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Drinking water quality and the commercial value of aquatic items are both significantly impacted by odor molecules like 2-methylisoborneol (2-MIB) and geosmin (GSM). Many investigations have been conducted to identify the microorganisms involved in the synthesis of 2-MIB and GSM. However, few studies have attempted to identify potential degradation factors in the natural environment. Here, pathway analysis of the relationship between water quality parameters and the distribution of odor compounds in water bodies led to a more significant connection (p < 0.05) between total nitrogen, total phosphorus, chemical oxygen demand, and salinity in water bodies for the distribution of their odor compounds. Salinity among them exhibited the strongest connection and had a direct impact. The establishment of a larger spatial scale statistical research method, mainly using the water environment with different salinities formed in different geographical areas, and the distribution of odor compounds in this water body as a research vehicle helped to find the most concise relationship between the two variables. The results show that the concentration of odor compounds is lower in waters with higher salinity, which proves the negative correlation between the two. The results of this study provide a theoretical basis for solving the problem of odorous pollutants in water bodies, with the aim of improving the utilization of water resources more effectively and, secondly, leading to a new guiding direction for the conservation and exploitation of impact plains and mudflats. [ABSTRACT FROM AUTHOR]

Taste and odour episodes associated with geosmin and 2-methylisoborneol (MIB) produced by Cyanobacteria are common problems affecting drinking water supplies. However, it is difficult to find the source and species responsible for taste and odour production. The aim of this study was to investigate the effect of temperature, one of the most important environmental factors, on the growth and odour production of Microcoleus sp. MCAS-MC01 and compare the results with those of two other odour-producing cyanobacteria (Oscillatoria sp. UHCC 0332 and Phormidium sp. NIVA-CYA 7) isolated and kept in culture collections from geographically different areas. Microcoleus sp. MCASMC01 is a newly isolated geosmin and MIB producer from Türkiye. After complaints arose from consumers in a nearby city, samples were taken and a cyanobacterium, Microcoleus sp., was isolated from the samples and grown in Z8 medium. Experiments were conducted at 20℃ and 25℃ for 10 weeks, and the growth and MIB-geosmin concentrations of cultures were monitored weekly. The geosmin concentration reached a maximum 65.73 μg/l and the maximum MIB concentration was 626.65 μg/l in the study. Higher temperature had a significant positive effect on MIB levels in Microcoleus sp. MCAS-MC01 and geosmin levels in Phormidium sp. NIVA-CYA7 (p<0.05). On the other hand, the temperature did not affect the growth of all three strains (p>0.05). The results showed that taste and odour problems are species-specific, and in some species, they are stimulated by an increase in temperature. This study contributes to the understanding of taste and odour problems in relation to temperature. [ABSTRACT FROM AUTHOR]

The escalating proliferation of cyanobacteria poses significant taste and odor (T/O) challenges, impacting freshwater ecosystems, public health, and water treatment costs. We examined monthly variations in four T/O compounds from September 2011 to August 2012 in Chaohu Lake's eastern drinking water source (DECL). More importantly, we compared the reported T/O occurrence and the related factors in freshwater bodies worldwide. The assessment of T/O issues indicated a severe and widespread problem, with many cases surpassing odor threshold values. Remarkably, China reported the highest frequency and severity of odor-related problems. A temporal analysis revealed variations in odor occurrences within the same water body across different years, emphasizing the need to consider high values in all seasons for water safety. Globally, T/O issues were widespread, demanding attention to variations within the same water body and across different layers. Algae were crucial contributors to odor compounds, necessitating targeted interventions due to diverse odorant sources and properties. A correlation analysis alone lacked definitive answers, emphasizing the essential role of further validation, such as algae isolation. Nutrients are likely to have influenced the T/O, as GSM and MIB correlated positively with nitrate and ammonia nitrogen in DECL, resulting in proposed control recommendations. This study offers recommendations for freshwater ecosystem management and serves as a foundation for future research and management strategies to address T/O challenges. [ABSTRACT FROM AUTHOR]

(-)-Geosmin has high demand in perfumes and cosmetic products for its earthy congenial aroma. The current production of (-)-geosmin is either by distillation of sun-baked soil or by inefficient chemical synthesis because of the presence of multiple chiral centers. Fermentation processes are not viable as the titers of the Streptomyces sp. based processes are low. This work presents an alternative route by the heterologous synthesis of (-)-geosmin in Saccharomyces cerevisiae. The enzyme involved is the bifunctional geosmin synthase that catalyzes the conversion of farnesyl diphosphate to germacradienol and germacradienol to geosmin. This study evaluated the activity of many orthologs of geosmin synthase when expressed heterologously in S. cerevisiae. When the well-characterized CAB41566 from Streptomyces coelicolor origin was tested, germacradienol and germacrene D were detected but no geosmin. Bioinformatic analysis based on high/low identities to N-terminal and C-terminal domains of CAB41566 was carried out to identify different orthologs of geosmin synthase proteins from different bacterial and fungal origins. ADO68918 of Stigmatella aurantiaca origin showed the best activity among the tested orthologs, not only in terms of geosmin production but also an order of magnitude higher total abundance of the products of geosmin synthase as compared to CAB41566. This study successfully demonstrated the production of (-)-geosmin in S. cerevisiae and offers an alternative, sustainable and environment-friendly approach to producing (-)-geosmin. • Functional expression of geosmin synthase orthologs in Saccharomyces cerevisiae • ADO68918 of Stigmatella aurantiaca showed best germacradienol and geosmin synthesis • Successful production of (-)geosmin in yeast was demonstrated [ABSTRACT FROM AUTHOR]

Concern over safe drinking water has increased. In this study, aluminum oxide was coated with carbon nanotubes by chemical vapor deposition using ethanol or methanol as precursors to remove N-nitrosamines, 2-methylisoborneol (MIB) and geosmin from water. Seven types of N-nitrosamines were investigated. The differences in the surface of the carbon nanotubes were attributed to the carbon precursors ethanol and methanol. Despite the high concentration of analytes, the adsorption capacity of both carbon nanotubes (CNTs) was around 19 mg/mg for MIB and geosmin. Against approximately 0.9 ng/mg for activated carbon. For N-nitrosamines, the adsorption capacity of CNTs reached 50 ng/mg for NDBA, N-nitrosamines with the highest molecular weight, while activated carbon had values below 6.0 ng/mg. The results showed π-π interactions play a dominant role in the adsorption of MIB and geosmin under the investigated conditions. On the other hand, for N-nitrosamines, both dipole-dipole and π-π interactions come into play, with the latter becoming more prominent as the molecular weight of N-nitrosamines increases. The removal efficiencies of CNT-coated aluminum oxide reached 84,0%. The analytes with longer carbon chains were removed more efficiently and CNT-coated aluminum oxide grown from ethanol or methanol had no statistical difference between the removal efficiencies of all evaluated analytes. [ABSTRACT FROM AUTHOR]

