{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,8]],"date-time":"2026-04-08T08:46:06Z","timestamp":1775637966171,"version":"3.50.1"},"reference-count":23,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,4,7]],"date-time":"2026-04-07T00:00:00Z","timestamp":1775520000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pathogens"],"abstract":"<jats:p>Background: Campylobacter jejuni, a leading foodborne pathogen in poultry, relies heavily on iron for survival and colonizes the gastrointestinal tract (GIT). Iron supplementation in poultry diets can inadvertently promote pathogen growth, particularly when excess or poorly absorbed iron accumulates in the lower GIT. Encapsulated iron products, such as SQM\u00ae Iron, offer a controlled-release mechanism that may mitigate this risk by reducing iron availability to microbes. Objective: This study evaluated the effects of free (FeSO4) versus polysaccharide\u2013iron complex (PIC) on C. jejuni growth under iron-limited conditions, hypothesizing that encapsulated iron would support slower and more limited bacterial proliferation due to delayed iron release. Methods: Growth kinetics of C. jejuni ATCC 700819 were assessed in chelated Mueller\u2013Hinton broth supplemented with three iron concentrations (10, 20, and 50 ppm) of FeSO4, PIC, or PIC matrix without iron. Optical density was measured every 20 min over 48 h under microaerophilic conditions. Maximum growth rate (\u00b5max) and carrying capacity (K) were derived using non-linear curve modeling. ANOVA evaluated statistical significance with Tukey\u2019s HSD post hoc comparisons. Results: Free iron (FeSO4) consistently supported the highest \u00b5max and K values across both trials, indicating rapid and robust C. jejuni proliferation. The effect of encapsulated iron was variable: at higher concentrations (50 ppm) it approached FeSO4 performance, but at lower concentrations (10 ppm) its effect differed markedly between trials, sometimes supporting growth comparable to free iron and sometimes supporting substantially slower growth. The PIC matrix alone did not promote growth. These variable results indicate that the relationship between encapsulated iron and C. jejuni proliferation is complex and concentration-dependent. Conclusions: Free iron consistently promotes robust C. jejuni growth due to immediate bioavailability. The impact of encapsulated iron on C. jejuni proliferation is nuanced and variable, particularly at lower concentrations, suggesting its role in pathogen control is not straightforward and requires further investigation under controlled conditions. Furthermore, in vivo research is warranted to validate its utility in poultry pathogen management strategies.<\/jats:p>","DOI":"10.3390\/pathogens15040400","type":"journal-article","created":{"date-parts":[[2026,4,8]],"date-time":"2026-04-08T07:25:12Z","timestamp":1775633112000},"page":"400","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Impact of Encapsulated Iron Availability on the Growth Kinetics of Campylobacter jejuni"],"prefix":"10.3390","volume":"15","author":[{"given":"Elena G.","family":"Olson","sequence":"first","affiliation":[{"name":"Meat Science & Animal Biologics Discovery Program, Department of Animal and Dairy Sciences, University of Wisconsin-Madison, 1933 Observatory Drive, Madison, WI 53706, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Emily A.","family":"Matiak","sequence":"additional","affiliation":[{"name":"Meat Science & Animal Biologics Discovery Program, Department of Animal and Dairy Sciences, University of Wisconsin-Madison, 1933 Observatory Drive, Madison, WI 53706, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joshua A.","family":"Jendza","sequence":"additional","affiliation":[{"name":"Qualitech LLC, 318 Lake Hazeltine Drive, Chaska, MN 55318, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3584-9915","authenticated-orcid":false,"given":"Steven C.","family":"Ricke","sequence":"additional","affiliation":[{"name":"Meat Science & Animal Biologics Discovery Program, Department of Animal and Dairy Sciences, University of Wisconsin-Madison, 1933 Observatory Drive, Madison, WI 53706, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,7]]},"reference":[{"key":"ref_1","unstructured":"Ryan, E.T., Hill, D.R., Solomon, T., Aronson, N., and Endy, T.P. (2020). Hunter\u2019s Tropical Medicine and Emerging Infectious Diseases, Elsevier."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Fouts, D.E., Mongodin, E.F., Mandrell, R.E., Miller, W.G., Rasko, D.A., Ravel, J., Brinkac, L.M., DeBoy, R.T., Parker, C.T., and Daugherty, S.C. (2005). Major Structural Differences and Novel Potential Virulence Mechanisms from the Genomes of Multiple Campylobacter Species. PLoS Biol., 3.","DOI":"10.1371\/journal.pbio.0030015"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1201","DOI":"10.1086\/319760","article-title":"Campylobacter jejuni Infections: Update on Emerging Issues and Trends","volume":"32","author":"Acheson","year":"2001","journal-title":"Clin. Infect. Dis."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"976","DOI":"10.1017\/S0950268812001641","article-title":"A population-based exposure assessment of risk factors associated with gastrointestinal pathogens: A Campylobacter study","volume":"141","author":"MacRitchie","year":"2013","journal-title":"Epidemiol. Infect."