WORLD FOOD SAFETY DAY WILL BE CELEBRATED BY THE UNITED NATIONS ON TUESDAY, JUNE 7TH. FOR THE OCCASION, THE STRATEGIC ALLIANCE OF CATHOLIC RESEARCH UNIVERSITIES HAS GATHERED THE OPINIONS OF ITS EXPERTS ON THE TOPIC

Selective Detection and Discrimination of Bacteria for Food Safety

Written by Takashi Hayashita, Takeshi Hashimoto, Nobuyuki Kanzawa, and Kazuhiro Ema, Faculty of Science and Technology

For Food Safety, the detection and identification of bacteria that cause food poisoning is an important issue. The food industry generally uses synthetic preservatives and antibiotics in the food manufacturing process to prevent contamination with food poisoning bacteria. However, overuse and improper use of antibiotics have led to the emergence of bacterial drug resistance, making it difficult to prevent an increase in food poisoning.　In fact, multidrug-resistant bacteria, the development of which has been accelerated by the excessive use of antibiotics, has become a global issue in the past decade. As the abuse of antibiotics stimulates undesired genetic mutations in bacteria, specific antibiotic usage is important from the standpoint of achieving sustainable development goals. The need for a bacterial recognition method that would enable the determination of the specific dose of an antibiotic is apparent because existing bacterial recognition methods require several days for bacterial culture or expensive reagents.

This problem has attracted the interest of many research groups, and novel bacterial recognition methods or microbial agents have been studied. Saccharide recognition offers a potential solution because bacteria have specific glycolipids on their surface. Phenylboronic acid in particular is known as a saccharide recognition site because it forms a bond with the cis-diol of saccharides. In 2019, our research team reported that a chemically modified poly(amidoamine) (PAMAM) dendrimer having five phenylboronic acid groups at the terminus was able to recognize bacteria. The B-PAMAM dendrimer probe showed selectivity toward Gram-positive bacteria. The recognition was observed as the aggregate formation between bacteria and probe, which resulted in turbidity change. Based on the results, we additionally introduced a fluorescent dansyl group on B-PAMAM and were able to achieve sensitivity improvement in fluorescence measurements. Recently we have also developed a convenient and selective method for the detection of Gram-positive bacteria using a PAMAM dendrimer probe. The dendrimer that was modified with dipicolylamine (dpa) and phenylboronic acid groups showed the superior selectivity toward Staphylococcus aureus [3]. Our study is expected to contribute to the elucidation of the interaction between synthetic molecules and bacterial surface. Moreover, our novel method showed potential for the rapid and species-specific recognition of various bacteria for Food Safety.