Screening of Heat-killed Lactic Acid Bacteria with Food Allergy Alleviating Effects and Its Whole Genome Sequencing Analysis

Food allergy(FA) is an abnormal response of the human immune system to a specific food that causes discomfort in several systems， including the digestive， respiratory， skin and cardiovascular systems. In this study， heat-killed Lactobacillus paracasei JY56 (HK-L. paracasei JY56) with strong anti-allergic activity was screened from 20 strains of lactic acid bacteria by hyaluronidase inhibition assay and RBL-2H3 cell assay. Subsequently， the safety of L. paracasei JY56 was evaluated by whole genome sequencing and in vitro safety assays. Finally， an ovalbumin (OVA)-induced FA mouse model was constructed to further clarify the effect of HK-L. paracasei JY56 on the alleviation of clinical symptoms in FA mice. The results showed that HK-L. paracasei JY56 had high β-aminohexosidase (β-HEX) inhibition rate， and the levels of cytokines IL-4， IL-5， IL-13 and TNF-α were significantly reduced after its intervention. Whole genome sequencing analysis revealed that L. paracasei JY56 does not possess the ability to virulently and transmitly receive antibiotic resistance genes. The safety evaluation experiments such as antibiotic susceptibility test， hemolysis test and harmful metabolite evaluation revealed that L. paracasei JY56 was susceptible to commonly used antibiotics and did not produce hemolysis or harmful metabolites. OVA stimulation resulted in decreased body weight and rectal temperature and increased allergy score in mice， while HK-L. paracasei JY56 intervention significantly alleviated allergy symptoms in mice. In conclusion， this study provides a theoretical basis for the use of HK-L. paracasei JY56 for the alleviation of food allergy and related diseases. © 2024 Chinese Institute of Food Science and Technology. All rights reserved.