Carbon-fixing bacteria and sediment organic carbon response to the introduction of mangrove plant Sonneratia caseolaris

BMC Biology https://doi.org/10.1186/s12915-026-02631-6 Article in Press Carbon-fixing bacteria and sediment organic carbon response to the introduction of exotic mangrove plant Sonneratia caseolaris Xiaofang Huang, Junde Dong, Youshao Wang, Hongbin Liu, Weiguo Zhou, Hao Cheng, Xi Yang, Tongyin Liang, Bing Yang & Juan Ling Received: 23 Sep 2025 Accepted: 11 May 2026 Cite this article as: Huang, X., Dong, J., Wang, Y. et al. Carbon-fixing bacteria and sediment organic carbon response to the introduction of exotic mangrove plant Sonneratia caseolaris . BMC Biol (2026). https://doi.org/10.1186/s1291 5-026-02631-6 A E R P S S We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply. IN If this paper is publishing under a Transparent Peer Review model then Peer Review reports will publish with the final article. I T R E L C ©The Author(s) 2026. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ ACCEPTED ARTICLEMANUSCRIPT IN PRESS Carbon-fixing bacteria and sediment organic carbon response to the introduction of exotic mangrove plant Sonneratia caseolaris Xiaofang Huang a,b,c, Junde Dong a,b,c, Youshao Wang a,c, Hongbin Liu d, Weiguo Zhou a,c, Hao Cheng a,c, Xi Yang e, Tongyin Liang a,b,c, Bing Yang a,b,c, Juan Ling a,b,c * a. State Key Laboratory of Tropical Oceanography; Guangdong Provincial Key Laboratory of Applied Marine Biology; South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China b. Sanya Institute of Ocean Eco-Environmental Engineering, SCSIO; Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Tropical Marine Biological S S University of Chinese Academy of Sciences, Beijing 100049, China EUniversity of Science and R Department of Ocean Science, The Hong Kong P Technology, Hong Kong, China N I Guangdong Provincial Field Observation and Research Station for Marine E L Ecosystem in Hanjiang River Estuary C - Nanao Island Area, Shantou 515900, China I T R A Research Station in Hainan, Chinese Academy of Sciences, Sanya 572000, China c. d. e. E-mail addresses: (J. Ling) ACCEPTED ARTICLEMANUSCRIPT IN PRESS Abstract Background The fast-growing Sonneratia caseolaris has been widely used in restoration efforts to accelerate the recovery of degraded mangrove ecosystems. Carbon-fixing bacteria (CFB) are recognized as major microbial contributors to sediment carbon accumulation in the mangrove wetlands. However, the response of the CFB community and sediment organic carbon (SOC) to introduced exotic S. caseolaris is still unknown. Results In this study, the sediment properties (especially SOC), the abundances of S S based on cbbL and cbbM functional genes and their interaction network, were E R P compared between the exotic mangrove species (S. caseolaris) and native species N I (Kandelia obovata, Aegiceras corniculatum, and Acanthus ilicifolius) in the E L CShantou, China. Our results showed that exotic S. Niutianyang Mangrove Forest, I T R caseolaris markedly A enhanced the SOC content and the abundances of the carbon-fixing genes (cbbL and cbbM), as well as the CFB community composition carbon-fixing genes (P < 0.05). The dominant CFB taxa were “purple sulfur bacteria” (PSB) (e.g., Chromatiales) and “purple nonsulfur bacteria” (PNSB) (e.g., Rhodobacterales). The relative growth-promoting rhizobacteria abundances (PGPR), of some especially the well-known Rhizobiales plant and Burkholderiales, were significantly increased (P < 0.05) by the exotic S. caseolaris introduction. In addition, there was a more complex but less stable CFB community interaction network in the exotic S. caseolaris sediments. It was well worth noting that a large number of the keystone taxa in the network were the sulfur-oxidizing ACCEPTED ARTICLEMANUSCRIPT IN PRESS bacteria (SOB), such as Sulfuriferula and Thioalkalivibrio, suggesting a tight connection between the carbon and sulfur cycles in mangrove wetlands, and these key genera might have decisive roles in reshaping CFB community structure and functioning. Conclusions These findings confirmed that introduced S. caseolaris can strongly affect the CFB communities and the SOC content, and provided new insights into the microbial carbon sequestration in the mangrove wetlands. Keywords Mangrove restoration; Sonneratia caseolaris; Carbon-fixing bacteria (CFB); Carbon-fixing genes; Sediment organic carbon (SOC). Background S S E R P N I in the sediment. Although covering only 0.5 % of the tropical forest area, they E L contribute to about 10 % terrestrial C dissolved organic carbon (DOC) exportation to the I T as the “blue carbon” (1). Mangrove sediments are the ocean, and are characterized R A main reservoir for organic carbon, which contain nearly 90 % of the total carbon pool Mangrove wetlands have an excellent potential for carbon fixation, particularly in the mangrove ecosystem (2). However, mangrove wetlands have suffered from large degradation, having lost 20-35% total cover over the past 70 years (3). The global decline in tropical mangrove wetlands can severely weaken their ecosystem services, leading to the release of previously stored sediment carbon into the atmosphere, increasing CO2 emissions and potentially contributing to global warming (4). Since the 1970s, mangrove restoration projects have been widely initiated to compensate for the mangrove loss or degradation, which is increasingly recognized as ACCEPTED ARTICLEMANUSCRIPT IN PRESS an essential driver for mitigating climate change and enhancing the carbon sequestration capacity (5-7). Existing research has focused on the sediment carbon drivers for mangrove restoration, such as carbon sequestration technology and vegetation structure modification (8, 9), but little attention has been directed towards the sediment microbi (...truncated)