What is the singular possessive of bacillus?

Answer 1

There are two accepted forms for possessive singular nouns ending in s:

Add an apostrophe (') after the existing s at the end of the word: bacillus'

Add an apostrophe s ('s) after the existing s at the end of the word: bacillus's

Examples:

This bacillus' function is to assist the decay of organic matter.

This bacillus's function is to assist the decay of organic matter.

Note: If you are a student, use the form that is preferred by your teacher.

Answer 2

The singular possessive form of bacillus is bacillus's.