Reinvestigating the regulatory gate hypothesis for a better understanding of microbial redundancy in soil

Keke Jin, Xiaomeng Wei, Haonan Wu, Sanfeng Chen, Sen Du, Gehong Wei

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Soil Ecology Letters ›› 2024, Vol. 6 ›› Issue (4) : 240256. DOI: 10.1007/s42832-024-0256-0
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Reinvestigating the regulatory gate hypothesis for a better understanding of microbial redundancy in soil

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Highlights

● Moderate dilution of natural soil with clay mineral complexes generated oligotrophic soils with a gradient of microbial abundance but similar C availability.

● In contrast to the regulatory gate hypothesis, small changes in microbial abundance strongly influenced soil C decomposition despite similar C availability.

Abstract

The regulatory gate hypothesis suggests that the mineralization of soil organic matter (SOM) is controlled by carbon accessibility due to microbial redundancy. However, this opinion is contentious because the extensively high available carbon released during the fumigation in these studies strongly stimulated microbial activity, which is unlikely to occur in real soil and would compensate for the effect of reduced microbial abundance. In this study, natural soil was moderately diluted with mineral complexes in varying proportions to obtain soils with a gradient of microbial abundance and low carbon availability. The results revealed that despite minimal changes in the dissolved organic carbon content (DOC), the CO2 emission rate and activity of SOM hydrolysis significantly decreased with decreasing microbial abundance. Regression analysis and the random forest model highlighted microbial abundance as the primary factor influencing carbon decomposition, which was more fundamental than DOC and microbial diversity. These findings underline the crucial role of microbes in soil carbon turnover and the importance of maintaining microbial abundance to preserve the soil carbon cycling capacity.

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Keywords

regulatory gate hypothesis / microbial abundance / microbial redundancy / carbon availability / carbon mineralization

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Keke Jin, Xiaomeng Wei, Haonan Wu, Sanfeng Chen, Sen Du, Gehong Wei. Reinvestigating the regulatory gate hypothesis for a better understanding of microbial redundancy in soil. Soil Ecology Letters, 2024, 6(4): 240256 https://doi.org/10.1007/s42832-024-0256-0

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Acknowledgements

This study was supported by the National Natural Science Foundation of China (Grant Nos. 42107369 and 42377347) and Chinese University Scientific Fund (Grant No. 2452024414).

Electronic supplementary material

Supplementary material is available in the online version of this article at https://doi.org/10.1007/s42832-024-0256-0 and is accessible for authorized users.

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