Comparison between surface hydrophobicity of heated and thermosonicated cells to detoxify aflatoxin B1 by co-culture Lactobacillus plantarum and Lactobacillus rhamnosus in sourdough: Modeling studies
Elahe Abedi, Kiana Pourmohammadi, Maryam Mousavifard, Mehran Sayadi
Abstract
The capacity and stability binding of aflatoxin B1 under various temperature and time conditions of dough proofing were evaluated. Single and co-culture Lactobacillus plantarum ATCC 8014 and Lactobacillus rhamnosus ATCC 7469 were inoculated in various modes, mainly viable, heat-, and ultrasound-inactivated along with the combination of viable + heat- or ultrasound-inactivated cells. The highest AFB1 adsorption in order was thermosonication- treated Lb. plantarum + Lb. rhamnosus (8.042 μg kg−1) > heat treated Lb. plantarum + Lb. rhamnosus (6.90 μg kg−1) > live Lb. plantarum + Lb. rhamnosus (5.533 μg kg−1) after 24 h incubation at 37 °C. Regarding to circular dichroism spectra results, α-helix and β-turn of LAB cells showed highly increasing pattern in thermosonicated LAB (22.1% and 25.8%) compared to live (16.8% and 23.7%) and heated (21.3% and 24.2%) cells, respectively. The surface hydrophobicity (%) increased from 37.7 to 45.1% for viable LAB to 67.2–80.5% and 54.5–65.9% following inactivation by thermosonication and heating, respectively. The results obtained by AFB1 binding stability on cell surfaces displayed that in ultrasound-treated bacteria, 18.3–33.3% of the bounded AFB1 was released from the cells, which is significantly lower than heat-treated cells (31.1–46.5%) and viable cells (49.9–64.8%).