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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. [ABSTRACT FROM AUTHOR]

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 odor (T&O) compounds have emerged as crucial parameters for assessing water quality. Therefore, identifying effective methodologies for the removal of these compounds is imperative. In this study, an effective approach utilizing laccase assisted by a micro-electric field was developed for the degradation of 2-methylisoborneol (2-MIB). For this purpose, the optimal conditions for the laccase-catalyzed degradation of 2-MIB were determined, and they were pH 4.0, 25 °C, 150 rpm, 0.1 U/mL of laccase, and 200 ng/L of 2-MIB. Under these specified conditions, the degradation efficiency of 2-MIB was approximately 78% after a 4 h reaction period. Subsequently, the introduction of an electric field yielded a synergistic effect with the enzyme for 2-MIB degradation. At an electric current intensity of 0.04 A over a 4 h duration, the degradation efficiency increased to 90.78%. An analysis using SPME-GC/MS provided information on the degradation intermediates of 2-MIB resulting from laccase-catalyzed degradation, electrocatalytic degradation, and micro-electric-assisted laccase degradation. The potential degradation pathways of 2-MIB illustrated that these three methods result in common degradation products, such as capric aldehyde, nonylaldehyde, and 2-ethylhexanol, and their final products include 3-pentanone, acetone, and 2-butanone. This study provides an enzyme–electrochemical method for the efficient and rapid degradation and removal of 2-MIB. The strategy of laccase catalysis assisted by a micro-electric field has good potential for the removal of pollutants from the natural environment. [ABSTRACT FROM AUTHOR]

The presence of the odorant 2-methylisoborneol (2-MIB) in drinking water sources is undesirable. Although 2-MIB production is known to be influenced by temperature, its regulation at the gene level and its relationship with Chlorophyll-a (Chl-a) at different temperatures remain unclear. This study investigates the impact of temperature on 2-MIB production and related gene expression in Pseudanabaena strains PD34 and PD35 isolated from Lake Paldang, South Korea. The strains were cultured at three temperatures (15, 25, and 30 °C) to examine cell growth, 2-MIB production, and mic gene expression levels. 2-MIB production per cell increased with higher temperatures, whereas mic gene expression levels were higher at lower temperatures, indicating a complex regulatory mechanism involving post-transcriptional and enzyme kinetics factors. Additionally, the relationship between Chl-a and 2-MIB involved in metabolic competition was analyzed, suggesting that high temperatures appear to favor 2-MIB synthesis more than Chl-a synthesis. The distinct difference in the total amount of the two products and the proportion of 2-MIB between the two strains partially explains the variations in 2-MIB production. These findings highlight the significant effect of temperature on 2-MIB biosynthesis in Pseudanabaena and provide a valuable background for gene data-based approaches to manage issues regarding 2-MIB in aquatic environments. [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]

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]

Following blood meals or questing bouts, hard ticks (Ixodidae) must locate moist off-host microhabitats as refuge. Soil-dwelling fungi, including entomopathogenic Beauveria bassiana (Bb), thrive in moist microhabitats. Working with six species of ixodid ticks in olfactometer bioassays, we tested the hypothesis that ticks avoid Bb. Contrary to our prediction, nearly all ticks sought, rather than avoided, Bb-inoculated substrates. In further bioassays with female black-legged ticks, Ixodes scapularis, ticks oriented towards both harmful Bb and harmless soil-dwelling fungi, implying that fungi—regardless of their pathogenicity—signal habitat suitability to ticks. Only accessible Bb-inoculated substrate appealed to ticks, indicating that they sense Bb or its metabolites by contact chemoreception. Bb-inoculated substrate required ≥24 h of incubation before it appealed to ticks, suggesting that they respond to Bb metabolites rather than to Bb itself. Similarly, ticks responded to Bb-inoculated and incubated cellulose but not to sterile cellulose, indicating that Bb detection by ticks hinges on the Bb metabolism of cellulose. 2-Methylisoborneol—a common fungal metabolite with elevated presence in disturbed soils—strongly deterred ticks. Off-host ticks that avoid disturbed soil may lower their risk of physical injury. Synthetic 2-methylisoborneol could become a commercial tick repellent, provided its repellency extends to ticks in diverse taxa. [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.

