Plants and other photosynthetic organisms get their energy from the sun by absorbing the light and using it to create energy-rich such as glucose.

Plants and other photosynthetic organisms get their energy directly from the sun by absorbing the light and using it to create energy-rich carbohydrates such as glucose. During the process of photosynthesis plants take in light energy from the air, and water through their roots to produce sugar and oxygen. Carbohydrates are organic macromolecules that are made up of carbon, hydrogen, and oxygen atoms and are used for energy storage or as structural molecules. 

This bacteria must be very strong as it has a large amount on antibiotic targeting it. this bacteria could be one of many different types and it is very hard to tell which one with out more information.

Exposure to solar flares would be the correct answer