The ascomycetes, the spore sac fungi, are accommodated in the phylum Ascomycota, the largest of the seven phyla of the true fungi with more than 60 000 species. Many are saprobes; others are parasites or live in symbiosis with other organisms. A majority of the lichens are ascomycetes. The ascomycetes are of great economic importance as decomposers of dead material, parasites on crops, producers of antibiotics and other industrial products in food production (bread, beer, wine, etc.).