Depuration is a proven pre-harvest procedure that eliminates off-flavor from Atlantic salmon produced in recirculating aquaculture systems. However, applied research indicates that depurating salmon lose weight while fasting, which reduces farmgate revenue. Low-ration feeding was therefore evaluated as a method to mitigate weight loss while depurating 3–4 kg Atlantic salmon. Salmon implanted with passive-integrated-transponders were weighed, exposed to concentrated geosmin (GSM) and 2-methylisoborneol (MIB), and stocked in eight pre-disinfected partial reuse systems. Feed was either offered for 4 days or withheld entirely (n = 4) during a 6-day depuration period. Salmon from both treatments rapidly eliminated GSM and MIB, but slightly lower levels remained in fish that were fed (P <.05). Fed and fasted salmon lost 0.3 and 1.1% of their initial body weight, respectively (P <.05). Under the conditions of this study, feeding Atlantic salmon during depuration minimized weight loss without negatively impacting off-flavor elimination. [ABSTRACT FROM AUTHOR]

In order to screen probiotics that can inhibit the growth of Streptomycetes spp. that produces geosmin （GSM） and 2-methylisobcamol （2-MIB） in aquaculture, Streptomyces thermocarboxydus, S. cyaneofuscatus and S. roseoflavus were used as test strains to carry out inhibition experiments, and the screened strains were identified. The results showed that eight strains of probiotics had inhibitory effects on the growth of S. spp., 2 strains of them could inhibit the growth of S. thermocarboxydus and S. roseoflavus, meanwhile, the other 6 strains affected the growth of S. thermocarboxydus. 2 strains belonged to Bacillus licheniformis and 6 strains belonged to B. subtilis. The 8 screened strains can serve as probiotics for preventing and controlling off-flavor, providing theoretical reference and practical basis for biological control and removal of off-flavor in aquaculture. [ABSTRACT FROM AUTHOR]

Numerous utilities encounter issues with taste and odor that alter the public's impression of the safety of drinking water. The creation of certain components in water naturally due to global climate change is another source of taste and odor components, in addition to industrial emissions. Geosmin and 2-methylisoborneol (2-MIB), both of which are generated by blue-green algae and actinomycetes, are two substances that contribute to the musty and earthy smells in drinking water sources. Unfortunately, current conventional treatment plants only partially remove 2-MIB and geosmin. Therefore, to protect the environment and public health, more up-to-date or optimized treatment methods should be applied to outdated treatment facilities. Best treatment practices, evaluation standards, and decision-making approaches, however, are still shrouded in mystery. The goal of this study was to identify the most effective treatment options for 2-MIB and geosmin. By using the analytical hierarchy process (AHP), a total of 22 assessment criteria were found and prioritized. A thorough literature search led to the identification of potential treatment options, and their effectiveness was evaluated. These options and priority rankings were decided upon using AHP in the decision-making process. Advanced oxidation techniques came out on top in the final priority ranking, followed by membrane filtering, adsorption, oxidation, hybrid processes, and traditional treatment methods. The applied analytical decision techniques may also be used to choose the optimal treatment options, even though the results are particular to 2-MIB and geosmin. [ABSTRACT FROM AUTHOR]

Compounds such as 2-methylisoborneol (2-MIB) and geosmin present in the final effluents of wastewater treatment plants may affect water treatment in downstream areas. To reduce the concentrations of 2-MIB and geosmin, we investigated the influence of the returned water from sludge treatment on their concentrations and behaviors during wastewater treatment in the reactor. The inflow of returned water from sludge treatment increased the geosmin concentration in the primary effluent (PE) making it higher than that in the influent. The dissolved 2-MIB concentration in the mixed liquor was higher than that in the PE. However, the geosmin concentration in the mixed liquor tended to be lower than that in the PE as the biological treatment progressed. Laboratory experiments indicated that the 2-MIB and geosmin concentrations varied in the reactor due to their release from activated sludge and removal by aeration and agitation. Our analyses revealed that the return activated sludge substantially impacts 2-MIB concentrations in secondary effluents. Moreover, the geosmin concentration in the reactor decreased, possibly due to removal by aeration and agitation.

The problem of the appearance of odors in drinking water associated with the development of algae and cyanobacteria in reservoirs of drinking water sources is considered. The results of the analysis of information on the main types of organisms that are sources of odorants in drinking water, chemicals produced by them and a description of odors are presented. Most often, the causes of odors in drinking water are the massive development of Aphanizomenon flos-aquae and Oscillatoria agardhii , which are producers of geosmin and 2-methylisoborneol. The classification of hazard levels for water pollution by cyanobacteria and recommended measures, including the frequency of monitoring and sampling, are given. The measures implemented with a decrease in the number of cyanobacteria in reservoirs of drinking water supply sources by physical, chemical and biological methods are presented. Methods of removal of intracellular and extracellular cyanotoxins from drinking water are described. The analysis of the efficiency of removal of various substances with odorizing effect from drinking water is presented.

Contamination by odor substances such as geosmin (GSM) and 2-methylisoborneol (2-MIB) was examined in the cultured water from aquaculture farming in the region of the Hongze Lake in 2022, and some factors influencing residual levels of them in the water were analyzed. Geographically, high concentrations of GSM were located mainly in the north and northeast culture areas of the lake, while those of 2-MIB were found in the northeast and southwest. Analysis of the water in the enclosure culture revealed significant differences in the concentrations of GSM and 2-MIB among the cultured species. The mean concentrations of GSM in culture water were ranked in the order: crab > the four major Chinese carps > silver and bighead carp, and silver and bighead carp > crab > the four major Chinese carps for 2-MIB. The concentration of GSM was significantly higher at 38.99 ± 18.93 ng/L in crab culture water compared to other fish culture water. Significant differences were observed in GSM concentrations between crab enclosure culture and pond culture, while 2-MIB levels were comparable. These findings suggest that cultural management practices significantly affect the generation of odor substances. The taste and odor (T&O) assessment revealed that the residual levels of GSM and 2-MIB in most samples were below the odor threshold concentrations (OTCs), although high levels of GSM and 2-MIB in all water bodies were at 30.9% and 27.5%, respectively. Compared with the corresponding data from other places and the regulation guidelines of Japan, USA, and China, the region in the Hongze Lake is generally classified as a slightly T&O area, capable of supporting the aquaculture production scale. [ABSTRACT FROM AUTHOR]

