Massive proliferations of cyanobacteria coexist and have different interactions with other microorganisms, including microcystin (MC)-degrading bacteria. Despite their relevance in the environment for the removal of MCs, this bacterial community has been scarcely studied. The influence of physicochemical factors and the seasonal dynamics of toxic cyanobacteria on the relative abundance and seasonal dynamics of the MC-degrading bacterial community with mlr genes (mlr⁺) were investigated during a two-year study at a water reservoir in central Spain. The capacity of the total bacterial community on the degradation of MCs during the whole period of study was also evaluated. The results showed that the relative abundance of mlr⁺ bacteria started to increase after the increase in the relative abundance of toxic cyanobacteria and MC concentrations in the water, indicating a related seasonal dynamic and an important interaction between the two communities. The correspondence of several peaks of mlr⁺ bacteria with decreases in the relative abundance of toxic cyanobacteria and vice versa may also suggest a possible antagonistic relationship that deserves an in-depth study. The lack of a significant relationship between the physicochemical factors and the temporal shifts of both MC producers and degraders also supports the notion that the interaction of the two communities is an important driver of their seasonal dynamics in nature. Regarding the capacity of the total bacterial community for the degradation of MCs, this capacity was only observed during the toxic cyanobacterial bloom episodes, highlighting the importance of the pre-exposure to MCs in the reservoir for triggering the MC biodegradation process.

蓝藻大量繁殖并存，并且与其他微生物（包括降解微囊藻毒素（MC）的细菌）具有不同的相互作用。尽管它们在环境中与去除MC有关，但对该细菌群落的研究很少。在西班牙中部水库进行的为期两年的研究中，研究了理化因素和有毒蓝细菌的季节性变化对带有mlr基因（mlr ⁺）的MC降解细菌群落的相对丰度和季节性变化的影响。还评估了整个研究期间总细菌群落对MC降解的能力。结果表明，mlr ⁺的相对丰度水中有毒蓝细菌的相对丰度和MC浓度增加后，细菌开始增加，这表明相关的季节动态以及两个群落之间的重要相互作用。mlr ⁺的几个峰的对应毒性蓝细菌相对丰度降低的细菌，反之亦然，也可能表明可能存在拮抗关系，值得深入研究。理化因子与MC生产者和降解者的时间变化之间缺乏显着关系，这也支持以下观点：两个社区的相互作用是其自然季节动态的重要驱动力。关于总细菌群落降解MCs的能力，仅在有毒的蓝藻水华发作期间才观察到这种能力，这突出显示了预先暴露于储库中的MCs对于触发MC生物降解过程的重要性。