{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,17]],"date-time":"2026-10-17T19:13:52Z","timestamp":1792264432026,"version":"4.4.0"},"reference-count":52,"publisher":"American Society for Microbiology","issue":"9","license":[{"start":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T00:00:00Z","timestamp":1788220800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T00:00:00Z","timestamp":1788220800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R35GM130399"],"award-info":[{"award-number":["R35GM130399"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Microbiol Spectr"],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      Cobamides (Cbas) are structurally complex biomolecules used by cells of all domains of life. However,\n                      <jats:italic toggle=\"yes\">de novo<\/jats:italic>\n                      Cba biosynthesis occurs only in some bacteria and archaea. The uptake, salvage, and remodeling of Cbas and their precursors have been well studied in several prokaryotes, but our understanding of the mechanism(s) of Cba release into the environment is limited. In this study, we quantitatively demonstrate Cba excretion by\n                      <jats:italic toggle=\"yes\">Salmonella enterica<\/jats:italic>\n                      subsp.\n                      <jats:italic toggle=\"yes\">enterica<\/jats:italic>\n                      sv. Typhimurium strain LT2 (hereafter\n                      <jats:italic toggle=\"yes\">S<\/jats:italic>\n                      . Typhimurium). We performed experiments in liquid and solid media using strains that produced Cbas from a precursor that can be converted to Cbas in the presence of oxygen. We show that under anaerobic conditions,\n                      <jats:italic toggle=\"yes\">S<\/jats:italic>\n                      . Typhimurium synthesizes Cbas\n                      <jats:italic toggle=\"yes\">de novo<\/jats:italic>\n                      and excretes this valuable cofactor into the medium. To do this,\n                      <jats:italic toggle=\"yes\">S<\/jats:italic>\n                      . Typhimurium requires \u226524 h of incubation under anaerobic conditions to form microcolonies that can continue synthesizing and excreting Cbas when shifted to aerobic growth conditions. We propose that\n                      <jats:italic toggle=\"yes\">de novo<\/jats:italic>\n                      Cba biosynthesis and excretion may be necessary for\n                      <jats:italic toggle=\"yes\">S<\/jats:italic>\n                      . Typhimurium to transition from an anaerobic to an aerobic environment, and that Cba excretion may allow growth of Cba-requiring members of polymicrobial communities.\n                    <\/jats:p>\n                    <jats:sec>\n                      <jats:title>IMPORTANCE<\/jats:title>\n                      <jats:p>\n                        This work is important for several reasons. First, this is the first evidence that\n                        <jats:italic toggle=\"yes\">Salmonella enterica<\/jats:italic>\n                        subsp.\n                        <jats:italic toggle=\"yes\">enterica<\/jats:italic>\n                        sv. Typhimurium strain LT2 excretes cobamides, a valuable nutrient for all forms of life, including humans. Second, although\n                        <jats:italic toggle=\"yes\">de novo<\/jats:italic>\n                        cobamide biosynthesis in\n                        <jats:italic toggle=\"yes\">S<\/jats:italic>\n                        . Typhimurium is blocked by oxygen, we show that once a microcolony of\n                        <jats:italic toggle=\"yes\">S<\/jats:italic>\n                        . Typhimurium is formed under anaerobic conditions, exposure to air does not block cobamide biosynthesis, and robust colony growth can proceed. Hence, the formation of microcolonies under anaerobic conditions may be a critical strategy for\n                        <jats:italic toggle=\"yes\">S<\/jats:italic>\n                        . Typhimurium survival in its free-living lifestyle. Third, in an environment where\n                        <jats:italic toggle=\"yes\">S<\/jats:italic>\n                        . Typhimurium is part of a polymicrobial community, this pathogen may allow growth of other microbes that require cobamides to survive, as it may occur in polymicrobial biofilms. Finally, this work provides the groundwork for advancing our understanding of why\n                        <jats:italic toggle=\"yes\">S<\/jats:italic>\n                        . Typhimurium excretes such a valuable cofactor and how excretion is accomplished.\n                      <\/jats:p>\n                    <\/jats:sec>\n                  <\/jats:sec>","DOI":"10.1128\/spectrum.01363-26","type":"journal-article","created":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T13:00:06Z","timestamp":1784898006000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":1,"title":["Cobamide excretion allows\n                    <i>Salmonella<\/i>\n                    to transition from its anaerobic to aerobic lifestyle"],"prefix":"10.1128","volume":"14","author":[{"given":"Lahiru","family":"Malalasekara","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02bjhwk41","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Microbiology, University of Georgia","place":["Athens, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7428-2811","authenticated-orcid":true,"given":"Jorge C.","family":"Escalante-Semerena","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02bjhwk41","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Microbiology, University of Georgia","place":["Athens, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_4_2_2","first-page":"557","volume-title":"Chemistry and biochemistry of B12","author":"Renz P","year":"1999","unstructured":"Renz P. 1999. 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