Geosmin and 2-methylisoborneol (MIB) are the most common causes of unpleasant odours in drinking water. A method was proposed to detect and recognise these compounds in water and determine their concentrations. The method utilises commercial solid-state gas sensors and data analysis. Sample preparation plays an important role. The aqueous solution is converted into a gas sample using a specially designed dynamic headspace. The responses of the sensors are recorded during exposure to headspace vapours in a dynamic mode. The best limit of detection for geosmin, LOD = 6.20 µg/L, was attained with a TGS2602 sensor. The best limit of detection for MIB, LOD = 0.52 µg/L, was attained with a TGS826 sensor. Geosmin and MIB recognition was 100% successful based on TGS826 and TGS2602 response classifications. Geosmin and MIB concentrations were effectively determined in solutions containing one or both compounds. The respective mathematical models utilised the responses of TGS826 and TGS2602. The smallest concentration prediction error was RMSE = 2.19 µg/L (for geosmin) and RMSE = 0.33 µg/L (for MIB). The study demonstrated the application potential of non-specific gas sensors for the early warning monitoring of geosmin and MIB presence in water. Further studies are needed to develop a system that can be tested in field conditions. [ABSTRACT FROM AUTHOR]

To investigate the effect of different C / N on the accumulation of off flavor in biofloc reactor,different initial DOC / DIN(Dissolved organic carbon,DOC:Dissolved inorganic nitrogen,DIN) gradients were set up for group A (no glucose added,C / N of 6),group B (C / N of 10) and group C (C / N of 20) by adding glucose to the bioflocs released from shrimp farming and a 7-day experiment was conducted. Water quality monitoring was carried out everyday. The concentrations of Geosmin (GSM) and 2-Methylisoborneol (2-MIB) in the BFT water were detected at the beginning and end of the experiment and the flocs were taken for nutrient index detection. The results showed that the accumulation of Geosmin (GSM) and 2-Methylisoborneol (2-MIB) was 22. 41 ng / L and -0. 19 ng / L at C / N of 10,which were significantly lower than those in the C / N of 6 group (76. 4 ng / L and 4. 43 ng / L) and C / N of 20 group (50. 98 ng / L and 3. 52 ng / L),respectively; the total ammonia nitrogen and nitrite nitrogen concentrations were lower than 0. 10 mg / L and 0. 15 mg / L,respectively, in all groups during the experiment; the crude protein content of bioflocs was highest at 31. 64 %±0. 22 % at C / N of 10. It was shown that the addition of glucose can effectively reduce the accumulation of GSM and 2-MIB production,and the most effective of reducing the accumulation of GSM and 2-MIB production was achieved when the C / N in the biofloc reactor was 10,as well as having water quality improvement effect. [ABSTRACT FROM AUTHOR]

The escalating proliferation of cyanobacteria poses significant taste and odor (T/O) challenges, impacting freshwater ecosystems, public health, and water treatment costs. We examined monthly variations in four T/O compounds from September 2011 to August 2012 in Chaohu Lake’s eastern drinking water source (DECL). More importantly, we compared the reported T/O occurrence and the related factors in freshwater bodies worldwide. The assessment of T/O issues indicated a severe and widespread problem, with many cases surpassing odor threshold values. Remarkably, China reported the highest frequency and severity of odor-related problems. A temporal analysis revealed variations in odor occurrences within the same water body across different years, emphasizing the need to consider high values in all seasons for water safety. Globally, T/O issues were widespread, demanding attention to variations within the same water body and across different layers. Algae were crucial contributors to odor compounds, necessitating targeted interventions due to diverse odorant sources and properties. A correlation analysis alone lacked definitive answers, emphasizing the essential role of further validation, such as algae isolation. Nutrients are likely to have influenced the T/O, as GSM and MIB correlated positively with nitrate and ammonia nitrogen in DECL, resulting in proposed control recommendations. This study offers recommendations for freshwater ecosystem management and serves as a foundation for future research and management strategies to address T/O challenges.

Every day, more and more consumers choose to drink bottled water instead of tap water, since they believe that it is superior in quality. One of the criteria used by European consumers to choose bottled water is the geographical region of the spring. The flavor of the water is an additional factor that influences consumers’ choices. As a result, determining the flavor of water is gaining popularity and is thus turning into a prominent field of study. However, studies on the potential environmental factors that affect the sensory characteristics of water (i.e., “terroir” of water) are limited. To this end, we investigated the composition of natural mineral water spring from Mount Smolikas in Greece over a two-year period to find any potential alterations in water composition. The physicochemical parameters (pH, conductivity, turbidity, color, and total hardness) of the water samples were examined, along with their content in metal ions, inorganic salts (cations and anions), and total organic carbon. Additionally, the water samples were analyzed for their content of off-odor volatile compounds (i.e., 2-methylisoborneol and geosmin) that can be naturally found in water. The study also examined the correlation of climate conditions (accumulated rainfall and mean temperature) with the parameters above using a principal component analysis and a multivariate correlation analysis. The results showed that the physicochemical characteristics of water samples complied with European regulations. Metals, anions, and cations were all below the corresponding parametric values established by the European Commission. The off-odor organic compounds, 2-methylisoborneol, and geosmin, had average concentrations of 9.4 and 2.7 ng/L, respectively. Chromium and aluminum elevated concentrations might be attributed to specific ores present near the water source, while pH, conductivity, total hardness, nitrates, and off-odor compounds levels could be fluctuated due to local climate conditions. The study revealed a good positive correlation (>0.7) between the quantity of rainfall and the level of potassium cations. Moreover, a strong negative correlation (>0.9) was observed between magnesium cations and the mean temperature of the local area. The study can be used as a benchmark for future studies to determine the terroir of mineral water.

