Fanny Hesse (Born Angelina Fanny Elishemius, June 22, 1850 – December 1, 1934) is best known for her work in microbiology alongside her husband, Walther Hesse. Together they were instrumental in developing Agar as a medium for culturing microorganisms. She was born in 1850 in New York City to Gottfried Elishemius, a wealthy import merchant, and his wife, Cecile Elise. Fanny met her husband and research partner Walther Hesse in 1872 while in Germany. They were engaged in 1873 and married in 1874 in Geneva.
In 1881, she worked for her husband as a technician in the laboratory of German physician and microbiologist Robert Koch. Hesse, working unpaid, would make drawings for her husband's publications. At the time, Koch was desperately searching for a suitable medium to grow bacterial cultures. He originally used potato slices, yet not all bacteria would grow on that surface. Then he used gelatin broths, yet during warm weather, these would liquefy and become all gooey. Besides, several bacteria used enzymes to break down the gelatin.
One day in 1881, while eating lunch, Walter asked Fanny about the jellies and puddings that she made and how they managed to stay gelled even in warm weather. Fannie told him about how she learned about the seaweed product, agar-agar, from a Dutch neighbor of hers while she was growing up in New York City. Her neighbor had emigrated from Indonesia, where it was the local custom to use agar in their cooking. Fannie suggested that they try this out in their laboratory. The rest is history. Agar turned out to be an ideal gelling agent that stayed firm even in the incubator and could not be digested by any bacterial enzymes. Walter Hesse notified Koch of this new technique, who immediately added agar to his nutrient broths. 
Lab work can be a lot like cooking. You have to follow directions to measure, mix, and heat different chemicals to the right temperature to get the desired result.
This led to Koch using agar to cultivate the bacteria that cause tuberculosis. While Koch, in an 1882 paper on tuberculosis bacilli, mentioned he used agar instead of gelatin, he did not credit Fanny or Walther Hesse or mention why he made the switch. Fanny Hesse's suggestion never resulted in financial benefit for the Hesse family.