. Author manuscript; available in PMC: 2016 Apr 12.
Published in final edited form as: J Microbiol Methods. 2015 Apr 21;113:72–74. doi: 10.1016/j.mimet.2015.04.006
This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).