beta-ionone and beta-cyclocitral

Carotenoids and apocarotenoids function as pigments and flavor volatiles in plants that enhance consumer appeal and offer health benefits. Tomato (Solanum lycopersicum.) fruit, especially those of wild species, exhibit a high degree of natural variation in carotenoid and apocarotenoid contents. Using positional cloning and an introgression line (IL) of Solanum habrochaites "LA1777', IL8A, we identified carotenoid cleavage dioxygenase 4 (CCD4) as the factor responsible for controlling the dark orange fruit color. CCD4b expression in ripe fruit of IL8A plants was ∼8,000 times greater than that in the wild type, presumably due to 5' cis-regulatory changes. The ShCCD4b-GFP fusion protein localized in the plastid. Phytoene, ζ-carotene, and neurosporene levels increased in ShCCD4b-overexpressing ripe fruit, whereas trans-lycopene, β-carotene, and lutein levels were reduced, suggestive of feedback regulation in the carotenoid pathway by an unknown apocarotenoid. Solid-phase microextraction-gas chromatography-mass spectrometry analysis showed increased levels of geranylacetone and β-ionone in ShCCD4b-overexpressing ripe fruit coupled with a β-cyclocitral deficiency. In carotenoid-accumulating Escherichia coli strains, ShCCD4b cleaved both ζ-carotene and β-carotene at the C9-C10 (C9'-C10') positions to produce geranylacetone and β-ionone, respectively. Exogenous β-cyclocitral decreased carotenoid synthesis in the ripening fruit of tomato and pepper (Capsicum annuum), suggesting feedback inhibition in the pathway. Our findings will be helpful for enhancing the aesthetic and nutritional value of tomato and for understanding the complex regulatory mechanisms of carotenoid and apocarotenoid biogenesis.

Topics: beta Carotene; Carotenoids; Dioxygenases; Fruit; Solanum lycopersicum; zeta Carotene

Cyanobacteria blooms have become a major environmental problem and concern because of secondary metabolites produced by cyanobacteria released into the water. Cyanobacteria produce volatile organic compounds (VOCs), such as the compounds β-cyclocitral and β-ionone, which comprise odors, off-flavors, defense compounds, as well as growth regulators. Therefore, the general objective of this work was to evaluate the VOCs produced by two strains of Microcystis aeruginosa, differing in their ability to produce microcystins (LTPNA 01-non-producing and LTPNA 08-toxin-producing). The analysis of VOC production was carried out in (1) normal culture conditions, (2) under different light intensities (LI), and (3) after the external application of β-ionone in both cultures.. The results showed that β-cyclocitral and β-ionone are produced in all growth phases of LTPNA 01 and LTPNA 08. Both strains were producers of β-cyclocitral and β-ionone in normal culture conditions. It was observed that the β-cyclocitral concentration was higher than β-ionone in all light intensities investigated in this study. Additionally, the strain LTPNA 01 produced more β-cyclocitral than LTPNA 08 at almost all times and LIs analyzed. However, the strain LTPNA 08 produced more β-ionone, mainly at the initial times. In addition, the experiment results with the external addition of β-ionone in the cultures showed that the strain LTPNA 01 produced more β-cyclocitral in control conditions than in treatment. Nonetheless, β-ionone production was higher in treatment conditions in LTPNA 08, indicating that the addition of β-ionone may favor the production of these compounds and inhibit the production of β-cyclocitral.. Our results showed that some abiotic factors, such as different light intensities and external application of β-ionone, can be triggers that lead to the production of VOCs.

Topics: Aldehydes; Cyanobacteria; Diterpenes; Microcystis; Norisoprenoids; Volatile Organic Compounds

Volatile organic compounds (VOCs) promote cyanobacteria dominating eutrophicated waters, with aquatic plant decrease and even disappearance. To uncover the toxic mechanism of cyanobacterial VOCs on aquatic plants, we investigated the growth, photosynthetic pigment levels, photosynthetic abilities and related gene expression in duckweed treated with β-cyclocitral and β-ionone, 2 main components in the VOCs. The levels of chlorophylls and carotenoids gradually declined with raising the concentration of the 2 compounds and prolonging the treatment time. Their decline should result from the down-regulation of 8 genes associated with photosynthetic pigment biosynthesis and up-regulation of 2 genes involved in carotenoid degradation. The reduction was also found in the photosystem II (PSII) efficiency and O

