Antibiotics affecting protein synthesis were used to differentiate between the activity of different groups of organisms (halophilic archaebacteria, eubacteria and eukaryotes) in water samples from hypersaline ecosystems. Anisomycin (inhibiting both archaebacterial halophiles and eukaryotes) can be used to quantitate the contribution of the archaebacterial halophiles to amino acid incorporation by the microbial community, when cycloheximide (inhibiting eukaryotic protein synthesis, but not affecting halobacteria) is used as a control. Both in saltern ponds at salinities above 300 g/1 and in Dead Sea surface water more than 95% of the amino acid incorporation activity was abolished by anisomycin, but not by cycloheximide. Inhibition by anisomycin was well correlated with inhibition by low concentrations of bile salts, which specifically affect bacteria of the Halobacterium group. Chloramphenicol (an inhibitor of eubacterial protein synthesis) quantitatively inhibited amino acid incorporation in saltern brines of relatively low salinity, but also caused significant (28-42%) inhibition at high salinities. Erythromycin was also found valuable in the estimation of activities of the different bacterial groups.
Bibliographical noteFunding Information:
I thank the Israel Salt Co., Ltd. for allowing access to the Eilat salt ponds, and the staff of the lnteruniversity Institute of Eilat for laboratory facilities and logistic support. This study was supported by grants from the Israeli Ministry of Energy and Infrastructure and the Hebrew University of Jerusalem Mutual Fund.
- Dead Sea
- Halophilic eubacteria