Bile salts (deoxycholate, taurocholate) were used to estimate the contribution of bacteria of the Halobacterium group to bacterial community size and activity at different salinities as found in a multi-pond saltern. Low concentrations of bile salts cause lysis of halophilic archaebacteria of the Halobacterium group, while halophilic eubacteria and halococci remain microscopically intact. Upon addition of bile salts, total bacterial numbers (as estimated microscopically) in saltern ponds at salinities below 250 g/l did not decrease, while above this salinity bacterial numbers decreased by 30-50%. To estimate the contribution of halobacteria to overall heterotrophic activity, the effect of bile salt addition was tested on the incorporation of labelled amino acids. In saltern ponds of a salinity below 250 g/l activity was not greatly inhibited by taurocholate, while at salinity above 300 g/l taurocholate completely abolished incorporation of amino acids.
Bibliographical noteFunding Information:
I thank the Israel Salt Co., Ltd. for allowing access to the Eilat salt ponds, and the staff of the Interuniversity Institute of Eilat for laboratory facilities and logistic support. I am grateful 1o Orna Palgi, Anina Ben-lzhak and Nissim Chalfon for their participation in the experiments, This study was supported by a grant from the Israeli Ministry of Energy and Infrastructure.
- Amino acid uptake
- Halophilic eubacteria