What do Microbes do?
How can we use this to our advantage?

Microbes have small genomes but can
• Not do a lot, but what do, do well
• Extremophiles
– Microbes live in extreme conditions of
• Temperature
• Acidity
• Alkalinity
• Salinity
• Eubacteria vs Archaebacteria

Biological definition of Organismal interactions
• Symbiosis: a relationship between two different species
– Parasitism: one org gets nutrients from another
– Mutualism: both partners benefit
– Commensalisms : one benefits more

• Other examples?

• Matter can neither be created or destroyed
• A constant amount of matter in the environment must be recycled
• Microbes are essential in the conversion of nutrients into organic and usable formats
• Microbes are essential in the conversion of nutrients into the inorganic form

• Photoautotrophs
• Chemoautorophs
• Both convert inorganic forms of carbon into organic forms using external sources of energy

• Inorganic form of carbon (CO2) to complete the cycle.
• Non living sinks include
• CaCO3 and fossil fuels

• Local shortages because of Nitrogen stuff
• Microbes decompose proteins form dead cells and release amino acids
• Ammonia is liberated by microbial ammonificaiton of amino acids
• Ammonia is oxidized to produce nitrates for energy by nitrifying bacteria

• Denitrifying bacteria reduce nitrogen in nitrates to molecular nitrogen
• N2 is converted into ammonia by nitrogen fixing bacteria
• Ammonium and nitrate are used by bacteria and plants to synthesize amino acids

• Fertilization and microbes
• Cyanobacteria for a symbiosis with small floating fern Azolla in rice paddy waters.

• Plants and certain microbes can use
SO42- to make amino acids
• H2S is oxidized to form SO42-

Proteins and waste products
Microbial decomposition
Amino acids
Amino acids ( –SH)
Microbial dissimilation
H
2
S
Thiobacillus
SO
4
2 –
H
2
S
(for energy, by respiration)
SO
4
2 –
Microbial & plant assimilation
Amino acids

• Inorganic phosphorus is solubilized by microbial acids
• Made available to plants and other microbes
• Is soluble in water
• Combines with calcium in calcium phosphate deposits of ancient seas.

• Primary producers in most ecosystems are photoautotrophs
• Primary producers in deep ocean and endolithic communities are chemoautotrophic bacteria
H
2
S SO
4
2 – Provides energy for bacteria which may be used to fix CO
2
CO
2
Calvin Cycle
Sugars Provides carbon for cell growth

Use of chemicals in soil and water
• Many man made chemicals do not biodegrade because they are not made by living organisms
• Why?

Components of agent orange
Figure 27.8

• Use of microorganism to remove pollution
• Cheaper
• Can use natural organism
• Is helped by preventing limited nutrients

• Many municipal waste piles are inefficiently run because they are dry and anaerobic

• Biofilms are composed of whole communities of microbes that are metabolically diverse
• Bodies of water are naturally set up to process waste
• Tend to grow in presence of oxygen and light
• Use is best when oxygen content is increased
• Phytoplankton in oceans are primary producers in the open ocean

Figure 27.12

Roll of microorganism in water quality
• Biomagnifications
• Indicators of fecal contamination
• Blooms
• Eutrophication

Table 27.2

• Coliforms are aerobic or facultatively anaerobic, gram negative non endospore forming rods that ferment lactose with the production of acid and gas within 48 hours of been placed in a medium at 35’C
• Fecal Coliforms predominantly E. coli are used to indicate the presence of human fecies

• Aerobic or facultatively anaerobic, gramnegative, non –endospore forming rods that ferment lactose to acid + gas within 48 hr, at
35 °C
• Indicator organisms
– Used to detect fecal contamination
• MPN
– Most probable number/100 ml of water

• Water held in a holding reservoir long enough that suspended matter settles
• Flocculation treatment uses a chemical such as alum to coalesce and settle colloidal material
• Filtration removes protozoan cyst and other microbes
• Drinking water is disinfected with chlorine to kill remaining pathogenic bacteria

• The quality of life that we see in our first world countries is due to our treatment of sewage
• Primary treatment: removal of solid materials (35% BOD)
• Secondary treatment: Reduction of BOD by the metabolic (95%BOD) degradation of organic matter

• BOD biochemical oxygen demand
• Tertiary provides essentially drinkable water is much more expensive to do

Figure 27.20a,b

Alternative treatments of sewage
• Septic tanks
• Oxidation ponds

Sludge produced by sewage treatment plants.

• CO
2
+ 4 H
2

CH
4
+ 2
H
2
O
• CH
3
COOH

CH
4
CO
2
+
Figure 27.23