string-split procedure

[Freeman Gilmore]

Example:
(string-split "root:x:0:0:root:/root:/bin/bash" #\:) ⇒ ("root" "x" "0"
"0" "root" "/root" "/bin/bash")

Now if i replace the ":"s with " "s, what do I put in the place of the ":" in:
(string-split "root x 0 0 root /root /bin/bash" #\:) ⇒ ("root" "x" "0"
"0" "root" "/root" "/bin/bash")

Thank you, ƒg