''Stichococcus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

in the family Stichococcaceae. It is a very common algal genus found in a variety of habitats, such as tree trunks, soil, snow, freshwater and marine habitats. One species, '' Stichococcus bacillaris'' is economically important as it produces

fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...

s useful for

biofuel Biofuel is a fuel that is produced over a short time span from Biomass (energy), biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricu ...

s. The name ''Stichococcus'' originates from the Ancient Greek στίχος (''stíkhos'', "row, line") and κόκκος (''kókkos'', "seed" or "berry").

Description

''Stichococcus'' consists of solitary cells or uniseriate filaments of few cells (2 to 4) that readily break apart. The cells are cylindrical, about three times longer than wide, straight or sometimes curved, with rounded ends often containing vacuoles. Cells are uninucleate with one thin, parietal

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

with or without a

pyrenoid Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...

. Pyrenoids if present are located in the middle of the chloroplast but usually difficult to see. Reproduction occurs by vegetative cell division, and by the fragmentation of filaments.

Taxonomy

''Stichococcus'' is placed within the order

Prasiolales Prasiolales is an order (biology), order of green algae in the Class (biology), class Trebouxiophyceae. Members of this order are ecologically widespread and are found in freshwater, marine, and terrestrial habitats from the Arctic to the Antarct ...

, equivalent to the '' Prasiola''-clade found in literature. The morphological form of ''Stichococcus'' is not monophyletic, and therefore in 2020 it was split into several genera: '' Protostichococcus'', '' Deuterostichococcus'', '' Tritostichococcus'', '' Tetratostichococcus'', and '' Pseudostichococcus''. The similar morphology of all of these genera and species makes identification using morphology difficult or even impossible. ''Stichococcus'' and its relatives produce

sorbitol Sorbitol (), less commonly known as glucitol (), is a sugar alcohol with a sweet taste which the human body metabolizes slowly. It can be obtained by reduction of glucose, which changes the converted aldehyde group (−CHO) to a primary alco ...

and

sucrose Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refined ...

as an

osmolyte Osmolytes are low-molecular-weight organic compounds that influence the properties of biological fluids. Osmolytes are a class of organic molecules that play a significant role in regulating osmotic pressure and maintaining cellular homeostasis in ...

, when subjected to salt stress.

References

Trebouxiophyceae genera Prasiolales {{green algae-stub