Perhaps I have missed something. I wasn't aware that there was life on Mars. Consequently, how could there be Martian microbes??
"Oh, sure Tom. Everyone knows about them we just didn't tell you"
Oh, wait. That's about graboids...
I was thinking the same thing. One Mars mission mixed soil with water, etc, and couldn't detect anything that
should have started to grow/generate waste, and NASA was able to reanimate some staph bacteria that spent some
time, exposed, on the Moon.
Whether there are microbes on Mars would have little to do with whether anyone was aware of life on Mars or not.