Microbiology of Microbial Growth
Indoor and outdoor environments naturally harbor a great variety of microscopic life forms termed microorganisms or microbes. Found everywhere in nature, their largest components are classified as bacteria and fungi. Bacteria are an extremely large and diverse group of single-celled organisms found in all earthly habitats to include the most extreme and harsh physical environments.
In addition to visible bacterial or fungal growth and detection of moisture in porous materials, an obvious indicator of microbial growth and contamination is a "musty", "moldy", or "mildewy" odor. Bacteria and fungi produce a variety of volatile organic compounds during active growth in damp or wet building, finishing, and furnishing materials. These microbial volatile organic compounds, which are detected through the smell are generated by many molds, and also gram-negative and actinomycete bacteria as they rapidly metabolize and amplify.