Characterization of Microbial Carbon Metabolism in Karst Soils from Citrus Orchards and Analysis of Its Environmental Drivers

Karst regions (KRs) have created significant karst carbon sinks globally through the carbon cycling process involving “water-carbon dioxide-carbonate rock-biota”. Soil organic carbon (SOC) represents a crucial component of these carbon sinks. Microorganisms play a vital role in the soil carbon cycle...

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Main Authors: Shixuan Wang, Zhenjiang Jin, Xuesong Li, Hongying Zhu, Fang Fang, Ting Luo, Jia Li
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Microorganisms
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Online Access:https://www.mdpi.com/2076-2607/13/2/267
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author Shixuan Wang
Zhenjiang Jin
Xuesong Li
Hongying Zhu
Fang Fang
Ting Luo
Jia Li
author_facet Shixuan Wang
Zhenjiang Jin
Xuesong Li
Hongying Zhu
Fang Fang
Ting Luo
Jia Li
author_sort Shixuan Wang
collection DOAJ
description Karst regions (KRs) have created significant karst carbon sinks globally through the carbon cycling process involving “water-carbon dioxide-carbonate rock-biota”. Soil organic carbon (SOC) represents a crucial component of these carbon sinks. Microorganisms play a vital role in the soil carbon cycle, influencing the formation and preservation of SOC. Therefore, investigating the carbon metabolism of soil microorganisms in KRs is essential for clarifying the unique biogeochemical cycling mechanisms within these regions. In this paper, soils from karst regions (KRs), mixed regions (MRs) and non-karst regions (NKRs) were collected from citrus orchards in Mao Village, Karst Experimental Field, Guilin City, Guangxi Zhuang Autonomous Region, China. The ability to use different carbon sources was analyzed by Biolog-Eco microtiter plate technique; the number of microorganisms was detected by the plate colony counting method, and the microbial biomass was determined by the chloroform fumigation method. The results showed that the soil bacterial number (5.69 ± 0.39 × 10<sup>6</sup> CFU/g), microbial biomass carbon (MBC) (608.24 ± 63.80 mg/kg), microbial quotient (SMQ) (3.45 ± 0.18%), and Shannon’s index (<i>H</i>′) (3.28 ± 0.05) of the KR were significantly higher than those of the NKR. The pH showed a significant positive correlation (<i>p</i> < 0.05) with the bacterial number and <i>H</i>′ (<i>p</i> < 0.05); SOC showed a highly significant positive correlation with bacterial number (<i>p</i> < 0.01), and a significant positive correlation with MBC, <i>H</i>′, and average well change development (AWCD) (<i>p</i> < 0.05). Total nitrogen (TN) showed a significant positive correlation with MBC (<i>p</i> < 0.05); available potassium (AK) showed a significant positive correlation with bacterial number and MBC (<i>p</i> < 0.05). Exchangeable calcium (Ca<sup>2+</sup>) demonstrated significant positive correlations with bacterial number, MBC, and <i>H</i>′ (<i>p</i> < 0.05). The above results indicate that soil bacterial number, carbon metabolic ability and diversity were highest in the KR. pH, SOC and exchangeable Ca<sup>2+</sup> were the main influencing factors for the differentiation of soil microbial carbon metabolic diversity between the KR and NKR.
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spelling doaj-art-4fe3951cc7a244cfa654808c158959be2025-08-20T02:44:32ZengMDPI AGMicroorganisms2076-26072025-01-0113226710.3390/microorganisms13020267Characterization of Microbial Carbon Metabolism in Karst Soils from Citrus Orchards and Analysis of Its Environmental DriversShixuan Wang0Zhenjiang Jin1Xuesong Li2Hongying Zhu3Fang Fang4Ting Luo5Jia Li6College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, ChinaCollege of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, ChinaCollege of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, ChinaCollege of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, ChinaCollege of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, ChinaCollege of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, ChinaCollege of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, ChinaKarst regions (KRs) have created significant karst carbon sinks globally through the carbon cycling process involving “water-carbon dioxide-carbonate rock-biota”. Soil organic carbon (SOC) represents a crucial component of these carbon sinks. Microorganisms play a vital role in the soil carbon cycle, influencing the formation and preservation of SOC. Therefore, investigating the carbon metabolism of soil microorganisms in KRs is essential for clarifying the unique biogeochemical cycling mechanisms within these regions. In this paper, soils from karst regions (KRs), mixed regions (MRs) and non-karst regions (NKRs) were collected from citrus orchards in Mao Village, Karst Experimental Field, Guilin City, Guangxi Zhuang Autonomous Region, China. The ability to use different carbon sources was analyzed by Biolog-Eco microtiter plate technique; the number of microorganisms was detected by the plate colony counting method, and the microbial biomass was determined by the chloroform fumigation method. The results showed that the soil bacterial number (5.69 ± 0.39 × 10<sup>6</sup> CFU/g), microbial biomass carbon (MBC) (608.24 ± 63.80 mg/kg), microbial quotient (SMQ) (3.45 ± 0.18%), and Shannon’s index (<i>H</i>′) (3.28 ± 0.05) of the KR were significantly higher than those of the NKR. The pH showed a significant positive correlation (<i>p</i> < 0.05) with the bacterial number and <i>H</i>′ (<i>p</i> < 0.05); SOC showed a highly significant positive correlation with bacterial number (<i>p</i> < 0.01), and a significant positive correlation with MBC, <i>H</i>′, and average well change development (AWCD) (<i>p</i> < 0.05). Total nitrogen (TN) showed a significant positive correlation with MBC (<i>p</i> < 0.05); available potassium (AK) showed a significant positive correlation with bacterial number and MBC (<i>p</i> < 0.05). Exchangeable calcium (Ca<sup>2+</sup>) demonstrated significant positive correlations with bacterial number, MBC, and <i>H</i>′ (<i>p</i> < 0.05). The above results indicate that soil bacterial number, carbon metabolic ability and diversity were highest in the KR. pH, SOC and exchangeable Ca<sup>2+</sup> were the main influencing factors for the differentiation of soil microbial carbon metabolic diversity between the KR and NKR.https://www.mdpi.com/2076-2607/13/2/267karst regionsforest soilcitrus orchardsmicroorganismscarbon sourcesmetabolism
spellingShingle Shixuan Wang
Zhenjiang Jin
Xuesong Li
Hongying Zhu
Fang Fang
Ting Luo
Jia Li
Characterization of Microbial Carbon Metabolism in Karst Soils from Citrus Orchards and Analysis of Its Environmental Drivers
Microorganisms
karst regions
forest soil
citrus orchards
microorganisms
carbon sources
metabolism
title Characterization of Microbial Carbon Metabolism in Karst Soils from Citrus Orchards and Analysis of Its Environmental Drivers
title_full Characterization of Microbial Carbon Metabolism in Karst Soils from Citrus Orchards and Analysis of Its Environmental Drivers
title_fullStr Characterization of Microbial Carbon Metabolism in Karst Soils from Citrus Orchards and Analysis of Its Environmental Drivers
title_full_unstemmed Characterization of Microbial Carbon Metabolism in Karst Soils from Citrus Orchards and Analysis of Its Environmental Drivers
title_short Characterization of Microbial Carbon Metabolism in Karst Soils from Citrus Orchards and Analysis of Its Environmental Drivers
title_sort characterization of microbial carbon metabolism in karst soils from citrus orchards and analysis of its environmental drivers
topic karst regions
forest soil
citrus orchards
microorganisms
carbon sources
metabolism
url https://www.mdpi.com/2076-2607/13/2/267
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