Integrating Stochastic and Deterministic Process in the Biogeography of N2-Fixing Cyanobacterium Candidatus Atelocyanobacterium Thalassa

Liuyang Li; Chao Wu; Danyue Huang; Changling Ding; Yuqiu Wei; Jun Sun

doi:10.3389/fmicb.2021.654646

Integrating Stochastic and Deterministic Process in the Biogeography of N₂-Fixing Cyanobacterium Candidatus Atelocyanobacterium Thalassa

Front Microbiol. 2021 Oct 21:12:654646. doi: 10.3389/fmicb.2021.654646. eCollection 2021.

Authors

Liuyang Li^{1

2}, Chao Wu³, Danyue Huang^{1

4}, Changling Ding^{3

5}, Yuqiu Wei⁶, Jun Sun¹

Affiliations

¹ College of Marine Science and Technology, China University of Geosciences, Wuhan, China.
² State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
³ Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, China.
⁴ School of Oceanography, Shanghai Jiao Tong University, Shanghai, China.
⁵ College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.
⁶ Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China.

Abstract

UCYN-A is one of the most widespread and important marine diazotrophs. Its unusual distribution in both cold/warm and coastal/oceanic waters challenges current understanding about what drives the biogeography of diazotrophs. This study assessed the community assembly processes of the nitrogen-fixing cyanobacterium UCYN-A, developing a framework of assembly processes underpinning the microbial biogeography and diversity. High-throughput sequencing and a qPCR approach targeting the nifH gene were used to investigate three tropical seas: the Bay of Bengal, the Western Pacific Ocean, and the South China Sea. Based on the neutral community model and two types of null models calculating the β-nearest taxon index and the normalized stochasticity ratio, we found that stochastic assembly processes could explain 66-92% of the community assembly; thus, they exert overwhelming influence on UCYN-A biogeography and diversity. Among the deterministic processes, temperature and coastal/oceanic position appeared to be the principal environmental factors driving UCYN-A diversity. In addition, a close linkage between assembly processes and UCYN-A abundance/diversity/drivers can provide clues for the unusual global distribution of UCYN-A.

Keywords: UCYN-A; community assembly; cyanobacteria; determinism; nifH; stochasticity; temperature.