Replacing bash comment character to an elisp comment character

[Heime]

I have the following variable storing a bash header. I want to construct an 
equivalent header
for elisp. I would not want to repeat the text, but replace the comment 
character "#" with ";"
when calling "elisp-header".

(defvar bash-header

"### Copying_conditions:

## This file belongs to PKNAME, a Gnu Package.

## PKNAME is free software.

### Commentary:")

(defun elisp-header ()

"TODO"

(insert bash-header))