Hello there!
Both Biological Science and Microbiology is a good course.
In biological science, where a little from all the subjects included in biology is included in the course work. It basically comprises of classical biology whereas in microbiology the course work comprises of study of micro level species.
Some universities provide both graduation and post graduation courses in Biological Science and related subject as well as in Microbiology.
Both are good courses. But from a personal point of view, Microbiolgy is a good course. It provides a lot of scope in both research and professional fields as well.
Choose what you want to study and as per your interest.
Good Luck!

Biological Science is a broad scientific part which have a lot of research scope and applicability in different sectors such as Botany, Zoology etc. But relatively if you consider the course in Life sciences are pretty much academic and can be concluded to have zero essentiality in industries (directly). But Microbiology has  a lot of scope to work in sectors of pathology and microbial R&D in Pharmaceutical companies etc. Thus if you want to learn an advanced applied topic which has some really amazing scope in research as well as in industries then I would suggest you to go for Microbiology. You will have a more efficient career in Microbiology than that of Biological Sciences.

To know about Biology as a course visit the link provided below:

https://www.careers360.com/courses/biology-course

To know more about Microbiology visit the link provided below:

https://www.careers360.com/courses/microbiology-course

I hope this answer helps. All the very best for your future endeavors!