Question

What would Earth look like today if purple bacteria had never evolved?

Answer 1

Purple sulphur bacteria represent one of the most ancient type of photosynthetic bacteria existing on the earth. These bacteria contain very specific photosynthetic pigments and carotenoids which make them purple in appearance. Since they are among the primitive bacteria which initiated oxygenic photosynthesis on earth, they have enormously contributed in changing the atmospheric conditions on the planet. Therefore, if these bacteria had never evolved, the planet would have different in many ways, some of which are enlisted as below:

1. Non-oxygenic environment or oxygenic with reduced oxygen content
2. Inability to reduce inorganic sulphates thereby accumulating their concentration
3. Accumulation of non-biodegradable waste
4. Enhanced reliance on non-aerobic respiration and metabolism.

Therefore, these bacteria have contributed in not only improving but also maintaining the atmospheric conditions of the planet to make them oxygenic in nature while reducing the non-organic content at the same time.