Taste and odor (T&O) compounds have emerged as crucial parameters for assessing water quality. Therefore, identifying effective methodologies for the removal of these compounds is imperative. In this study, an effective approach utilizing laccase assisted by a micro-electric field was developed for the degradation of 2-methylisoborneol (2-MIB). For this purpose, the optimal conditions for the laccase-catalyzed degradation of 2-MIB were determined, and they were pH 4.0, 25 °C, 150 rpm, 0.1 U/mL of laccase, and 200 ng/L of 2-MIB. Under these specified conditions, the degradation efficiency of 2-MIB was approximately 78% after a 4 h reaction period. Subsequently, the introduction of an electric field yielded a synergistic effect with the enzyme for 2-MIB degradation. At an electric current intensity of 0.04 A over a 4 h duration, the degradation efficiency increased to 90.78%. An analysis using SPME-GC/MS provided information on the degradation intermediates of 2-MIB resulting from laccase-catalyzed degradation, electrocatalytic degradation, and micro-electric-assisted laccase degradation. The potential degradation pathways of 2-MIB illustrated that these three methods result in common degradation products, such as capric aldehyde, nonylaldehyde, and 2-ethylhexanol, and their final products include 3-pentanone, acetone, and 2-butanone. This study provides an enzyme–electrochemical method for the efficient and rapid degradation and removal of 2-MIB. The strategy of laccase catalysis assisted by a micro-electric field has good potential for the removal of pollutants from the natural environment.

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]

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]

High concentrations of 2-methylisoborneol (2-MIB) were reported during winter in the Paldang reservoir and North Han River, South Korea. The causes of the unusual taste and odor problems in the regulated river-reservoir system were not understood; however, a short-term solution is to flush out 2-MIB-rich water to secure water sources for over 20 million people. Approximately 150 million tons of water was released from upstream dams for 12 days (late November to early December 2018) to reduce the elevated levels of 2-MIB. Simultaneously, the spatio-temporal variations of the measured concentration of sample 2-MIB from five sites were simulated using a multi-dimensional hydrodynamics-based solute transport model to monitor the flushing effect. A modified environmental fluid dynamics code (EFDC) was adopted as the primary model framework. Five scenarios on the kinetic constants related to the characteristics of 2-MIB transport and behavior, such as conservative, net decay, and net production, were applied, and the results were compared. We found that the simulation errors on the elapsed times to satisfy the Korean drinking water monitoring standard (≤20 ngL−1) were smallest with the conservative dye transport option, indicating that the physical and biochemical characteristics of 2-MIB may not play an essential role. [ABSTRACT FROM AUTHOR]

2-methylisoborneol (2-MIB), a secondary metabolite produced by cyanobacteria, often causes a musty odour in water, threatening the safety of drinking water supplies. This study investigated the effects of the growth phases on the production of 2-MIB by Pseudanabaena. The effects of cell characteristics on the production and release of 2-MIB were also explored. The total 2-MIB concentration increased during the exponential phase and decreased during the declining phase, which was consistent with the changes in cell density. However, the total 2-MIB yield (1.12–1.27 fg cell−1) of Pseudanabaena did not significantly differ throughout the growth cycle (p > 0.05). Meanwhile, the extracellular 2-MIB yield increased significantly from 0.31 fg cell−1 in the exponential phase to 0.76 fg cell−1 in the declining phase (p < 0.05), and the corresponding proportion of extracellular 2-MIB improved from 25.13% to 59.16% (p < 0.05). The surge in extracellular 2-MIB during the declining phase could be attributed to the breaking of the Pseudanabaena filament, as indicated by the decrease in Dmean during cell ageing. The findings of this study contribute to a more inclusive comprehension and management of musty odour issues resulting from cyanobacteria in the water supply.

The presence of the odorant 2-methylisoborneol (2-MIB) in drinking water sources is undesirable. Although 2-MIB production is known to be influenced by temperature, its regulation at the gene level and its relationship with Chlorophyll-a (Chl-a) at different temperatures remain unclear. This study investigates the impact of temperature on 2-MIB production and related gene expression in Pseudanabaena strains PD34 and PD35 isolated from Lake Paldang, South Korea. The strains were cultured at three temperatures (15, 25, and 30 °C) to examine cell growth, 2-MIB production, and mic gene expression levels. 2-MIB production per cell increased with higher temperatures, whereas mic gene expression levels were higher at lower temperatures, indicating a complex regulatory mechanism involving post-transcriptional and enzyme kinetics factors. Additionally, the relationship between Chl-a and 2-MIB involved in metabolic competition was analyzed, suggesting that high temperatures appear to favor 2-MIB synthesis more than Chl-a synthesis. The distinct difference in the total amount of the two products and the proportion of 2-MIB between the two strains partially explains the variations in 2-MIB production. These findings highlight the significant effect of temperature on 2-MIB biosynthesis in Pseudanabaena and provide a valuable background for gene data-based approaches to manage issues regarding 2-MIB in aquatic environments.

