they are single celled organisms that do not originate from here.
No. Another answer is: There is certainly alien microbes.
No. Another answer is: Maybe, life on Earth may have come from microbes from meteorites.
There may be- but none have yet been found. Will still have to class this as "Not that we know."
In "War of the Worlds," the alien invaders are ultimately defeated by Earth's microbes, which they have no immunity to. The aliens perish from infections, and humanity emerges victorious.
No alien life, including microbes, has been found so far, so it is really hard to tell what would happen. It is conceivable that alien life may wipe out all life on Earth, or all higher-level life; or vice versa, that Earth life may wipe out all life on some other planet. It is also conceivable that the biochemical processes are so different that none can eat the other.
1) Prokaryotes2) Bacteria3) Archaea4) Eukaryotes5) Protists6) Micro-animal7) Fungi8) Plants
microbes can live anywhere!
sometimes Bactria can kill microbes
they kill them!
Fermentation process microbes.
Alexander flaming discovered microbes
Microbes live best in grass because of cellulose in the grass. But microbes can live anywhere.