microbial

Of, relating to, or caused by microbes or microorganisms.

The close analogies between DNA-containing eukaryotic cell organelles and microbial symbionts require revision of classic cell theory, wrote Scwemmler and Schenk (1980) on introducing the field of endocytobiology.

Many genes with reproductive roles also have antibacterial and immune functions, which indicate that the threat of microbial attack on the sperm or egg may be a major influence on rapid evolution during reproduction.

Small; tiny; minuscule.

As I say, one must not blame the Christians too much for all this - partly because, after the communal periods which I have just mentioned, Christianity was evidently deeply influenced by the rise of Commercialism to which during the last two centuries it has so carefully and piously adapted itself; and partly because - if our view is anywhere near right - this microbial injection of self-consciousness was just the necessary work which (in conjunction with commercialism) it had to perform.

A microbe or bacterium.