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.

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]

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.;

Following blood meals or questing bouts, hard ticks (Ixodidae) must locate moist off-host microhabitats as refuge. Soil-dwelling fungi, including entomopathogenic Beauveria bassiana (Bb), thrive in moist microhabitats. Working with six species of ixodid ticks in olfactometer bioassays, we tested the hypothesis that ticks avoid Bb. Contrary to our prediction, nearly all ticks sought, rather than avoided, Bb-inoculated substrates. In further bioassays with female black-legged ticks, Ixodes scapularis, ticks oriented towards both harmful Bb and harmless soil-dwelling fungi, implying that fungi—regardless of their pathogenicity—signal habitat suitability to ticks. Only accessible Bb-inoculated substrate appealed to ticks, indicating that they sense Bb or its metabolites by contact chemoreception. Bb-inoculated substrate required ≥24 h of incubation before it appealed to ticks, suggesting that they respond to Bb metabolites rather than to Bb itself. Similarly, ticks responded to Bb-inoculated and incubated cellulose but not to sterile cellulose, indicating that Bb detection by ticks hinges on the Bb metabolism of cellulose. 2-Methylisoborneol—a common fungal metabolite with elevated presence in disturbed soils—strongly deterred ticks. Off-host ticks that avoid disturbed soil may lower their risk of physical injury. Synthetic 2-methylisoborneol could become a commercial tick repellent, provided its repellency extends to ticks in diverse taxa.

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]

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]

2‐Methylisoborneol is a widespread musty odourant that is produced by many bacteria including actinomycetes, cyanobacteria and myxobacteria. Two 2‐methylisoborneol synthases (MIBS) that are phylogenetically distant to the known enzyme from Streptomyces coelicolor were found to be highly active for 2‐methylisoborneol biosynthesis. Based on the enzyme structure and on an amino acid sequence alignment, the MIBS from S. coelicolor was extensively studied through site‐directed mutagenesis. [ABSTRACT FROM AUTHOR]

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.

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]

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]

• Planktothricoides is the primary contributor to 2-MIB production. • Hydrometeorological factors are significant for the succession of MIB-producing cyanobacteria. • Nutrient concentration is the main reason for the difference of 2-MIB between algae and macrophyte dominated lakes. The proliferation of filamentous cyanobacteria in lakes can result in the generation of odor-causing compounds, predominantly 2-methylisoborneol (2-MIB), which pose odor-related challenges. In an effort to elucidate the spatiotemporal dynamics of 2-MIB and related influencing factors in East Lake Taihu, monthly investigations were undertaken from April 2022 to March 2023. In addition to the monthly survey, a whole-lake survey was conducted during the high-temperature period from July to September. The monthly survey revealed a distinct unimodal fluctuation in the concentration of 2-MIB in East Lake Taihu, with an average concentration at 297.0 ng/L during the high-temperature period. During the high-temperature period, the filamentous cyanobacterial communities detected in East Lake Taihu consisted primarily of species belonging to genera Leptolyngbya, Oscillatoria, Planktothricoides , and Pseudanabaena. However, no significant correlations were found between their densities and 2-MIB concentration. In addition, the mic gene was predominantly detected in genera Pseudanabaena and Planktothricoides , with the latter being the primary contributor to 2-MIB production. Furthermore, a succession of cyanobacteria capable of producing 2-MIB was detected, with water temperature and radiation intensity being identified as the primary driving factors. The temporal variation of 2-MIB concentration within East Lake Taihu during the whole year was primarily modulated by factors such as water temperature, water transparency, dissolved oxygen, and chlorophyll- a. During the high-temperature period, the 2-MIB concentration in the alga-dominated zone of East Lake Taihu was approximately 1.7 times greater than that in the macrophyte-dominated zone, with nutrient and transparency being identified as the main influencing factors. Consequently, our findings are of great significance for monitoring the sources and variation of 2-MIB in shallow lakes, providing a scientific foundation and theoretical guidance for odor management. [Display omitted] [ABSTRACT FROM AUTHOR]