Geosmin is an environmental pollutant that causes off-flavor in water and aquatic products. The high occurrence of geosmin contamination in aquatic systems and aquaculture raises public awareness, however, few studies have investigated the response pathways of geosmin stress on freshwater fish. In this research, grass carp were exposed to 50 μg/L geosmin for 96 h, liver tissue was sequenced and validated using real-time qPCR. In total of 528 up-regulated genes and 488 down-regulated genes were observed, includes cytochrome P450 and uridine diphosphate (UDP)-glucuronosyltransferase related genes. KEGG analysis showed that chemical carcinogenesis-DNA adducts, metabolism of xenobiotics by cytochrome P450, drug metabolism-cytochrome P450 pathway was enriched. Common genes from the target genes of microRNAs and differential expression genes are enriched in metabolism of xenobiotics cytochrome P450 pathway. Two miRNAs (dre-miR-146a and miR-212–3p) down regulated their target genes (LOC127510138 and adh5, respectively) which are enriched cytochrome P450 related pathway. The results present that geosmin is genetoxic to grass carp and indicate that cytochrome P450 system and UDP-glucuronosyltransferase play essential roles in biotransformation of geosmin. MicroRNAs regulate the biotransformation of geosmin by targeting specific genes, which contributes to the development of strategies to manage its negative impacts in both natural and artificial environments.

Freshwater fish grown in earthen ponds in the southeastern US can acquire "earthy" and "musty" taints due to the bioaccumulation of the cyanobacteria metabolites geosmin and 2-methyisoborneol (MIB) in the fish flesh and result in unmarketable fish. Dense cyanobacteria communities occur because nutrient inputs (phosphorus) are high in fish production ponds due to high feed application rates. In this study, hybrid striped bass (Morone chrysops x M. saxatilis) grown in earthen ponds was offered one of the six diets including diets supplemented with phytase to reduce phosphorus input to the pond and the subsequent intention of reducing the abundance of undesirable cyanobacteria. Water samples collected biweekly from each pond were analyzed for phytoplankton community structure and concentrations of geosmin and MIB. Differences in dietary phosphorus consumption among diets did not significantly affect soluble reactive phosphorus and total phosphorus concentrations, cyanobacteria abundance, and geosmin and MIB concentrations in pond water. [ABSTRACT FROM AUTHOR]

The present study aimed to propose a new cause of odorous compounds release, i.e., the presence of antibiotics in water bodies and its toxicity to cyanobacteria, known to be the main producer of geosmin (GEO) and 2-methylisoborneol (2-MIB). Therefore, a literature review was carried out regarding the problems caused by antibiotics in aquatic environment, including cyanobacterial blooms and GEO and 2-MIB release. In addition, a bibliometric analysis was performed using the VOSviewer software based on the results obtained from the Web of Science (WOS) database. This review aims to build a scientific understanding of the problem, presenting interesting points that converge with the proposed association. It is worth mentioning that no work has been found in the literature that has proposed this relationship. Thus, based on the bibliographic survey, observations and information acquired in recent years about cyanobacterial blooms and environmental contamination by pharmaceutical drugs, one of the main causes of an earthy and musty flavour and odour in a drinking water supply is the toxicity imposed by the presence of antibiotics in aquatic environments on cyanobacteria. [ABSTRACT FROM AUTHOR]

Every day, more and more consumers choose to drink bottled water instead of tap water, since they believe that it is superior in quality. One of the criteria used by European consumers to choose bottled water is the geographical region of the spring. The flavor of the water is an additional factor that influences consumers' choices. As a result, determining the flavor of water is gaining popularity and is thus turning into a prominent field of study. However, studies on the potential environmental factors that affect the sensory characteristics of water (i.e., "terroir" of water) are limited. To this end, we investigated the composition of natural mineral water spring from Mount Smolikas in Greece over a two-year period to find any potential alterations in water composition. The physicochemical parameters (pH, conductivity, turbidity, color, and total hardness) of the water samples were examined, along with their content in metal ions, inorganic salts (cations and anions), and total organic carbon. Additionally, the water samples were analyzed for their content of off-odor volatile compounds (i.e., 2-methylisoborneol and geosmin) that can be naturally found in water. The study also examined the correlation of climate conditions (accumulated rainfall and mean temperature) with the parameters above using a principal component analysis and a multivariate correlation analysis. The results showed that the physicochemical characteristics of water samples complied with European regulations. Metals, anions, and cations were all below the corresponding parametric values established by the European Commission. The off-odor organic compounds, 2-methylisoborneol, and geosmin, had average concentrations of 9.4 and 2.7 ng/L, respectively. Chromium and aluminum elevated concentrations might be attributed to specific ores present near the water source, while pH, conductivity, total hardness, nitrates, and off-odor compounds levels could be fluctuated due to local climate conditions. The study revealed a good positive correlation (>0.7) between the quantity of rainfall and the level of potassium cations. Moreover, a strong negative correlation (>0.9) was observed between magnesium cations and the mean temperature of the local area. The study can be used as a benchmark for future studies to determine the terroir of mineral water. [ABSTRACT FROM AUTHOR]

Alert levels can be established using baseline data to trigger action in source water management and/or water treatment. [ABSTRACT FROM AUTHOR]

Cyanobacteria can exist in water resources and produce odorants. 2-Methylisoborneol (2-MIB) and geosmin are the main odorant compounds affecting the drinking water quality in reservoirs. In this study, encoding genes 2-MIB (mic, monoterpene cyclase) and geosmin (geo, putative geosmin synthase) were investigated using newly developed primers for quantitative PCR (qPCR). Gene copy numbers were compared to 2-MIB/geosmin concentrations and cyanobacterial cell abundance. Samples were collected between July and October 2020, from four drinking water sites in South Korea. The results showed similar trends in three parameters, although the changes in the 2-MIB/geosmin concentrations followed the changes in the mic/geo copy numbers more closely than the cyanobacterial cell abundances. The number of odorant gene copies decreased from upstream to downstream. Regression analysis revealed a strong positive linear correlation between gene copy number and odorant concentration for mic (R2 = 0.8478) and geo (R2 = 0.601). In the analysis of several environmental parameters, only water temperature was positively correlated with both mic and geo. Our results demonstrated the feasibility of monitoring 2-MIB/geosmin occurrence using qPCR of their respective synthase genes. Odorant-producing, gene-based qPCR monitoring studies may contribute to improving drinking water quality management. [ABSTRACT FROM AUTHOR]

