Fungal Phylum Microsporidia

Members of Microsporidia are classified as fungi based on their phylogenetic link to Chytridiomycota.

This phylum comprises obligate intracellular parasites that infect animals. They are unicellular, non-motile, and range from 2 to 5 micrometers in size.

Microsporidia lack mitochondria, hydrogenosomes, and the Golgi complex, making them highly dependent on hosts for metabolism.

Their genomes are significantly reduced; the Encephalitozoon species has a 2.9 Mbp genome with about 2000 genes, which is much smaller than the genome size of E. coli.

Microsporidia exist in the environment as resistant chitin-shelled spores with various shapes, including spherical, rodlike, and crescent.

When they are near a host, Microsporidia use a polar tubule to penetrate its cells and inject infectious sporoplasm.

Inside the host, sporoplasm replicates, forming new spores that rupture the host cell and spread.

Various species of the genus Enterocytozoon are pathogenic to humans.

These fungi mainly affect immunocompromised individuals, causing chronic diarrhea, keratoconjunctivitis, encephalitis, and nephritis.