Abstract:

Fildes Peninsula is located at the southern end of King George Island in Antarctica. It is an ideal place to study Antarctic ecology and biological resources because of its unique geographical location and ecological environment. In this study, three different soil sample types were collected from the peninsula. The population sizes of soil nitrogen cycle microbes and their functional activities were determined using the Most Probable Number (MPN) and conventional Griess and Nessler’s active color test methods. The experimental results were also comprehensively analyzed regarding the ecology and physicochemical properties of the soil. The objectives were to develop a preliminary understanding of the soil nitrogen cycle microbes of Fildes Peninsula, and to prepare a scientific foundation for further study within this area. The results showed that the population sizes of nitrogen cycle microbes in the 13 collected soil samples in descending order were ammonification bacteria > denitrifying bacteria > nitrobacteria or nitrogen-fixing bacteria. Except for a few samples, most exhibited differing degrees of nitrification, denitrification, and ammonification activity. Furthermore, all soil samples had relatively high levels of ammonification bacteria and ammonification activity. The population sizes of denitrifying bacteria and the denitrifying activity of hillslope soils were higher than soils occupied by animals and plants. Although lower levels of nitrobacteria existed in soils occupied by animals and plants, they showed higher nitrifying activity, which might indicate the existence of strains with efficient function. Furthermore, the population sizes of nitrobacteria and the nitrifying activity of hillslope soils varied. This study provides a preliminary reference for further research of the characteristics of nitrogen cycling microbes in Antarctica.

Key words: Fildes Peninsula, Antarctica, soil nitrogen cycle microbes, MPN method, population size, functional active intensity, soil physicochemical properties