High concentrations of 2-methylisoborneol (2-MIB) were reported during winter in the Paldang reservoir and North Han River, South Korea. The causes of the unusual taste and odor problems in the regulated river-reservoir system were not understood; however, a short-term solution is to flush out 2-MIB-rich water to secure water sources for over 20 million people. Approximately 150 million tons of water was released from upstream dams for 12 days (late November to early December 2018) to reduce the elevated levels of 2-MIB. Simultaneously, the spatio-temporal variations of the measured concentration of sample 2-MIB from five sites were simulated using a multi-dimensional hydrodynamics-based solute transport model to monitor the flushing effect. A modified environmental fluid dynamics code (EFDC) was adopted as the primary model framework. Five scenarios on the kinetic constants related to the characteristics of 2-MIB transport and behavior, such as conservative, net decay, and net production, were applied, and the results were compared. We found that the simulation errors on the elapsed times to satisfy the Korean drinking water monitoring standard (≤20 ngL−1) were smallest with the conservative dye transport option, indicating that the physical and biochemical characteristics of 2-MIB may not play an essential role.

Integrated constructed wetland-reservoirs (referred to as CW-Rs) are being built for ensuring drinking water supply in plain areas where the source water often cannot meet the quality criteria for drinking water. CW-Rs consist of a series of treatment units and have been reported to reduce the concentration of major nutrients. The efficiency of CW-Rs in mitigating odor compounds and their producer(s) remains largely unclear. In this study, Yanlonghu CW-R located in Jiangsu province, eastern China, was selected to monitor the occurrence and dynamics of 2-methylisoborneol (2-MIB). Two peaks of 2-MIB, attributed mainly to Pseudanabaena in April, and Pseudanabaena and Oscillatoria in July, were observed. This indicated that benthic Oscillatoria is also a threatening factor and should be considered. The concentrations of 2-MIB at the inlet and outlet were 9.75 and 50.08 ng/L in April and 73.11 and 25.21 ng/L in July, respectively. Yanlonghu CW-R was reported to be effective in reducing the content of major nutrients (total phosphorus in particular) throughout the year. In addition, it was effective in mitigating the levels of 2-MIB-producers/2-MIB during the summer season. It is proposed that qPCR for mic gene detection can be performed to screen and establish an early warning method. We revealed that the 2-MIB episode is related to the function of the CW-R, which is shown to be different from what is known in lakes or reservoirs. It is emphasized that each treatment unit of CW-R should be maintained at full capacity so that the frequency and hazardous effects caused by 2-MIB in the system can be controlled or reduced. This finding is implicated in the control strategy selection and contributes to the better management and improvement of future applications. [ABSTRACT FROM AUTHOR]

Water users consider the safety of water according to its aesthetic properties, primarily taste and odour. Geosmin (GEO) and 2-methylisoborneol (MIB) are the most common taste and odour compounds in freshwaters which cause an earthy and musty odour in water. Since human nose can detect these compounds in concentrations as low as 10 ng/L, it is essential to monitor drinking waters before consumer complaints and to produce a timely solution. Therefore, it is necessary to identify GEO and MIB producers to manage the problem at its source. Cyanobacteria are one of the main producers of these compounds in freshwater ecosystems. In this study, we analyzed 13 samples (9 cyanobacteria cultures from Bafa Lake, Elmalı Dam Lake, İznik Lake, Küçükçekmece Lake, Manyas Lake and Taşkısığı Lake, and 4 environmental water samples from Erfelek and Günpınar Waterfalls and Ömerli Dam Lake) for GEO and MIB production by HS-SPME (Head space-solid phase microextraction) coupled with GC-MS (gas chromatography-mass spectrometry). The presence of Cyanobacteria-specific GEO and MIB synthase genes were also analyzed by PCR (Polymerase Chain Reaction). Taste and odour production was confirmed in 2 samples by GC-MS while 4 samples yielded positive results by PCR. All positive samples were environmental samples (3 samples from waterfalls from Günpınar and Erfelek Waterfalls, 1 sample from Ömerli Dam Lake -a drinking water reservoir) which were dominated by Nostoc Vaucher ex Bornet amp; Flahault, Phormidium Kützing ex Gomont and Pseudanabaena Lauterborn. This is the first report of GEO and MIB producing cyanobacteria in Turkish freshwaters by combining microscopy, analytical and molecular techniques.