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Al Hakeem, W.G., Fathima, S., Shanmugasundaram, R., and Selvaraj, R.K. (2022). Campylobacter jejuni in Poultry: Pathogenesis and Control Strategies. Microorganisms, 10.","DOI":"10.3390\/microorganisms10112134"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4714","DOI":"10.1128\/JB.186.14.4714-4729.2004","article-title":"Iron Acquisition and Regulation in Campylobacter jejuni","volume":"186","author":"Palyada","year":"2004","journal-title":"J. Bacteriol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2436060","DOI":"10.1080\/21505594.2024.2436060","article-title":"Pathogenicity and virulence of Campylobacter jejuni: What do we really know?","volume":"15","author":"Sharafutdinov","year":"2024","journal-title":"Virulence"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"5291","DOI":"10.1128\/JB.180.20.5291-5298.1998","article-title":"Iron-Responsive Gene Regulation in a Campylobacter jejuni fur Mutant","volume":"180","author":"Wooldridge","year":"1998","journal-title":"J. Bacteriol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"491","DOI":"10.3390\/microbiolres12020033","article-title":"Oral Iron Supplementation\u2014Gastrointestinal Side Effects and the Impact on the Gut Microbiota","volume":"12","author":"Bloor","year":"2021","journal-title":"Microbiol. Res."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Malesza, I.J., Bartkowiak-Wieczorek, J., Winkler-Galicki, J., Nowicka, A., Dzi\u0119cio\u0142owska, D., B\u0142aszczyk, M., Gajniak, P., S\u0142owi\u0144ska, K., Niepolski, L., and Walkowiak, J. (2022). The Dark Side of Iron: The Relationship between Iron, Inflammation and Gut Microbiota in Selected Diseases Associated with Iron Deficiency Anaemia\u2014A Narrative Review. Nutrients, 14.","DOI":"10.3390\/nu14173478"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Jing, Y., Zhang, S., Li, M., Zhang, R., Zhang, H., Zheng, Y., Zhang, D., and Wu, L. (2022). Structural characterization and biological activities of polysaccharide iron complex synthesized by plant polysaccharides: A review. Front. Nutr., 9.","DOI":"10.3389\/fnut.2022.1013067"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"289","DOI":"10.1016\/j.ijfoodmicro.2004.03.026","article-title":"Statistical evaluation of mathematical models for microbial growth","volume":"96","author":"Prieto","year":"2004","journal-title":"Int. J. Food Microbiol."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Stahl, M., Butcher, J., and Stintzi, A. (2012). Nutrient Acquisition and Metabolism by Campylobacter jejuni. Front. Cell. Infect. Microbiol., 2.","DOI":"10.3389\/fcimb.2012.00005"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"5433","DOI":"10.1128\/IAI.00052-06","article-title":"Major Role for FeoB in Campylobacter jejuni Ferrous Iron Acquisition, Gut Colonization, and Intracellular Survival","volume":"74","author":"Naikare","year":"2006","journal-title":"Infect. Immun."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1099\/mic.0.27412-0","article-title":"Campylobacter jejuni gene expression in response to iron limitation and the role of Fur","volume":"151","author":"Holmes","year":"2005","journal-title":"Microbiology"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"e0314823","DOI":"10.1128\/spectrum.03148-23","article-title":"Dissecting components of the Campylobacter jejuni fetMP-fetABCDEF gene cluster under iron limitation","volume":"12","author":"Chan","year":"2024","journal-title":"Microbiol. Spectr."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"10197","DOI":"10.1080\/10408398.2022.2076652","article-title":"Iron delivery systems for controlled release of iron and enhancement of iron absorption and bioavailability","volume":"63","author":"Hu","year":"2023","journal-title":"Crit. Rev. Food Sci. Nutr."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Lin, X., Gou, Z., Wang, Y., Li, L., Fan, Q., Ding, F., Zheng, C., and Jiang, S. (2020). Effects of Dietary Iron Level on Growth Performance, Immune Organ Indices and Meat Quality in Chinese Yellow Broilers. Animals, 10.","DOI":"10.3390\/ani10040670"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"100101","DOI":"10.1016\/j.japr.2020.09.016","article-title":"Iron requirement in the infection of Salmonella and its relevance to poultry health","volume":"30","author":"Tan","year":"2021","journal-title":"J. Appl. Poult. Res."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"20441","DOI":"10.1021\/acsomega.2c01833","article-title":"Iron Absorption: Factors, Limitations, and Improvement Methods","volume":"7","author":"Piskin","year":"2022","journal-title":"ACS Omega"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Yilmaz, B., and Li, H. (2018). Gut Microbiota and Iron: The Crucial Actors in Health and Disease. Pharmaceuticals, 11.","DOI":"10.3390\/ph11040098"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Yang, T., Chen, S., Qiu, L., Guo, Q., Wang, Z., Jiang, Y., Bai, H., Bi, Y., and Chang, G. (2024). Effect of High Dietary Iron on Fat Deposition and Gut Microbiota in Chickens. Animals, 14.","DOI":"10.3390\/ani14152254"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Bereswill, S., Mousavi, S., Weschka, D., Buczkowski, A., Schmidt, S., and Heimesaat, M.M. (2023). Iron Deprivation by Oral Deferoxamine Application Alleviates Acute Campylobacteriosis in a Clinical Murine Campylobacter jejuni Infection Model. Biomolecules, 13.","DOI":"10.3390\/biom13010071"}],"container-title":["Pathogens"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/4\/400\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,8]],"date-time":"2026-04-08T07:49:01Z","timestamp":1775634541000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/4\/400"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,4,7]]},"references-count":23,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2026,4]]}},"alternative-id":["pathogens15040400"],"URL":"https:\/\/doi.org\/10.3390\/pathogens15040400","relation":{},"ISSN":["2076-0817"],"issn-type":[{"value":"2076-0817","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4,7]]}}}