Bioinformatic, phylogenetic and chemical analysis of the UV-absorbing compounds scytonemin and mycosporine-like amino acids from the microbial mat communities of Shark Bay, Australia.

Shark Bay, Western Australia is a World Heritage area with extensive microbial mats and stromatolites. Microbial communities that comprise these mats have developed a range of mitigation strategies against changing levels of photosynthetically active and ultraviolet radiation, including the ability to biosynthesise the UV-absorbing natural products scytonemin and mycosporine-like amino acids (MAAs). To this end, the distribution of photoprotective pigments within Shark Bay microbial mats was delineated in the present study. This involved amplicon sequencing of bacterial 16S rDNA from communities at the surface and subsurface in three distinct mat types (smooth, pustular and tufted), and correlating this data with the chemical and molecular distribution of scytonemin and MAAs. Employing UV spectroscopy and MS/MS fragmentation, mycosporine-glycine, asterina and an unknown MAA were identified based on typical fragmentation patterns. Marker genes for scytonemin and MAA production (scyC and mysC) were amplified from microbial mat DNA and placed into phylogenetic context against a broad screen throughout 363 cyanobacterial genomes. Results indicate that occurrence of UV screening compounds is associated with the upper layer of Shark Bay microbial mats, and the occurrence of scytonemin is closely dependent on the abundance of cyanobacteria.

Communication within East Antarctic Soil Bacteria.

Antarctica, being the coldest, driest, and windiest continent on Earth, represents the most extreme environment in which a living organism can survive. Under constant exposure to harsh environmental threats, terrestrial Antarctica remains home to a great diversity of microorganisms, indicating that the soil bacteria must have adapted a range of survival strategies that require cell-to-cell communication. Survival strategies include secondary metabolite production, biofilm formation, bioluminescence, symbiosis, conjugation, sporulation, and motility, all of which are often regulated by quorum sensing (QS), a type of bacterial communication. Until now, such mechanisms have not been explored in terrestrial Antarctica. In this study, LuxI/LuxR-based quorum sensing (QS) activity was delineated in soil bacterial isolates recovered from Adams Flat, in the Vestfold Hills region of East Antarctica. Interestingly, we identified the production of potential homoserine lactones (HSLs) with chain lengths ranging from medium to long in 19 bacterial species using three biosensors, namely, Agrobacterium tumefaciens NTL4, Chromobacterium violaceum CV026, and Escherichia coli MT102, in conjunction with thin-layer chromatography (TLC). The majority of detectable HSLs were from Gram-positive species not previously known to produce HSLs. This discovery further expands our understanding of the microbial community capable of this type of communication, as well as provides insights into physiological adaptations of microorganisms that allow them to survive in the harsh Antarctic environment.IMPORTANCE Quorum sensing, a type of bacterial communication, is widely known to regulate many processes, including those that confer a survival advantage. However, little is known about communication by bacteria residing within Antarctic soils. Employing a combination of bacterial biosensors, analytical techniques, and genome mining, we found a variety of Antarctic soil bacteria speaking a common language, via LuxI/LuxR-based quorum sensing, thus potentially supporting survival in a mixed microbial community. This study reports potential quorum sensing activity in Antarctic soils and has provided a platform for studying physiological adaptations of microorganisms that allow them to survive in the harsh Antarctic environment.

Untapped Resources: Biotechnological Potential of Peptides and Secondary Metabolites in Archaea.

Archaea are an understudied domain of life often found in "extreme" environments in terms of temperature, salinity, and a range of other factors. Archaeal proteins, such as a wide range of enzymes, have adapted to function under these extreme conditions, providing biotechnology with interesting activities to exploit. In addition to producing structural and enzymatic proteins, archaea also produce a range of small peptide molecules (such as archaeocins) and other novel secondary metabolites such as those putatively involved in cell communication (acyl homoserine lactones), which can be exploited for biotechnological purposes. Due to the wide array of metabolites produced there is a great deal of biotechnological potential from antimicrobials such as diketopiperazines and archaeocins, as well as roles in the cosmetics and food industry. In this review we will discuss the diversity of small molecules, both peptide and nonpeptide, produced by archaea and their potential biotechnological applications.

Adaptation, ecology, and evolution of the halophilic stromatolite archaeon Halococcus hamelinensis inferred through genome analyses.

