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Biodegradation of microcystins by bacteria

Freshwater cyanobacterial blooms are common natural phenomena, but their increasing frequency and intensity worldwide are considered undesirable consequences of the eutrophication and global change on aquatic systems. The excessive growth of cyanobacteria entails significant disruption to ecosystem function, especially when the toxin-producing cyanobacteria dominate blooms. The most widespread and frequent toxins are the microcystins which cause liver damage, among others.

The microcystins are affected by various slow natural degradation processes related to solar radiation, temperature, and pH of the water. On the other hand, a specific group of bacteria degrade quickly and efficiently the cyanotoxins, removing them from the water.

Mª Ángeles Lezcano and Rehab El-Shehawy, researchers from IMDEA Water, in collaboration with David Velázquez and Antonio Quesada, researchers from Universidad Autónoma de Madrid, have carried out a study which has allowed to know the composition of the bacterial community, before, during and after of bloom episode to identify bacteria degrading of microcystins.

It has been identify two bacteria groups which are able to degrade microcystins. The first of them the bacteria use an enzymatic pathway encoded by mlr gene culster and the second bacterial isolates lacking mlr genes have also been microcystins degraders.

The results of study have been recently published in the journal Water Research.

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Referencia bibliográfica:

Lezcano MÁ, Velázquez D, Quesada A, El-Shehawy R. Diversity and temporal shifts of the bacterial community associated with a toxic cyanobacterial bloom: An interplay between microcystin producers and degraders. Water Research. DOI:10.1016/j.watres.2017.08.025.