Fungi, common on Old Earth and moreso on this planet, are eukaryotic organisms ranging from microorganisms such as yeast and mold to large mushrooms. Fungi, unlike plants and protists, have cell walls containing chitin instead of cellulose. Essentially symbionts, fungi have been used for centuries as food and in the processing of food as fermentation, leavening and coagulating agents. In the last two centuries before the Great Mistake, mycologists uncovered many other uses for various fungi: production of antibiotics, as biological pesticides, as industrial enzymes, and as bioactive mycotoxins. Continuing research begun on Old Earth, scientists since planetfall have utilized indigenous fungi in bioremediation, using them to degrade coal tars, creosote, pentachlorophenal and petroleum to release carbon dioxide, water and certain base elements; in addition, they have been employed extensively in colonial industry to produce citric, gluconic and malic acids. Most recently, some local fungi have been utilized in genetic engineering research in one gene-one enzyme methods of cell cycle regulation, chromatin modification and gene mapping. Finally, various species were used on Old Earth as psychotropic compounds, either illegally or in religious ceremonies … a practice that has continued on this new world in some colonies.