Biology subjects

Hansel, C. M.

Publications and source records attributed to Hansel, C. M..

3 recordsLinked to original sources

bioRxiv2026

Deep-sea siliceous sponges harbor distinct and functionally diverse microbiomes

Sponges, phylum Porifera, are long-lived and basal-branching metazoans that play important roles in ocean biogeochemistry and host diverse microbial communities. Siliceous sponges form a major clade of the Porifera, yet their microbiome is not well-characterized, particularly in the deep ocean. Here, we used shotgun metagenomics to investigate the composition of the microbial communities of 13 siliceous sponges collected from four sites near Puerto Rico from depths ranging from 400-1900 meters. Nine of the sponges in this study are from five sponge family taxa that have not previously been sequenced using shotgun metagenomics. We assembled a total of 176 metagenome-assembled-genomes from 20 bacterial and 1 archaeal phyla. Ammonia-oxidizing archaea (AOA) Nitrosopumilaceae dominated most siliceous sponge microbial communities and was strikingly the sole symbiont associated with one sponge (Farrea). Overall, microbiome diversity was relatively low across siliceous sponges, except for a Phloeodictyidae, which was likely a high microbial abundance (HMA) sponge. Our results suggest that host sponge phylogeny may shape microbial community structure, with limited evidence for environmental influence. The sponge-associated microbial communities contained genetic capabilities for diverse metabolic functions, particularly contributing to the carbon, nitrogen, and sulfur cycles. In addition to the AOA, evidence of potential for microbial autotrophy was found through the presence of genes for RuBisCO, methanotrophy, and ATP citrate lyase. These results reveal both conserved relationships and metabolic flexibility across siliceous sponge lineages, suggesting unique evolutionary dynamics and demonstrating the importance of microbial metabolism to sponge host health and nutrient cycling in the oligotrophic deep ocean. ImportanceMarine sponges, emerging [~]600 million years ago, have close relationships with microorganisms, but the microbiome of deep-sea siliceous sponges is not well understood. Siliceous sponges play essential roles in deep-sea ecosystems by providing habitats for other metazoans and mediating carbon, nitrogen, and sulfur cycling, yet they remain some of the least studied sponges. By shotgun sequencing DNA from 13 siliceous sponges collected near Puerto Rico, this study found that host sponge phylogeny influences microbial community composition and structure. Ammonia-oxidizing archaea dominated the microbial communities associated with marine sponges, likely playing key roles in utilizing metabolic byproducts and supporting host health. Other microbes also contributed to nutrient cycling and contained the potential to fix carbon, suggesting metabolic flexibility which may benefit sponge hosts in low-resource environments. These findings emphasize the ecological importance of siliceous sponge-microbe symbioses and contribute to our understanding of the drivers shaping their structure and function.

microbiology↗

bioRxiv2022

Two canonically aerobic foraminifera express distinct peroxisomal and mitochondrial metabolisms

Certain benthic foraminifera are known to thrive in marine sediments with low oxygen or even without detectable oxygen. Potential survival avenues used by these supposedly aerobic protists include fermentation and anaerobic respiration, although details on their adaptive mechanisms remain somewhat elusive. To better understand the metabolic versatility of foraminifera, we studied two benthic species that thrive in oxygen-depleted marine sediments. Here we detail, via transcriptomics and metatranscriptomics, differential gene expression of Nonionella stella and Bolivina argentea, collected from Santa Barbara Basin, California, USA, in response to varied oxygenation and chemical amendments. Organelle-specific metabolic reconstructions revealed that these two species utilize adaptable mitochondrial and peroxisomal metabolism that reflect their differing lifestyles. N. stella, most abundant in anoxia and characterized by the lack of food vacuoles and the abundance of intracellular lipid droplets, was predicted to couple the putative peroxisomal beta-oxidation and glyoxylate cycle with a versatile electron transport system and a partial TCA cycle running in the reductive direction. In contrast, B. argentea, most abundant in hypoxia and contains food vacuoles, was predicted to utilize the putative peroxisomal gluconeogenesis and a full TCA cycle but lacks the expression of key beta-oxidation and glyoxylate cycle genes. These metabolic adaptations likely confer ecological success while encountering deoxygenation and illuminate the importance of metabolic modifications and interactions between mitochondria and peroxisomes in protists. ImportanceForaminiferan protists are nearly ubiquitous in todays oceans and likely were major components of the Neoproterozoic protistan community. While largely considered aerobic, certain foraminifera demonstrate surprising adaptability to hypoxia and anoxia, contributing to biogeochemical cycling in benthic environments. The analyses of Rhizarian adaptive metabolism set the stage for studying other microeukaryotes under increasing ocean deoxygenation. Revealing the metabolic roles of foraminifera in anaerobic biogeochemical cycling should spur reassessments of existing paleoecological datasets as well as new perspectives on the metabolic evolution of eukaryotic cells.

microbiology↗

bioRxiv2020

Mechanisms and heterogeneity of mineral use by natural colonies of the cyanobacterium Trichodesmium

The keystone marine nitrogen fixer Trichodesmium thrives in high dust environments, and while experimental observations suggest that Trichodesmium colonies can access the essential nutrient iron from dust particles, it is not known the extent to which this occurs in the field. Here we demonstrate that Trichodesmium colonies actively process mineral particles in nature with direct molecular impacts. Microscopy and synchrotron-based imaging demonstrated heterogeneous associations with particles consistent with iron oxide and iron silicate minerals. Metaproteomic analysis of individual colonies revealed enrichment of biogeochemically-relevant proteins including photosynthesis proteins and metalloproteins containing iron, nickel, copper and zinc when particles were present. The iron-storage protein ferritin was particularly enriched implying accumulation of particle-derived iron, and multiple iron acquisition pathways including Fe(II), Fe(III), and Fe-siderophore transporters were engaged, including evidence of superoxide-driven particle dissolution. While the particles clearly provided iron, there was also evidence that the concentrated metals had toxic effects. The molecular mechanisms allowing Trichodesmium to interact with particulate minerals are fundamental to its success and global impact on nitrogen biogeochemistry, and may contribute to the leaching of particulate trace metals with implications for global iron and carbon cycling.

ecology↗