Friedrich Jüttner

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

The majority of all biologically caused taste-and-odor outbreaks in drinking water characterized worldwide are caused by microbial production of (−)-geosmin [(−)-(4S,4aS,8aR)-4,8a-dimethyloctahydronaphthalen-4a-ol] and (−)-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.

Seasonal analysis of volatile organic biogenic substances (VOBS) in freshwater phytoplankton populations dominated by Dinobryon, Microcystis and Aphanizomenon

Over the course of one year the volatile organic biogenic substances (VOBS) found in the water of a eutrophied shallow lake were determined by gas chromatographic and mass spectrometric methods. The substances detected belonged to nor‐carotenoids, terpenoids, unsaturated hydrocarbons, ketones, and aldehydes. The occurrence of particular VOBS correlated with the frequency with which certain phytoplankton species were recorded. The latter showed a well developed succession in that year. The following correspondences were found: β‐cyclocitral and Microcystis; heptadec‐cis 5‐ene and Oscillatoria redekei; geosmin and argosmin and Aphanizomenon gracile; hepta‐trans, cis 2,4‐dienal, deca‐trans, cis 2,4‐dienal and Dinobryon; octa‐trans, cis 1,3,5‐triene and Asterionella formosa. Dictyopterenes and ectocarpene were only detected in high amounts in one sample obtained in August. The VOBS exhibited marked dynamics in the lake and usually were rapidly eliminated from the water body.

Evidence of β-carotene 7,8(7′,8′) oxygenase (β-cyclocitral, crocetindial generating) in Microcystis

A β-carotene oxygenase is described which occurs in the Cyanobacterium Microcystis. It cleaves β-carotene and zeaxanthin specifically at the positions 7,8 and 7′,8′, while echinenone and myxoxanthophyll are not affected. The oxidative cleavage of β-carotene leads to the formation of β-cyclocitral and crocetindial and that of zeaxanthin to hydroxy-β-cyclocitral and crocetindial in nearly stoichiometric amounts. Oxidant is dioxygen as has been demonstrated by high incroporation (86%) of 18O2 into β-cyclocitral. β-Carotene oxygenase is membrane bound, sensitive to sulfhydryl reagents, antioxidants and chelating agents. Iron seems to be an essential part of the enzyme activity. Cofactors necessary for the reaction could not be detected.

The reducing capacities of cyanobacteria for aldehydes and ketones

SummarySeveral strains of filamentous and unicellular cyanobacteria are capable of converting aldehydes and ketones into their corresponding alcohols during the active growth phase. Efficient conversions have been observed with aliphatic aldehydes, methyl and ethyl ketones. Cyanobacteria proved to be potent reducters of nor-carotenoids, acyclic monoterpene aldehydes and ketopantolactone. Neither bicyclic monoterpene ketones nor aromatic aldehydes have been reduced by any cyanobacterial strain so far tested.

Volatile Substances From Tissue Cultures of Potato, Tomato and Their Somatic Fusion Products — Comparison of Gas Chromatographic Patterns For Identification of Hybrids

Summary Comparison of gas chromatographically separated volatile compounds of potato, tomato and their somatic hybrid tissue cultures provides a sensitive means for hybrid identification. Verified and putative fusion products of Solanum tuberosum + Lycopersicon esculentum var. cerasiforme were analyzed.

Nor-Carotenoids as the Major Volatile Excretion Products of Cyanidium

Cyanidium caldarium excretes a series of nor-carotenoids. A 110 litre culture was used to isolate and determine the structure of 5 compounds: methylheptone, geranylacetone, β-ionone, dihydrotrimethylnaphthalene, butenylidenetrimethylcyclohexene. An algal bioassay was used to determine their effectivness on the growth of photoautotrophic organisms. The growth of Anabaena, Synechococcus, Nannochloris and Cyanidium was found to be inhibited at concentrations between 10 to 50 ppm.

β-Cyclocitral and Alkanes in Microcystis (Cyanophyceae)

Abstract A tobacco-like odorous compound isolated from a bloom of the blue-green alga Microcystis wesenbergii and a laboratory culture of M . aeruginosa was analysed by gas-liquid chromatography and mass spectrometry. Its structure was determined as β-cyclocitral. No other monoterpenes have been detected in these and in other blue-green algae. The hydrocarbon content was 0.10 - 0.18% of the dry weight. n-Hexadecane, n-heptadecane, 4-methylheptadecane and n-octadecane constituted the main components. The relation of the different alkanes to each other, especially 4-methylheptadecane and n-octadecane, revealed marked differences in the two organisms.

Excretion products ofOchromonas with special reference to pyrrolidone carboxylic acid

Cell suspensions ofOchromonas malhamensis andO. danica excrete a considerable part of low molecular organic material into the medium. Experiments with radioactive bicarbonate were performed to identify the most prominent substances. It could be demonstrated that one of the main products is the pyrrolidone carboxylic acid.

Massenanzucht phototropher Organismen in einer automatischen Kulturanlage

SummaryA new apparatus is described which permits pure cultivation of 110 l amounts of phototrophic organisms. Some data are given to prove its utility for mass production (kilogram amounts) of algae and photosynthetic bacteria.

Sesquiterpenes of the Geosmin-Producing Cyanobacterium Calothrix PCC 7507 and their Toxicity to Invertebrates

The occurrence of sesquiterpenes was investigated with the geosmin-producing cyanobacterium Calothrix PCC 7507. The essential oil obtained by vacuum destillation was studied in more detail by GC-MS methods and superposition with authentic compounds. Geosmin was the dominating compound while the other sesquiterpenes were minor components. Sesquiterpenes that have not been described before in cyanobacteria were isodihydroagarofuran, eremophilone and 6,11-epoxyisodaucane. Closed-loop stripping analysis revealed that most of the sesquiterpenes were found in the biomass of Calothrix, while eremophilone was mainly observed in the medium of the axenic culture. Eremophilone showed acute toxicity (LC50) against Chironomus riparius (insecta) at 29 μM and against Thamnocephalus platyurus (crustacea) at 22 μM. The compound was not toxic for Plectus cirratus (nematoda). 6,11-Epoxyisodaucane and isodihydroagarofuran exhibited no toxicity to invertebrates when applied in concentrations up to 100 μM.