Halococcus hamelinensis was the first archaeon isolated from stromatolites. These geomicrobial ecosystems are thought to be some of the earliest known on Earth, yet, despite their evolutionary significance, the role of Archaea in these systems is still not well understood. Detailed here is the genome sequencing and analysis of an archaeon isolated from stromatolites. The genome of H. hamelinensis consisted of 3,133,046 base pairs with an average G+C content of 60.08% and contained 3,150 predicted coding sequences or ORFs, 2,196 (68.67%) of which were protein-coding genes with functional assignments and 954 (29.83%) of which were of unknown function. Codon usage of the H. hamelinensis genome was consistent with a highly acidic proteome, a major adaptive mechanism towards high salinity. Amino acid transport and metabolism, inorganic ion transport and metabolism, energy production and conversion, ribosomal structure, and unknown function COG genes were overrepresented. The genome of H. hamelinensis also revealed characteristics reflecting its survival in its extreme environment, including putative genes/pathways involved in osmoprotection, oxidative stress response, and UV damage repair. Finally, genome analyses indicated the presence of putative transposases as well as positive matches of genes of H. hamelinensis against various genomes of Bacteria, Archaea, and viruses, suggesting the potential for horizontal gene transfer.

Sulfide intrusion in a habitat forming seagrass can be predicted from relative abundance of sulfur cycling genes in sediments.

Sulfide intrusion from sediments is an increasingly recognized contributor to seagrass declines globally, yet the relationship between sediment microorganisms and sulfide intrusion has received little attention. Here, we use metagenomic sequencing and stable isotope (34S) analysis to examine this relationship in Cockburn Sound, Australia, a seagrass-dominated embayment with a gradient of sulfide stress and seagrass declines. There was a significant positive relationship between sulfide intrusion into seagrasses and sulfate reduction genes in sediment microbial communities, which was greatest at sites with long term seagrass declines. This is the first demonstration of a significant link between sulfur cycling genes present in seagrass sediments and sulfide intrusion in a habitat-forming seagrass that is experiencing long-term shoot density decline. Given that microorganisms respond rapidly to environmental change, the quantitative links established in this study can be used as a potential management tool to enable the prediction of sulfide stress on large habitat forming seagrasses; a global issue expected to worsen with climate change.

Genome sequence of the halophilic archaeon Halococcus hamelinensis.

Halococcus hamelinensis was isolated from hypersaline stromatolites in Shark Bay, Australia. Here we report the genome sequence (3,133,046 bp) of H. hamelinensis, which provides insights into the ecology, evolution, and adaptation of this novel microorganism.

Eukarya the chimera: eukaryotes, a secondary innovation of the two domains of life?

One of the most significant events in the evolution of life is the origin of the eukaryotic cell, an increase in cellular complexity that occurred approximately 2 billion years ago. Ground-breaking research has centered around unraveling the characteristics of the Last Eukaryotic Common Ancestor (LECA) and the nuanced archaeal and bacterial contributions in eukaryogenesis, resulting in fundamental changes in our understanding of the Tree of Life. The archaeal and bacterial roles are covered by theories of endosymbiogenesis wherein an ancestral host archaeon and a bacterial endosymbiont merged to create a new complex cell type - Eukarya - and its mitochondrion. Eukarya is often regarded as a unique and distinct domain due to complex innovations not found in archaea or bacteria, despite housing a chimeric genome containing genes of both archaeal and bacterial origin. However, the discovery of complex cell machineries in recently described Asgard archaeal lineages, and the growing support for diverse bacterial gene transfers prior to and during the time of LECA, is redefining our understanding of eukaryogenesis. Indeed, the uniqueness of Eukarya, as a domain, is challenged. It is likely that many microbial syntrophies, encompassing a 'microbial village', were required to 'raise' a eukaryote during the process of eukaryogenesis.

Genome-resolved metagenomics provides insights into the functional complexity of microbial mats in Blue Holes, Shark Bay.

