Earthy-smelling substance from a blue-green alga

Safferman, Robert S.; Rosen, A. A.; Mashni, Charles I.; Morris, Mary-Ellen

doi:10.1021/es60005a009

Cited by 98 publications

(35 citation statements)

References 8 publications

(10 reference statements)

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“…While the genes and enzymes for the biosynthesis of compound 2 in bacteria are well described (61,62) and its biosynthesis has been thoroughly studied in feeding experiments (59,63), the corresponding fungal genes and enzymes still await identification. Similarly, the degraded sesquiterpenoid compound 4 was first isolated from a streptomycete (64) and later also reported from cyanobacteria and myxobacteria (41,65). Its biosynthesis was also studied in detail by feeding experiments with isotopically labeled precursors (66), followed by identification of the geosmin synthase (67).…”

Section: Discussionmentioning

confidence: 99%

The AngFus3 Mitogen-Activated Protein Kinase Controls Hyphal Differentiation and Secondary Metabolism in Aspergillus niger

et al. 2015

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cAdaptation to a changing environment is essential for the survival and propagation of sessile organisms, such as plants or fungi. Filamentous fungi commonly respond to a worsening of their growth conditions by differentiation of asexually or sexually produced spores. The formation of these specialized cell types is, however, also triggered as part of the general life cycle by hyphal age or density. Spores typically serve for dispersal and, therefore, translocation but can also act as resting states to endure times of scarcity. Eukaryotic differentiation in response to environmental and self-derived signals is commonly mediated by threetiered mitogen-activated protein (MAP) kinase signaling cascades. Here, we report that the MAP kinase Fus3 of the black mold Aspergillus niger (AngFus3) and its upstream kinase AngSte7 control vegetative spore formation and secondary metabolism. Mutants lacking these kinases are defective in conidium induction in response to hyphal density but are fully competent in starvation-induced sporulation, indicating that conidiation in A. niger is triggered by various independent signals. In addition, the mutants exhibit an altered profile of volatile metabolites and secrete dark pigments into the growth medium, suggesting a dysregulation of the secondary metabolism. By assigning the AngFus3 MAP kinase pathway to the transduction of a potentially selfderived trigger, this work contributes to the unraveling of the intricate signaling networks controlling fungal differentiation. Moreover, our data further support earlier observations that differentiation and secondary metabolism are tightly linked in filamentous fungi.G rowth and propagation of filamentous fungi typically involve the differentiation of specialized cell types or multicellular structures, such as spores, spore-bearing hyphae, and fruiting bodies, which serve specific biological functions. Differentiation of sexual and vegetative spores, for example, allows the dispersal and, therefore, translocation of otherwise sessile fungi. In addition, spores commonly function as resting structures to endure hostile growth conditions, such as wintertime or droughts. The induction of fungal differentiation usually involves both internal and external signals. For example, conidiation in the red bread mold Neurospora crassa underlies an internal circadian rhythm but is also induced through environmental signals, including light and nutrient deprivation (1, 2). There is growing evidence that fungi also produce a wide range of chemical signals to govern the development and differentiation of individual cells or a mycelial colony within a population (3). It has, for example, long been appreciated that in sexually propagating, heterothallic fungi, cells polarize and direct their growth toward peptide pheromones secreted by the mating partner (4). Cell-to-cell signaling also occurs on the population level or within an individual colony. For example, the primarily unicellular fungus Candida albicans secretes the sesquiterpene alcohol farnesol and ...

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Section: Discussionmentioning

confidence: 99%

The AngFus3 Mitogen-Activated Protein Kinase Controls Hyphal Differentiation and Secondary Metabolism in Aspergillus niger

et al. 2015

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“…Cyanobacteria (previously termed "blue-green algae") were also known as producers at that time (55,80) (see below), but it was not until the important study by Tabachek and Yurkowski (93) that these photoautotrophs were recognized as a more frequent source of geosmin and 2-MIB in water than actinomycetes. Indeed, a careful review of the taste-and-odor literature to date reveals that actinomycetes have been clearly implicated in comparatively few odor episodes.…”

