Expression of rSEB in Lactococcus lactis pSEC:rSEB (secreted) and pCYT:rSEB (cytoplasm) after induction by 1% xylose, assayed in supernatants or cell pellets, respectively. rSEB expression was analyzed by Western blot using a commercial polyclonal anti-staphylococcal enterotoxin B antibody (anti-SEB), as a probe. rSEB (27 kDa) is indicated by an arrow. Lane 1 – prestained protein molecular weight markers (Fermentas); lanes 2 and 4, -induced (+ xyl); lanes 3 and 5, non-induced (+ xyl) cultures; lanes 6, 7 and 8, cell pellets from S. aureus cultures + SEB (ATCC 14458 strain/SEB producer strain); lane 9, – SEB (29 strain/SEB non-producer strain). The arrow indicates the SEB of an apparent molecular mass of 27 kDa.