UV-C suppression on hazardous metabolites in Microcystis aeruginosa: Unsynchronized production of microcystins and odorous compounds at population and single-cell level

• Published in: Journal of hazardous materials 2018-10, Vol.359, p.281-289
• Main Authors: Tao, Yi, Hou, Delin, Zhou, Tingru, Cao, Huansheng, Zhang, Wen, Wang, Xuejian
• Format: Article
• Language: English
• Subjects: Cell quota; MC-LR; Microcystis; UV-C irradiation; β-cyclocitral
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2018.07.052

[Display omitted] •Intracellular MC-LR (CMC) and BCC (CBCC) of Microcystis increased at similar rates.•Cellular quota of MC-LR (QMC) and BCC (QBCC) varied differently under non-stressful conditions.•Photolysis by UV-C leads to the suppression on CMC but not on CBCC.•Disruption of biosynthesis of both compounds contributes to suppression at population level.•The suppression by UV-C on either CBCC or QBCC was more severe than that on CMC and QMC. The effectiveness of UV-C towards the toxin and odor of M. aeruginosa at population and single cell levels were investigated in three ways. In the absence of UV-C, MC-LR and β-cyclocitral production show similar pattern of incremental rate with growth rate on population level shown as intracellular concentrations of MC-LR (CMC) and β-cyclocitral (CBCC), but the cellular quota of MC-LR (QMC) and β-cyclocitral (QBCC) at single-cell level reached the maximum values, 37.5 ± 1.2 fg cell−1 and 4.3 ± 0.1 fg cell−1, just after the early exponential phase. Second, upon UV-C irradiation, the CMC consistently decreased by 10–41% with increase of UV-C dosage (50–200 mJ cm-2) while CBCC increased by 2–14%. Third, during the 14 days’ post-UV incubation, UV-C at 75–200 mJ cm-2 induced remarkable suppressing effects on both CMC and CBCC for 3–14 days. The suppressing effects on QMC and QBCC were induced by UV-C at 100 mJ cm-2 and above, with shorter suppressing periods by 1–4 days and lower decremental rates by 21%–30% than that of CMC and CBCC, indicating interruptions on biosynthesis processes partially contribute to suppression effects of CMC and CBCC. The suppression effect on either CBCC or QBCC, with higher decrement rates while lower recovery rates, was more severe than CMC and QMC.