The present study describes for the first time the community composition and functional potential of the microbial mats found in the supratidal, gypsum-rich and hypersaline region of Blue Holes, Shark Bay. This was achieved via high-throughput metagenomic sequencing of total mat community DNA and complementary analyses using hyperspectral confocal microscopy. Mat communities were dominated by Proteobacteria (29%), followed by Bacteroidetes/Chlorobi group (11%) and Planctomycetes (10%). These mats were found to also harbour a diverse community of potentially novel microorganisms, including members from the DPANN, Asgard archaea and candidate phyla radiation, with highest diversity found in the lower regions (∼14-20 mm depth) of the mat. In addition to pathways for major metabolic cycles, a range of putative rhodopsins with previously uncharacterized motifs and functions were identified along with heliorhodopsins and putative schizorhodopsins. Critical microbial interactions were also inferred, and from 117 medium- to high-quality metagenome-assembled genomes, viral defence mechanisms (CRISPR, BREX and DISARM), elemental transport, osmoprotection, heavy metal resistance and UV resistance were also detected. These analyses have provided a greater understanding of these distinct mat systems in Shark Bay, including key insights into adaptive responses and proposing that photoheterotrophy may be an important lifestyle in Blue Holes.

A Cyanobacteria Enriched Layer of Shark Bay Stromatolites Reveals a New Acaryochloris Strain Living in Near Infrared Light.

The genus Acaryochloris is unique among phototrophic organisms due to the dominance of chlorophyll d in its photosynthetic reaction centres and light-harvesting proteins. This allows Acaryochloris to capture light energy for photosynthesis over an extended spectrum of up to ~760 nm in the near infra-red (NIR) spectrum. Acaryochloris sp. has been reported in a variety of ecological niches, ranging from polar to tropical shallow aquatic sites. Here, we report a new Acarychloris strain isolated from an NIR-enriched stratified microbial layer 4-6 mm under the surface of stromatolite mats located in the Hamelin Pool of Shark Bay, Western Australia. Pigment analysis by spectrometry/fluorometry, flow cytometry and spectral confocal microscopy identifies unique patterns in pigment content that likely reflect niche adaption. For example, unlike the original A. marina species (type strain MBIC11017), this new strain, Acarychloris LARK001, shows little change in the chlorophyll d/a ratio in response to changes in light wavelength, displays a different Fv/Fm response and lacks detectable levels of phycocyanin. Indeed, 16S rRNA analysis supports the identity of the A. marina LARK001 strain as close to but distinct from from the A. marina HICR111A strain first isolated from Heron Island and previously found on the Great Barrier Reef under coral rubble on the reef flat. Taken together, A. marina LARK001 is a new cyanobacterial strain adapted to the stromatolite mats in Shark Bay.

Between a Rock and a Soft Place: The Role of Viruses in Lithification of Modern Microbial Mats.

Stromatolites are geobiological systems formed by complex microbial communities, and fossilized stromatolites provide a record of some of the oldest life on Earth. Microbial mats are precursors of extant stromatolites; however, the mechanisms of transition from mat to stromatolite are controversial and are still not well understood. To fully recognize the profound impact that these ecosystems have had on the evolution of the biosphere requires an understanding of modern lithification mechanisms and how they relate to the geological record. We propose here viral mechanisms in carbonate precipitation, leading to stromatolite formation, whereby viruses directly or indirectly impact microbial metabolisms that govern the transition from microbial mat to stromatolite. Finding a tangible link between host-virus interactions and changes in biogeochemical processes will provide tools to interpret mineral biosignatures through geologic time, including those on Earth and beyond.

Identification and characterization of Helicobacter pylori genes essential for gastric colonization.

Helicobacter pylori causes one of the most common, chronic bacterial infections and is a primary cause of severe gastric disorders. To unravel the bacterial factors necessary for the process of gastric colonization and pathogenesis, signature tagged mutagenesis (STM) was adapted to H. pylori. The Mongolian gerbil (Meriones unguiculatus) was used as model system to screen a set of 960 STM mutants. This resulted in 47 H. pylori genes, assigned to 9 different functional categories, representing a set of biological functions absolutely essential for gastric colonization, as verified and quantified for many mutants by competition experiments. Identification of previously known colonization factors, such as the urease and motility functions validated this method, but also novel and several hypothetical genes were found. Interestingly, a secreted collagenase, encoded by hp0169, could be identified and functionally verified as a new essential virulence factor for H. pylori stomach colonization. Furthermore, comB4, encoding a putative ATPase being part of a DNA transformation-associated type IV transport system of H. pylori was found to be absolutely essential for colonization, but natural transformation competence was apparently not the essential function. Thus, this first systematic STM application identified a set of previously unknown H. pylori colonization factors and may help to potentiate the development of novel therapies against gastric Helicobacter infections.

