Optimization of Extraction Method for Easily Extractable Glomalin-Related Soil Protein from Calcareous Soil

JIANG Li; KANG Zhiqiang; LIANG Yueming; WU Zeyan; TU Chun; LI Qiang

doi:10.15898/j.ykcs.202402060015

Rock and Mineral Analysis > 2024 > 43(4): 582-591. > DOI: 10.15898/j.ykcs.202402060015

JIANG Li，KANG Zhiqiang，LIANG Yueming，et al. Optimization of Extraction Method for Easily Extractable Glomalin-Related Soil Protein from Calcareous Soil[J]. Rock and Mineral Analysis，2024，43（4）：582−591. DOI: 10.15898/j.ykcs.202402060015

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Optimization of Extraction Method for Easily Extractable Glomalin-Related Soil Protein from Calcareous Soil

JIANG Li^{1, 2, 3,},
KANG Zhiqiang⁴,
LIANG Yueming²,
WU Zeyan²,
TU Chun²,
LI Qiang^2, ,

1.
Environmental Science and Engineering College, Guilin University of Technology, Guilin 541004, China
2.
Key Laboratory of Karst Dynamics, Ministry of Natural Resources and Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China
3.
Collaborative Innovation Center for Water Pollution Control and Water Safety in Karst Area, Guilin University of Technology, Guilin 541006, China
4.
Bureau of Geology and Mineral Prospecting and Exploitation of Guangxi Zhuang Autonomous Region, Nanning 530023, China

More Information

Received Date: February 05, 2024
Revised Date: June 12, 2024
Accepted Date: July 05, 2024
Available Online: August 08, 2024

Abstract

HIGHLIGHTS
(1) The amount of easily extractable glomalin-related soil protein from calcareous soil will be increased by increasing extraction temperature and prolonging extraction time.

(2) An optimization condition was selected and applied to four types of calcareous soil based on orthogonal experiments, which verifies the experimental hypothesis.

(3) The extraction condition about easily extractable glomalin-related soil protein from particulate organic matter and mineral-associated organic matter is different from bulk soil, so it is necessary to increase extracting temperature and prolong extracting time.

ABSTRACT

Glomalin-related soil protein (GRSP) secreted by arbuscular mycorrhizal fungi is widely distributed worldwide, has stable properties and is not easily decomposed, which is an important component of soil organic matter. Extracting high quality GRSP is important for in-depth research on organic carbon sinks in calcareous soil from karst areas. However, in previous studies, the mechanism of GRSP in organic matter could not be further studied due to low extraction yield, insufficient extraction and non-specific products. Therefore, the high extraction amount of GRSP is of great significance to explore the formation and stabilization mechanism of organic matter in calcareous soil. This experiment selected four types of calcareous soil from karst areas: black, brown, yellow and red calcareous soil. By using orthogonal experiments of temperature and time, the optimal extraction conditions for easily extractable glomalin-related soil protein (EE-GRSP) related to particulate organic matter (POM) and mineral-associated organic matter (MAOM) in calcareous soil were selected. The experimental results showed that the highest extraction amount of EE-GRSP was achieved when POM and MAOM were extracted at 123℃ and 80min. After application into the four types of calcareous soil, the EE-GRSP contents increased from 4.6% to 34.2%. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202402060015.
BRIEF REPORT
Significance: Under the interaction of water-carbon dioxide-carbonate rocks-organisms, a global karst carbon sink of 8.24×10⁸t C/a is formed. Some of the carbon sinks were sequestered in the form as soil organic matter, which plays an important role in the dual carbon goals. Glomalin-related soil protein, as a part of soil organic carbon, is stable and difficult to decompose, and plays an important role in soil carbon sequestration^[6]. The extraction process of GRSP remains inadequate. Many scholars have improved the extraction time and centrifugal force, but few of them have optimized the extraction temperature and time by orthogonal optimization. After a single adjustment of the extraction condition, EE-GRSP from soils was mostly concentrated in 0.5−1.0mg/g^[46-47]. In this study, temperature, time experiment and two-factor orthogonal experiments were carried out sequentially. After an optimized condition was selected, four types of calcareous soil from the karst area were used to verify the experimental hypothesis. By using this optimization extracting method, EE-GRSP content from calcareous soil can reach up to 1.375mg/g.

Methods: Black, brown, yellow, and red calcareous soil were collected in Nonggang Nature Reserve in Guangxi, China. Bulk samples were mixed well by removing debris such as gravel and stubs. Bulk soil was air-dried and sieved through a 10-mesh sieve. POM and MAOM were obtained by applying the wet sieving method. The 0.5g samples were placed in a 15mL centrifuge tube and parallel samples were set up. According to the ratio of sample and extraction solution (1∶8), 20mmol/L sodium citrate solution (pH=7) was added into the centrifuge tube. Samples were put into an autoclave with the lid open and extracted for 80min at 123℃, and then centrifuged at 9500r/min for 10min after sterilization. The supernatant was retained at 4℃ for the determination of EE-GRSP content.

Data and Results: (1) The main factors affecting EE-GRSP extraction. Sterilization samples were used with open or closed lids. After the lid was closed, EE-GRSP content decreased from 0.591mg/g to 0.105mg/g in brown calcareous soil and in red calcareous soil from 0.071mg/g to 0.011mg/g, as shown in Fig.1. With the extension of extraction time, EE-GRSP content increased in the brown calcareous soil and red calcareous soil sample, as listed in Fig.2.

　　(2) Results of time and temperature orthogonal optimization experiment. By comparing the extracted amount of EE-GRSP, POM peaked at 123℃ and 80min, which was significantly higher than the other extraction conditions (p<0.05), as seen in Table 1.

　　(3) Extraction results of actual samples. After increasing the extraction temperature and time, EE-GRSP content of the black calcareous soil-particulate organic matter increased from 0.833 to 1.118mg/g. The previous studies indicated that the extraction amount of EE-GRSP from non-karst area soil was 0.5−0.6mg/g^[46], and the EE-GRSP content of brown calcareous soil was 0.4−1.17mg/g^[47]. In this study, the EE-GRSP contents of POM and MAOM in black, brown and yellow calcareous soil were significantly increased about 11.5%−30.4% by using this optimization extraction method, as shown in Fig.3. Compared to bulk soil, MAOM had higher stability and stronger organic carbon protection ability. Therefore, by using increased temperature and extraction time, the EE-GRSP content in MAOM is completely released, and the extraction amount can be significantly increased.

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References (49)

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