Chapter 22: Microbiology of the Built Environment

Microbial activities are widely exploited in industrial mineral recovery through microbial leaching, where acidophilic iron and sulfur oxidizing microorganisms such as Acidithiobacillus ferrooxidans promote the dissolution of metal sulfide ores to extract valuable metals like copper, uranium, and gold. However, similar microbial processes can also generate environmental problems such as acid mine drainage when sulfide minerals like pyrite are exposed to oxygen and water, producing sulfuric acid and dissolved metals that contaminate aquatic systems. Microorganisms are also essential for bioremediation, the biological removal or detoxification of environmental pollutants. Hydrocarbon degrading bacteria can metabolize petroleum compounds during oil spill cleanup, while specialized microbes can reduce soluble metal contaminants such as uranium to insoluble forms, immobilizing them in sediments. Certain bacteria perform reductive dechlorination of chlorinated organic pollutants such as tetrachloroethene and trichloroethene, converting them into less harmful compounds, and some organisms such as Ideonella sakaiensis can enzymatically degrade synthetic plastics like polyethylene terephthalate. The chapter further explores microbial processes used in wastewater treatment systems, where physical separation, aerobic microbial degradation, and advanced biological nutrient removal processes reduce organic pollutants, nitrogen, and phosphorus. Processes such as nitrification, denitrification, and anaerobic ammonium oxidation are central to nitrogen removal, while anaerobic digestion of sludge generates methane as a bioenergy source. Drinking water treatment systems rely on sedimentation, coagulation, filtration, and disinfection to produce potable water, yet microbial biofilms can still develop within distribution systems and may harbor opportunistic pathogens. The indoor environment also supports complex microbial communities influenced by human occupants, pets, and building materials, shaping microbial populations in air, dust, plumbing systems, and surfaces. Finally, the chapter discusses microbially influenced corrosion, in which microbial metabolic processes accelerate the degradation of metals and infrastructure through activities such as sulfate reduction and iron oxidation, as well as biodeterioration of materials like concrete and stone. These examples illustrate how microorganisms both benefit and challenge human built systems, demonstrating the importance of understanding microbial processes in industrial, environmental, and urban contexts.