Identification and regulation of novel compatible solutes from hypersaline stromatolite-associated cyanobacteria.

Cyanobacteria are able to survive in various extreme environments via the production of organic compounds known as compatible solutes. In particular, cyanobacteria are capable of inhabiting hypersaline environments such as those found in intertidal regions. Cyanobacteria in these environments must possess regulatory mechanisms for surviving the changing osmotic pressure as a result of desiccation, rainfall and tidal fluxes. The objective of this study was to determine the compatible solutes that are accumulated by cyanobacteria from hypersaline regions, and specifically, the stromatolite ecosystems of Shark Bay, Western Australia. Previously, the cyanobacterial populations associated with these stromatolites were characterized in two separate studies. Compatible solutes were extracted from isolated cyanobacteria here and identified by nuclear magnetic resonance. As the media of isolation contained no complex carbon source, the solutes accumulated were likely synthesized by the cyanobacteria. The data indicate that from this one habitat taxonomically distinct cyanobacteria exposed to varying salinities accumulate a range of known compatible solutes. In addition, taxonomically similar cyanobacteria do not necessarily accumulate the same compatible solutes. Glucosylglycerol, a compatible solute unique to marine cyanobacteria was not detected; however, various saccharides, glycine betaine, and trimethylamine-N-oxide were identified as the predominant solutes. We conclude that the cyanobacterial communities from these hypersaline stromatolites are likely to possess more complex mechanisms of adaptation to osmotic stress than previously thought. The characterization of osmoregulatory properties of stromatolite microorganisms provides further insight into how life can thrive in such extreme environments.

Archaea join the conversation: detection of AHL-like activity across a range of archaeal isolates.

Quorum sensing is a mechanism of genetic control allowing single cell organisms to coordinate phenotypic response(s) across a local population and is often critical for ecosystem function. Although quorum sensing has been extensively studied in bacteria comparatively less is known about this mechanism in Archaea. Given the growing significance of Archaea in both natural and anthropogenic settings, it is important to delineate how widespread this phenomenon of signaling is in this domain. Employing a plasmid-based AHL biosensor in conjunction with thin-layer chromatography (TLC), the present study screened a broad range of euryarchaeota isolates for potential signaling activity. Data indicated the presence of 11 new Archaeal isolates with AHL-like activity against the LuxR-based AHL biosensor, including for the first time putative AHL activity in a thermophile. The presence of multiple signals and distinct changes between growth phases were also shown via TLC. Multiple signal molecules were detected using TLC in Haloferax mucosum, Halorubrum kocurii, Natronococcus occultus and Halobacterium salinarium. The finding of multiple novel signal producers suggests the potential for quorum sensing to play an important role not only in the regulation of complex phenotypes within Archaea but the potential for cross-talk with bacterial systems.

Discovery of an Abundance of Biosynthetic Gene Clusters in Shark Bay Microbial Mats.

Microbial mats are geobiological multilayered ecosystems that have significant evolutionary value in understanding the evolution of early life on Earth. Shark Bay, Australia has some of the best examples of modern microbial mats thriving under harsh conditions of high temperatures, salinity, desiccation, and ultraviolet (UV) radiation. Microorganisms living in extreme ecosystems are thought to potentially encode for secondary metabolites as a survival strategy. Many secondary metabolites are natural products encoded by a grouping of genes known as biosynthetic gene clusters (BGCs). Natural products have diverse chemical structures and functions which provide competitive advantages for microorganisms and can also have biotechnology applications. In the present study, the diversity of BGC were described in detail for the first time from Shark Bay microbial mats. A total of 1477 BGCs were detected in metagenomic data over a 20 mm mat depth horizon, with the surface layer possessing over 200 BGCs and containing the highest relative abundance of BGCs of all mat layers. Terpene and bacteriocin BGCs were highly represented and their natural products are proposed to have important roles in ecosystem function in these mat systems. Interestingly, potentially novel BGCs were detected from Heimdallarchaeota and Lokiarchaeota, two evolutionarily significant archaeal phyla not previously known to possess BGCs. This study provides new insights into how secondary metabolites from BGCs may enable diverse microbial mat communities to adapt to extreme environments.

Microbial dark matter filling the niche in hypersaline microbial mats.

