Geosmin Concentrations Research Articles

Accumulation and Release of Geosmin during the Growth Phases of Anabaena circinalis (Kutz.) Rabenhorst

Anabaena circinalis (Kutz.) Rabenhorst was isolated during a taste and odor episode characterized by high concentrations of geosmin, with raw water containing up to 45 ng geosmin/L. This species has been successfully cultured with sustained geosmin synthesis on both sterile river water and defined medium. Gas chromatography of cellular extracts and closed-loop stripping of growth media indicated that this organism produces geosmin and not 2-methylisoborneol (MIB). With cultures we examined the changes in cell-associated geosmin, chlorophyll and released geosmin during exponential and stationary growth phases of Anabaena. Cell-associated geosmin samples were collected daily from cultures and filtered onto a polycarbonate filter, extracted in acetone, and quantified by capillary gas Chromatograph using flame ionization detection. Media-associated geosmin was quantified from algae-free filtrates from each culture concentrated by closed-loop stripping and analyzed as above. Cell-associated geosmin averaged at 8 × 10−6 ng geosmin/cell in the exponential phase and dropped to 2.5 × 10−6 ng geosmin/cell in the stationary phase of growth. The loss in cell-associated geosmin was accompanied by an increase in geosmin released into the media. Media-associated geosmin reached 12 ng/mL in the stationary phase. Apparently cell lysis in the stationary phase caused the release of cell-associated geosmin into the media. Cell-associated geosmin was closely correlated with filament number (average r2 from 4 experiments =0.96) during the exponential growth phase and was correlated with chlorophyll a (average r2 from 3 experiments =0.95).

Geosmin and 2-Methylisoborneol Production by Cyanobacteria in Fish Ponds in the Southeastern United States

Levels of geosmin and 2-methylisoborneol and composition of phytoplankton communities were determined for water samples collected from 35 fish ponds at Auburn, Alabama, and 34 ponds in west-central Mississippi. In Auburn ponds, geosmin levels ranged from 0.05 to 8.9 µg/l but 2-methylisoborneol was never detected. Highest geosmin concentrations were measured in ponds with plankton blooms dominated by Anabaena species with straight trichomes. In Mississippi ponds, 2-methylisoborneol levels ranged from 0.05 to 76 µg/l. Highest 2-methylisoborneol concentrations were associated with blooms of Oscillatoria cf. chalybea, a cyanobacterium that produces 2-methylisoborneol in unialgal culture. Geosmin was found infrequently in Mississippi pond waters; geosmin levels ranging from 0.05 to 6.25 µg/l could be associated with blooms of Anabaena spiroides, and always concurred with 2-methylisoborneol concentrations ranging from 0.45 to 3.25 µg/l. Neither geosmin nor 2-methylisoborneol at either location could be associated with phytoplankton blooms of Aphanizomenon flos-aquae, Oscillatoria agardhii, Raphidiopsis brookii, or Microcystis aeruginosa.

A Comparison of 1988-1990 Flavor Profile Analysis Results with Water Conditions in Two Northern California Reservoirs

Flavor Profile Analysis (FPA) results were compared with water quality data for two storage reservoirs of the East Bay Municipal Utility District in Oakland, California to determine what conditions exist at the time of an earthy or musty taste and odor episode. Strong musty and earthy aromas coincided most frequently with fall Anabaena sp. blooms and summer Anacystis sp. blooms. Occasional Aphanizomenon sp. blooms were concurrent with Anabaena sp. blooms, so odor problems associated with Aphanizomenon sp. could not be distinguished. Geosmin concentrations of 30-140 ng/L were found in water containing 100,000-300,000 Anabaena sp. cells/100 mL, but 2-methylisoborneol concentrations never exceeded 25 ng/L. Both reservoirs experienced relatively odorless large spring diatom blooms resulting in high chlorophyll a concentrations, so chlorophyll a alone did not serve as a helpful indicator of imminent odor problems. Fall cyanobacteria blooms closely followed the onset of reservoir destratification, so weekly temperature and dissolved oxygen depth profiles successfully predicted the start of a cyanobacteria bloom. Musty and earthy odors in the filter plant effluent were lower than those in the influent, but effluent FPA numbers reached 4 during two large taste and odor episodes, suggesting that granular activated carbon installed 1-2 years earlier may not remove all odor-causing compounds of a large taste and odor episode.

