You may use any reference style you’d like as long as it is organized and one of the standard formats for scientific writing.
We live in constant association with trillions of microorganisms, most of which do us no harm (commensals) and some of which benefit us (mutualists). However, a select few microorganisms are pathogenic in nature, and it is these organisms that make a large impact on public health. For your pathogen essay, you can select any pathogen that peaks your interest. It should be ~500-800 words in length and should utilize >5 references outside of your textbook. You may use any reference style you’d like as long as it is organized and one of the standard formats for scientific writing. For example, it is common to put a number in parentheses (1) or superscriipted1 at the end of the sentences or paragraphs to which a specific reference was applied, and then to have a corresponding numerical list of references at the end of the essay.