BACKGROUND: Shark Bay, Australia, harbours one of the most extensive and diverse systems of living microbial mats that are proposed to be analogs of some of the earliest ecosystems on Earth. These ecosystems have been shown to possess a substantial abundance of uncultivable microorganisms. These enigmatic microbes, jointly coined as 'microbial dark matter' (MDM), are hypothesised to play key roles in modern microbial mats. RESULTS: We reconstructed 115 metagenome-assembled genomes (MAGs) affiliated to MDM, spanning 42 phyla. This study reports for the first time novel microorganisms (Zixibacterial order GN15) putatively taking part in dissimilatory sulfate reduction in surface hypersaline settings, as well as novel eukaryote signature proteins in the Asgard archaea. Despite possessing reduced-size genomes, the MDM MAGs are capable of fermenting and degrading organic carbon, suggesting a role in recycling organic carbon. Several forms of RuBisCo were identified, allowing putative CO2 incorporation into nucleotide salvaging pathways, which may act as an alternative carbon and phosphorus source. High capacity of hydrogen production was found among Shark Bay MDM. Putative schizorhodopsins were also identified in Parcubacteria, Asgard archaea, DPANN archaea, and Bathyarchaeota, allowing these members to potentially capture light energy. Diversity-generating retroelements were prominent in DPANN archaea that likely facilitate the adaptation to a dynamic, host-dependent lifestyle. CONCLUSIONS: This is the first study to reconstruct and describe in detail metagenome-assembled genomes (MAGs) affiliated with microbial dark matter in hypersaline microbial mats. Our data suggests that these microbial groups are major players in these systems. In light of our findings, we propose H2, ribose and CO/CO2 as the main energy currencies of the MDM community in these mat systems. Video Abstract.

Functional Gene Expression in Shark Bay Hypersaline Microbial Mats: Adaptive Responses.

Microbial mat communities possess extensive taxonomic and functional diversity, which drive high metabolic rates and rapid cycling of major elements. Modern microbial mats occurring in hypersaline environments are considered as analogs to extinct geobiological formations dating back to ∼ 3.5 Gyr ago. Despite efforts to understand the diversity and metabolic potential of hypersaline microbial mats in Shark Bay, Western Australia, there has yet to be molecular analyses at the transcriptional level in these microbial communities. In this study, we generated metatranscriptomes for the first time from actively growing mats comparing the type of mat, as well as the influence of diel and seasonal cycles. We observed that the overall gene transcription is strongly influenced by microbial community structure and seasonality. The most transcribed genes were associated with tackling the low nutrient conditions by the uptake of fatty acids, phosphorus, iron, and nickel from the environment as well as with protective mechanisms against elevated salinity conditions and to prevent build-up of ammonium produced by nitrate reducing microorganisms. A range of pathways involved in carbon, nitrogen, and sulfur cycles were identified in mat metatranscriptomes, with anoxygenic photosynthesis and chemoautotrophy using the Arnon-Buchanan cycle inferred as major pathways involved in the carbon cycle. Furthermore, enrichment of active anaerobic pathways (e.g., sulfate reduction, methanogenesis, Wood-Ljungdahl) in smooth mats corroborates previous metagenomic studies and further advocates the potential of these communities as modern analogs of ancient microbialites.

Asgard archaea: Diversity, function, and evolutionary implications in a range of microbiomes.

Elucidating the diversity of the Archaea has many important ecological and evolutionary implications. The Asgard superphylum of the archaea, described recently from metagenomic data, has reignited the decades-old debate surrounding the topology of the tree of life. This review synthesizes recent findings through publicly available genomes and literature to describe the current ecological and evolutionary significance of the Asgard superphylum. Asgard archaea have been found in a diverse range of microbiomes across the globe, primarily from sedimentary environments. Within these environments, positive correlations between specific members of the Asgard archaea and Candidate Division TA06 bacteria have been observed, opening up the possibility of symbiotic interactions between the groupings. Asgard archaeal genomes encode functionally diverse metabolic pathways, including the Wood-Ljungdahl pathway as a carbon-fixation strategy, putative nucleotide salvaging pathways, and novel mechanisms of phototrophy including new rhodopsins. Asgard archaea also appear to be active in nitrogen cycling. Asgard archaea encode genes involved in both dissimilatory nitrate reduction and denitrification, and for the potential to use atmospheric nitrogen or nitrite as nitrogen sources. Asgard archaea also may be involved in the transformation of sulfur compounds, indicating a putative role in sulfur cycling. To date, all Asgard archaeal genomes identified were described as obligately anaerobic. The Asgard archaea also appear to have important evolutionary implications. The presence of eukaryotic signature proteins and the affiliation of Asgard archaea in phylogenetic analyses appears to support two-domain topologies of the tree of life with eukaryotes emerging from within the domain of archaea, as opposed to the eukaryotes being a separate domain of life. Thus far, Heimdallarchaeota appears as the closest archaeal relative of eukaryotes.

