Soluble extracellular polymeric substance (SEPS) of histo-blood group antigen (HBGA) expressing bacterium Sphingobacterium sp. SC05 influences the survival and persistence of norovirus on lettuce

Authors: LIAO, NINGBO - Jiangxi Agricultural University; TANG, MENGXUAN - Jiangxi Agricultural University; CHEN, LILI - Chinese Center For Disease Control; Tian, Peng; WANG, DAPENG - Shanghai Jiaotong University; CHENG, DONGQING - Shanghai Jiaotong University; WU, GUOPING - Zhejiang University

Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2022
Publication Date: 2/1/2023
Citation: Liao, N., Tang, M., Chen, L., Tian, P., Wang, D., Cheng, D., Wu, G. 2023. Soluble extracellular polymeric substance (SEPS) of histo-blood group antigen (HBGA) expressing bacterium Sphingobacterium sp. SC05 influences the survival and persistence of norovirus on lettuce. Food Microbiology. 109. Article 104126. https://doi.org/10.1016/j.fm.2022.104126.
DOI: https://doi.org/10.1016/j.fm.2022.104126

Interpretive Summary: Human norovirus (HuNoV) outbreaks linked to leafy greens are on the rise due to a lack of efficient strategies to prevent HuNoV from spreading from contaminated surfaces. In our previous reports, we found that the Sphingobacterium sp. SC015 , a resident bacterium on lettuce, could express high level of human blood group antigens-like substances which help human norovirus binding to lettuce. In collaboration with scientists at Jiangxi Agricultural University, Zhejiang Chinese Medical University and Shanghai JiaoTong University, we extracted the soluble extracellular polymeric substance from SC015 , analyzed its chemical composition and tested the role in survival and protection on HuNoV as well as Tulane virus and murine norovirus on lettuce. We found that in the presence of the bacterial extracellular substance, the survival and persistence of the viruses tested were significantly increased. In addition, in the presence of the bacterial extracellular substance, human norovirus, Tulane virus and murine norovirus were more resistance to traditional inactivation treatments such as heat inactivation and sodium hypochlorite inactivation. However, the bacterial extracellular substance was not found to be effective for protection of human norovirus under ultraviolet inactivation. Binding of virus to the bacterial extracellular substance were visualized by transmission electron microscopy. The results suggest that the protection of the bacterial extracellular substance to viruses tested might be related to the direct interaction between the substance and viral particles.

Technical Abstract: Human norovirus (HuNoV) outbreaks linked to leafy greens are on the rise due to a lack of efficient strategies to prevent HuNoV from spreading from contaminated surfaces. In our previous reports, we found that a resident bacteria SC015 could express HBGA-like substances in soluble extracellular polymeric substances (SEPS) which contribute to norovirus adherence on lettuce. In this study, we extracted the SEPS from Sphingobacterium sp. SC015 (SEPSSC015), analyzed its chemical composition and tested its roles in survival and protection of HuNoV and surrogates (TuV and MNV-1) on lettuce. We found that in the presence of SEPSSC015, the survival and persistence of HuNoN, TuV and MNV-1were significantly increased. In the presence of SEPS-SC015, HuNoV, TuV and MNV-1 were more resistance to traditional inactivation treatments. HuNoV, TuV and MNV-1 inoculated with SEPS-SC015 were more resistant to heat than these viruses alone. SEPS-SC015 also increased viral resistance to sodium hypochlorite inactivation. However, the SEPS-SC015 was not found to be effective for protection of HuNoV under UV inactivation. Binding of TuV to SC015 bacteria and SEPSSC015 were visualized by transmission electron microscopy. The results suggest that the protection might be related to the direct interaction between SEPS-SC015 and viral particles, although the exact mechanism remains unclear.