Paldang Lake in the Han River system is an important source for supplying drinking water. Recently, the occurrence of odor compounds geosmin and 2-methylisoborneol (2-MIB), in Lake Paldang has adversely affected the drinking water supply. The causative organisms of odor compounds have not been identified. Thus, this study analyzed the correlation between odor compounds and microorganisms and identified the odor-producing microorganisms in the Han River system. Odor compounds were primarily detected in the Bukhan River system but not in the Namhan River system. Geosmin was detected at high concentrations in summer, whereas 2-MIB was detected at high concentrations in summer and autumn. Microorganisms that appeared at the time of geosmin occurrence were actinobacteria (0.317, p < 0.01) and Dolichospermum (0.326, p < 0.01) among cyanobacteria, and the correlation was significant. The occurrence of 2-MIB mainly coincided with actinobacteria (0.745, p < 0.01) and Pseudanabaena (0.321, p < 0.01) among cyanobacteria, and the correlation was significant. Therefore, to manage the odor compounds in Lake Paldang, which is a drinking water source, it is important to control the appearance of actinobacteria and cyanobacteria in the Bukhan River system. HIGHLIGHTS The generation of odor substances in Paldang Lake, the source of drinking water, was greatly influenced by the Bukhan River.; Geosmin positively correlated with Dolichopermum and Actinobacteria.; 2-MIB positively correlated with Pseudanabaena and Actinobacteria.; For the management of odor compounds in Lake Paldang, the drinking water source, it is important to identify the appearance of cyanobacteria and actinomycetes.;

Abstract Land‐based Atlantic salmon, Salmo salar, grow‐out facilities utilize depuration to remediate off‐flavor. Water used in this process is either discharged or repurposed as supply water in recirculating aquaculture systems (RAS). Both approaches require an understanding of water quality and waste production for water treatment decisions and compliance with pollution discharge standards; however, these data were lacking. Therefore, a study was carried out to characterize these parameters. To begin, 311 salmon (5–6 kg) originally cultured in freshwater RAS were stocked at 100 kg/m3 in an 18 m3 depuration tank. Feed was withheld 1 day before transfer and throughout the 7‐day study period. Hours after stocking, total suspended solids (TSS), total phosphorus (TP), and total ammonia nitrogen (TAN) levels spiked, and concentrations declined thereafter. Delta TSS and TP were negligible by the end of the trial; however, TAN plateaued, indicating that salmon began to catabolize somatic tissue in the absence of feeding. Geosmin and 2‐methylisoboreol levels in water and fish were low throughout the study. This research indicates that residual waste production occurs while depurating Atlantic salmon. Procedural refinements and recommendations were gleaned including locality for introducing depuration system water within RAS and extension of the feed withholding period before depuration.

A novel liquid phase microextraction method based on solvent oil droplets was optimized and validated for sample pretreatment of algal odorous metabolites (i.e., 2-Methylisoborneol, Geosmin, etc.) in drinking water supplies prior to gas chromatography. Segregation and condensation are based on the diffusion of solvent oil micro drops as an extracting solvent in the sample solution (drinking water supplies) and then back extraction of the analytes to another organic solvent, which is a three-phase direct immersion type of LPME. The important variables influencing the microextraction procedure such as type and volume of extracting oil and back extracting solvent, time and temperature of extraction, and ionic strength were optimized separately. Under optimal conditions, the correlation coefficient, limits of detection, linear dynamic ranges, preconcentration factors, and precision of the method were evaluated. The method displayed a high linearity range for the analytes (R2 ≥ 0.9808–0.9959), low limit of detection (0.03–3.01 μg L−1), and a good linear dynamic range (0.08–50 μg L−1). The precision comprised of reproducibility and repeatability were evaluated by computing the relative standard deviation (RSD %), which was ranged as 3.48–3.87%. Consequently, the optimized method along with the GC-FID method was successfully extracted the algal metabolites from water samples, with satisfactory recoveries (94–97%). [ABSTRACT FROM AUTHOR]

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Environmental context: Everyone is familiar with the earth odour that comes from digging in the soil. We measured the chemicals comprising this odour and studied how the environment influences how much of these chemicals are released from disturbed soils. Understanding what conditions affect emission of these compounds from soils could provide new technologies for remotely assessing soil health and what people are doing to soils. Rationale: Earth scent is the odour emitted from soils. This scent, primarily comprising the alcohols geosmin and 2-methylisoborneol (MIB), has not been fully characterised, but offers high potential for use as an environmental interrogation tool. Methodology: We utilised our field-based, solid-phase microextraction fibre method to test the hypothesis that soil activity and soil property variation can be detected in situ by comparing biogenic volatile emissions. Results: We eliminated sources of error utilising field-based sampling with these fibres, concluding that room temperature storage for up to 7 days is acceptable with minimal loss. Variation in individual fibre affinity for both compounds was higher than expected but no measured concentrations were observed to constitute outliers. Disturbance of minor soil volumes led to significantly higher emission of both compounds over background levels. Soil texture and soil cover had a significant effect on the emission of both compounds. Simulated rainfall, producing the characteristic odour known as petrichor, initiates elevated emission of geosmin. Background (undisturbed soil) concentrations of MIB were occasionally detectable during some sampling events, but geosmin concentrations in the air were always below detection limits without soil disturbance. Virtually all background and disturbed soil samples contained much higher concentrations of MIB compared to geosmin, but geosmin variation between replicates and experimental units was much lower. Discussion: Soil disturbance and soil property variation can be remotely detected using emission of volatile compounds. Correlating emission from the soil with respect to disturbance events and environmental properties could yield a powerful new tool for acquiring soil information. Mechanical disturbance increases emission of two biogenic alcohols from soils. Mechanical disturbance increases emission of two biogenic alcohols from soils. Environmental context. Everyone is familiar with the earth odour that comes from digging in the soil. We measured the chemicals comprising this odour and studied how the environment influences how much of these chemicals are released from disturbed soils. Understanding what conditions affect emission of these compounds from soils could provide new technologies for remotely assessing soil health and what people are doing to soils. [ABSTRACT FROM AUTHOR]

We determined the concentrations of 2-methylisoborneol (2-MIB) and geosmin in final effluent from wastewater treatment plants in Kyoto City, Japan, investigating variations during treatment. The concentrations of 2-MIB and geosmin in final effluent were 5.1-29.8 and 3.9-13.9 ng/L, respectively. Geosmin concentrations in primary effluent were higher than those in influent. The concentration of 2-MIB increased in the reactors, while that of geosmin decreased. The anaerobic-anoxic-oxic and step-feed biological nitrogen removal processes lowered 2-MIB and geosmin concentrations more than did the anaerobic-oxic activated sludge process. Other factors regulating the concentrations of earthy and musty odor compounds may include activated sludge flowing from the secondary settling tank, changes in total nitrogen removal efficiency, anaerobic conditions in reactors or secondary settling tanks, and deterioration of activated sludge, including by formation of a scum layer.