Topics: Aldehydes; Araceae; Cyanobacteria; Diterpenes; Gene Expression; Norisoprenoids; Photosynthesis; Volatile Organic Compounds

Dee are a unique and rapidly growing part of the global snack food market and are recognised as having distinct sensory properties (taste and texture). In this study, the development of important volatile aroma compounds over storage was evaluated and their chemical origin explained. Sweet potatoes were batch fried in high oleic sunflower oil (HOSO) and subjected to accelerated shelf life testing. Headspace volatiles were analysed using SPME GC-MS and correlated with sensory perception. All the components (sweet potatoes, oil and β-carotene) showed significant degradation after 3 weeks of storage at accelerated conditions (equivalent to 12 weeks in real-time at 25 °C). Marker volatiles associated with lipid oxidation such as hexanal, octanal, pentanal were identified, in addition to norisoprenoids from β-carotene degradation such as β-ionon, 5,6-epoxy-β-ionone, dihydroactinidiolide (DHA) and β-cyclocitral. The most prominent marker of lipid oxidation (hexanal) rapidly increased at week 1, whereas the carotene degradation makers did not rapidly increase until week 3 suggesting a delayed response. The frying temperature during the batch frying process of SPC was also shown to play a significant role in the sensory perception of the product over the shelf life. Overall, the results suggest that tight control of process variables and raw material design may enable extended shelf life and potentially enhanced health credentials for the product. These findings are unique to SPC, but also of value to the wider food industry.

Topics: Aldehydes; Benzofurans; beta Carotene; Cooking; Diterpenes; Food Industry; Gas Chromatography-Mass Spectrometry; Hot Temperature; Ipomoea batatas; Lipid Metabolism; Lipids; Norisoprenoids; Odorants; Oxidation-Reduction; Sensation; Sunflower Oil; Taste; Volatile Organic Compounds

In this study, the antioxidant capacity and oxidative stability of zeaxanthin with different concentrations in soybean oil were evaluated. The oxidative or isomerization products of zeaxanthin were monitored during oxidation for 12 h at 110 °C. It was found that the ability to scavenge the free radicals (DPPH, FRAP, and ABTS) was dependent upon the concentration of zeaxanthin. However, antioxidation of zeaxanthin was observed when the concentration was less than 50 μg/g. When the concentration exceeded 50 μg/g, zeaxanthin acted as a pro-oxidant. There were three kinds of non-volatile products of zeaxanthin that were detected: (a)

Topics: Aldehydes; Antioxidants; Diterpenes; Molecular Structure; Norisoprenoids; Oxidation-Reduction; Soybean Oil; Zeaxanthins

Organic matter-induced black bloom frequently occurs in a number of large eutrophic shallow lakes; this can result in the release of malodorous compounds and has a negative impact on water quality. In the study, a microcosm system containing Zizania latifolia (Z. latifolia), a common aquatic plant, was established and the release of seven taste and odour compounds, dimethyl sulphide (DMS), dimethyl disulphide (DMDS), dimethyl trisulphide (DMTS), 2-methylisoborneol (MIB), geosmin (GSM), β-cyclocitral, and β-ionone, was investigated. The results showed that these compounds were all detected during Z. latifolia decay, and that volatile organic sulphur compounds (VOSCs), such as DMS, DMDS, and DMTS, were the main factors responsible for the strong foul odour (the maximum reached 5.0 μg L

Topics: Aldehydes; Biodegradation, Environmental; Camphanes; Diterpenes; Ecosystem; Lakes; Naphthols; Norisoprenoids; Odorants; Poaceae; Sulfides; Taste; Volatile Organic Compounds; Water Quality

The odor problem caused by the decay of aquatic plants is widespread in many freshwater lakes. In this study, the spatial distributions of seven taste and odor (T&O) compounds (dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, 2-methylisoborneol, geosmin, β-cyclocitral, and β-ionone) in the sediments and overlying water of the east of Taihu Lake were investigated. The effects of plant and physico-chemical parameters on the release of T&O compounds were also analyzed. The results showed that high concentrations of T&O compounds were detected in the area where Eichhornia crassipes was flourishing. Volatile organic sulfur compounds were not found in the water source area, which was not covered by aquatic plants. High plant biomass and aquiculture activities might increase the release of the taste and odor compounds. The correlation between the concentrations of odorous compounds and nutrients in the sediment was also analyzed. The production of odorants was positively correlated with the nitrogen, and they may migrate from sediment to overlying water. The result suggested that controlling the plant density and aquaculture activities could reduce the release of odorous compounds.