Geosmin Production by Cyanobacteria (Blue‐green Algae) in Fish Ponds at Auburn, Alabama

AbstractStudies on production of geosmin, the compound responsible for earthy‐muddy flavor in water and fish, were carried out at the Auburn University Fisheries Research Station. Water was collected from ponds during 44 cyanobacterial bloom periods from April to September. Geosmin (trans‐1, 10‐dimethyl‐trans‐9‐decalol) was detected at levels averaging 4.77 μg/L when Anabaena species with straight trichomes were predominant. Lower geosmin concentrations were associated with blooms of Anabaena species with coiled trichomes, Microcystis aeruginosa, and Aphanizomenon flos‐aquae, and averaged 0.24, 0.12, and 0.07 μg/L, respectively. Study of four Anabaena blooms over a period of 4–8 weeks showed that changes in geosmin were correlated significantly with changes in trichome abundance. Geosmin disappeared from the water in seven days when Anabaena died. Comparison of geosmin concentrations in raw and filtered water showed that, on average, 90% of the geosmin could be associated with the particulate fraction. Dissolved geosmin concentrations ranged from 0.07–0.85 μg/L.

Variation of geosmin content in Anabaena cells and its relation to nitrogen utilization

The addition of the proper amount of ammonium to the culture medium containing nitrate as nitrogen source enhanced the growth rate of Anabaena viguieri. The amount of geosmin produced by these cells varied with the concentrations of ammonium added. A negative correlation between the amount of geosmin produced and of the growth rate of cells was revealed. This was also found in cells grown on various forms of nitrogen sources. Without supply of any nitrogen compound, this organism is capable of fixing gaseous nitrogen, and under these conditions the cells grew relatively slowly. However, they produced more geosmin (per unit protein mass) than cells grown in the presence of combined nitrogen. The isolation of heterocysts, in which nitrogen was fixed, showed that these cells produced higher amounts of geosmin than vegetative cells. The possible relation of nitrogen assimilation to the production of geosmin in the cells was discussed.

DETERMINATION OF ORGANIC COMPOUNDS IN WATER USING INHIBITORY EFFECT ON THE LUMINOL-HYDROGEN PEROXIDE-PEROXODISULFATE CHEMILUMINESCENCE REACTION

A simple and rapid method for the determination of such organic compounds as geosmin, 2-methylisoborneol (2-MIB) was investigated by chemiluminescence method. Luminol-hydrogen peroxide-potassium peroxodisulfate co-oxidation system in alkaline solution was adopted as chemiluminescence reaction. The chemiluminescence intensity was clearly decreased with an increase in concentration of geosmin and 2-MIB

Methodology for Quantification of Geosmin and Levels in Rangia Clam (Rangia cuneata)

ABSTRACTThe concentration of geosmin was determined in freshly dredged and 2‐wk relayed rangia clam (Rangia cuneata) samples in different seasons of the year. Vacuum distillation/solvent extraction using an internal standard was followed by multiple‐level standard addition gas chromatography/selective ion monitoring mass spectrometry. Most coefficients of variation were lower than 10%. On a dry‐weight basis, the geosmin level in dredged clams was highest (343 ng/g) in August and averaged 51.6 ng/g in other months. A 52% reduction of geosmin was found after two week relaying during the period of May‐June. However, only 1% reduction of geosmin was observed during February‐March.

The Relationship between Concentration and Sensory Properties of 2-Methylisoborneol and Geosmin in Drinking Water

The study of the relations between the senses of smell and taste and odorant concentration is important for the solution of odor problems. The threshold concentrations of odor and taste (TOC, TTC) of 2-methylisoborneol (MIB) and geosmin were measured by the non-forced choice triangle method using 12-20 panelists. Both TOC and TTC were found to be functions of water temperature and the concentration of residual chlorine. The TOC and TTC of mixed samples were rather lower than the concentrations calculated from the mixing ratio. The sensitivities of the consumer panel and the number of musty odor complaints from consumers are related to MIB or geosmin concentration. The ratio of the number of complaints to MIB (or geosmin) concentration decreased after maximum complaint, but the sensitivity of the consumer panel remained the same.

Occurrence of Musty Odor in the Yodo River

Geosmin and 2-methylisoborneol (MIB) for the past seven years have been responsible for the occurrence of musty odors in Lake Biwa. These odorous compounds are present in the water either in solution or in a form attached to or sited in the body of the responsible cyanobacteria. The concentration of geosmin was found to decrease during its passage through the river. However, MIB was not affected. During the water shortage period of the summer of 1985, the concentration of geosmin was found to increase downstream of the Yodo river. This was attributed to a regrowth of Anabaenamacrospora caused by stagnation of the water in this region.

