pheophytin-a and 2-methylisoborneol

Cyanobacteria can sense different light color by adjusting the components of photosynthetic pigments including chlorophyll a (Chl a), phycoerythrin (PE), and phycocyanin (PC), etc. Filamentous cyanobacteria are the main producer of 2-methylisoborneol (MIB) and many can increase their PE levels so that they are more competitive in subsurface layer where green light is more abundant, and have caused extensive odor problems in drinking water reservoirs. Here, we identified the potential correlation between MIB biosynthesis and ambient light color induced chromatic acclimation (CA) of a MIB-producing Pseudanabaena strain. The results suggest Pseudanabaena regulates the pigment proportion through Type III CA (CA3), by increasing PE abundance and decreasing PC in green light. The biosynthesis of MIB and Chl a share the common precursor, and are positively correlated with statistical significance regardless of light color (R

Topics: Acclimatization; Chlorophyll A; Cyanobacteria; Phycocyanin; Phycoerythrin

The effect of cyanobacterial bloom decay on water quality and the complete degradation of cyanobacterial blooms in a short period were examined by an enclosure experiment in Gonghu Bay of Lake Taihu, China. Water quality parameters as well as taste and odor compounds during the breakdown of cyanobacterial blooms were measured. Results showed that the decay of cyanobacterial blooms caused anoxic water conditions, decreased pH, and increased nutrient loading to the lake water. The highest concentrations of dimethyl sulfide (DMS), dimethyl trisulfide (DMTS), and beta-cyclocitral were observed in the anoxic water, at 62331.8, 12413.3, and 1374.9 ng/L, respectively. 2-Methylisoborneol was dominant during the live growth phase of cyanobacterial blooms, whereas DMS and DMTS were dominant during the decomposition phase. Dissolved oxygen, pH, and chlorophyll a were negatively correlated with DMS, DMTS, and beta-cyclocitral, whereas total phosphorus, total nitrogen, and ammonium (NH(4+)-N) were positively correlated with DMS, DMTS, beta3-cyclocitral, and beta-ionone. The experimental results suggested that preventing the anaerobic decomposition of cyanobacterial blooms is an important strategy against the recurrence of a malodor crisis in Lake Taihu.

Topics: Camphanes; China; Chlorophyll; Chlorophyll A; Cyanobacteria; Eutrophication; Geography; Hydrogen-Ion Concentration; Lakes; Nitrogen; Odorants; Particulate Matter; Phosphorus; Solubility; Taste; Water Pollutants, Chemical; Water Quality

Geosmin and 2-methylisoborneol (MIB) related odor events caused by cyanobacteria have been a very common problem to water supply. This paper investigated the effects of temperature (18 and 25 °C) and light intensity (10 and 100 μmol photons m(-2) s(-1)) on the production behaviors of earthy odor compounds by three odorous cyanobacteria, i.e., the geosmin-producing planktonic Anabaena circinalis (Ana 318), geosmin-producing benthic Phormidium amoenum (Pho 012) and MIB-producing benthic Phormidium sp. (Pho 689). At the same time, the effects of biodegradation and volatilization on the fates of the released odor compounds in water were also evaluated. The combination of high temperature (25 °C) and light intensity (100 μmol photons m(-2) s(-1)) favored the growth of the three cyanobacteria and the production of chl-a and odor compounds. However, higher chl-a and odor yields (average odor compounds per cell) were achieved for the two benthic cyanobacteria at the temperature of 18 °C. Most of geosmin was included within the cells for Ana 318 (95-99%) and Pho 012 (85-60%), while only 20-40% MIB was bound to the cells for Pho 689. The half-life times of MIB and geosmin due to volatilization varied between 18.8 and 35.4 days, while 8 out of 10 samples exhibited a half-life time (t(1/2)) for geosmin biodegradation shorter than 1 day (0.38-15.0 h), showing that biodegradation could affect the fate of geosmin significantly in aquatic environments. In comparison, biodegradation of MIB was much slower (t(1/2): 122-2166 h). Denaturing gradient gel electrophoresis (DGGE) analysis showed that Pseudomonas- and Sphingomonas-like bacteria coexisted with cyanobacteria in the cultures, and may have played an important role in geosmin/MIB biodegradation. The result of this study will be helpful for better understanding and managing the earthy odor problems caused by cyanobacteria in water supply.

Topics: Australia; Biodegradation, Environmental; California; Camphanes; Chlorophyll; Chlorophyll A; Cyanobacteria; Denaturing Gradient Gel Electrophoresis; Light; Naphthols; Odorants; Species Specificity; Temperature; Volatilization; Water Supply

The algal extracellular products (ECPs) in three cultures of cyanobacteria species (Anabaena, Microcystis, and Oscillatoria) dominating the eutrophic reservoir populations and their toxins have been investigated in the present work. Using gas chromatography coupled with high-resolution electron-impact mass spectrometry (GC/EI-MS) and high performance anion-exchange chromatography (HPAEC) techniques, more than 20 compounds were found in the algal culture (including cells and filtrates) extracts. The main identified ECPs were classified to polysaccharides, hydrocarbons, and aldehydes. Odor causing substances such as trans-1,10-dimethyl-trans-9-decalol (geosmin) and 2-methylisoborneol (2-MIB)were also found in the algal cultures. The potential mutagenicity of the algal suspensions was also studied with the Ames test. The organic extracts of the algal suspension from the axenic cultures were mutagenicity in TA98 without S9 mix and in TA100 with and without S9 mix. The results indicate that the ECPs of three algae species dominating the eutrophic reservoir were mutagenic clearly in the bacterial test.

Topics: Camphanes; Carbon; Carboxylic Acids; Chlorophyll; Chlorophyll A; Complex Mixtures; Cyanobacteria; Eutrophication; Hydrocarbons; Marine Toxins; Microcystins; Mutagenicity Tests; Naphthols; Polysaccharides; Salmonella typhimurium; Taiwan; Water Supply

Lake Dianchi is the sixth largest freshwater lake in China. The pilot experimental area (6 km2) in Lake Dianchi is one of the most severely polluted areas in the lake with heavy cyanobacteria blooms. During June 2002 to May 2003, the algal composition and number, and odorous compounds were identified monthly and monitored in the area. Meanwhile, physicochemical parameters such as total phosphorus (TP), total nitrogen (TN), 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD(Mn)), dissolved oxygen (DO), pH, transparency, temperature and chlorophyll a (chla) were determined. Four odorous compounds: 2-methylisoborneol (MIB), geosmin, beta-cyclocitral and beta-ionone were found in the lake water. Both the concentration of particulate beta-cyclocitral and that of beta-ionone correlated significantly with the annual variation of Chla, biomass of total phytoplankton, cyanobacteria and Microcystis. The concentration of particulate MIB correlated significantly with the biomass of Oscillatoria, while the concentration of particulate geosmin correlated significantly with the biomass of Anabaena. Off-flavour in the pilot area was found to be caused by a combination of beta-cyclocitral- and beta-ionone-producing Microcystis, MIB-producing Oscillatoria and geosmin-producing Anabaena. beta-ionone, MIB and geosmin contributed collectively to the odour intensity in the lake water.

Topics: Aldehydes; Camphanes; China; Chlorophyll; Chlorophyll A; Diterpenes; Environmental Monitoring; Eutrophication; Fresh Water; Naphthols; Nitrogen; Norisoprenoids; Oxygen; Phosphorus; Phytoplankton; Water Pollutants, Chemical; Water Purification