Biology subjects

Wilburn, P.

Publications and source records attributed to Wilburn, P..

3 recordsLinked to original sources

bioRxiv2022

Adaptations of endolithic communities to abrupt environmental changes in a hyper-arid desert

The adaptation mechanisms of microbial communities to natural perturbations remain relatively unexplored, particularly in extreme environments. The extremophilic communities of halite (NaCl) nodules from the hyper-arid core of the Atacama Desert are self-sustained and represent a unique opportunity to study functional adaptations and community dynamics with changing environmental conditions. We transplanted halite nodules to different sites in the desert and investigated how their taxonomic, cellular, and biochemical changes correlated with water availability, using environmental data modeling and metagenomic analyses. Salt-in strategists, mainly represented by haloarchaea, significantly increased in relative abundance at sites characterized by extreme dryness, multiple wet/dry cycles, and colder conditions. The functional analysis of metagenome-assembled genomes (MAGs) revealed site-specific enrichments in archaeal MAGs encoding for the uptake of various compatible solutes and for glycerol utilization. These findings suggest that opportunistic salt-in strategists took over the halite communities at the driest sites. They most likely benefited from metabolites newly released in the environment by the death of microorganisms least adapted to the new conditions. The observed changes were consistent with the need to maximize cellular bioenergetics when confronted with lower water availability and higher salinity, providing valuable information on microbial community adaptations and resilience to climate change.

microbiology↗

bioRxiv2020

Dual thermal ecotypes detected within a nearly genetically-identical population of the unicellular marine cyanobacterium Synechococcus

The extent and ecological significance of intraspecific diversity within marine microbial populations is still poorly understood, and it remains unclear if such strain-level microdiversity will affect fitness and persistence in a rapidly changing ocean environment. In this study, we cultured 11 sympatric strains of the ubiquitous marine picocyanobacterium Synechococcus isolated from a Narragansett Bay (Rhode Island, USA) phytoplankton community thermal selection experiment. Despite all 11 isolates being highly similar (with average nucleotide identities of >99.9%, with 98.6-100% of the genome aligning), thermal performance curves revealed selection at warm and cool temperatures had subdivided the initial population into thermotypes with pronounced differences in maximum growth temperatures. Within the fine-scale genetic diversity that did exist within this population, the two divergent thermal ecotypes differed at a locus containing genes for the phycobilisome antenna complex. Our study demonstrates that present-day marine microbial populations can contain microdiversity in the form of cryptic but environmentally-relevant thermotypes that may increase their resilience to future rising temperatures. SignificanceNumerous studies exist comparing the responses of distinct taxonomic groups of marine microbes to a warming ocean (interspecific thermal diversity). For example, Synechococcus, a nearly globally distributed unicellular marine picocyanobacterium that makes significant contributions to oceanic primary productivity, contains numerous taxonomically distinct lineages with well documented temperature relationships. Little is known though about the diversity of functional responses to temperature within a given population where genetic similarity is high (intraspecific thermal diversity). This study suggests that understanding the extent of this functional intraspecific microdiversity is an essential prerequisite to predicting the resilience of biogeochemically essential microbial groups such as marine Synechococcus to a changing climate.

microbiology↗

bioRxiv2019

Environmental drivers define contrasting microbial habitats, diversity and functional redundancy in Lake Baikal, Siberia

Understanding how microbial communities respond to environmental change requires knowing the main drivers of their structure, diversity and potential resilience. Lake Baikal is the worlds most ancient, deep, voluminous, and biodiverse lake, holding 20 percent of unfrozen fresh water that is undergoing rapid warming. Despite its global importance, little is known about Baikals bacterioplankton communities and their drivers. In this extensive survey, we show that temperature, along with stratification, nutrients, and dissolved oxygen, but not geographic distance, define major microbial habitats and community similarity. Mixed layer and deep water communities exhibited contrasting patterns of richness, diversity and evenness, and comprised different cohesive modules in the whole Baikal OTU co-occurrence network. The networks small-world properties indicated likely resistance to perturbations but sensitivity to abundance changes of central, most connected OTUs. Previous studies showed Baikal water temperature rising by over 1.2{degrees}C since 1946, and this trend is predicted to accelerate. Because temperature emerged as the most significant predictor of the mixed layer community structure, we hypothesize that it is most likely to drive future community changes. Understanding how temperature and other abiotic factors structure microbial communities in this and other rapidly changing ecosystems will allow better predictions of ecosystem responses to anthropogenic stressors.

ecology↗