If you touch a surface, you leave behind millions of bacteria and other microbes. If each person’s community of microbes is unique, this bacterial smudge could act like a fingerprint. Why does the author use the description “bacterial smudge”?
From: Cool Jobs Part 1
1.) to illustrate the most difficult part of analyzing a bacteria sample from a person
2.) to show that a collection of microbes is the surest way to catch people
3.) to describe the best way to collect more than one microbial sample from a person
4.) to emphasize that all people leave behind an identifiable trace of themselves