By bioconversion, I mean a microbial process during which resting cells are used in order to convert a substrate to a desired product, whithout cell growth. For example, in this paper, they used Lactobacillus reuteri to convert glycerol to 3-hydroxypropionaldehyde, while L. reuteri can't grow on glycerol. Basically, during bioconversions, cells produce energy for their metabolism, but do not grow.
The energy thus yielded by cells is supposed to ensure their energetical maintenance cost. I was wondering what happens to cells if the energy gain is superior to maintenance needs? Is there some kind of homeostatic regulation of the ATP/ADP ratio? If not, what could be the consequences of too much ATP?