Topics: Aldehydes; Aquatic Organisms; Camphanes; China; Diterpenes; Geologic Sediments; Lakes; Naphthols; Norisoprenoids; Odorants; Plants; Sulfides; Taste; Volatile Organic Compounds; Water Pollutants, Chemical

β-cyclocitral and β-ionone are ones of major algal odorants produced by oxidation of the β-carotene that exists in algae cells. These compounds degraded the quality of drinking water therefore it needed to be treated in drinking water treatment by advanced oxidation processes. In this study, UV photolysis and UV-chlorination reactions along with chlorination to remove these odorants in water were compared. Kinetics of three reactions were well fitted at pseudo-first order model. Among three reactions, UV-chlorination was the most effective due to generation of OH and Cl radicals. β-ionone showed faster degradation compared to β-cyclocitral due to the existence of double bond in the alkyl carbon chain. In addition, radical contributions of degradation of odorants were examined. During UV-chlorination, UV photolysis contributed around 50% of removal for two odorants. OH radical took part of 36% removal of β-ionone and 50% removal of β-cyclocitral. Unlike β-ionone, β-cyclocitral was not degraded by reactive chlorine species during UV-chlorination. Acidic pH was favorable for UV-chlorination due to different quantum yield and radical scavenging effect by chlorine species. Formation of trace amount of chloroform was observed during UV-chlorination. The methyl ketone group of β-ionone was the main site for chloroform production. Several byproducts during UV photolysis and UV-chlorination of β-ionone were identified by GC-MS, and these were degraded with further reaction by UV-induced isomerization, OH radical, and bond scission mechanisms. β-cyclocitral was formed as byproducts during UV-chlorination of β-ionone. Based on degradation byproducts, the degradation pathways of β-ionone and β-cyclocitral of UV photolysis and UV-chlorination were suggested based on the identified byproducts. This study showed UV-chlorination process can be applied for degrading odorants like β-cyclocitral and β-ionone.

Topics: Aldehydes; Chlorine; Diterpenes; Halogenation; Kinetics; Norisoprenoids; Oxidation-Reduction; Photolysis; Ultraviolet Rays; Water Pollutants, Chemical; Water Purification

After large-scale outbreaks of algal blooms in eutrophic water, considerable amounts of algae residue accumulate in near-shore zones before fermenting rapidly and becoming malodorous. Taste and odor pollution caused by secondary metabolites from cyanobacterial blooms has become a serious and widespread environmental problem. Two typical odorous compounds, β-cyclocitral and β-ionone, have gained increasing attention in recent years. In this paper, the spatial distributions of β-cyclocitral and β-ionone in the sediments and overlying water off the west shore of Taihu Lake were investigated. The results showed that β-cyclocitral, β-ionone and nutrients are released during the degradation of fresh cyanobacteria, especially in the early stages. The odorous compounds and nutrients greatly decreased as the depth of sediment increased, indicating that reed roots can absorb β-cyclocitral, β-ionone and nutrients. Furthermore, removing cyanobacteria and dredging sludge might reduce the release of β-cyclocitral and β-ionone.