To develop a sensitive and specific ELISA for geosmin (GSM), the research of this study is focused on the design and synthesis of several GSM derivatives, which maintain the whole GSM structure as much as possible and contain a spacer arm with an active group at the end. To form the GSM backbone, tandem organic reaction strategies were used to replace the traditional Robinson cyclization reaction. Five GSM derivatives were synthesized and the formed GSM derivative-protein conjugates were used as the immunogens for the production of polyclonal antibodies against GSM, while four GSM derivatives were synthesized and the GSM derivative-protein conjugates were used as coating antigens for establishing ELISA. The relationship between the structures of GSM derivatives and the antibody properties was explored. Under optimal conditions, the LOD of the ELISA for GSM was found to be 0.16 ng mL−1, and the antiserum was able to specifically recognize the GSM backbone.

Cyanobacteria commonly form large blooms in waterbodies; they can produce cyanotoxins, with toxic effects on humans and animals, and volatile compounds, causing bad tastes and odors (T&O) at naturally occurring low concentrations. Notwithstanding the large amount of literature on either cyanotoxins or T&O, no review has focused on them at the same time. The present review critically evaluates the recent literature on cyanotoxins and T&O compounds (geosmin, 2-methylisoborneol, β-ionone and β-cyclocitral) to identify research gaps on harmful exposure of humans and animals to both metabolite classes. T&O and cyanotoxins production can be due to the same or common to different cyanobacterial species/strains, with the additional possibility of T&O production by non-cyanobacterial species. The few environmental studies on the co-occurrence of these two groups of metabolites are not sufficient to understand if and how they can co-vary, or influence each other, perhaps stimulating cyanotoxin production. Therefore, T&Os cannot reliably serve as early warning surrogates for cyanotoxins. The scarce data on T&O toxicity seem to indicate a low health risk (but the inhalation of β-cyclocitral deserves more study). However, no data are available on the effects of combined exposure to mixtures of cyanotoxins and T&O compounds and to combinations of T&O compounds; therefore, whether the co-occurrence of cyanotoxins and T&O compounds is a health issue remains an open question. [ABSTRACT FROM AUTHOR]

The removal of four Contaminants of Emerging Concern, namely bisphenol A, sulfamethoxazole, diclofenac and benzotriazole; two odorous compounds, geosmin and 2-methylisoborneol, frequently detected in recirculating aquaculture systems; and Hg(II) was investigated using ZnO-based materials doped or co-doped with Ce and Cu under simulated solar radiation. Photocatalysts were synthetized via a hydrothermal route and their efficiency was assessed by changing some operational parameters in different water matrices of increasing complexity. The mixture of contaminants was successfully degraded in just 1 h, while the complete mineralization was achieved in a few hours; experiments performed in an actual aquaculture water confirmed the efficiency and broad versatility of the synthesized materials. [ABSTRACT FROM AUTHOR]

A 12‐event survey of 8 water treatment plants (WTPs) was conducted to determine the impact of the 2021 summer (January) to winter (August) cyanobacterial challenge on WTP performance. High cyanobacterial numbers (>20,000 cells/mL) and high taste and odor (T&O) concentrations (>100 ng/L) were encountered. The summer to winter transition of this cyanobacterial challenge also saw the proliferation of Pseudanabaena blooms which challenged conventional WTPs and a breakthrough of cells was detected. This required further investigation into optimizing Pseudanabaena removal in WTP processes. WTP sampling determined that the sludge lagoons provided conducive conditions for cell accumulation and metabolite release. These cells and T&O compounds were recycled back into the head of the WTP through the supernatant return flows. In the most extreme case, 512 ng/L of T&O compounds was detected in the supernatant return. This study highlighted the need to understand the potential risks that treatment plants can encounter and ensure appropriate management during and after cyanobacterial events. [ABSTRACT FROM AUTHOR]

Cyanobacteria continue to contribute to the taste and odor issues (T&O) in the lower River Murray. A review on the cyanobacteria and T&O data collected in the last 22 years showed that there has been a shift in cyanobacterial community and subsequent T&O profiles. The increased numbers and changes in cyanobacteria occurrence have likely influenced the resultant T&O profiles. T&O challenges started occurring more frequently post‐2015. Although the river has historically been affected by geosmin challenges, up to 999 ng/L of geosmin and 155 ng/L of 2‐methylisoborneol (MIB) concentrations that have been detected along the river. Findings from this study showed that of the 22 water treatment plants investigated, the more advanced ultrafiltration membrane and granular activated carbon system treatment plants were able to mitigate most of the T&O challenges whereas the conventional water treatment plants were more likely to have T&O breakthrough instead. [ABSTRACT FROM AUTHOR]

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Drinking water treatment plants (DWTP) use chlorination as an oxidation stage in the first step of the processes used to eliminate the natural organic matter (NOM) responsible for the formation of 2-methylisoborneol (2-MIB) and Geosmin (GM), which produce odor and taste to the water. However, chlorination processes give rise to disinfectant toxic subproducts, such as trihalomethanes (THMs). In this work, a headspace solid-phase microextraction coupled with a gas chromatography/mass spectrometric method has been developed for the quality control of drinking water. 2-MIB, GM, and THMs at different stages of the drinking water treatment process were monitored. The method was validated following the Environmental Protection Agency guidelines. Neither carryover nor the matrix effect was observed. The performance of the method was satisfactory in terms of selectivity, repeatability, and accuracy and exhibited a linear concentration range of 0.8–50 µg/L for trichloromethane (TCM), 0.05–20 µg/L for bromodichloromethane, 0.01–20 µg/L for dibromochloromethane and tribromomethane, and 0.005–0.05 µg/L for GM and 2-MIB. The THMs concentration obtained for all the water samples was below the thresholds established by international organizations and, for 2-MIB and GM, were lower for their limit of quantification. The method was also applied to the adsorption kinetic study of TCM on granulated activated carbon, which is the main barrier to reducing the NOM in DWTP. [ABSTRACT FROM AUTHOR]

