Transcript Lecture 14 soil and air microbiology - Cal State LA

Acid Mine Drainage
Microorganisms and Metal
Toxicity
• microorganisms can modify toxicity of metals
• differing sensitivities of multicellular
organisms and microorganisms to metals are
basis of many antiseptic procedures
Soil as an Environment for
Microorganisms
• dominated by inorganic geological
material, which is modified by
organisms to form soils
• typically not water saturated, so O2
readily available
• can contain “mini” aquatic environments
Microorganisms in the Soil
Environment
peds – aggregated
soil particles
Microbial populations in soils
• numbers can be very high
– only small portion have been cultured
• microbes are constantly being added to
soil
– most do not survive
• make important contributions to
biogeochemical cycling
• gram-positive bacteria are important
members of soil communities
Deserts Soils
• desert crusts
– microbial communities on soil surface
• cyanobacteria and associated commensals
– help retain water from infrequent rainfalls
– are fragile and easily damaged
Desert crusts or cryptogamic crusts
Biological soil crusts are formed by living organisms
and their by-products, creating a crust of soil particles
bound together by organic materials
Crusts are predominantly composed of cyanobacteria,
algae, mosses, and lichens. Liverworts, fungi, and
bacteria can also be important components