Topics: Aldehydes; China; Diterpenes; Environmental Monitoring; Eutrophication; Geologic Sediments; Lakes; Norisoprenoids; Water Pollutants, Chemical

The seasonal variations of taste and odor (T&O) compounds in western Lake Chaohu were evaluated from July to December 2013. High values were detected in particulate fractions, with peak values 28.25 ng/L for geosmin (GEO), 45.18 ng/L for dimethyltrisulfide (DMTS), 714.77 ng/L for β-cyclocitral, 11.23 ng/L for β-ionone in surface water, and 14.21 ng/L for GEO, 103.68 ng/L for DMTS, 11.97 ng/L for β-ionone in overlying water, all exceeding their odor thresholds. The maximum off-flavor concentrations in sediment ranged from 2010.76 ng/kg for GEO to 1.7 ng/kg for β-ionone. Positive correlations could be found not only between Anabaena and particulate GEO (r = 0.813, p < 0.01), but also between Microcystis and total β-cyclocitral (r = 0.652, p < 0.01) or β-ionone (r = 0.560, p < 0.01) in surface water. TP, TN, PO4-P, Chl-a and organic matter contributed significantly to the variations of T&O compounds in water or sediment. The cause of the variations of T&O compounds was the accumulation and degradation of cyanobacteria in water rather than nutrient-rich sediment.

Topics: Aldehydes; China; Cyanobacteria; Diterpenes; Environmental Monitoring; Geologic Sediments; Lakes; Naphthols; Norisoprenoids; Odorants; Seasons; Sulfides; Taste; Water Pollutants, Chemical

Ranunculus nipponicus var. submersus is an aquatic macrophyte; it is known as a wild edible plant in Japan for a long time. In this study, the essential oils from the fresh and dried aerial parts of R. nipponicus var. submersus were extracted by hydrodistillation and analyzed by gas chromatography (GC) and GC-mass spectrometry (GC-MS). Moreover, important aroma-active compounds were also detected in the oil using GC-olfactometry (GC-O) and aroma extract dilution analysis (AEDA). Thus, 98 compounds (accounting for 93.86%) of the oil were identified. The major compounds in fresh plant oil were phytol (41.94%), heptadecane (5.92%), and geranyl propionate (5.76%), while those of. Dried plant oil were β-ionone (23.54%), 2-hexenal (8.75%), and dihydrobovolide (4.81%). The fresh and dried oils had the green-floral and citrus-floral odor, respectively. The GC-O and AEDA results show that phenylacetaldehyde (green, floral odor, FD-factor = 8) and β-ionone (violet-floral odor, FD-factor = 8) were the most characteristic odor compounds of the fresh oils. β-Cyclocitral (citrus odor, FD-factor = 64) and β-ionone (violet-floral odor, FD-factor = 64) were the most characteristic odor compounds of the dried oil. These compounds are thought to contribute to the flavor of R. nipponicus var. submersus.

Topics: Acetaldehyde; Aldehydes; Alkanes; Chromatography, Gas; Distillation; Diterpenes; Gas Chromatography-Mass Spectrometry; Indicator Dilution Techniques; Japan; Norisoprenoids; Odorants; Oils, Volatile; Olfactometry; Phytol; Propionates; Ranunculus; Water

Apocarotenoids modulate vital physiological and developmental processes in plants. These molecules are formed by the cleavage of carotenoids, a reaction catalyzed by a family of enzymes called carotenoid cleavage dioxygenases (CCDs). Apocarotenoids like β-ionone and β-cyclocitral have been reported to act as stress signal molecules during high light stress in many plant species. In Crocus sativus, these two apocarotenoids are formed by enzymatic cleavage of β-carotene at 9, 10 and 7, 8 bonds by CsCCD4 enzymes. In the present study three isoforms of CsCCD4 were subjected to molecular modeling and docking analysis to determine their substrate specificity and all the three isoforms displayed high substrate specificity for β-carotene. Further, expression of these three CsCCD4 isoforms investigated in response to various stresses revealed that CsCCD4a and CsCCD4b exhibit enhanced expression in response to dehydration, salt and methylviologen, providing a clue towards their role in mediating plant defense response. This was confirmed by overexpressing CsCCD4b in Arabidopsis. The transgenic plants developed longer roots and possessed higher number of lateral roots. Further, overexpression of CsCCD4b imparted enhanced tolerance to salt, dehydration and oxidative stresses as was evidenced by higher survival rate, increased relative root length and biomass in transgenic plants as compared to wild type. Transgenic plants also displayed higher activity and expression of reactive oxygen species (ROS) metabolizing enzymes. This indicates that β-ionone and β-cyclocitral which are enzymatic products of CsCCD4b may act as stress signals and mediate reprogramming of stress responsive genes which ultimately leads to plant defense.