Land‐based Atlantic salmon, Salmo salar, grow‐out facilities utilize depuration to remediate off‐flavor. Water used in this process is either discharged or repurposed as supply water in recirculating aquaculture systems (RAS). Both approaches require an understanding of water quality and waste production for water treatment decisions and compliance with pollution discharge standards; however, these data were lacking. Therefore, a study was carried out to characterize these parameters. To begin, 311 salmon (5–6 kg) originally cultured in freshwater RAS were stocked at 100 kg/m3 in an 18 m3 depuration tank. Feed was withheld 1 day before transfer and throughout the 7‐day study period. Hours after stocking, total suspended solids (TSS), total phosphorus (TP), and total ammonia nitrogen (TAN) levels spiked, and concentrations declined thereafter. Delta TSS and TP were negligible by the end of the trial; however, TAN plateaued, indicating that salmon began to catabolize somatic tissue in the absence of feeding. Geosmin and 2‐methylisoboreol levels in water and fish were low throughout the study. This research indicates that residual waste production occurs while depurating Atlantic salmon. Procedural refinements and recommendations were gleaned including locality for introducing depuration system water within RAS and extension of the feed withholding period before depuration. [ABSTRACT FROM AUTHOR]

IntroductionLow temperature is the most common method used to maintain the freshness of Phlebopus portentosus during long-distance transportation. However, there is no information regarding the nutritional changes that occur in P. portentosus preserved postharvest in low temperature.MethodsIn this study, the changes in flavor quality and bioactive components in fruiting bodies stored at 4 °C for different storage periods were determined through LC/MS and GC/MS analyses. Sampling was performed at 0, 3, 5, 7, and 13 days storage.Results and DiscussionBased on the results, the metabolites present in caps and stipes were different at the same period and significantly different after 7 days of storage. A total of 583 and 500 different metabolites were detected in caps and stipes, respectively, and were mainly lipids and lipid-like molecules, organic acids and derivatives, organic oxygen compounds and others. Except for prenol lipids and nucleotides, the expression levels of most metabolites increased with longer storage time. In addition, geosmin was identified as the major contributor to earthy-musty odors, and the level of geosmin was increased when the storage time was short.ConclusionThe variations in these metabolites might cause changes in flavor quality and bioactive components in P. portentosus. Variations in these metabolites were thoroughly analyzed, and the results revealed how storage processes affect the postharvest quality of P. portentosus for the first time.

Geosmin is one of the most common earthy-musty odor compounds, which is mainly produced by Streptomyces. Streptomyces radiopugnans was screened in radiation-polluted soil, which has the potential to overproduce geosmin. However, due to the complex cellular metabolism and regulation mechanism, the phenotypes of S. radiopugnans were hard to investigate. A genome-scale metabolic model of S. radiopugnans named iZDZ767 was constructed. Model iZDZ767 involved 1,411 reactions, 1,399 metabolites, and 767 genes; its gene coverage was 14.1%. Model iZDZ767 could grow on 23 carbon sources and five nitrogen sources, which achieved 82.1% and 83.3% prediction accuracy, respectively. For the essential gene prediction, the accuracy was 97.6%. According to the simulation of model iZDZ767, D-glucose and urea were the best for geosmin fermentation. The culture condition optimization experiments proved that with D-glucose as the carbon source and urea as the nitrogen source (4 g/L), geosmin production could reach 581.6 ng/L. Using the OptForce algorithm, 29 genes were identified as the targets of metabolic engineering modification. With the help of model iZDZ767, the phenotypes of S. radiopugnans could be well resolved. The key targets for geosmin overproduction could also be identified efficiently.

To develop a sensitive and specific ELISA for geosmin (GSM), the research of this study is focused on the design and synthesis of several GSM derivatives, which maintain the whole GSM structure as much as possible and contain a spacer arm with an active group at the end. To form the GSM backbone, tandem organic reaction strategies were used to replace the traditional Robinson cyclization reaction. Five GSM derivatives were synthesized and the formed GSM derivative-protein conjugates were used as the immunogens for the production of polyclonal antibodies against GSM, while four GSM derivatives were synthesized and the GSM derivative-protein conjugates were used as coating antigens for establishing ELISA. The relationship between the structures of GSM derivatives and the antibody properties was explored. Under optimal conditions, the LOD of the ELISA for GSM was found to be 0.16 ng mL−1, and the antiserum was able to specifically recognize the GSM backbone. [ABSTRACT FROM AUTHOR]

Geosmin produced by Streptomyces can cause an earthy off-flavor at trace levels, seriously deteriorating the quality of Chinese liquor. Geosmin was detected during the Daqu (Chinese liquor fermentation starter)-making process, which is a multi-species fermentation process in an open system. Here, biocontrol, using the native microbiota present in Daqu making, was used to control the geosmin contamination. Six native strains were obtained according to their inhibitory effects on Streptomyces and then were inoculated into the Daqu fermentation. After inoculation, the content of geosmin decreased by 34.40% (from 7.18 ± 0.13 μg/kg to 4.71 ± 0.30 μg/kg) in the early stage and by 55.20% (from 8.86 ± 1.54 μg/kg to 3.97 ± 0.78 μg/kg) in the late stage. High-throughput sequencing combined with an interaction network revealed that the fungal community played an important role in the early stage and the correlation between Pichia and Streptomyces changed from the original indirect promotion to direct inhibition after inoculation. This study provides an effective strategy for controlling geosmin contamination in Daqu via precisely regulating microbial communities, as well as highlights the potential of biocontrol for controlling off-flavor chemicals at trace levels in complex fermentation systems. [ABSTRACT FROM AUTHOR]

Cyanobacteria can exist in water resources and produce odorants. 2-Methylisoborneol (2-MIB) and geosmin are the main odorant compounds affecting the drinking water quality in reservoirs. In this study, encoding genes 2-MIB (mic, monoterpene cyclase) and geosmin (geo, putative geosmin synthase) were investigated using newly developed primers for quantitative PCR (qPCR). Gene copy numbers were compared to 2-MIB/geosmin concentrations and cyanobacterial cell abundance. Samples were collected between July and October 2020, from four drinking water sites in South Korea. The results showed similar trends in three parameters, although the changes in the 2-MIB/geosmin concentrations followed the changes in the mic/geo copy numbers more closely than the cyanobacterial cell abundances. The number of odorant gene copies decreased from upstream to downstream. Regression analysis revealed a strong positive linear correlation between gene copy number and odorant concentration for mic (R2 = 0.8478) and geo (R2 = 0.601). In the analysis of several environmental parameters, only water temperature was positively correlated with both mic and geo. Our results demonstrated the feasibility of monitoring 2-MIB/geosmin occurrence using qPCR of their respective synthase genes. Odorant-producing, gene-based qPCR monitoring studies may contribute to improving drinking water quality management.

