Thermophytes

A thermophyte from the Greek thérmos, which means “warmth,” “heat,” and phyton, which means “plant,” is an organism that is tolerant of or thrives in extreme temperatures. These creatures are classified based on their ecological valences at high temperatures, including severe biological temperatures. Taxa from hot springs were included in this category of creatures. 

Algae, notably blue-green algae, commonly known as cyanobacteria, account for a significant portion of the thermophyte biomass. Unlike other plants and organisms, thermophyte algae have unique characteristics. This species can flourish in temperatures ranging from 50 to 70 degrees Celsius, unlike others. They can endure severe temperatures because their cells contain an “unorganised nucleus.”

Mutualism in thermophytes 

Occasionally, fungi and plants create symbiotic relationships that result in thermophytes. Several plants, algae, and virus thermophytes are symbiotic and coexist with a fungal partner. They are mutualists, like the panic grass and its fungal companion, both of which cannot exist independently but thrive when they join forces. This means that the fungus, plant, and virus all work together to help one another survive in such harsh conditions. Typically, the fungus lives in the gaps between the cells of plants.

According to a Washington State University study, the fungus Curvularia protuberata was essential to the survival of panic grass near Yellowstone’s hot springs.

At these temperatures, neither organism has a chance of surviving on its own. These plants and algae are infected by mycoviruses, which infect the fungus that resides there. These mycoviruses keep fungi from hurting plants by stopping them from causing harmful effects. The panic grass benefits from the fungi because they may help spread the heat and warn the plant of any environmental stress.

Common thermophyte organisms 

• Deinococcus–Thermus

Bacteria belonging to the Deinococcota species are characterised as “extremophiles” for their ability to survive in hostile environments. Gram-positive staining bacteria have thick cell walls and a second membrane, making them more like gram-negative bacteria in structure. Due to their survival in hot temperatures, they are known as thermophytes.

• Cyanobacteria

Gram-negative bacteria in the Cyanobacteria phylum rely on photosynthesis for their energy. Cyanobacteria get their alternative name, blue-green algae, from their colour. However, current botanists only use the term “algae” to refer to eukaryotes and do not use it to describe cyanobacteria, which are prokaryotes. Freshwater or terrestrial environments appear to be where they came from. Ancestors of both photosynthetic and non-photosynthetic groups of bacteria are thought to have originated from Sericytochromatia, the paraphyletic and most basal of all groups. It is also believed to be the origin of cyanobacteria, also termed Oxyphotobacteria. 

Blue-green filamentous cyanobacteria, known as Oscillatoria, are common in freshwater habitats such as hot springs.

• Oscillatoria

When the filaments move across each other, they create an oscillating motion that orients the colony toward a light source. Deathly cells help fragment the filament into hormogonia, which then develop and multiply as Oscillatoria.

Photosynthesis is essential for Oscillatoria’s survival and reproduction. There are trichomes in each oscillatoria filament, and each trichome is made up of rows of cells. The trichome’s tip swings back and forth like a ping-pong ball. Reproduction only occurs through vegetative means. Hormogonia are the segments of the filament that usually fall off. Each hormogonium comprises one or more cells that divide in one direction to form a filament.

• Oscillatoria Brevis

It is a mesophile, yet Oscillatoria brevis is capable of photosynthesis at 70°C and can tolerate temperatures as low as -16°C. Chlorophyll A and c-phycocyanin make it a photoautotroph, although it can also do anoxygenic photosynthesis by decomposing sulphur.

• Cyanobacteria 

It is capable of fixing nitrogen and can be grown from the soil. It and other nitrogen-fixing cyanobacteria found in the soil have been discovered to correlate with soil richness and the density of microbes positively. Copper, silver, zinc, and cadmium ions have all been tolerable to O. brevis. Microfibrils allow oscillatoria to glide. Oscillatoria takes its name from the appearance of oscillation while gliding. Even though the species name Brevis translates to “little” in Latin, the microbes in this genus range in size from 10 M across to 5-70 M across. 

• Scytonema

Cyanobacteria that use light to produce energy are known as Scytonema. It forms black mats of filamentous growth. Others grow on terrestrial rocks, wood, soil, and plants. Many aquatic species are free-floating or connected to submerged substrates. Scytonema is a nitrogen fixer, which means it may supply plants’ leaves with fixed nitrogen. To create lichen, some Scytonema species have a mutualistic interaction with fungus. Scytonema is also a thermophyte, and it can survive in hot environments.

Conclusion 

Thermophytes, as the name implies, thrive in sweltering conditions. Yellowstone National Park and Lassen Volcanic National Park are great places to look for them because of their abundance of freshwater hot springs and thus thermophytes. There are a lot of algae seen in hot springs. These algae can withstand temperatures of up to and even above 70°C. Chroococcaceae can withstand temperatures of up to 84°C, according to Copeland’s list of 53 genera and 153 species. Some Oscillatoriaceae can withstand temperatures of up to 85°C. Myxophyceae (blue-green algae) are primitive.