Topics: Aldehydes; Amino Acid Sequence; Arabidopsis; Base Sequence; beta Carotene; Carotenoids; Crocus; Dehydration; Dioxygenases; Diterpenes; Models, Structural; Molecular Docking Simulation; Norisoprenoids; Oxidative Stress; Phylogeny; Plant Proteins; Plants, Genetically Modified; Reactive Oxygen Species; Sequence Analysis, DNA; Sodium Chloride

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

Apocarotenoid compounds play diverse communication functions in plants, some of them being as hormones, pigments and volatiles. Apocarotenoids are the result of enzymatic cleavage of carotenoids catalyzed by carotenoid cleavage dioxygenase (CCD). The CCD4 family is the largest family of plant CCDs, only present in flowering plants, suggesting a functional diversification associated to the adaptation for specific physiological capacities unique to them. In saffron, two CCD4 genes have been previously isolated from the stigma tissue and related with the generation of specific volatiles involved in the attraction of pollinators. The aim of this study was to identify additional CCD4 members associated with the generation of other carotenoid-derived volatiles during the development of the stigma. The expression of CsCCD4c appears to be restricted to the stigma tissue in saffron and other Crocus species and was correlated with the generation of megastigma-4,6,8-triene. Further, CsCCD4c was up-regulated by wounding, heat, and osmotic stress, suggesting an involvement of its apocarotenoid products in the adaptation of saffron to environmental stresses. The enzymatic activity of CsCCD4c was determined in vivo in Escherichia coli and subsequently in Nicotiana benthamiana by analyzing carotenoids by HPLC-DAD and the volatile products by GC/MS. β-Carotene was shown to be the preferred substrate, being cleaved at the 9,10 (9',10') bonds and generating β-ionone, although β-cyclocitral resulting from a 7,8 (7',8') cleavage activity was also detected at lower levels. Lutein, neoxanthin and violaxanthin levels in Nicotiana leaves were markedly reduced when CsCCD4c is over expressed, suggesting that CsCCD4c recognizes these carotenoids as substrates.

Topics: Aldehydes; Amino Acid Sequence; beta Carotene; Carotenoids; Crocus; Dioxygenases; Diterpenes; Flowers; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Hot Temperature; Isoenzymes; Lutein; Molecular Sequence Data; Multigene Family; Nicotiana; Norisoprenoids; Osmotic Pressure; Phylogeny; Plant Proteins; Plants, Genetically Modified; Sequence Homology, Amino Acid; Stress, Mechanical; Substrate Specificity; Xanthophylls

Off-flavors are among the most troublesome compounds in the environment worldwide. The lack of a viable theory for studying the sources, distribution, and effect of odors has necessitated the accurate measurement of odors from environmental compartments. A rapid and flexible microwave-assisted purge-and-trap extraction device for simultaneously determining five predominant odors, namely, dimethyltrisulfide, 2-methylisoborneol, geosmin, β-cyclocitral and β-ionone, from the primary sources and sinks is demonstrated. This instrument facilitates the extraction and concentration of odors from quite different matrices simultaneously. This device is a solvent-free automated system that does not require cleaning and is timesaving. The calibration curves of the five odor compounds showed good linearity in the range of 1-500 ng/L, with correlation coefficients above 0.999 (levels=7) and with residuals ranging from approximately 77% to 104%. The limits of detection (S/N=3) were below 0.15 ng/L in algae sample and 0.07 ng/g in sediment and fish tissue samples. The relative standard deviations were between 2.65% and 7.29% (n=6). Thus the proposed design is ready for rapid translation into a standard analytical tool and is useful for multiple applications in the analysis of off-flavors.

