Table 4.
Identities of microcystins detected by LC-HRMS/MS analysis in Microcystis strains AB2017/14 and /15 isolated from Meiktila Lake, their retention times (tR), concentrations, relative abundances (%) and observed m/z values in negative ionisation modea.
| m/z | Compound Name | Confidence | tR (min) | Concentrationb | ||||
|---|---|---|---|---|---|---|---|---|
| AB2017/14 | AB2017/15 | |||||||
| μg g−1 | % | μg g−1 | % | |||||
| 1 | 1022.5443 | [D-Asp3]MC-RRc | Confirmed | 4.18 | 2.4 | 0.21 | 1002.4 | 7.21 |
| 2 | 1022.5454 | [Dha7]MC-RRc | Probable | 4.53 | 0.1 | 0.01 | 31.8 | 0.23 |
| 3 | 1036.5597 | MC-RRc | Confirmed | 4.55 | 19.4 | 1.74 | 1458.0 | 10.49 |
| 4 | 995.4858 | [D-Asp3]MC-ERc | Probable | 6.14 | ND | - | 119.6 | 0.86 |
| 5 | 1114.5657 | MC-LR–Cysd | Probable | 6.16 | 0.1 | 0.01 | ND | - |
| 6 | 1045.5378 | MC-(H2)YRc | Probable | 6.18 | 32.4 | 2.90 | ND | - |
| 7 | 1031.5224 | [D-Asp3]MC-(H2)YRc | Probable | 6.20 | 32.9 | 2.95 | ND | - |
| 8 | 1033.5381 | [D-Asp3]MC-(H4)YRc | Probable | 6.27 | 0.6 | 0.05 | 148.1 | 1.07 |
| 9 | 1009.5015 | MC-ERc | Probable | 6.55 | 0.6 | 0.05 | 37.8 | 0.27 |
| 10 | 1029.5072 | [D-Asp3]MC-YRc | Probable | 6.59 | ND | - | 144.1 | 1.04 |
| 11 | 1047.5540 | MC-(H4)YRc | Probable | 6.64 | 6.4 | 0.57 | 310.8 | 2.24 |
| 12 | 1011.5530 | [Mser7]MC-LR | Probable | 6.80 | 0.4 | 0.04 | 13.3 | 0.10 |
| 13 | 979.5273 | [D-Asp3]MC-LRc | Confirmed | 6.89 | 40.8 | 3.65 | 1870.3 | 13.45 |
| 14 | 1043.5224 | MC-YRc | Confirmed | 6.99 | 9.1 | 0.81 | 317.4 | 2.28 |
| 15 | 1011.4999 | MC-MRc,d,e | Probable | 6.99 | 3.6 | 0.32 | ND | - |
| 16 | 1073.5329 | MC-Y(OMe)Rc | Probable | 7.07 | 7.2 | 0.64 | ND | - |
| 17 | 993.5435 | MC-LRc | Confirmed | 7.12 | 183.0 | 16.38 | 3332.5 | 23.97 |
| 18 | 979.5289 | [Dha7]MC-LRc | Confirmed | 7.13 | 0.8 | 0.07 | 37.4 | 0.27 |
| 19 | 1080.5170 | Unidentified MCc | Unidentified | 7.15 | 59.0 | 5.28 | ND | - |
| 20 | 1070.5332 | MC-KynRc | Probable | 7.35 | 4.5 | 0.40 | ND | - |
| 21 | 1007.5582 | MC-HilRc | Confirmed | 7.38 | 41.8 | 3.74 | 17.9 | 0.13 |
| 22 | 1080.5169 | Unidentifiedc | Unidentified | 7.38 | 59.6 | 5.34 | ND | - |
| 23 | 1082.5311 | MC-OiaRc | Tentative | 7.40 | 102.4 | 9.17 | ND | - |
| 24 | 995.4857 | [D-Asp3]MC-REc | Probable | 7.43 | ND | - | 110.1 | 0.79 |
| 25 | 1027.5269 | MC-FRc | Confirmed | 7.48 | 255.2 | 22.85 | ND | - |
| 26 | 1066.5380 | MC-WRc | Confirmed | 7.64 | 0.7 | 0.06 | ND | - |
| 27 | 1009.5015 | MC-REc | Probable | 7.79 | 3.8 | 0.34 | 1281.0 | 9.21 |
| 28 | 951.4955 | MC-RAc | Probable | 8.24 | 13 | 1.16 | ND | - |
| 29 | 965.5116 | MC-RAbuc | Probable | 8.83 | 7.1 | 0.64 | ND | - |