Porous coordination polymers (PCPs) are porous materials with large specific surface area and pore ume, and are expected to be used as separation materials for environmental pollutants. The aim of this study was to evaluate the applicability of MIL-53(Al), a type of PCP, for the separation of geosmin and 2-MIB. The adsorption performance of MIL-53 (Al) for methylene blue and iodine was determined to be lower than that of activated carbon. The time required for the adsorption of musty odorants by MIL-53(Al) was longer than that by activated carbon, and the final adsorption amount was lower than that by activated carbon. Furthermore, adsorption isotherms for the adsorption of musty odorants by each adsorbent were prepared and their adsorption performance was evaluated. The amount of odorant adsorbed by MIL-53(Al) in pure water was extremely low compared to that of activated carbon. On the other hand, the amount of odorants adsorbed by MIL-53(Al) in raw water for water supply was not much lower than that of activated carbon. This study suggests that adsorbents with uniform pore size, such as MIL-53(Al), are less susceptible to interference by other coexisting substances. This finding may be important for future development of adsorbents for musty odorants.

Members of the phylum Actinomycetota (commonly known as actinomycetes) are the most prominent part of the soil microbiota, more specifically the species within the genus Streptomyces of this phylum. Key functions of Streptomyces species (or streptomycetes in general terms) include nutrient cycling and plant growth promotion and disease protection. However, these species can also produce volatile organic compounds, predominantly geosmin, which is responsible for musty and mildew scents that are unpleasant to humans and can negatively impact the nut crop industry as odorous nuts generally lose their market value. Bacterial viruses, called bacteriophages have been previously used successfully in agriculture and aquaculture to remove such odorous species and they may therefore be applied to the nut industry. To eliminate these compounds, the producer streptomycetes may be selectively removed from nut surfaces using streptophages. The removal of Streptomyces species from nut surfaces can then be expected to minimise geosmin production, therefore removing the unpleasant off-flavours and benefiting the nut industry.

The San Francisco Public Utilities Commission needed a simple yet effective method for screening and training sensory analysts to detect geosmin in drinking water. The result was a modified version of the agency's triangle test, using sets of 40‐mL vials for each participant. [ABSTRACT FROM AUTHOR]

Geosmin, produced by cyanobacteria and actinomycetes, is a common cause of earthy odor in lakes, rivers, and reservoirs. Drinking water quality standards in Japan requires that geosmin concentration be maintained at < 10 ng/L. The concentration of musty/earthy odor compounds in water bodies tends to exhibit a positive correlation with the cell density of cyanobacteria producing these compounds. In general, it is difficult to accurately distinguish and quantify musty/earthy odor-producing cyanobacteria through microscopic observation. Thus, it is essential to develop simple and rapid monitoring methods to assess the abundance of musty/earthy odor-producers and predict the onset of musty odor events to ensure good water quality. In this study, we developed PCR and qPCR-based assays using whole cells to effectively monitor geosmin-producing cyanobacteria using a gene encoding geosmin synthase (geoA). Geosmin-producing cyanobacteria Dolichospermum smithii NIES-824 and Dolichospermum macrosporum were used as representative strains for the study. The brightness of the specific electrophoresis band related to geoA gene amplified using whole-cell PCR was found to be positively correlated (R2 > 0.9) to the cell density of Dolichospermum spp. In addition, the whole-cell qPCR analysis presented a high correlation (R2 > 0.8) as well, between the copy number of geoA gene and cyanobacterial biomass. These results affirm the potential of using whole-cell PCR and qPCR-based detection methods for the rapid prediction and monitoring of geosmin producers in aquatic environments. [ABSTRACT FROM AUTHOR]

Since the 1990s, the raw water of Huangpu River in Shanghai, China, has intermittently encountered off-flavor contamination. In this work, the concentrations of typical odor, geosmin, in raw water of Huangpu River are found to shift along with the seasons. However, microbes recognized as the producer of geosmin such as Cyanobacteria and Actinobacteria are not consistent with the shift of geosmin. Cyanobacteria blooms in summer rather than winter, whereas Actinobacteria thrives in winter. Representational difference analysis (RDA) reveals that microbes associated with blooming algae have positive co-occurrence correlations with the concentrations of geosmin and nutrients in winter, whereas those within Cyanobacteria and Planctomycete are in a positive correlation with temperature and thrive in summer. This causes the concentration of geosmin in raw water to appear to depend on the abundance of Actinobacteria rather than that of Cyanobacteria. However, combining with the synthesis and storage properties of geosmin in algae, as well as the decomposition properties of algae with Actinobacteria, geosmin might be synthesized by Cyanobacteria in summer, which is stored in cells of Cyanobacteria and released only via the decomposition of Actinobacteria in winter. This potential olfactory mechanism of geosmin is quite different from that derived from pure culture of odor producers or correlation analysis of bacteria and odors; thus, providing insights into the mechanism of practical off-flavor events. [ABSTRACT FROM AUTHOR]

Cyanobacterial blooms have become a serious water pollution problem in many parts of the world, and the monitoring and study of the impacts of biotoxins on human health are of vital importance. In this study, the contents of microcystin-LR, 2-methylisoborneol, and geosmin were measured in water and sediment samples from Nanwan Reservoir, China, by means of bimonthly sampling between February and December 2023. The physicochemical and hydrochemical factors and phytoplankton dynamics in the reservoir were also investigated. The results showed that the overall mean concentration of microcystin-LR (0.729 μg/L) in summer approached the guiding standard (1 μg/L) set by the WHO for drinking water. Furthermore, the content of 2-methylisoborneol (143.5 ng/L) was 14 times higher than the national standard (10 ng/L). The results of laboratory cultures showed that lower light levels and medium temperatures were suitable for the growth of Microcystis and Planktothricoides but higher temperatures promoted the synthesis and release of microcystin-LR and 2-methylisoborneol. In addition, the results of co-cultures showed that the growth of Planktothricoides was inhibited by Microcystis . Our results suggest that cyanobacterial bloom and the presence of the metabolites 2-methylisoborneol and microcystin-LR can decrease the drinking water quality of Nanwan Reservoir.