Section: Biological Origins Of Geosmin and 2-mibmentioning

confidence: 99%

Biochemical and Ecological Control of Geosmin and 2-Methylisoborneol in Source Waters

Jüttner

Watson

2007

Appl Environ Microbiol

355

262

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2The majority of all biologically caused taste-and-odor outbreaks in drinking water characterized worldwide are caused by microbial production of (Ϫ)-geosmin [(Ϫ)-(4S,4aS,8aR)-4,8a-dimethyloctahydronaphthalen-4a-ol] and (Ϫ)-2-methylisoborneol (2-MIB) {(1R-exo)-1,2,7,7-tetramethylbicyclo[2.2.1]heptan-2-ol}. Since they were first identified in the early 1960s, these two earthy-muddy-smelling metabolites have been the focus of considerable research, which has collectively produced over 400 scientific articles, reports, websites, and conference proceedings. Yet despite this substantial body of knowledge, geosmin and 2-MIB remain poorly understood throughout much of the water industry, and misconceptions which impede the prediction, treatment, and control of these volatile organic compounds (VOCs) persist. This paper reviews salient aspects of our current knowledge on the sources and properties of geosmin and 2-MIB which are essential to understanding and managing drinking water malodors. In particular, we highlight some key factors regulating the storage and release of these compounds by cells. These important factors are often overlooked and may contribute to some of the apparent ambiguity of many taste-and-odor outbreaks.

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“…were the most likely and significant sources of geosmin and 2-MIB in the Xionghe Reservoir. Geosmin and 2-MIB were first isolated from actinomycetes (Gerber & Lechevalier 1965) and later evidenced in cyanobacteria (Safferman et al 1967;Medsker et al 1968;Kikuchi et al 1973); however, cyanobacteria are known to be the main contributor to off-flavour episodes (Yagi 1988). Actinomycetes may contribute to off-flavour episodes in lakes, reservoirs and aquaculture ponds following cyanobacterial bloom die-offs (Schrader & Blevins 1999).…”

Section: Annual Variations In Chl a And Algal Abundancementioning

confidence: 99%

Biological origins and annual variations of earthy-musty off-flavours in the Xionghe Reservoir in China

Zhang

Zuo

et al. 2010

Journal of Water Supply: Research and Technology-Aqua

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The annual variations in physicochemical parameters, algal abundance and odorous compounds in the Xionghe Reservoir were investigated, in order to identify the possible odorous compounds and their origins. From May 2007 to April 2008, the algal composition, cell number and earthy-musty odorous compounds both in the water and in the flesh of fish at Sites A, B and C were determined monthly. The physicochemical parameters such as total nitrogen (TN), total phosphorus (TP), dissolved oxygen (DO), pH, transparency, water temperature and chlorophyll a (chl a) were simultaneously determined. A statistical correlation was noted between the chl a and water temperature: 0.678 (P , 0.05) for Site A, 0.831 (P , 0.01) for Site B and 0.659 (P , 0.05) for Site C. Geosmin and 2-methylisoborneol (2-MIB)-in the reservoir were identified by gas chromatography-mass spectrometry (GC-MS). We observed that a large amount of Anabaena circinalis bloomed in surface water during the off-flavour episodes. In July 2007, we detected the highest concentration of geosmin (2.7 mg/L in the water, 0.27 mg/kg in the silver carp and 0.10 mg/kg in the crucian carp), while no 2-MIB was detected, which indicated that geosmin was mainly responsible for the off-flavour episodes in summer.

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Earthy-smelling substance from a blue-green alga

Abstract: The blue-green alga Symploca muscorum produces an earthy-smelling metabolite at an estimated concentration of 0.6 mg. per liter of culture medium. The substance has been

Cited by 98 publications

References 8 publications

The AngFus3 Mitogen-Activated Protein Kinase Controls Hyphal Differentiation and Secondary Metabolism in Aspergillus niger

The AngFus3 Mitogen-Activated Protein Kinase Controls Hyphal Differentiation and Secondary Metabolism in Aspergillus niger

Biochemical and Ecological Control of Geosmin and 2-Methylisoborneol in Source Waters

Biological origins and annual variations of earthy-musty off-flavours in the Xionghe Reservoir in China

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