Effect of Environmental Factors on Geosmin Production by Fischerella Muscicola

The production of geosmin by axenic cultures of Fischerellamuscicola (ATCC 29114) was analysed by gas chromatography and mass spectrometry. A methanol based extraction procedure preceding closed loop stripping was successfully applied for quantitative analysis. The major part of geosmin produced by this cyanobacterium was bound in the cells. Less than 1% of the total geosmin was released. The content of geosmin in cells varied with culture conditions. Higher concentrations (based on protein amount) were observed in lag phase cultures and under anaerobic growth conditions. The synthesis of geosmin was temperature dependent showing minimum percentage concentrations at the optimum growth temperature (30°C). Heat shock treatment at 47°C did not affect the subsequent production of geosmin.

Effect of Chelating Agents on the Growth of Blue-Green Algae and the Release of Geosmin

The effect of chelating agents on the growth of Anabaenamacrospora, a planktonic blue-green algae, and on its production of geosmin was studied. When A.macrospora was cultured in CT medium containing EDTA (an artificial chelator), the maximum cell numbers were about 1×106 cells/ml. However, in an EDTA-free CT medium, the maximum cell numbers were a tenth of the normal growth level in the complete medium. In addition the chlorophyll-a content was reduced almost a fourth and the color of the algal cell bodies changed from green to yellow. These results showed that growth of this alga in a chelator-free medium was not healthy. At this time, though the geosmin content was constant and in the same range of 1.0-4.0×10−5 ng/cell as in the complete medium, the ratio of the extracellular geosmin concentration in the medium to the gross concentration was 2:10 to 3:10 and 2 to 3 times its normal level. It was considered that the deterioration of alga's physiological condition increased the release of geosmin to the medium. These results suggested that the extracellular concentration of geosmin produced by A.macrospora was affected by the alga's physiological condition. Finally EDTA can be substituted by humic acid. When this alga was grown in a medium containing humic acid instead of EDTA, the maximum cell numbers and the release ratio of geosmin was of the same level as in the case of the complete medium.

Transient states of geosmin, pigments, carbohydrates and proteins in continuous cultures of Oscillatoria brevis induced by changes in nitrogen supply

Transitions in the growth limiting factor from light (I) to nitrogen (N) and vice versa caused changes in geosmin production, protein and carbohydrate content, and the synthesis of pigments such as chlorophyll a (Chl a), phycobiliproteins (PBPs), and β-carotene of the cyanobacterium Oscillatoria brevis. Following I→N transition the first 150h, the decrease in protein content was compensated for by an increase of carbohydrates, and thereby, a constant biomass level was maintained in this period. Thereafter, biimass dropped to 15% of its initial level. A decrease in geosmin and pigment content was observed during transition from I→N-limited growth. However, geosmin increased relative to phytol (Chl a) and β-carotene which may indicate that a lowered demand for phytol and β-carotene during N-limited growth allows isoprenoid precursors to be directed to geosmin rather than to pigment synthesis. Synthesis of Chl a and β-carotene at the expense of geosmin was suggested for the observed start of increase in geosmin production only at the time that Chl a and β-carotene had reached their I-limited steady state. Transition from nitrogen to light limited growth caused an acceleration of metabolism shown by a rapid decrease in carbohydrate content accompanied by an increase in protein content. The growth rate of the organisms temporarily exceeded the dilution rate of the culture and the biomass level increased 6-fold. Due to the only modest changes in geosmin production (2-fold) compared to changes in biomass level (6-fold) during I-or N-limited growth, environmental factors seem to have limited effect on geosmin production.

Factors Influencing Geosmin Production by the Cyanobacterium Oscillatoria Brevis

Environmental factors affecting geosmin production by Oscillatoria brevis have been investigated under laboratory conditions using continuous culture techniques. Transition from light to nutrient limited growth conditions caused a two-fold decrease in geosmin production. However, geosmin content increased relative to pigment content (chlorophyll a and carotenoids). It has been suggested that geosmin biosynthesis in O. brevis proceeds via the isoprenoid pathway as was found in actinomycetes. Accordingly, we investigated the effect of inhibitors of the intermediate stages in this synthetic pathway in order to study the regulation of geosmin production in relation to pigment synthesis. It was concluded that geosmin seemed to function as an overflow metabolite in this pathway. Due to the only modest changes in geosmin production per dry weight compared to changes in biomass levels during light- or nutrient limited growth, contamination of eutrophic fresh waters with geosmin appears to depend mainly on the species present and its biomass level and only to a limited extent on nutrient enhanced synthesis.