Isolation of novel quorum-sensing active bacteria from microbial mats in Shark Bay Australia.

Quorum sensing is a potent system of genetic control allowing phenotypes to be coordinated across localized communities. In this study, quorum sensing systems in Shark Bay microbial mats were delineated using a targeted approach analyzing whole mat extractions as well as the creation of an isolate library. A library of 165 isolates from different mat types were screened using the AHL biosensor E. coli MT102. Based on sequence identity 30 unique isolates belonging to Proteobacteria, Actinobacteria and Firmicutes were found to activate the AHL biosensor, suggesting AHLs or analogous compounds were potentially present. Several of the isolates have not been shown previously to produce signal molecules, particularly the members of the Actinobacteria and Firmicutes phyla including Virgibacillus, Halobacillius, Microbacterium and Brevibacterium. These active isolates were further screened using thin-layer chromatography (TLC) providing putative identities of AHL molecules present within the mat communities. Nine isolates were capable of producing several spots of varying sizes after TLC separation, suggesting the presence of multiple signalling molecules. This study is the first to delineate AHL-based signalling in the microbial mats of Shark Bay, and suggests quorum sensing may play a role in the ecosphysiological coordination of complex phenotypes across microbial mat communities.

Correlation of bio-optical properties with photosynthetic pigment and microorganism distribution in microbial mats from Hamelin Pool, Australia.

Microbial mats and stromatolites are widespread in Hamelin Pool, Shark Bay, however the phototrophic capacity of these systems is unknown. This study has determined the optical properties and light-harvesting potential of these mats with light microsensors. These characteristics were linked via a combination of 16S rDNA sequencing, pigment analyses and hyperspectral imaging. Local scalar irradiance was elevated over the incident downwelling irradiance by 1.5-fold, suggesting light trapping and strong scattering by the mats. Visible light (400-700 nm) penetrated to a depth of 2 mm, whereas near-infrared light (700-800 nm) penetrated to at least 6 mm. Chlorophyll a and bacteriochlorophyll a (Bchl a) were found to be the dominant photosynthetic pigments present, with BChl a peaking at the subsurface (2-4 mm). Detailed 16S rDNA analyses revealed the presence of putative Chl f-containing Halomicronema sp. and photosynthetic members primarily decreased from the mat surface down to a depth of 6 mm. Data indicated high abundances of some pigments and phototrophic organisms in deeper layers of the mats (6-16 mm). It is proposed that the photosynthetic bacteria present in this system undergo unique adaptations to lower light conditions below the mat surface, and that phototrophic metabolisms are major contributors to ecosystem function.

The Vulnerability of Microbial Ecosystems in A Changing Climate: Potential Impact in Shark Bay.

The potential impact of climate change on eukaryotes, including humans, has been relatively well described. In contrast, the contribution and susceptibility of microorganisms to a changing climate have, until recently, received relatively less attention. In this review, the importance of microorganisms in the climate change discourse is highlighted. Microorganisms are responsible for approximately half of all primary production on earth, support all forms of macroscopic life whether directly or indirectly, and often persist in "extreme" environments where most other life are excluded. In short, microorganisms are the life support system of the biosphere and therefore must be included in decision making regarding climate change. Any effects climate change will have on microorganisms will inevitably impact higher eukaryotes and the activity of microbial communities in turn can contribute to or alleviate the severity of the changing climate. It is of vital importance that unique, fragile, microbial ecosystems are a focus of research efforts so that their resilience to extreme weather events and climate change are thoroughly understood and that conservation efforts can be implemented as a response. One such ecosystem under threat are the evolutionarily significant microbial mats and stromatolites, such as those present in Shark Bay, western Australia. Climate change models have suggested the duration and severity of extreme weather events in this region will increase, along with rising temperatures, sea levels, and ocean acidification. These changes could upset the delicate balance that fosters the development of microbial mats and stromatolites in Shark Bay. Thus, the challenges facing Shark Bay microbial communities will be presented here as a specific case study.