High-resolution spatial and genomic characterization of coral-associated microbial aggregates in the coral <i>Stylophora pistillata</i>
Naohisa Wada, Ming‐Tsung Hsu, Kshitij Tandon, Silver Sung‐Yun Hsiao, Hsing‐Ju Chen, Yu‐Hsiang Chen, Pei‐Wen Chiang, Sheng-Ping Yu, Chih-Ying Lu, Yu‐Jing Chiou, Yung‐Chi Tu, Xuejiao Tian, Bi‐Chang Chen, Der‐Chuen Lee, Hideyuki Yamashiro, David G. Bourne, Sen‐Lin Tang
Abstract
Bacteria commonly form aggregates in a range of coral species [termed coral-associated microbial aggregates (CAMAs)], although these structures remain poorly characterized despite extensive efforts studying the coral microbiome. Here, we comprehensively characterize CAMAs associated with Stylophora pistillata and quantify their cell abundance. Our analysis reveals that multiple Endozoicomonas phylotypes coexist inside a single CAMA. Nanoscale secondary ion mass spectrometry imaging revealed that the Endozoicomonas cells were enriched with phosphorus, with the elemental compositions of CAMAs different from coral tissues and endosymbiotic Symbiodiniaceae, highlighting a role in sequestering and cycling phosphate between coral holobiont partners. Consensus metagenome-assembled genomes of the two dominant Endozoicomonas phylotypes confirmed their metabolic potential for polyphosphate accumulation along with genomic signatures including type VI secretion systems allowing host association. Our findings provide unprecedented insights into Endozoicomonas -dominated CAMAs and the first direct physiological and genomic linked evidence of their biological role in the coral holobiont.