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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.

Known as the smell of earth after rain, geosmin is an odorous terpene detectable by humans at picomolar concentrations. Geosmin production is heavily conserved in actinobacteria, myxobacteria, cyanobacteria, and some fungi, but its biological activity is poorly understood. We theorized that geosmin was an aposematic signal used to indicate the unpalatability of toxin-producing microbes, discouraging predation by eukaryotes. Consistent with this hypothesis, we found that geosmin altered the behavior of the bacteriophagous nematode Caenorhabditis elegans on agar plates in the absence of bacteria. Normal movement was restored in mutant worms lacking differentiated ASE (amphid neurons, single ciliated endings) neurons, suggesting that geosmin is a taste detected by the nematodal gustatory system. In a predation assay, geosmin and the related terpene 2-methylisoborneol reduced grazing on the bacterium Streptomyces coelicolor. Predation was restored by the removal of both terpene biosynthetic pathways or the introduction of C. elegans that lacked differentiated ASE taste neurons, leading to the apparent death of both bacteria and worms. While geosmin and 2-methylisoborneol appeared to be nontoxic, grazing triggered bacterial sporulation and the production of actinorhodin, a pigment coproduced with a number of toxic metabolites. In this system, geosmin thus appears to act as a warning signal indicating the unpalatability of its producers and reducing predation in a manner that benefits predator and prey. This suggests that molecular signaling may affect microbial predator-prey interactions in a manner similar to that of the well-studied visual markers of poisonous animal prey. [ABSTRACT FROM AUTHOR]

Water is vital for mammals. Yet, as ephemeral sources can be difficult to find, it raises the question, how do mammals locate water? Elephants (Loxodonta africana) are water-dependent herbivores that possess exceptional olfactory capabilities, and it has been suggested that they may locate water via smell. However, there is no evidence to support this claim. To explore this, we performed two olfactory choice experiments with semi-tame elephants. In the first, we tested whether elephants could locate water using olfactory cues alone. For this, we used water from two natural dams and a drinking trough utilised by the elephants. Distilled water acted as a control. In the second, we explored whether elephants could detect three key volatile organic compounds (VOCs) commonly associated with water (geosmin, 2-methylisoborneol, and dimethyl sulphide). We found that the elephants could locate water olfactorily, but not the distilled water. Moreover, they were also able to detect the three VOCs associated with water. However, these VOCs were not in the odour profiles of the water sources in our experiments. This suggests that the elephants were either able to detect the unique odour profiles of the different water sources or used other VOCs that they associate with water. Ultimately, our findings indicate that elephants can locate water olfactorily at small spatial scales, but the extent to which they, and other mammals, can detect water over larger scales (e.g. km) remains unclear. [ABSTRACT FROM AUTHOR]

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.

Water users consider the safety of water according to its aesthetic properties, primarily taste and odour. Geosmin (GEO) and 2-methylisoborneol (MIB) are the most common taste and odour compounds in freshwaters which cause an earthy and musty odour in water. Since human nose can detect these compounds in concentrations as low as 10 ng/L, it is essential to monitor drinking waters before consumer complaints and to produce a timely solution. Therefore, it is necessary to identify GEO and MIB producers to manage the problem at its source. Cyanobacteria are one of the main producers of these compounds in freshwater ecosystems. In this study, we analyzed 13 samples (9 cyanobacteria cultures from Bafa Lake, Elmalı Dam Lake, İznik Lake, Küçükçekmece Lake, Manyas Lake and Taşkısığı Lake, and 4 environmental water samples from Erfelek and Günpınar Waterfalls and Ömerli Dam Lake) for GEO and MIB production by HS-SPME (Head space-solid phase microextraction) coupled with GC-MS (gas chromatography-mass spectrometry). The presence of Cyanobacteriaspecific GEO and MIB synthase genes were also analyzed by PCR (Polymerase Chain Reaction). Taste and odour production was confirmed in 2 samples by GC-MS while 4 samples yielded positive results by PCR. All positive samples were environmental samples (3 samples from waterfalls from Günpınar and Erfelek Waterfalls, 1 sample from Ömerli Dam Lake -a drinking water reservoir) which were dominated by Nostoc Vaucher ex Bornet & Flahault, Phormidium Kützing ex Gomont and Pseudanabaena Lauterborn. This is the first report of GEO and MIB producing cyanobacteria in Turkish freshwaters by combining microscopy, analytical and molecular techniques. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

