What kind of micro organisms should be present in a dark plant infusion, a peppercorn infusion, and a Bacillus culture? What kind of micro organisms should be present in a dark plant infusion, a peppercorn infusion, and a Bacillus culture? Solution Dark plant infusion contains a lotamount of humus so it can easily attract mosquitos. These mosquito are carrier of some species of virus. Bacterias are also easily grow in these. Peppercorn infusion contains microorganisms like Trichomonas sp. And Enterobius. Bacillus culture contains Bacillus substilis. Because this species can soon and easily groun in any kind of environment..