Bacteria biomass and carbonic anhydrase activity in some karst areas of Southwest China

To determine the role of microbes in karst processes, it is necessary to investigate the ecological distribution and characteristics of soil microorganisms in karst areas. In this paper, a preliminary study was carried out in two different karst areas of Southwest China: Nongla and the Guilin Yaji Karst Experimental Site (Guangxi). Soil samples from 10-20 cm in depth were analyzed for the number of bacteria, and the predominant bacteria were identified. Analysis showed that the amount of soil bacteria correlated highly with characteristics of the karst ecosystems, including their different geochemical environments and vegetation. The predominance of Azotobacteraceae, colonies showed that the soil fertility of both types of karst areas may be improving. Also, the origin of carbonic anhydrase (CA), which could accelerate karst processes, was explored. The CA-producing bacteria were screened, and activities of extracellular and intracellular CA were measured. Obvious differences existed in intracellular and extracellular CA activities of soil bacteria between the two karst ecosystems with different vegetation conditions. This suggests that the activity of CA from soil bacteria in the two different karst areas was also correlated with karst ecosystem characteristics, including their different geochemical environments and vegetation features. (C) 2003 Elsevier Ltd. All rights reserved.