Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: Bacteria and Viruses Bacteria and viruses can cause diseases. 
Sentence2: bacteria can have a negative impact on an organism.
Bacteria

Sentence1: Scyphozoans are the next group of Cnidarians, and they are the familiar jellyfish. 
Sentence2: Scyphozoans are aquatic organisms.
Scyphozoans

Sentence1: a sifter is used for separating mixtures. 
Sentence2: a sifter is used for separating combined ingredients.

separating