be able to degrade a broad range of substances [ 42 , 43 ].…”

“…Previously, there was only one enzymatic pathway clearly described for MC biodegradation, known as the mlr pathway, considering biochemical and molecular aspects [ 23 , 24 , 25 , 26 , 27 ]; however, other pathways have been elucidated from different intermediate products or mlr -lacking biodegradation activity [ 19 , 21 , 27 , 28 , 29 , 30 ].…”

“…and refers to a gene cluster that generates enzymes responsible for the linearization of the cyclic structure (Mlr A), following a breakdown of linear MC to smaller fragments, such as the tetrapeptide (Adda-Glu-Mdha-Ala) and Adda amino acid by sequential reactions (Mlr B and C) [ 23 , 24 , 25 , 26 , 27 ]. Meanwhile, an enzyme would be involved in the transportation of either entire MCs or their fragments into or out the cells (MlrD) [ 24 , 25 , 27 ]. Nonetheless, some findings showed that MlrD-lacking strains were still able to degrade MC and excrete the intermediate products out of the cells [ 31 , 32 ].…”

“…Regarding the mlr pathway, it was initially observed in Sphingomonas sp. and refers to a gene cluster that generates enzymes responsible for the linearization of the cyclic structure (Mlr A), following a breakdown of linear MC to smaller fragments, such as the tetrapeptide (Adda-Glu-Mdha-Ala) and Adda amino acid by sequential reactions (Mlr B and C) [23][24][25][26][27]. Meanwhile, an enzyme would be involved in the transportation of either entire MCs or their fragments into or out the cells (MlrD) [24,25,27].…”