Microbial transglutaminase (mTg) is a highly serviceable additive with the property of crosslinking protein residues by forming isopeptide bonds in between the active chains of the substances involved. Although distributed along varied industries due to mainly its robustness and affordability, mTg prominently assists the food industry. Despite its popularity, the effects of mTg on the permeability of the small intestine have evaded profound scrutiny and are now called into question. Hence, it is the purpose of this study to study said effects with a molecular perspective, using a standardized in-vitro cell model.

By virtue of a 75:25 Caco-2 / HT29-MTX cellular model and of Transepithelial Electrical Resistance (TEER), Lucifer Yellow (LY) and immunocytochemistry (ICC) assays, the permeability of the monolayer formed by the co-culture was evaluated. The co-cultures were acutely exposed to three doses of mTg, namely low, medium and high doses, and the resilience of the membrane was tested after 4 hours had elapsed. From the TEER and LY experiments, only the high dose had a statistically relevant detrimental effect on the integrity of the monolayer, by showing a 7.2 % reduction in electrical resistance and a 136.44 % decrease in the apparent permeability coefficient (P_app) of the membrane when compared with control wells. On the other hand, after a semiquantitative analysis of the % area covered by the tight junction protein zonula occludens-1 (ZO-1), it was found that the detection of ZO-1 diminished in a 52.14 % for the medium and a 61.06 % for the high doses when compared with the controls.