不同演替阶段岩溶石灰土可培养细菌的群落特征

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

摘要:

岩溶土壤是岩溶生态系统的重要组成部分，其母质碳酸盐岩在气候、地形、时间及生物等因素的综合作用下可依次演替出黑色石灰土、棕色石灰土、黄色石灰土和红色石灰土。[目的] 了解可培养细菌群落对岩溶石灰土演替过程的响应，可为岩溶石漠化治理、生态恢复和重建等提供理论依据。[方法] 以黑色石灰土、棕色石灰土、黄色石灰土和红色石灰土为研究对象，对土壤SOC、TN和TP含量以及可培养细菌群落进行测定。[结果] 土壤SOC和TN含量表现为：黑色石灰土 > 棕色石灰土 > 黄色石灰土 > 红色石灰土，TP含量在黑色石灰土中最高，在红色石灰土中最低。本研究共分离纯化得到144株细菌，其中R2A培养基分离纯化出的细菌最多。细菌主要来自Actinobacteria、Bacteroidetes、Firmicutes和Proteobacteria门，Pseudomonas、Cupriavidus和Bacillus等是可培养菌中的优势属。在属水平上，黑色石灰土中分离得到的菌株最多并以Arenimonas、Thermomonas、Achromobacter、Brevibacillus等作为优势特有属。具有固碳、固氮和解磷功能的细菌主要分布在岩溶石灰土演替的早期。[结论] 基于母质碳酸盐岩特性，富含有机质的黑色石灰土在参与碳氮磷循环细菌的作用下形成。随着石灰土淋溶程度的增加，岩溶石灰土理化性质和可培养细菌多样性呈现降低的趋势。

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.