2-Methylisoborneol (2-MIB) is the primary cause of the earthy and musty odor produced by cyanobacteria, which deteriorates the quality of fishery products and tap water. Despite the need for controlling outbreaks, few studies have been conducted on 2-MIB in brackish lakes, where capture fisheries are active. This study examined the association between water quality and the outbreak of 2-MIB in a brackish lake using statistical analysis of long-term monitoring data and developed forecasting models for 2-MIB outbreaks. We investigated Lake Ogawara, which is a brackish lake with a cool-temperate climate in Japan, where 2-MIB outbreaks frequently occur between August and December. Logistic regression analyses were performed using the outbreak or non-outbreak of 2-MIB (2-MIB(+ / −)) as the dependent variable and water quality parameters as the independent variables. The results suggested that the density of 2-MIB-producing cyanobacteria was higher when (1) dissolved inorganic nitrogen concentrations were low under the relaxation of phosphorus limitation and/or (2) salinity or micronutrient concentrations were high. In addition, we successfully developed forecasting models with a high predictive power that determined 2-MIB(+ / −) in August–December using only two water quality parameters: dissolved inorganic phosphate and pH in April and total nitrogen/total phosphorous and salinity in May. [ABSTRACT FROM AUTHOR]

[Display omitted] • The removal of 2-MIB by NF mainly depends on size exclusion. • NOM in raw water facilitates the removal of 2-MIB by NF. • The interactions of NOM and 2-MIB are hydrogen bond and hydrophobic effect. • In the binding of NOM to 2-MIB, protein-like substances play a major role. • NF270 is capable of virtually eliminating NOM from the water. The presence of natural organic matter (NOM) in surface water and its significance for removing pollutants during nanofiltration (NF) are overlooked since most previous studies were conducted in synthetic water rather than real water. In this paper, using raw water collected from Lake Tai (the third largest lake in China), we investigate the removal of 2-methylisoborneol (2-MIB, one of the most concerned off-flavor compounds in raw water) by NF and analyze the binding behaviors between 2-MIB and NOM, which affect their corresponding migration and removal behaviors of 2-MIB during NF. The results show that the removal of 2-MIB in real raw water is 12.2 ∼ 22.0 % higher than that in pure water (PW). Additionally, we evaluate the increment of the removal of 2-MIB under different backgrounds, which follow the order NOM (17.2 %∼22.0 %) > bovine serum albumin (BSA 16.0 %∼19.1 %) > intracellular organic matter (IOM) of M. aeruginosa (8.3 %∼9.4 %) > sodium carboxymethyl cellulose (CMC 3.9 %∼6.5 %) > humic acid (HA 0.28 %∼0.31 %). These findings demonstrate that the protein-like components in raw water play a major role in binding to 2-MIB, while humic-like components exhibit a weak association with 2-MIB. Overall, the conclusion and findings in this study provide a new perspective on the NOM effect on micropollutant removal during water treatment. [ABSTRACT FROM AUTHOR]

2-methylisoborneol (2-MIB), a secondary metabolite produced by cyanobacteria, often causes a musty odour in water, threatening the safety of drinking water supplies. This study investigated the effects of the growth phases on the production of 2-MIB by Pseudanabaena. The effects of cell characteristics on the production and release of 2-MIB were also explored. The total 2-MIB concentration increased during the exponential phase and decreased during the declining phase, which was consistent with the changes in cell density. However, the total 2-MIB yield (1.12–1.27 fg cell−1) of Pseudanabaena did not significantly differ throughout the growth cycle (p > 0.05). Meanwhile, the extracellular 2-MIB yield increased significantly from 0.31 fg cell−1 in the exponential phase to 0.76 fg cell−1 in the declining phase (p < 0.05), and the corresponding proportion of extracellular 2-MIB improved from 25.13% to 59.16% (p < 0.05). The surge in extracellular 2-MIB during the declining phase could be attributed to the breaking of the Pseudanabaena filament, as indicated by the decrease in D mean during cell ageing. The findings of this study contribute to a more inclusive comprehension and management of musty odour issues resulting from cyanobacteria in the water supply. [Display omitted] • Effects of growth phases on cell characteristics and 2-MIB yield were studied. • Total 2-MIB yield remained stable (1.12–1.27 fg cell−1) in all growth phases. • Extracellular 2-MIB production continued to increase during cell ageing. • Mechanisms of 2-MIB production and release were proposed. [ABSTRACT FROM AUTHOR]

