Ultraviolet-C inactivation and hydrophobicity of Bacillus subtilis and Bacillus velezensis spores isolated from extended shelf-life milk

dc.contributor.authorElegbeleye, James Ayokunle
dc.contributor.authorGervilla, Ramon
dc.contributor.authorRoig-Sagues, Artur X.
dc.contributor.authorBuys, E.M. (Elna Maria)
dc.contributor.emailelna.buys@up.ac.zaen_ZA
dc.date.accessioned2022-01-13T09:22:30Z
dc.date.issued2021-07
dc.description.abstractBacterial spores are important in food processing due to their ubiquity, resistance to high temperature and chemical inactivation. This work aims to study the effect of ultraviolet C (UVC) on the spores of Bacillus subtilis and Bacillus velezensis at a molecular and individual level to guide in deciding on the right parameters that must be applied during the processing of liquid foods. The spores were treated with UVC using phosphate buffer saline (PBS) as a suspension medium and their lethality rate was determined for each sample. Purified spore samples of B. velezensis and B. subtilis were treated under one pass in a UVC reactor to inactivate the spores. The resistance pattern of the spores to UVC treatment was determined using dipicolinic acid (Ca-DPA) band of spectral analysis obtained from Raman spectroscopy. Flow cytometry analysis was also done to determine the effect of the UVC treatment on the spore samples at the molecular level. Samples were processed for SEM and the percentage spore surface hydrophobicity was also determined using the Microbial Adhesion to Hydrocarbon (MATH) assay to predict the adhesion strength to a stainless-steel surface. The result shows the maximum lethality rate to be 6.5 for B. subtilis strain SRCM103689 (B47) and highest percentage hydrophobicity was 54.9% from the sample B. velezensis strain LPL-K103 (B44). The difference in surface hydrophobicity for all isolates was statistically significant (P < 0.05). Flow cytometry analysis of UVC treated spore suspensions clarifies them further into sub-populations unaccounted for by plate counting on growth media. The Raman spectroscopy identified B4002 as the isolate possessing the highest concentration of Ca-DPA. The study justifies the critical role of Ca-DPA in spore resistance and the possible sub-populations after UVC treatment that may affect product shelf-life and safety. UVC shows a promising application in the inactivation of resistant spores though there is a need to understand the effects at the molecular level to design the best parameters during processing.en_ZA
dc.description.departmentConsumer Scienceen_ZA
dc.description.departmentFood Scienceen_ZA
dc.description.embargo2022-05-04
dc.description.librarianhj2022en_ZA
dc.description.sponsorshipThe Erasmus+ KA107 International Credit Mobility Programme and the research project AGL2014-60005-R of the Spanish Ministry of Economy, Industry and Competence co-funded by FEDER.en_ZA
dc.description.urihttp://www.elsevier.com/ locate/ijfoodmicroen_ZA
dc.identifier.citationElegbeleye, J.A., Gervilla, R., Roig-Sagues, A.X. et al. 2021, 'Ultraviolet-C inactivation and hydrophobicity of Bacillus subtilis and Bacillus velezensis spores isolated from extended shelf-life milk', International Journal of Food Microbiology, vol. 349, art. 109231, pp. 1-11.en_ZA
dc.identifier.issn0168-1605 (print)
dc.identifier.issn1879-3460 (online)
dc.identifier.other10.1016/j.ijfoodmicro.2021.109231
dc.identifier.urihttp://hdl.handle.net/2263/83318
dc.language.isoenen_ZA
dc.publisherElsevieren_ZA
dc.rights© 2021 Elsevier B.V. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in International Journal of Food Microbiology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. A definitive version was subsequently published in International Journal of Food Microbiology, vol. 349, art. 109231, pp. 1-11, 2021. doi : 10.1016/j.ijfoodmicro.2021.109231.en_ZA
dc.subjectUltraviolet C (UVC)en_ZA
dc.subjectPhosphate buffer saline (PBS)en_ZA
dc.subjectLethality rateen_ZA
dc.subjectAdhesion strengthen_ZA
dc.subjectRaman spectroscopyen_ZA
dc.subjectDipicolinic acid (Ca-DPA)en_ZA
dc.titleUltraviolet-C inactivation and hydrophobicity of Bacillus subtilis and Bacillus velezensis spores isolated from extended shelf-life milken_ZA
dc.typePostprint Articleen_ZA

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