Periplasmic acid trehalase that catalyzes hydrolysis of the disaccharide trehalose and required for growth on trehalose as carbon source (PubMed:7502577, PubMed:8647289, PubMed:19703229, PubMed:8764988). Growth on trehalose is strictly respiratory (By similarity). alpha,alpha-trehalose + H2O = alpha-D-glucose + beta-D-glucose May exist in the periplasm either as a membrane-bound or as a free protein (By similarity). Vacuolar localization is dependent on the multivesicular body (MVB) sorting pathway (PubMed:17475771). Vacuolar localization appears to be associated with its degradation (PubMed:19703229). Glycosylated. Ubiquitinated in the N-terminal region; ubiquitination is not required for vacuolar targeting. Abolishes cellular acid trehalase activity (PubMed:7502577, PubMed:19703229). Abolishes growth on trehalose carbon source (PubMed:8647289). Belongs to the glycosyl hydrolase 65 family. The functional relevance of vacuolar localization is disputed.