The heat resistant bacteria you develop through selective pressures and heat stress is different from the original bacteria in its DNA and the resulting proteins the DNA codes for that are more heat stable. Difference in DNA = mutation.
What mechanism are you suggesting allows the bacteria to “adapt” to become more heat stable? How do the proteins in the heat resistant bacteria become more stable at high temperature?
In reality, the “information” on how to make those proteins, as contained in DNA, changed. This is mutation.
Why would a bacteria under stress have a mechanism that INCREASES its mutation rate?
The theory of evolution through natural selection of genetic variation provides an answer.
Creationism, as usual, provides nothing of any use.
As usual, you arrive at your conclusions by assuming what you’re trying to prove.
good day