{"id":5942,"date":"2026-03-17T09:19:31","date_gmt":"2026-03-17T01:19:31","guid":{"rendered":"https:\/\/transactions.nast.ph\/?p=5942"},"modified":"2026-03-30T16:22:59","modified_gmt":"2026-03-30T08:22:59","slug":"light-inhibition-of-photobacterium-leiognathi-as-bioindicator-of-heavy-metal-pollution","status":"publish","type":"post","link":"https:\/\/transactions.nast.ph\/?p=5942","title":{"rendered":"Light Inhibition of Photobacterium leiognathi as Bioindicator of Heavy Metal Pollution"},"content":{"rendered":"\n<p class=\"has-text-align-center\">Thomas Edison E. dela Cruz, Maripaz B. Ancheta, Rosemarie P. Capaque, Arnel E. Mantes, and Ma. Estellita Perez<br>Department of Biological Sciences<br>University of Sto. Tomas<\/p>\n\n\n\n<p class=\"has-text-align-center\"><a href=\"http:\/\/doi.org\/10.57043\/transnastphl.1997.5942\" data-type=\"link\" data-id=\"doi.org\/10.57043\/transnastphl.1997.5942\">doi.org\/10.57043\/transnastphl.1997.5942<\/a><br><\/p>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-1 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<p><strong>Abstract<\/strong><\/p>\n\n\n\n<p>Heavy metal pollution in the biosphere has become a serious health and ecological concern. Its occurrence in nature is usually monitored by chemical analyzes with the use of high-cost instruments. An alternative method is presented for determination of water pollution with heavy metals and detergents using biological system. It is a test tube assay involving the naturally luminescent Photobacterium leiognathi as bioindicator. Three-milliliter bacterial suspension (10 6 cells\/ml) is mixed with 0.5 ml of the test solution to find the minimum anti-luminescent concentration (MAC) of the pollutant. Light inhibition is determined simply by gross visual observation inside the dark room. Tests showed MAC at 714.29 ppm for PbNO3, 142.86 ppm for CuSO4 , 14.29 ppm for ZnSO4\u200b and 1.43 ppm for HgCl2. A local commercial detergent inhibited bioluminescence of the bioindicator bacterium at 14 ppm MAC. Inhibition of light emission in the bioassay literally means &#8220;turning off&#8221; the light of the bioindicator bacterium. Light is &#8220;turned on&#8221; again, i.e., light emission is restored, when the bacterium is transferred to a fresh medium. Since the assay simply involves &#8220;on&#8221; and &#8220;off&#8221; of luminescence, this can serve as a preliminary test for toxicity of heavy metals in polluted waters.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<h5 class=\"wp-block-heading\">Keywords<\/h5>\n\n\n<div class=\"taxonomy-post_tag wp-block-post-terms\"><a href=\"https:\/\/transactions.nast.ph\/?tag=bioassay\" rel=\"tag\">Bioassay<\/a><span class=\"wp-block-post-terms__separator\">, <\/span><a href=\"https:\/\/transactions.nast.ph\/?tag=bioindicator\" rel=\"tag\">Bioindicator<\/a><span class=\"wp-block-post-terms__separator\">, <\/span><a href=\"https:\/\/transactions.nast.ph\/?tag=bioluminescence\" rel=\"tag\">Bioluminescence<\/a><span class=\"wp-block-post-terms__separator\">, <\/span><a href=\"https:\/\/transactions.nast.ph\/?tag=heavy-metals\" rel=\"tag\">Heavy Metals<\/a><span class=\"wp-block-post-terms__separator\">, <\/span><a href=\"https:\/\/transactions.nast.ph\/?tag=light-inhibition\" rel=\"tag\">Light Inhibition<\/a><span class=\"wp-block-post-terms__separator\">, <\/span><a href=\"https:\/\/transactions.nast.ph\/?tag=minimum-anti-luminescent-concentration-mac\" rel=\"tag\">Minimum Anti-luminescent Concentration (MAC)<\/a><span class=\"wp-block-post-terms__separator\">, <\/span><a href=\"https:\/\/transactions.nast.ph\/?tag=photobacterium-leiognathi\" rel=\"tag\">Photobacterium leiognathi<\/a><\/div><\/div>\n<\/div>\n\n\n\n<div data-wp-interactive=\"core\/file\" class=\"wp-block-file\"><object data-wp-bind--hidden=\"!state.hasPdfPreview\"  class=\"wp-block-file__embed\" data=\"https:\/\/transactions.nast.ph\/wp-content\/uploads\/2026\/03\/TNP-1997-19_17_Light-Inhibition-of-Photobacterium-Leiognathi-as-Bioindicator-of-Heavy-Metal-Pollution.pdf\" type=\"application\/pdf\" style=\"width:100%;height:1090px\" aria-label=\"Embed of TNP 1997 (19)_17_Light Inhibition of Photobacterium Leiognathi as Bioindicator of Heavy Metal Pollution.\"><\/object><a id=\"wp-block-file--media-1833b95f-3130-42b7-8c07-3bfa14b92857\" href=\"https:\/\/transactions.nast.ph\/wp-content\/uploads\/2026\/03\/TNP-1997-19_17_Light-Inhibition-of-Photobacterium-Leiognathi-as-Bioindicator-of-Heavy-Metal-Pollution.pdf\">TNP 1997 (19)_17_Light Inhibition of Photobacterium Leiognathi as Bioindicator of Heavy Metal Pollution<\/a><a href=\"https:\/\/transactions.nast.ph\/wp-content\/uploads\/2026\/03\/TNP-1997-19_17_Light-Inhibition-of-Photobacterium-Leiognathi-as-Bioindicator-of-Heavy-Metal-Pollution.pdf\" class=\"wp-block-file__button wp-element-button\" download aria-describedby=\"wp-block-file--media-1833b95f-3130-42b7-8c07-3bfa14b92857\">Download<\/a><\/div>\n","protected":false},"excerpt":{"rendered":"<p>Thomas Edison E. dela Cruz, Maripaz B. Ancheta, Rosemarie P. Capaque, Arnel E. Mantes, and Ma. Estellita Perez<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[835],"tags":[1118,1117,1121,1119,1122,1116,1120],"class_list":{"0":"post-5942","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-1997-technical-papers","7":"tag-bioassay","8":"tag-bioindicator","9":"tag-bioluminescence","10":"tag-heavy-metals","11":"tag-light-inhibition","12":"tag-minimum-anti-luminescent-concentration-mac","13":"tag-photobacterium-leiognathi","14":"czr-hentry"},"_links":{"self":[{"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=\/wp\/v2\/posts\/5942"}],"collection":[{"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5942"}],"version-history":[{"count":2,"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=\/wp\/v2\/posts\/5942\/revisions"}],"predecessor-version":[{"id":6230,"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=\/wp\/v2\/posts\/5942\/revisions\/6230"}],"wp:attachment":[{"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5942"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5942"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/transactions.nast.ph\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5942"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}