Topics: Aldehydes; Animals; Camphanes; Chemical Fractionation; Chlorophyta; Diterpenes; Equipment Design; Fishes; Gas Chromatography-Mass Spectrometry; Geologic Sediments; Limit of Detection; Linear Models; Microwaves; Naphthols; Norisoprenoids; Odorants; Reproducibility of Results

Production and fate of taste and odor (T&O) compounds in natural waters are a pressing environmental issue. Simultaneous determination of these complex compounds (covering a wide range of boiling points) has been difficult. A simple and sensitive method for the determination of eight malodors products of cyanobacterial blooms was developed using automatic purge and trap (P&T) coupled with gas chromatography-mass spectrometry (GC-MS). This extraction and concentration technique is solvent-free. Dimethylsulfide (DMS), dimethyltrisulfide (DMTS), 2-isopropyl-3-methoxypyrazine (IPMP), 2-isobutyl-3-methoxypyrazine (IBMP), 2-methylisoborneol (MIB), β-cyclocitral, geosmin (GSM) and β-ionone were separated within 15.3 min. P&T uses trap #07 and high-purity nitrogen purge gas. The calibration curves of the eight odors show good linearity in the range of 1-500 ng/L with a correlation coefficient above 0.999 (levels=8) and with residuals ranging from approximately 83% to 124%. The limits of detection (LOD) (S/N=3) are all below 1.5 ng/L that of GSM is even lower at 0.08 ng/L. The relative standard deviations (RSD) are between 3.38% and 8.59% (n=5) and recoveries of the analytes from water samples of a eutrophic lake are between 80.54% and 114.91%. This method could be widely employed for monitoring these eight odors in natural waters.

Topics: Adsorption; Aldehydes; Camphanes; Diterpenes; Eutrophication; Fresh Water; Gas Chromatography-Mass Spectrometry; Naphthols; Norisoprenoids; Odorants; Pyrazines; Reproducibility of Results; Sensitivity and Specificity; Sulfides; Temperature

Tomatoes contain high levels of several carotenoids including lycopene and β-carotene. Beyond their functions as colorants and nutrients, carotenoids are precursors for important volatile flavor compounds. In order to assess the importance of apocarotenoid volatiles in flavor perception and acceptability, we conducted sensory evaluations of near-isogenic carotenoid biosynthetic mutants and their parent, Ailsa Craig.. The carotenoid contents of these tomatoes were extremely low in the r mutant, increased in lycopene in old gold, and higher in tetra-cis-lycopene and ζ-carotene in tangerine. The volatiles derived from these carotenoids (β-ionone, geranylacetone and 6-methyl-5-hepten-2-one) were proportionally altered relative to their precursors. Fruits were also analyzed for soluble solids, sugars, acids and flavor volatiles. Consumer panels rated the r mutant lowest for all sensory attributes, while Ailsa Craig was generally rated highest. Old gold and tangerine were rated intermediate in two of the three harvests.. Several chemicals were negatively correlated with at least one of the hedonic scores while several others were positively correlated with tomato flavor acceptability. The results permitted identification of positive and negative interactions of volatiles with tomato flavor.

Topics: Adolescent; Adult; Aldehydes; Carotenoids; Consumer Behavior; Diterpenes; Female; Food Preferences; Fruit; Humans; Lycopene; Male; Mutation; Norisoprenoids; Principal Component Analysis; Sensation; Solanum lycopersicum; Taste Perception; Volatile Organic Compounds; Young Adult; zeta Carotene

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

One of bacteria collected from Lake Sagami, Japan, Brevibacillus sp., was found to have a lytic activity of cyanobacteria, but did not produce active compounds. Instead, the co-culturing of Microcystis with the Brevibacillus sp. enhanced the production of two volatile compounds, beta-cyclocitral and 3-methyl-1-butanol, and the former had a characteristic lytic activity. It was confirmed that these volatile compounds were derived from the cyanobacteria themselves. beta-Ionone, geosmin and 2-methylisoborneol derived from cyanobacteria and similar volatile compounds, terpenoids, produced by plants also had a lytic activity. The minimum inhibitory concentration values of the cyanobacterial metabolites were estimated to be higher than those of compounds from plants except for a few compounds. Among them, beta-cyclocitral only produced a characteristic color change of culture broth from green to blue. This color change is similar to the phenomenon observed when a sudden decline in growth of cyanobacteria begins in a natural environment.

Topics: Aldehydes; Bacteriolysis; Camphanes; Cyanobacteria; Diterpenes; Japan; Molecular Structure; Naphthols; Norisoprenoids; Organic Chemicals; Pentanols; Terpenes; Volatilization

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