Biology subjects

Pointing, S.

Publications and source records attributed to Pointing, S..

4 recordsLinked to original sources

bioRxiv2026

Geothermal gradients restructure metabolism in hot spring microbial communities

Hot springs are employed as model systems for understanding how environmental stress structures microbial communities, yet the mechanisms by which geothermal stress reorganizes community metabolism remain poorly understood. Here we combined genome-resolved metagenomics, metatranscriptomics, aqueous geochemistry, and community metabolic modelling to investigate photosynthetic biofilms across the geothermal gradient of a hot spring in Singapore. We reconstructed community taxonomic and functional composition via metagenome-assembled genomes and identified three transcriptionally coordinated ecological guilds defined by convergent metabolic strategies rather than phylogeny. Community metabolic models revealed that increasing geothermal stress reorganized nutrient exchange networks, progressively reducing metabolic redundancy and increasing dependence on reciprocal interactions among thermophilic guilds. Increasing geothermal stress redirected relative modelled elemental demand from carbon-associated metabolism towards nitrogen and sulfur metabolism, highlighting nitrogen limitation and sulfur-linked bioenergetics as defining features of stress adaptation. Electron allocation modelling further demonstrated a systems-level transition from growth-oriented biosynthesis toward catabolic energy conservation, respiratory metabolism, and oxidative stress management under geothermal stress. These coordinated metabolic shifts indicate that hot spring communities become increasingly specialized and energetically constrained near their upper geothermal limits. Overall, the findings demonstrate how environmental stress restructures microbial ecosystems through guild-level metabolic partitioning and cooperative resource exchange and establishes an integrative systems biology framework for predicting microbial ecosystem function in extreme environments.

microbiology↗

bioRxiv2019

Air mass source determines airborne microbial diversity at the ocean-atmosphere interface of the Great Barrier Reef marine ecosystem

The atmosphere is the least understood biome on Earth despite its critical role as a microbial transport medium. The influence of surface cover on composition of airborne microbial communities above marine systems is unclear. Here we report evidence for a dynamic microbial presence at the ocean-atmosphere interface of a major marine ecosystem, the Great Barrier Reef, and identify that recent air mass trajectory over an oceanic or continental surface associated with observed shifts in airborne bacterial and fungal diversity. Relative abundance of shared taxa between air and coral microbiomes varied between 2.2-8.8% and included those identified as part of the core coral microbiome. We propose that this variable source of atmospheric inputs may in part contribute to the diverse and transient nature of the coral microbiome.

microbiology↗

bioRxiv2018

Microbial dispersal limitation to isolated soil habitats in the McMurdo Dry Valleys of Antarctica

Dispersal is a critical yet poorly understood factor underlying macroecological patterns in microbial communities. Airborne microbial transport is assumed to occupy a central role in determining dispersal outcomes and extra-range dispersal has important implications for predicting ecosystem resilience and response to environmental change. One of the most pertinent biomes in this regard is Antarctica given its geographic isolation and vulnerability to climate change and human disturbance. Here we report the first characterisation of microbial diversity in near-ground and high-altitude air above a typical Antarctic Dry Valley as well as that of underlying soil microbial communities. We found that persistent airborne inputs were unable to fully explain local soil community assembly. Comparison with airborne microbial diversity from non-polar sources suggests that strong selection occurs during atmospheric transport resulting in regionally isolated airborne inputs and highly specialized soil communities where fungi displayed greater isolation than bacteria from non-polar sources. Overall microbial communities from this isolated Antarctic ecosystem displayed limited connectivity to the global microbial pool. Our findings provide critical insights to forecast the potential outcomes for microbial communities of climate change-mediated shifts in air circulation to the Dry Valleys, the largest ice-free region of Antarctica.

microbiology↗

bioRxiv2018

Soil microbial habitats in an extreme desert Mars-analogue environment

Sediments in the hyper-arid core of the Atacama Desert are a terrestrial analogue to Mars regolith. Understanding the distribution and drivers of microbial life in the sediment may give critical clues on how to search for biosignatures on Mars. Here, we identify the spatial distribution of highly specialised bacterial communities in previously unexplored depth horizons of subsurface sediments. We deployed an autonomous rover in a mission-relevant Martian drilling scenario with manual sample validation. Subsurface communities were delineated by depth related to sediment moisture. Geochemical analysis indicated soluble salts and minerology that influenced water bio-availability, particularly in deeper sediments. Colonization was also patchy and uncolonized sediment was associated with indicators of extreme osmotic challenge. The study identifies linkage between biocomplexity, moisture and geochemistry in Mars-like sediments at the limit of habitability and demonstrates feasibility of the rover-mounted drill for future Mars sample recovery.

microbiology↗