{
    "@context": "https://schema.org",
    "@type": "NewsArticle",
    "@id": "https://badiyaa.com/fanny-hesse-agar-1881-koch-bacteria/#article",
    "mainEntityOfPage": "https://badiyaa.com/fanny-hesse-agar-1881-koch-bacteria/",
    "headline": "Fanny Hesse suggested kitchen agar for growing bacteria in 1881, and Robert Koch never credited her",
    "description": "The New York-born homemaker used the seaweed jelly for summer desserts. Agar stays solid far above the 37°C at which gelatin melts, and labs still rely on it today.",
    "datePublished": "2026-11-10T04:40:00+00:00",
    "dateModified": "2026-11-10T04:40:00+00:00",
    "author": {
        "@type": "Organization",
        "name": "Badiyaa Editorial Desk",
        "url": "https://badiyaa.com/author/editorial-desk/"
    },
    "publisher": {
        "@type": "NewsMediaOrganization",
        "@id": "https://badiyaa.com/#organization",
        "name": "Badiyaa",
        "url": "https://badiyaa.com/",
        "logo": {
            "@type": "ImageObject",
            "url": "https://badiyaa.com/wp-content/uploads/2026/10/badiyaa-logo-color-600x60-1.png",
            "width": 600,
            "height": 60
        },
        "email": "badiyaavideo@gmail.com",
        "publishingPrinciples": "https://badiyaa.com/editorial-policy/",
        "correctionsPolicy": "https://badiyaa.com/corrections/",
        "actionableFeedbackPolicy": "https://badiyaa.com/contact/",
        "ownershipFundingInfo": "https://badiyaa.com/about/#ownership",
        "sameAs": [
            "https://www.facebook.com/profile.php?id=61595518283625",
            "https://www.instagram.com/badiyaa.com.ai/",
            "https://www.threads.net/@badiyaa.com.ai"
        ],
        "parentOrganization": {
            "@type": "Organization",
            "name": "Rezilient Digital",
            "url": "https://www.rezilientdigital.com/",
            "address": {
                "@type": "PostalAddress",
                "streetAddress": "Fl No 3, Nav Shyam Sadan, Plot No 38, Pestom Sagar, Chembur",
                "addressLocality": "Mumbai",
                "addressRegion": "Maharashtra",
                "postalCode": "400089",
                "addressCountry": "IN"
            },
            "sameAs": [
                "https://www.linkedin.com/company/rezilientdigital"
            ]
        }
    },
    "isAccessibleForFree": true,
    "inLanguage": "en-US",
    "wordCount": 648,
    "image": [
        "https://badiyaa.com/wp-content/uploads/2026/11/agarplate-redbloodcells-edit.webp",
        "https://badiyaa.com/wp-content/uploads/2026/11/agarplate-redbloodcells-edit-1024x649.webp"
    ],
    "articleSection": "History",
    "keywords": "Agar, Fanny Hesse, Microbiology, Robert Koch, women in science",
    "articleBody": "The jelly that fills nearly every Petri dish in the world started in a home kitchen. In 1881, Fanny Hesse, a New York-born homemaker living near Dresden, told her husband to stop fighting with melting gelatin and try agar, the seaweed jelly she used to set desserts in summer. Her husband, Walther Hesse, was working with the German bacteriologist Robert Koch. Within a year Koch was growing the tuberculosis germ on agar. His 1882 paper mentioned the ingredient. It did not mention her. A dessert trick that solved a lab problem Bacteriologists of the time grew microbes on gelatin, and gelatin had two flaws. It turns to liquid at about 37°C, which is body temperature and the very warmth an incubator needs for many disease germs. And several microbes digest it, leaving a runny mess where neat colonies should be. Walther ran into both problems while trying to count bacteria in the air. Historians of the episode say the summer of 1881 was hot near Dresden, which made his gelatin plates even worse. Fanny, who had cooked with agar for years, suggested he switch. Here is why it worked, in plain numbers. Agar sets once it cools below about 45°C, but it does not melt again until roughly 85°C. Gelatin gives way at 37°C. That leaves agar with a safety margin of about 48 degrees above the point where gelatin collapses, so an incubated plate stays firm. Microbes also cannot easily digest it, and it can be sterilized and stored. Where a New Jersey girl learned about agar Fanny Hesse was born Angelina Fanny Eilshemius in New York City on June 22, 1850, the eldest of ten children of a wealthy merchant. She grew up at Laurel Hill Manor in what is now the Kearny area of New Jersey, learned cooking from her mother and the household, and was sent to a Swiss finishing school at 15. Agar itself comes from red seaweed and has long been used in Southeast Asian cooking; “agar-agar” means jelly in Malay. Accounts say she first heard of it from Dutch acquaintances with ties to Java, then a Dutch colony. She used it in puddings and fruit jellies because it held up in summer heat, when gelatin went soft. She married Walther in 1874. Besides cleaning equipment and preparing growth media without pay, she painted watercolors of bacterial colonies, and those illustrations appeared in her husband’s 1884 article on airborne microbes. Koch’s paper and the missing name In his work on the cause of tuberculosis, Koch wrote that the bacilli “are able to grow on a solidified gel which remains solid at incubator temperature, prepared by adding agar-agar to a meat infusion or peptone medium.” No credit to either Hesse appears there. The couple never published anything on agar themselves, and they chose not to profit from it, regarding that as improper. Many family papers were lost when Dresden was bombed in the Second World War. Two historians writing in 1939, five years after her death, made the point sharply: “Lesser innovations and discoveries are commemorated with the name of the discoverer.” How the story compares with the Petri dish The shallow glass dish is named after Julius Richard Petri, another member of Koch’s circle, who designed it a few years later. The agar inside it, the part that actually makes the method work, carried no one’s name for well over a century. Only one of the two pieces of standard lab kit got a name attached, and it was not hers. Recognition has arrived slowly. The University of Virginia gave a “Frau Hesse Award” from 1981 to 1996, the Dutch microbiology society began a Fanny Hesse Award in 2024, and that same year researchers named a newly described microbe Streptomyces hesseae in her honor. Further reading Wikipedia: Fanny Hesse Illustrative image. Image: Bill Branson, Public domain via Wikimedia Commons This article was produced with AI assistance and reviewed by our Editorial Desk. How we work.",
    "markdown": "https://badiyaa.com/fanny-hesse-agar-1881-koch-bacteria.md"
}