Dear aspirant,

BAMS, BSc microbiology, BSc zoology, all three have it's pros and cons and it depends on your priorities and interests which one you would choose.

From the point of view of job prospects, I would say BAMS is a better option as you can be self employed and it is a growing field. Between microbiology and zoology, microbiology has vast job prospects since it involves more lab/pathology/research work. You can also go for research in zoology (there are many opportunities in wildlife, insect identification) or you can opt for teaching field in any of the above.

Secondly, yes you can definitely go for msc microbiology after bsc zoology, or the other way round there's no restriction as far as I know.

Hope this cleared your doubt.

Regards!!