Seasonal Dynamics of Bathyarchaeota-Dominated Benthic Archaeal Communities Associated with Seagrass (Zostera japonica) Meadows

Changes in the Rhizosphere Prokaryotic Community Structure of Halodule wrightii Monospecific Stands Associated to Submarine Groundwater Discharges in a Karstic Costal Area

Belowground seagrass associated microbial communities regulate biogeochemical dynamics in the surrounding sediments and influence seagrass physiology and health. However, little is known about the impact of environmental stressors upon interactions between seagrasses and their prokaryotic community in coastal ecosystems. Submerged groundwater discharges (SGD) at Dzilam de Bravo, Yucatán, Mexico, causes lower temperatures and salinities with higher nutrient loads in seawater, resulting in Halodule wrightii monospecific stands. In this study, the rhizospheric archaeal and bacterial communities were characterized by 16S rRNA Illumina sequencing along with physicochemical determinations of water, porewater and sediment in a 400 m northwise transect from SGD occurring at 300 m away from coastline. Core bacterial community included Deltaproteobacteria, Bacteroidia and Planctomycetia, possibly involved in sulfur metabolism and organic matter degradation while highly versatile Bathyarchaeia was the most abundantly represented class within the archaeal core community. Beta diversity analyses revealed two significantly different clusters as result of the environmental conditions caused by SGD. Sites near to SGD presented sediments with higher redox potentials and sand contents as well as lower organic matter contents and porewater ammonium concentrations compared with the furthest sites. Functional profiling suggested that denitrification, aerobic chemoheterotrophy and environmental adaptation processes could be better represented in these sites, while sulfur metabolism and genetic information processing related profiles could be related to SGD uninfluenced sites. This study showed that the rhizospheric prokaryotic community structure of H. wrightii and their predicted functions are shaped by environmental stressors associated with the SGD. Moreover, insights into the archaeal community composition in seagrasses rhizosphere are presented.

Fate and Transformation of 6:2 Fluorotelomer Sulfonic Acid Affected by Plant, Nutrient, Bioaugmentation, and Soil Microbiome Interactions

6:2 Fluorotelomer sulfonic acid (6:2 FTSA) is a dominant per- and poly-fluoroalkyl substance (PFAS) in aqueous film-forming foam (AFFF)-impacted soil. While its biotransformation mechanisms have been studied, the complex effects from plants, nutrients, and soil microbiome interactions on the fate and removal of 6:2 FTSA are poorly understood. This study systematically investigated the potential of phytoremediation for 6:2 FTSA byArabidopsis thalianacoupled with bioaugmentation ofRhodococcus jostiiRHA1 (designated as RHA1 hereafter) under different nutrient and microbiome conditions. Hyperaccumulation of 6:2 FTSA, defined as tissue/soil concentration > 10 and high translocation factor > 3, was observed in plants. However, biotransformation of 6:2 FTSA only occurred under sulfur-limited conditions. Spiking RHA1 not only enhanced the biotransformation of 6:2 FTSA in soil but also promoted plant growth. Soil microbiome analysis uncovered Rhodococcus as one of the dominant species in all RHA1-spiked soil. Different nutrients such as sulfur and carbon, bioaugmentation, and amendment of 6:2 FTSA caused significant changes in - microbial community structure. This study revealed the synergistic effects of phytoremediation and bioaugmentation on 6:2 FTSA removal. and highlighted that the fate of 6:2 FTSA was highly influced by the complex interactions of plants, nutrients, and soil microbiome.