Many industrial and biotechnological processes make use of cold-active enzymes or could benefit from the use, as the reduced temperature can be beneficial in multiple ways. Such processes may save energy and production costs, improve hygiene, maintain taste and other organoleptic properties, and reduce the risk of contaminations. Cold- and alkaline-active enzymes can be found in microorganisms adapted to living in natural environments with these conditions, which are extremely rare but found in the unique ikaite columns from SW Greenland (4-6 °C, pH >10). It is estimated that less than 1% of the microorganisms in an environmental sample can be cultured in the laboratory with standard techniques, which is also the case for the ikaite columns. Thus, there is an enormous potential in the uncultured microorganisms, which cannot be accessed through cultivation based methods. This PhD thesis presents studies on the diversity of microorganisms from the ikaite columns as well as bioprospecting for enzyme activities using both culture dependent and independent methods. Two cold-active β-galactosidases and one extremely cold-active α-amylase, all related to Clostridia, were characterized in more details.