Toxins are produced by all except

Corynebacterium resembling C.diphtheria occurs as normal commensals in the throat, skin, conjunctiva and other areas. These may sometimes be mistaken for diphtheria bacilli and are called diphtheroids. C.hofmanii: found in the throat and C.xerosis found in the conjunctival sac are the common diphtheroids. C.hofmanii is urease positive and does not ferment glucose. C.xerosis is urease negative and ferments glucose. Both are pyrazinamidase-positive, unlike Diptheria bacilli. Reference: Textbook of Microbiology; Anathanarayan and paniker's; 10th edition; page no 246