Following recent research by scientists at Newcastle University UK, bacteria have been observed to react to the smell of rival bacteria which is in the same area. Therefore scientists believe that bacteria have 4 of the 5 physical senses that humans have, that is they can see by responding to light, they can feel by responding to physical touch, taste through direct contact with environmental chemicals, and now smell by detecting airborn molecules. They only thing they are missing is the ability to hear. Therefore it begs the question "Can bacteria be considered a sentient being ?"
I myself have never considered bacteria to be a sentient being, but it does make you think where the line is which defines life to be sentient or not.
Anyway interesting research a link to the story is belowhttp://www.bbc.co.uk/news/science-environment-10985313
metta to all sentient beings (where ever the line is drawn):)