Integrated constructed wetland-reservoirs (referred to as CW-Rs) are being built for ensuring drinking water supply in plain areas where the source water often cannot meet the quality criteria for drinking water. CW-Rs consist of a series of treatment units and have been reported to reduce the concentration of major nutrients. The efficiency of CW-Rs in mitigating odor compounds and their producer(s) remains largely unclear. In this study, Yanlonghu CW-R located in Jiangsu province, eastern China, was selected to monitor the occurrence and dynamics of 2-methylisoborneol (2-MIB). Two peaks of 2-MIB, attributed mainly to Pseudanabaena in April, and Pseudanabaena and Oscillatoria in July, were observed. This indicated that benthic Oscillatoria is also a threatening factor and should be considered. The concentrations of 2-MIB at the inlet and outlet were 9.75 and 50.08 ng/L in April and 73.11 and 25.21 ng/L in July, respectively. Yanlonghu CW-R was reported to be effective in reducing the content of major nutrients (total phosphorus in particular) throughout the year. In addition, it was effective in mitigating the levels of 2-MIB-producers/2-MIB during the summer season. It is proposed that qPCR for mic gene detection can be performed to screen and establish an early warning method. We revealed that the 2-MIB episode is related to the function of the CW-R, which is shown to be different from what is known in lakes or reservoirs. It is emphasized that each treatment unit of CW-R should be maintained at full capacity so that the frequency and hazardous effects caused by 2-MIB in the system can be controlled or reduced. This finding is implicated in the control strategy selection and contributes to the better management and improvement of future applications.

The exposure to geosmin (GSM) and 2-methylisoborneol (2-MIB) in water has caused a negative impact on product reputation and customer distrust. The occurrence of these compounds and their metabolites during drinking water treatment processes has caused different health challenges. Conventional treatment techniques such as coagulation, sedimentation, filtration, and chlorination employed in removing these two commonest taste and odor compounds (GSM and 2-MIB) were found to be ineffective and inherent shortcomings. The removal of GSM and MIB were found to be effective using combination of activated carbon and ozonation; however, high treatment cost associated with ozonation technique and poor regeneration efficiency of activated carbon constitute serious setback to the combined system. Other shortcoming of the activated carbon adsorption and ozonation include low adsorption efficiency due to the presence of natural organic matter and humic acid. In light of this background, the review is focused on the sources, effects, environmental pathways, detection, and removal techniques of 2-MIB and GSM from aqueous media. Although advanced oxidation processes (AOPs) were found to be promising to remove the two compounds from water but accompanied with different challenges. Herein, to fill the knowledge gap analysis on these algal metabolites (GSM and 2-MIB), the integration of treatment processes vis-a-viz combination of one or more AOPs with other conventional methods are considered logical to remove these odorous compounds and hence could improve overall water quality. [ABSTRACT FROM AUTHOR]

Objective: To establishe an analysis and identification method for 2-methylisoborneol(2-MIB) and geosmin(GSM) in water using purge and trap-gas chromatography-mass spectrometry., Methods: The samples were enriched and analyzed using a purge and trap system, followed by the separation on a DB-624(30 m×0.25 mm, 1.4 μm) chromatographic column. Quantification was performed using gas chromatography-mass spectrometry with the selected ion monitoring and internal standard calibration., Results: The calibration curves for 2-MIB and GSM showed an excellent linearity in the range of 1 to 100 ng/L with R~2 values greater than 0.999. The detection limit and quantification limit for both 2-MIB and GSM were 0.33 ng/L and 1.0 ng/L, respectively. Spike recovery experiments were further carried on the source water and drinking water at three concentration levels. It showed that the average recoveries were from 82.0% to 111.0% for 2-MIB while 84.0% to 110% for GSM. Additionally, the test precision of 2-MIB and GSM ranged from 1.9% to 7.3% and 1.9% to 5.0%(n=6), respectively. The analysis of multiple samples including the local source water, treated water and distribution network water confirmed the existence of 2-MIB and GSM., Conclusion: Compared to the national standard(GB/T 5750.8-2023), the proposed method enables fully automated sample introduction and analysis without the extra pre-treatment. It provides the advantages of simplicity, good repeatability and high accuracy.