They produce oxygen as a by-product, are widely spread and important in nature, but not medically significant except perhaps rarely as a source of gastrointestinal illness. We will not study them further. These bacteria show a limited similarity to fungal growth patterns of branching, hyphae, mycelia, and even spore-like structures. As a result, it can more readily withstand drying or disinfectants. This group includes Mycobacterium tuberculosis and Mycobacterium leprae , important human pathogens.
Streptomyces grisieus produces an important anti-tubercular drug, streptomycin .
Other streptomycetes give the characteristic odor to soil. Nocardioforms can degrade petroleum pollutants and produce the antibiotic vancomycin . An example is Treponema pallidum which causes syphilis. A tick-borne spirochete is responsible for Lyme disease. Typical bacteria are the bacteria which command much attention in this course, and will be discussed fully in the next major section.