The carbon having 6 electrons adopts an electronic configuration in the ground state 1s2 2s2 2p2. It has four electrons on its valence layer, which allows it to form four covalent bonds, including "sigma" (first bond with one atom) or "pi" type bonds (second or third bond). "Pi" type links are always accompanied by a "sigma" type link. The recovery of electronic functions in a "pi" link is weaker. These links are therefore less "solid".
This would be mutualism, since both organisms benefit from this relationship. (the termite is able to eat the plant material, the bacteria gets to digest the fiber)
