beta-ionone and microcystin

The previous studies indicated that Tychonema-like strains from Lake Erhai could release geosmin so that the species was listed as the potential harmful cyanobacteria influencing the drinking water safety around Lake Erhai. But, the dynamics and biological information of this species were too limited. In this study, the polyphasic approach was used to reveal its biological characterization and the dynamics in Lake Erhai. The characters of trichomes, including filaments with solitary or bundle state, reddish-brown or blue-green color, planktonic habitat, and presence of keritomized content, were examined by the microscopic method. The 16S rDNA sequences of these strains were used for phylogenetic analysis and molecular identification. The strains were morphologically classified as Tychonema bourrellyi, and geosmin and β-ionone were identified as the major volatile substances using gas chromatography-mass spectrometry (GC-MS) analysis. No strains of T. bourrellyi were found to produce microcystin by the HPLC and mcy gene approaches. Cell numbers at 12 sampling sites in Lake Erhai were shown as an average of 3 × 10(4) cells L(-1) in 2009 and 2010. The obvious peaks occurred in July and August each year. This was the first report on occurrence of T. bourrellyi from outside of Europe, and T. bourrellyi was also a newly recorded species in China. Such a result demonstrated that T. bourrellyi could distribute extending from cold waters in North Europe to the warm waters in subtropical regions. It was interesting to observe the coincidence of the occurrence of T. bourrellyi with slightly eutrophicated waters since Lake Erhai had been regarded as an early phase of eutrophicated lake.

Topics: China; Cyanobacteria; DNA, Bacterial; DNA, Ribosomal; Ecosystem; Europe; Gas Chromatography-Mass Spectrometry; Lakes; Microcystins; Naphthols; Norisoprenoids; Odorants; Phylogeny; Plankton; Water Microbiology

The distributions of cyanobacterial bioactive and odorous metabolites were investigated in the fifth largest lake in China in the fishing season 2012. The highest microcystins (MCs) concentration in water reached 3.4 µg L(-1). A high β-ionone concentration reached 35.6 ng L(-1) in water. Mean MCs concentration in muscle was highest in omnivorous Carassius auratus (20.9 ng g(-1) dry weight), followed by phytoplanktivorous Hypophthalmichthys molitrix (7.4 ng g(-1) DW) and carnivorous Coilia ectenes (3.0 ng g(-1) DW). The maximum off-flavor concentrations kept 9.5 µg kg(-1) wet weight for geosmin (C. auratus), 5.5 µg kg(-1) WW for β-cyclocitral (C. ectenes) and 25.5 µg kg(-1) WW for β-ionone (C. ectenes). Positive correlation was found between the off-flavor and fat contents in C. ectenes. To be different with MCs, β-cyclocitral content was highest in fore-gut contents (87.6 µg kg(-1) WW) in H. molitrix. It should not be reliable to predict odorous compounds level in fish muscle by only measuring the off-flavor in lake water only.

Topics: Aldehydes; Animals; China; Cyanobacteria; Diterpenes; Environmental Monitoring; Feeding Behavior; Fishes; Lakes; Microcystins; Norisoprenoids; Odorants; Risk Adjustment; Seasons

A systematic study was conducted on seasonal and spatial patterns of taste and odor (T&O) compounds with relation to biotic and abiotic parameters at fifteen sites in Gonghu Bay of Lake Taihu in 2008. We developed a sensitive and automated method to simultaneously analyze eight T&O compounds (boiling points ranging from 38°C to 239°C) by using Purge-and-Trap (P&T) coupled with GC/MS. Maximum particulate dimethyl trisulfide (DMTS, 69.6 ng/L) exceeded its odor threshold concentrations (OTC, 10 ng/L) and maximum dissolved DMTS was 6.1 ng/L, but still far below concentration in the drinking water pollution incident of Wuxi City in 2007 when DMTS reached 1768-11,399 ng/L. Geosmin (GEO), 2-methylisoborneol (MIB), β-cyclocitral, β-ionone and 2-isobutyl-3-methoxypyrazine (IBMP) occasionally or frequently exceeded their OTCs, whereas 2-isopropyl-3-methoxypyrazine (IPMP) and dimethyl sulfide (DMS) did not. We found for the first time significant correlations between particulate β-cyclocitral and β-ionon concentrations and intracellular and extracellular microcystin concentrations. Spatially, Nanquan Waterworks faced more risk by T&O contamination than Xidong Waterworks. High concentrations of NO(3)-N, TDN and TN could be risky signs of taste and odor events by DMS, DMTS, IPMP, IBMP and GEO.

Topics: Aldehydes; Camphanes; China; Diterpenes; Environmental Monitoring; Fresh Water; Microcystins; Naphthols; Norisoprenoids; Odorants; Phytoplankton; Pyrazines; Seasons; Sulfides; Taste; Water Pollutants, Chemical; Water Supply