How are unicellular organisms ,such as bacteria and fungi useful to humans and the environment. and what are 2 examples

Unicellular organisms like bacteria and fungi are very useful for human in various way.  Bacteria such as NItrobactor, Psuedomonas, Lactobacillus, E.coli are very useful in variety of use., Some fungi like Penicillium,  produce antibiotics, fungi is a good source of food.

Explanation:

Here we can understand the usefulness of bacteria and fungi by following points-

Bacteria play an important role in fermentation, bakery, brewing, dairy industries.They are very important factor in production of beer, wine, ethanol and other beverages including tea and coffee in production of tea , curling of leaves is not possible without bacteria.They are important in production of penicillin, and other antibiotics.Mushroom consumed as a single cell protein is a fungi and rich source of protein.As nitrogen fixer bacteria plays very important role.Lactobacillus converts milk into curd and dairy product cant be prepare without these organisms.E.coli is common resident  of human intestine produce vitamin B12.Fungi are very effective in decomposition and help in cleaning environment.These are helpful in manure forming and biogas production.