A few previous posts here - most recently in Technobabble - have asserted that thinking and feeling are not uniquely animal behaviors.

Plants talk to one another, even bacteria talk to one another, and we can listen to them. They don't rattle and hum so much as stink their thoughts, but it is certainly communication carrying information, often at surprisingly great distances.

Some researchers are working to learn bacterial senses and language.

She and her colleagues focused on a receptor [in Azospirillum brasilense] they suspected was related to the way bacteria convert nitrogen gas from the atmosphere into a form -- ammonium -- that can be used by all organisms. This ability is called nitrogen fixation and while it is uniquely found in bacteria, it is critically important to all living organisms, as it is the only way nitrogen can eventually be incorporated into building blocks of cells.

Well, no, there are natural chemical forms of nitrogen fixation too though they tend to need more energy or catalysts or both, but go with it for now.

The process is carried out by an enzyme which is damaged in the presence of high concentrations of oxygen, which presents a dilemma for the bacterium, as the energy needed for the process is usually acquired in the presence of oxygen.

When Alexandre and her team created mutant versions of the bacteria without the receptor, the mutant bacteria were unable to detect where the right position in oxygen concentration was, affecting the nitrogen fixation reaction. In other words, the mutant bacteria were somewhat "blind" and could not detect the right position, showing them their hunch was correct about the receptor's purpose. But their curiosity expanded: if they were able to uncover the receptor's purpose, would they be able to figure out exactly how it functioned?

For that, they enlisted the help of UT-Oak Ridge National Laboratory distinguished scientist Igor Jouline, an expert in carrying out complex computations of biological systems, such as the one governing the receptor at the heart of Alexandre's research. Working with Alexandre's data, Jouline was able to generate a model of the receptor's structure and compare it to other structures on a nearly atom-by-atom basis.

This enabled them to predict which one of the more than 100 amino acids in the sensory part of the receptor is responsible for sensing the precise oxygen concentration that this bacterium needs for nitrogen fixation. . .

"We see now that bacteria are, in their way, big thinkers, and by knowing how they 'feel' about the environment around them, we can look at new and different ways to work with them."

I've long been fascinated by the notion of the chemical basis of sensing, feeling and so thinking. It supports ideas of distributed cognition - thought happens in the body in addition to the brain - as well as ideas of plant and microorganism thinking. If what makes a human brain powerful is the number of brain cells working together and some specialized structures for task specialization and coordination, it is imaginable that a bacterial colony that endured long enough could do as much or more. This is in part the claim of Gaia consciousness.

I've also read fictional treatments that imagined such minds in surprising locations such as carbonaceous chondrite asteroids that have existed relatively undisturbed for billions of years. Since they were not repeatedly disrupted or destroyed as they would have been on a planet prone to plate tectonics, volcanoes, climate etc. they grew large and wise. A brain miles in diameter that was billions of years old might well be quite powerful even if it existed in the cold of space and chemistry proceeded at a slow pace.