Actinobacterial communities of boreal forest soil and lake water are rich in mycobacteria

The actinobacterial communities present in two Finnish lakes and in the surrounding conifer forest soil were investigated using DNA based methods. The dominant actinobacteria in the soil were found to belong to genus Mycobacterium. Therefore specific primers were designed and tested to study the mycobacterial communities in boreal environment more closely. The denaturing gradient gel electrophoresis (DGGE) and sequencing analysis showed that the microbial populations in lakes were different from those in the surrounding soil. Thus, each of the environments had their own actinobacterial and mycobacterial populations. The majority of the obtained mycobacterial sequences were closely related to the described species of environmental mycobacteria, some of which are pathogenic. However, several sequences were not closely related to any presently known species. The chemical characteristics of boreal forest soil seem to favour proliferation of mycobacteria, many of which still remain to be isolated.