|actinomycete (āk'tə-nō-mī'sēt') Pronunciation Key
Any of various bacteria belonging to the phylum Actinobacteria that grow as branching filaments resembling fungal hyphae and are found in soil. The filaments often grow in colonies but sometimes break off into rod-shaped structures. Many species of actinomycetes produce important antibiotics such as streptomycin, while others are pathogenic in humans and other animals, especially for skin diseases. One species lives symbiotically in the roots of alders and conducts nitrogen fixation. Because of their resemblance to fungi, actinomycetes were once classified as fungi.