Enables the transfer of trehalose from one side of a membrane to the other. Trehalose is the disaccharide alpha-D-glucopyranosyl-alpha-D-glucopyranoside that acts of a reserve carbohydrate in certain fungi, algae and lichens. [ https://www.worldcat.org/search?q=bn%3A0198506732 https://www.worldcat.org/search?q=bn%3A0815340729 GOC:mtg_transport ]