Community characteristics of culturable bacteria in calcareous soil at different succession stages

Abstract:

Karst soil is an important part of karst ecosystem, and its parent material, carbonate rock, can successively evolve into black calcareous soil, brown calcareous soil, yellow calcareous soil and red calcareous soil under the comprehensive effect of climate, topography, time and biology. [Objective] To better understand the response of soil bacterial community to calcareous soil at different succession stages, which can provide the basic references for rocky desertification control and soil erosion control in karst area. [Methods] The contents of SOC, TN and TP, and the abundance and diversity of culturable bacteria in calcareous soils (black, brown, yellow and red) were determined. [Results] The contents of soil SOC and TN at different succession stages were in the order of black calcareous soil > brown calcareous soil > yellow calcareous soil > red calcareous soil. The content of TP was highest in black calcareous soil and lowest in red calcareous soil. A total of 144 strains of bacteria were isolated and purified, and R2A medium was the suitable medium. Then, the bacterial strains were classified into Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. Pseudomonas, Cupriavidus and Bacillus were the dominant genera of culturable bacteria. At the genus level, the most strains were isolated from the black calcareous soil, and the dominant genera such as Arenimonas, Thermomonas, Achromobacter and Brevibacillus appeared. In the early succession stages, a large number of bacteria involved in carbon, nitrogen and phosphorus cycling appeared. [Conclusion] Based on the characteristics of parent material carbonate rock, black calcareous soil rich in organic matter is formed under the action of bacteria participating in carbon, nitrogen and phosphorus cycle. The physicochemical properties and culturable bacterial diversity of karst limestone soil decreased with the increase of leaching degree of limestone soil.

Key words:karst;calcareous soil;soil succession;culturable bacteria