Microbiological Studies on Nitrogen Fixation in Aquatic Environments-II:On the Distribution of Nitrogen Fixing Bacteria in Sea Water Regions

In aquatic environments, nitrogen fixation is one of the most important processes in nitrogen cycle, on the account that the process is responsible for the recovery of nitrogen loss caused by denitrification and that the productivity of the water region is sometimes restricted by the nitrogen budget of the region. In the first step of the study, the authors have intended to obtain the information about the distribution of nitrogen fixing bacteria in various water regions, M. P. N. method with the liquid media containing sucrose and non-nitrogenous compound being used for the enumeration of the bacteria. This paper is concerned primarily with the occurrence and abundance of nitrogen fixing bacteria in some fresh water regions. In Lake Biwa and Lake Yunoko, the number of the bacteria was somewhat small in the water i.e. 10-1-102 cells/ml, while, 102-101 cells per 1g of the bacteria were detected in the bottom sediments of the lakes.