Science

You could try Indian Institute of Astrophysics, Bengaluru. It is one of the oldest institutions in India (1786 AD) and right now, the premier institute for Astrophysics (in my opinion). They offer three courses:
M.Tech, Ph.D. Dual degree GATE written test)
M.Sc, Ph.D. Dual degree JEST written test)
PhD. Currently they operate out of their campus in Koramangala, Bengaluru, though the CREST campus - Hosakote, Kodaikanal Solar Observatory, Vainu Bappu Observatory, the Gauribidanur radio telescope and the Handle Observatory are under them. For more information visit Indian Institute of Astrophysics
2. You could also try IUCAA (Inter University Center for Astronomy and Astrophysics), Pune. Visit IUCAA (qualifying exam: JEST)
3. If you are interested in theoretical Sciences, You could try TIFR (Tata Institute of Fundamental Research) or JNCASR (Jawaharlal Nehru Centre for Advanced Scientific Research) or RRI (Raman Research Institute) (qualifying exam: JEST or GATE)
4. IISc (Indian Institute of Science, Bangalore) provides courses related to astronomy. The advantage is the beautiful campus of the best Institute of India. GATE or JEST or written test)
5. Not really Astronomy, but Indian Institute of Space Science and Technology (Home : IIST) runs courses in Engineering related to Aerospace and Avionics. In-so-far as job opportunities are concerned, Research and teaching would be primary. For example, the Handle telescope in Leh is controlled through CREST, Hosakote. So that's a more technical job. IIST, however is quite different from the rest. It is a company (ISRO) backed institute and the placement might be different. The institute is possibly the most beautiful one you will see.

After your B.Sc Microbiology, you can go for M.Sc. (Microbiology). You'll be acquiring knowledge at a higher level than what you studied during your Bachelor's degree, and the course should help you develop the necessary skills for your field of work. With a postgraduate qualification on your CV, securing a good graduate job is more likely, and the possibility of attracting a higher salary is increased. This will leave you feeling confident that the time and money invested in your postgraduate education was worth it. Career prospects of M.Sc. Microbiology are:
Teaching in college / universities, Junior / senior research fellow, Research posts in ICAR / CSIR labs, Microbiologist post in dairy industries, breweries, food Processing Beverage industries, pathology labs, agriculture, quality assurance divisions in industries, Self Employed (Establishing small scale industries - production of nonalcoholic fruit beverages, mushroom production).