Something else not specified in this section are viruses. Viruses are not strictly microorganisms, and no mention is made of them, but yet they can be manufactured and used for treatments- recently even for cancer:
http://www.mayo.edu/research/departments-divisions/departmen...
http://www.theguardian.com/society/2015/nov/02/fda-approval-...
If viruses could be excluded from patentability since they aren't mentioned, then any research or manufacturing done would not be patentable, and therefore some companies may hesitate to invest too heavily in research.