Evaluation of Bacillus as a practical means for degradation of geosmin

A specific method for analysis of geosmin in bacterial cultures was developed which used a minimum of manipulation. Strains of Bacillus cereus, previously reported to degrade geosmin, were tested for their ability to degrade synthetic geosmin. The initial concentration of geosmin in media was not appreciably changed by the growth of the Bacillus strains. The natural isomer of geosmin was also tested with one of these strains and was not degraded. Previous evidence for the degradation of geosmin by Bacillus is discussed critically.

Production and degradation of geosmin in a stratified lake with anaerobic hypolimnion (Schleinsee)

Depth profiles of geosmin concentrations were determined over the year in a stratified lake with anaerobic hypolimnion. Two independent sources of geosmin were observed. Most geosmin was produced under anaerobic conditions in the hypolimnion in the autumn. A much smaller source of geosmin production was actinomycetes in the epilimnion. With the onset of the autumnal circulation of the water body, rapid aerobic degradation of geosmin was observed.

Production and degradation of geosmin in a stratified lake with anaerobic hypolimnion (Schleinsee)

Depth profiles of geosmin concentrations were determined over the year in a stratified lake with anaerobic hypolimnion. Two independent sources of geosmin were observed. Most geosmin was produced under anaerobic conditions in the hypolimnion in the autumn. A much smaller source of geosmin production was actinomycetes in the epilimnion. With the onset of the autumnal circulation of the water body, rapid aerobic degradation of geosmin was observed.

Cause of musty flavor in pond-cultured penaeid shrimp

In 1983, pond-cultured penaeid shrimp imported into the United States from culture ponds in Ecuador were found to have an intense earthy-musty flavor which made them unmarketable. High concentrations of geosmin ( trans, 1,10-dimethyl-9-decalol), a musty odorous compound, were found in the tail muscle of the shrimp. The level of geosmin, 78 μg/kg muscle, was much higher than levels found in earthy-musty flavored freshwater channel catfish from culture ponds in the United States, which is around 9.8 mg/kg. Cause of the rare occurrence of off-flavor in the shrimp is hypothesized to be reduction in salinity in the coastal culture ponds which allowed growth of geosmin-producing blue-green algae.

Identification of Taste and Odour Compounds from Western Lake Ontario

Abstract During August, 1983 geosmin was identified in a municipal water supply drawn from western Lake Ontario. The geosmin concentrations were 0.01-0.07 μg L-1, within the range for threshold odour concentration of 0.01-0.2 μg L-1. 2-Methylisoborneol was not detected. The odour 'event' coincided with a dieoff of Cladophora in the lake, but we were not able to establish a direct link between the dieoff and geosmin production. Decomposing Cladophora in shoreline areas produced a strong odour in the air. 3-Methylindole, elemental sulfur, dimethyl tetrasulfide, and dimethyl pentasulfide were tentatively identified in water samples collected from these areas, but geosmin and 2-methylisoborneol were not detected.

SENSORY EVALUATION OF GEOSMIN IN JUICE MADE FROM COOKED BEETS

ABSTRACTA selected panel was used to determine the odor threshold of geosmin [trans‐1, 10‐dimethyl‐trans‐(9)decalol], an important aroma constituent of table beets, in juice made from cooked and peeled beets. The estimated threshold of 5.8 parts geosmin in 109 parts beet juice was 35 times higher than the odor threshold of geosmin in water determined by the same panel. Four samples of cooked beet juice containing different levels of geosmin were subsequently ranked according to their characteristic beet‐like aroma. An increase in geosmin content was perceived as an increase in beet‐like aroma up to a 5.8 ng/g concentration of geosmin. Juice made from cooked and peeled beets showed a 56–60% reduction in geosmin content in comparison with juice prepared from raw beets (with geosmin concentration below 5.8 ng/g). Therefore processing may reduce the characteristic aroma of beets.

Effect of maturity, cultivar, field history, and the operations of peeling and coring on the geosmin content of Beta vulgaris

Effect of maturity, cultivar, field history, and the operations of peeling and coring on the geosmin content of Beta vulgaris