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Microbial Ecosystems - Microbial mats

11 important questions on Microbial Ecosystems - Microbial mats

What are microbial mats?

Microbial mats are thin layers of bacteria and other microorganisms that grow on surfaces.

How are microbial mats related to biofilms, and what distinguishes them?

Microbial mats are extremely thick biofilms supported by phototrophic or chemolithotrophic bacteria. They can be several centimeters thick, with layers composed of different microbial guilds.

What factors govern the activities within microbial mats, and how do they create unique niches?

Microbial metabolism and nutrient transport controlled by diffusion result in steep concentration gradients of microbial nutrients and metabolites, creating unique niches at different depth intervals in the mats.

Why are filamentous cyanobacteria considered versatile phototrophic mat builders?

Filamentous cyanobacteria are oxygenic phototrophs that tolerate extreme environmental conditions, including high and low temperatures, salinities exceeding 12%, and pH values as high as 10.

What role do cyanobacterial mats play in aquatic ecosystems, and why are they restricted to certain environments?

Cyanobacterial mats are complete microbial ecosystems, mediating all key nutrient cycles. They are found in aquatic environments with environmental stresses, such as high temperatures or high salt concentrations, restricting grazing by small animals and insects.

How does the chemical and biological structure of cyanobacterial mats change during a diel cycle, and what are the key activities during the day and night?

During a diel cycle, cyanobacterial mats exhibit changes in pH, H2S, and O2. During the day, there is intense oxygen production in the surface layer, while at night, the entire mat turns anoxic as H2S accumulates.

Where do microbial mats of oxidized iron form, and what environmental consequences can arise from their activities?

Iron-rich microbial mats form in metal-rich, low-pH environments, such as mining operations and iron-rich hot springs. The activities of acidophilic iron-oxidizing microbes can lead to environmental damage when acidity and toxic heavy metals enter aquatic systems.

What novel phylum of microaerophilic Archaea is associated with iron-rich microbial mats, and what are their capabilities?

The Marsarchaeota is a novel phylum associated with iron-rich microbial mats. Enrichment cultures of Marsarchaeota suggest that they can oxidize both organic carbon and ferrous iron, contributing to the mat communities.

How do iron-rich mats differ from chemolithotrophic mats, and what are examples of sulfur-oxidizing chemolithotrophs?

Iron-rich mats lack phototrophic components and are supported by iron-oxidizing chemolithotrophs. Chemolithotrophic mats, like those composed of filamentous sulfur bacteria such as Beggiatoa and Thioploca, grow on marine sediment surfaces at the interface between O2 and H2S.

What unique strategy does Thioploca employ to bridge spatially separated resources, and where are extensive microbial mats of this type found?

Thioploca cells contain large internal vacuoles that concentrate nitrate from overlying water and oxidize sulfide in sediments. Extensive mats of Thioploca are found on the Chilean and Peruvian continental shelf in oxygen-depleted bottom waters with significant nitrate levels.

How do metabolic interactions and nutrient diffusion contribute to the complexity of biofilms and microbial mats?

Metabolic interactions among microbes and the diffusion of nutrients determine the physical and biological structures of biofilms and microbial mats. As biofilms form on a surface, they become increasingly complex, generating new niches for organisms of differing physiologies. Molecular community sampling has revealed microbial mats to be among the most complex microbial communities discovered.

The question on the page originate from the summary of the following study material:

Brock Biology of Microorganisms, Global Edition | 9781292235103 | Michael T Madigan, et al

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Microbial Ecosystems - Microbial mats

11 important questions on Microbial Ecosystems - Microbial mats

What are microbial mats?

How are microbial mats related to biofilms, and what distinguishes them?

What factors govern the activities within microbial mats, and how do they create unique niches?

Why are filamentous cyanobacteria considered versatile phototrophic mat builders?

What role do cyanobacterial mats play in aquatic ecosystems, and why are they restricted to certain environments?

How does the chemical and biological structure of cyanobacterial mats change during a diel cycle, and what are the key activities during the day and night?

Where do microbial mats of oxidized iron form, and what environmental consequences can arise from their activities?

What novel phylum of microaerophilic Archaea is associated with iron-rich microbial mats, and what are their capabilities?

How do iron-rich mats differ from chemolithotrophic mats, and what are examples of sulfur-oxidizing chemolithotrophs?

What unique strategy does Thioploca employ to bridge spatially separated resources, and where are extensive microbial mats of this type found?

How do metabolic interactions and nutrient diffusion contribute to the complexity of biofilms and microbial mats?

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