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Griebler, C.* ; Slezak, D.*

Microbial activity in aquatic environments measured by dimethyl sulfoxide reduction and intercomparison with commonly used methods.

Appl. Environ. Microbiol. 67, 100-109 (2001)
DOI
Open Access Green möglich sobald Postprint bei der ZB eingereicht worden ist.
A new method to determine microbial (bacterial and fungal) activity in various freshwater habitats is described. Based on microbial reduction of dimethyl sulfoxide (DMSO) to dimethyl sulfide (DMS), our DMSO reduction method allows measurement of the respiratory activity in interstitial water, as well as in the water column. DMSO is added to water samples at a concentration (0.75% [vol/vol] or 106 mM) high enough to compete with other naturally occurring electron acceptors, as determined with oxygen and nitrate, without stimulating or inhibiting microbial activity. Addition of NAN3, KCN, and formaldehyde, as well as autoclaving, inhibited the production of DMS, which proves that the reduction of DMSO is a biotic process. DMSO reduction is readily detectable via the formation of DMS even at low microbial activities. All water samples showed significant DMSO reduction over several hours. Microbially reduced DMSO is recovered in the form of DMS from water samples by a purge and trap system and is quantified by gas chromatography and detection with a flame photometric detector. The DMSO reduction method was compared with other methods commonly used for assessment of microbial activity. DMSO reduction activity correlated well with bacterial production in predator-free batch cultures. Cell-production-specific DMSO reduction rates did not differ significantly in batch cultures with different nutrient regimes but were different in different growth phases. Overall, a cell-production-specific DMSO reduction rate of 1.26 (CD) 10-17 ± 0.12 (CD) 10-17 mol of DMS per produced cell (mean ± standard error; R2 = 0.78) was calculated. We suggest that the relationship of DMSO reduction rates to thymidine and leucine incorporation is linear (the R2 values ranged from 0.783 to 0.944), whereas there is an exponential relationship between DMSO reduction rates and glucose uptake, as well as incorporation (the R2 values ranged from 0.821 to 0.931). Based on our results, we conclude that the DMSO reduction method is a nonradioactive alternative to other methods commonly used to assess microbial activity.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
ISSN (print) / ISBN 0099-2240
e-ISSN 1098-5336
Zeitschrift Applied and Environmental Microbiology
Quellenangaben Band: 67, Heft: 1, Seiten: 100-109 Artikelnummer: , Supplement: ,
Verlag American Society for Microbiology (ASM)
Begutachtungsstatus Peer reviewed
Institut(e) Institute of Groundwater Ecology (IGOE)