Linkages between organic carbon composition and microbial community structure in two contrasting subtropical mangrove sediments in southern China

Terrestrial and marine derived organic carbon (OC) accumulated in coastal mangrove sediment affect the structure of the benthic microbial community. This study collected sediment cores from subtropical coastal Xiwan and Maipo mangrove in southern China to study the linkages between the sedimentary OC and microbial community structure. The Maipo sediments showed more TOC (2.20 ± 0.20 vs. 1.67 ± 0.35 %), slightly depleted δC(−25.59 ± 0.71 vs. −25.07 ± 1.46 ‰), higher average Chl-a (62.25 ± 30.74 vs. 34.65±12.92μg/g TOC) and lignin (3.14 ± 2.21 vs. 1.80 ± 0.80 mg/100 mg TOC) content mostly due to larger coverage area of mangrove forests than coastal Xiwan sediment. While the dominate bacteria phylum and archaea class were the same, the microbes stratified to top, middle​ and bottom community with depths. The two cores also showed different indicator species and relative microbial abundance. Certain bacteria and archaea were positively correlated with the phenolic compounds indicating their involvement in lignin degradation. Therefore, different OC sources and decomposition status could be crucial shaping the microbial community.