Regex mach letters inside statement to make a word

Regex mach letters inside statement to make a word

So I am trying to write a java program that will match (example : eat) in
the string
asdasdjhaskldhlasdklsadeaadsasdkljhasdklhjt
So what would happen is
asdasdjhaskldhlasdklsad_**E**__**A**_adsasdkljhasdklhj_**T**_
So what i have got so far in regex is matching the first letter...
^([e]+) - E
But I so not know how to allow letters and spaces between the matches.