Microbial community response to environmental change during the Anthropocene

Abstract

Microbial community composition and functional potential can be affected by human-derived environmental changes during the Anthropocene with important consequences for elemental cycling and whole ecosystem processes. This study tested the hypothesis that environmental changes impact microbial communities across different spatial and temporal scales. The main objectives of this study were to determine 1) biocorrosion-causing organism colonization and abundance on man-made steel structures, 2) the identity and function of a core microbiome across steel microbial communities, and 3) the response of coastal microbial communities to extreme hurricane disturbance events. Steel microbiomes represent microbial responses to environmental disturbance (i.e., introduction of a novel substrate and surface environment) on small spatial scales but long temporal scales. Conversely, microbial responses to extreme storm events provide insight into disturbances affecting large spatial scales but short temporal scales. Stainless steel (304 and 316) deployments along salinity gradients in two North Carolina estuarine river systems resulted in increased colonization of iron-oxidizing bacteria on more-corrosion-resistant stainless steel (316) and at higher salinities. A novel iron-oxidizer species Mariprofundus erugo was isolated and sequenced, revealing genes for molybdenum utilization and reactive oxygen species protection, which may represent adaptations towards advanced steel types. Comparisons of microbial communities across stainless steel and historic ferrous-hulled shipwreck steel in the Pamlico Sound, NC revealed a "core steel microbiome" of heterotrophic generalists that likely play important roles in biofilm protection and functional stability for biocorrosion communities. Shifting scales, extreme hurricane events were correlated with changes in total (DNA) and active (RNA) coastal bacterial but not archaeal communities, and in the water column but not in sediments. Offshore marine sites exhibited decreased community diversity and evenness and increased abundance of copiotrophs. Hurricanes were also correlated with increased putative function of pathogenic taxa (i.e., Prevotella and Legionella) and lignin-degrading taxa, likely causing decreased water quality and increased bacterial production. These environmental disturbances across different spatial and temporal scales show that microbial communities are constantly responding and adapting to survive. Microbial communities have shown to be extremely resilient to Anthropocene conditions, and the microbial responses in this study can be applied to better understand future global change scenarios.