hi,

see there is only a few colleges offers b.sc course in astrobiology, I have mentioned the institute name below,

INdian Institute of Science, Bangalore

Ramana Research Institute, Bangalore

Tata Institute of Fundamental Research, Mumbai

NOW coming to  isro Job Opportunity  from past years , it mostly recruits engineering and msc course holders on discipline of physics, chemistry, electronics and communication engineering, mechanical engineering , civil engineering, computer science engineering, electrical engineering. however time to time research works need various types of professionals , so you may see about the recruitment of astrobiologist in near future.