Hello, Kalyani.

I'm a bit unclear about your query, however, i guess you wish to teach students studying microbiology and are unsure which subject to start with.

In that case, it depends which subject you're strong in and where does your interest lie. From my end, i can suggest Immunology or general microbiology to begin with. And then you can move on to difficault topics such as biochemistry and microbial genetics, once you become strongs with the fundamental concepts.

Food microbiology is another area you can teach and also one of the most interesting ones. It is one of the topics found in the syllabus of many allied areas such as nutrition and dietetics, food science, biotechnology, etc.

Hope this answers your query.