MUC5AC and infection: Moreover, the alginate data suggest that not only artificial, but also natural polymers may suppress effector secretion; alginate is the major component of biofilms formed by P. aeruginosa. Mucin, a major component of the mucin layers produced by epithelial cells to defend against the bacterial (e.g. P. aeruginosa) infection [15], also suppressed effector secretion (figure 7).