Thanks for your response.
I meant viruses. Viruses can only ‘live’ by destroying LIVE cells. Bacteria can grow on non-living surfaces, and live BETWEEN cells. Many bacteria are beneficial. There are no ‘beneficial’ viruses.
Here is a pretty good comparison, and explanation of their functions.
http://www.diffen.com/difference/Bacteria_vs_Virus
Thanks for the hyperlink.
It's been many years since I took Microbiology in college, so I don't understand why you are claiming that, without viruses, life would have ceased on Earth a long time ago.
In what way are viruses a necessary precondition for the continued existence of life on Earth?
Forgive my denseness!
Regards,