The eligibility criteria for MSc Microbiology are:

• The candidate must have 55% marks or 5.5 CGPA in there BSc
• The eligible fields for BSc are: Botany, Zoology, Chemistry, Physiology, Microbiology

As you have completed BSc Botany then you are also eligible for the course provided you must satisfy the minimum marks criteria. Also a 5% relaxation is provided to the marks for SC/ST/OBC students.

Also you may have to qualify an entrance exam for the admission in MSc. Although there are few universities that gives admission through merit also.

Some of the best colleges for MSc Microbiology are:

• St. Xavier's College Mumbai.
• University of Lucknow.
• The Oxford College of Science Bangalore.
• Fergusson College Pune.
• St. Xavier's College Kolkata.
• Barkatullah University, Bhopal.
• Lady Brabourne College, Kolkata.

To know more about the colleges visit the link provided below:

https://university.careers360.com/colleges/list-of-microbiology-and-virology-universities-in-india

I hope this answer helps.