Bacteria is the smallest microscopic organism of the tundra with numbers into the billions. Psychrophiles live in very low temperatures, usually below 15 degrees Celsius, and cannot grow in areas above 20 degrees Celsius. Some of the adaptations have a high content of unsaturated fatty acids in their plasma membrane to accommodate colder climates. Examples of specific bacteria finds include Achromobacter, Alcaligenes, Flavobacterium and Pseudomonas. Grampositive forms have also been identified, including Bacillus, Micrococcus and Streptococcus faecalis. Anaerobic bacteria produces methane and often exist in the tundra mud or sludge. These bacteria require oxygen to carry out the process. Of microscopic organisms, only Prokaryotes can carry this classification.
More than 150 species of cyanobacteria and algae flora have been found in various areas of the tundra. Each area is different in moisture levels, soil type and vegetation. Studies demonstrate the algae's adverse effects from pollution. One study in particular by the Wroclaw University of Environmental and Life Sciences at Hornsund fjord focused on algae in a coal mine complex of eastern Russia. Scientists based their findings on algae gathered from select tundra areas. Out of 42 species in all areas, the species were decreasing to 19 in polluted areas.
There are small protozoans as well as burrowing micro metazoans in central parts of micro fauna. Soil fauna such as collembola and acari have little direct effect on the speed of litter mineralization but indirectly cuts the dead material in small pieces so it becomes easier for microbes to grow in this substrate. The organisms decompose and regenerate nutrients as they metabolize organic molecules in their food. They graze the microbial biomass so it is renewed faster, and essential nutrients become available for the new microbial biomass production.