| 30 | 946.4577 | MC-(H2)YGc | Probable | 9.06 | 5.4 | 0.48 | ND | - |
| 31 | 1011.4966 | MC-RMc,d,e | Probable | 9.23 | 0.2 | 0.02 | ND | - |
| 32 | 960.4738 | MC-(H2)YAc | Probable | 9.34 | 10.1 | 0.90 | ND | - |
| 33 | 953.4783 | Unidentified MCc | Unidentified | 9.50 | 12 | 1.07 | ND | - |
| 34 | 967.4942 | Unidentified MCc | Unidentified | 9.78 | 2.3 | 0.21 | ND | - |
| 35 | 984.4735 | Unidentified MCc | Unidentified | 9.96 | 3.7 | 0.33 | ND | - |
| 36 | 968.4272 | [D-Asp3]MC-EEc | Probable | 11.43 | ND | - | 403.3 | 2.90 |
| 37 | 982.4432 | MC-EEc | Probable | 12.58 | 0.9 | 0.08 | 1533.5 | 11.03 |
| 38 | 952.4690 | [D-Asp3]MC-LEc | Probable | 12.82 | 1.2 | 0.11 | 358.8 | 2.58 |
| 39 | 894.4631 | [D-Asp3]MC-LAc | Probable | 13.32 | 6.5 | 0.58 | ND | - |
| 40 | 966.4849 | MC-LEc | Probable | 13.69 | 12.9 | 1.15 | 1376.1 | 9.90 |
| 41 | 908.4788 | MC-LAc | Confirmed | 14.87 | 44.8 | 4.01 | ND | - |
| 42 | 922.4942 | MC-HilAc | Probable | 15.29 | 5.9 | 0.53 | ND | - |
| 43 | 981.4737 | MC-WAc | Probable | 15.88 | 4.4 | 0.39 | ND | - |
| 44 | 942.4629 | MC-FAc | Probable | 15.95 | 42.3 | 3.79 | ND | - |
| 45 | 922.4943 | MC-LAbuc | Probable | 16.09 | 16.6 | 1.49 | ND | - |
| 46 | 936.5110 | MC-HilAbuc | Probable | 16.55 | 2.2 | 0.20 | ND | - |
| 47 | 995.4898 | MC-WAbuc | Probable | 17.20 | 13.4 | 1.20 | ND | - |
| 48 | 956.4784 | MC-FAbuc | Probable | 17.39 | 26.4 | 2.36 | ND | - |
| 49 | 936.5106 | MC-LVc | Probable | 17.62 | 3.6 | 0.32 | ND | - |
| 50 | 950.5254 | MC-LLc | Probable | 17.93 | 3.9 | 0.35 | ND | - |
| 51 | 970.4944 | MC-FVc | Probable | 18.40 | 0.7 | 0.06 | ND | - |
| 52 | 950.5262 | iso-MC-LLc | Tentative | 18.49 | 1.2 | 0.11 | ND | - |
| 53 | 1009.5041 | MC-WVc | Probable | 18.54 | 2.9 | 0.26 | ND | - |
| 54 | 1023.5210 | MC-WLc | Probable | 18.74 | 2.8 | 0.25 | ND | - |
| 55 | 970.4942 | iso-MC-FVc | Tentative | 18.79 | 2.1 | 0.19 | ND | - |
| 56 | 1023.5216 | iso-MC-WLc | Tentative | 19.16 | 1.3 | 0.12 | ND | - |
a A comprehensive version of this table, including positive and negative ionisation MS data, reactivity towards thiols and mild oxidising agents, number of rings plus double-bond equivalents (RDBE) and presence of characteristic ions observed in positive and negative ionisation MS/MS spectra, is in the Supporting Information (Table S1) together with LC–HRMS/MS spectra (Figures S1–S59). b Concentration expressed per weight of biomass (FW) and as a percentage of total microcystins detected in each culture); ND = not detected; c Reacted with mercaptoethanol; d Oxidised by Oxone/DMSO; e HRMS/MS spectrum of oxidation product obtained.