Abstract.
Alkaliphilic bacteria were isolated from soil and water samples obtained from Ethiopian soda lakes in the Rift Valley area – Lake Shala, Lake Abijata, and Lake Arenguadi. Starch-hydrolyzing isolates were selected on the basis of their activity on starch agar plate assay. Sixteen isolates were chosen, characterized, and subjected to 16S rRNA gene sequence analysis. All the isolates were gram positive and catalase- and β-galactosidase positive. All isolates except one were motile endospore-forming rods and were found to be closely related to the Bacillus cluster, being grouped with Bacillus pseudofirmus, Bacillus cohnii, Bacillus vedderi, and Bacillus agaradhaerens. The one exception had nonmotile coccoid cells and was closely related to Nesterenkonia halobia. The majority of the isolates showed optimal growth at 37°C and tolerated salinity up to 10% (w/v) NaCl. Both extracellular and cell-bound amylase activity was detected among the isolates. The amylase activity of two isolates, related to B. vedderi and B. cohnii, was stimulated by ethylenediaminetetraacetic acid (EDTA) and inhibited in the presence of calcium ions. Pullulanase activity was expressed by isolates grouped with B. vedderi and also most of the isolates clustered with B. cohnii; cyclodextrin glycosyltransferase was expressed by most of the B. agaradhaerens-related strains. Minor levels of α-glucosidase activity were detected in all the strains.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Electronic Publication
Rights and permissions
About this article
Cite this article
Martins, R.F., Davids, W., Al-Soud, W. et al. Starch-hydrolyzing bacteria from Ethiopian soda lakes. Extremophiles 5, 135–144 (2001). https://doi.org/10.1007/s007920100183
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s007920100183