Tetraspora

Tetraspora is a genus of green algae found within the monophyletic group Volvocales, which is under the phylum Chlorophyta. Species of Tetraspora are unicellular green algae that exist in arrangements of four and consist of cells being packaged together in a gelatinous envelope that creates macroscopic colonies. These are primarily freshwater organisms, although there have been few cases where they have been found inhabiting marine environments and even contaminated water bodies. Tetraspora species can be found all around the globe, with the exception of Antarctica. Despite the ubiquitous presence, greatest growth of the genera's species is seen in the polar climatic zones. Tetraspora species are non-motile and instead of having flagella, they possess pairs of pseudoflagella which are part of the pseudociliary apparatus. On average the cell diameter of Tetraspora ranges from 6-13 μm. Energy is accumulated via photosynthesis through two cup-shaped chloroplasts, making the species primary producers. Blooms have been noted in contaminated environments due to excess augmentation of ammonia from industrial waste and are now being associated with the drop in biodiversity in such water bodies. Both sexual and asexual reproduction are possible for species within this genus. In addition, mitosis is well defined in Tetraspora species; particularly investigated in T. gelatinosa. Cell division involves elaborate arrangement of microtubules, basal body complexes and involve the use of structures like phycoplasts and protoplast. Studies have shown antimicrobial properties of certain species. In addition, Tetraspora is an important photobiological hydrogen producers and therefore is intensively being looked at for biofuel purposes. As of 2019, thirty species have been classified into this genus. The genus name Tetraspora is derived from the word tetrad; which refers to the confirmation of four. Tetra is Greek for four and spora is Latin for cells, thus describing species of this genus as existing in groups of four. The genus Tetraspora was first described by Link ex Desvaux in the year 1818, where the purpose for the genus was to organize algae with spores arranged in confirmations of tetrads. In the very first classifications, species of Tetraspora were classified into the order Tetrasporales under Chlorophyta. However, with molecular analysis, it was found that Tetraspora species had similar basal body morphology to Chlamydomonas and also had molecular similarity in the SSU rDNA. This changed the classification from being under the order Tetrasporales to order Volvocales, where they still reside today. Tetraspora species are primarily freshwater organisms which inhabit ecosystems like streams, lakes, rivers, ponds. They can be found in harsh environments like thermal effluents and industrial waste. However, just recently it has been found that Tetraspora species have the ability to adapt and reside in marine environments that are exceptionally nutrient rich and receive freshwater river outflows. Species have been found in both stagnant and free flowing water bodies, although morphology of species between the two water types slightly differs. Physio-chemical studies of the habitats have shown that Tetraspora species tolerate wide pH ranges: (4.5-9.63) but are most commonly found in water bodies with a pH between 6-7. Likewise, the optimal growth conditions for species of the genus Tetraspora are alkaline, low mesotrophic and shallow bodies of freshwater. Interestingly, species have also shown to be most abundant and well established on the beds of slow-flowing streams and rivers; where they generally take on the form of thin filamentous macroscopic colonies. Tetraspora species are found on every continent, with the exception of Antarctica, and can be located at all latitudes. Therefore, they are found in all climatic zones: polar, tropics, warm and cool temperate zones and the equatorial zones. While they can be present in all climatic zones, the most optimal zones are cool temperate and the polar zones. This is because of the species preferring cold water to warm.