Abstract

The bacterial abundance, proportion of respiring bacteria, and bacterial community of southern Lake Baikal were analyzed at 1 m and 400m depths during winter. The total bacterial numbers were 5.1×10^5 cells m^l-1 at 1 m and 2.5×10^5 cells ml^-1 at 400 m depth, which are about half and quarter of the numbers of other lakes. The proportion of respiring bacteria was as low as 2.5% at 1 m and 1.4% at 400 m depth. Considering the amount of organic carbon which need to be degraded and low proportion of respiring bacteria, the bacteria could be assumed to have high activities. The EUB/DAPI ratios were 77 and 89% at 1 m and 400 m depths, respectively. Of the bacterial community, the other group was dominant at both depths, and gamma group of proteobacteria followed next. But the beta group of proteobacteria and Cytophaga-Flavobacterium groups occupied very small proportions.

• Keywords: Lake Baikal; bacterial abundance; respiring bacteria; probe community