{"id":30996,"date":"2021-08-18T15:32:33","date_gmt":"2021-08-18T13:32:33","guid":{"rendered":"https:\/\/fermentis.com\/?page_id=30996"},"modified":"2021-08-18T16:00:11","modified_gmt":"2021-08-18T14:00:11","slug":"killer-yeast","status":"publish","type":"page","link":"https:\/\/fermentis.com\/en\/knowledge-center\/expert-insights\/wine\/killer-yeast\/","title":{"rendered":"What are \u2018killer\u2019 yeast strains and are they important?"},"content":{"rendered":"\n  <div class=\"banner has-hover\" id=\"banner-344934245\">\n          <div class=\"banner-inner fill\">\n        <div class=\"banner-bg fill\" >\n            <img loading=\"lazy\" decoding=\"async\" width=\"1020\" height=\"506\" src=\"https:\/\/fermentis.com\/wp-content\/uploads\/2020\/10\/saf-yeast-1024x508.jpg\" class=\"bg attachment-large size-large\" alt=\"\" \/>                        <div class=\"overlay\"><\/div>            \n                    <\/div>\n\t\t\n        <div class=\"banner-layers container\">\n            <div class=\"fill banner-link\"><\/div>            \n   <div id=\"text-box-1585556245\" class=\"text-box banner-layer x50 md-x50 lg-x50 y50 md-y50 lg-y50 res-text\">\n                                <div class=\"text-box-content text dark\">\n              \n              <div class=\"text-inner text-center\">\n                  \n\t<div id=\"text-1725922176\" class=\"text\">\n\t\t\n<h2><span style=\"font-size: 100%;\">What are \u2018killer\u2019 yeast strains and are they important?<\/span><\/h2>\n<p><i>By Etienne Dorignac, Technical Manager &amp; Oenologist, Fermentis<\/i><\/p>\n<h2><\/h2>\n\t\t\n<style>\n#text-1725922176 {\n  color: rgb(255,255,255);\n}\n#text-1725922176 > * {\n  color: rgb(255,255,255);\n}\n<\/style>\n\t<\/div>\n\t\n              <\/div>\n           <\/div>\n                            \n<style>\n#text-box-1585556245 {\n  width: 82%;\n}\n#text-box-1585556245 .text-box-content {\n  font-size: 100%;\n}\n<\/style>\n    <\/div>\n \n        <\/div>\n      <\/div>\n\n            \n<style>\n#banner-344934245 {\n  padding-top: 300px;\n  background-color: rgb(255, 255, 255);\n}\n#banner-344934245 .overlay {\n  background-color: rgba(0, 0, 0, 0.331);\n}\n#banner-344934245 .banner-bg img {\n  object-position: 28% 40%;\n}\n<\/style>\n  <\/div>\n\n\n<div class=\"row align-center\"  id=\"row-952629098\">\n\n\t<div id=\"col-891706647\" class=\"col small-12 large-12\"  >\n\t\t\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n<div class=\"row\"  id=\"row-799417328\">\n\n\t<div id=\"col-1132799330\" class=\"col medium-5 small-12 large-5\"  >\n\t\t\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_1406283997\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" >\n\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"724\" height=\"1024\" src=\"https:\/\/fermentis.com\/wp-content\/uploads\/2020\/05\/killer-yeast-724x1024.png\" class=\"attachment-large size-large\" alt=\"\" srcset=\"https:\/\/fermentis.com\/wp-content\/uploads\/2020\/05\/killer-yeast-724x1024.png 724w, https:\/\/fermentis.com\/wp-content\/uploads\/2020\/05\/killer-yeast-565x800.png 565w, https:\/\/fermentis.com\/wp-content\/uploads\/2020\/05\/killer-yeast-768x1087.png 768w, https:\/\/fermentis.com\/wp-content\/uploads\/2020\/05\/killer-yeast-600x849.png 600w, https:\/\/fermentis.com\/wp-content\/uploads\/2020\/05\/killer-yeast-424x600.png 424w, https:\/\/fermentis.com\/wp-content\/uploads\/2020\/05\/killer-yeast-212x300.png 212w, https:\/\/fermentis.com\/wp-content\/uploads\/2020\/05\/killer-yeast.png 848w\" sizes=\"auto, (max-width: 724px) 100vw, 724px\" \/>\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n<style>\n#image_1406283997 {\n  width: 100%;\n}\n<\/style>\n\t<\/div>\n\t\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\n\t\n\n\t<div id=\"col-1268394883\" class=\"col medium-7 small-12 large-7\"  >\n\t\t\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n<p>In a lot of documentations about wine yeasts, you will probably find an information about their \u201cKiller\u201d status\u2026 scary indication isn\u2019t it? Let\u2019s talk a bit about the meaning of this status \u2013 which seems like it was taken straight from a thriller movie!<\/p>\n<p>Certain yeast strains can effectively produce and excrete proteins that are toxic for other strains. These proteins will bind to a specific receptor located on the surface of the cell wall and slowly induce the death of the affected strain.<\/p>\n<p>There are 3 common types of strains: \u201cKiller\u201d ones which secrete the toxin and don\u2019t possess its receptor (K+R-), \u201cSensitive\u201d which don\u2019t secrete the toxin but can bind to it (K-R+) and \u201cNeutral\u201d which neither excrete nor bind (K-R-).<\/p>\n<p>As several toxins exist, in the wine world we almost always talk about the \u201cK2\u201d toxin when referring to the killer factor as this protein expresses its activity at wine pH (2.8-4.8).<\/p>\n<p>However, the ratio between Killer and Sensitive strains \u2013 in order to move the population towards the predominance of Killer strains in winemaking conditions \u2013 is highly variable, from 1\/1000 to 25\/1!<\/p>\n<p>The efficiency of the toxin depends on several parameters including temperature (thermo-sensitive) and pH (inactive below 2.9) which are the most important and can also be affected by the presence of polyphenols or additives.<\/p>\n<p>But above all, the strains themselves show very different killer activity or sensitivity degrees\u2026 Anyhow, even if it is highly variable, it is generally recognized that the possession of this killer factor gives a better chance of implantation of said strain into the must and that is why it is something we rather look for when selecting wine yeast\u2026.<\/p>\n<p><em>And we haven\u2019t even mentioned the \u201csuicide\u201d strains (K+R+) which secrete toxins that can affect themselves\u2026 but that\u2019s another story\u00a0<\/em><em>!<\/em><\/p>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\n\t\n<\/div>\n<div class=\"row\"  id=\"row-1187488645\">\n\n\t<div id=\"col-1837704467\" class=\"col small-12 large-12\"  >\n\t\t\t\t<div class=\"col-inner text-center\"  >\n\t\t\t\n\t\t\t\n<a href=\"https:\/\/fermentis.com\/en\/knowledge-center\/expert-insights\/\" class=\"button primary\" >\n\t<i class=\"icon-angle-right\" aria-hidden=\"true\"><\/i>\t<span>Back to expert insights<\/span>\n\t<\/a>\n\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\n\t\n<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\n\t\n<\/div>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":2,"featured_media":25847,"parent":27897,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"page-blank.php","meta":{"_acf_changed":false,"footnotes":""},"class_list":["post-30996","page","type-page","status-publish","has-post-thumbnail","hentry"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.5 (Yoast SEO v27.5) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>What are \u2018killer\u2019 yeast strains and are they important? 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