Ch 18.1 Bacteria one celled prokaryotes (“before

nucleus”) first life on earth and most

numerous divided into two kingdoms

 1. Eubacteria live almost everywhere (soil, air,

water, and inside others) have cell wall of peptidoglycan some have second cell wall

2. Archaebacteria

have different membrane lipids and ribosome proteins

more like eukaryotes than eubacteria

may be ancestors of eukaryotes live in harsh environments

thermoacidophiles halophiles methanogens

Identifying Prokaryotes

by shape - bacilli, cocci, spirilla (spirochete)

By arrangement - diplo, strepto and staphylo

by cell wall type- gram positive or gram negative,

by way they move –flagella, spiraling, gliding or no movement

- by way they obtain energy Autotrophs capture energy to make food

-photoautotrophs called cyanobacteria

- chemoautotrophs (break down hydrogen

sulfide) Heterotrophs must eat to get energy and

nutrients - saprobes decompose organic molecules

(dead stuff)

-by the way they break down molecules in respiration some need oxygen for

respiration – obligate aerobes

some can only live in absence of oxygen – obligate anaerobes

some can live in both – facultative anaerobes

Benefits of bacteria

1. Most important role is ecological-breakdown and

decomposition of organic matter (decay)

- makes nutrients available for others

- cleans the environment

Other Benefits of Bacteria2. Nitrogen fixation - converts nitrogen in

air, to a useable form for plants (in soil or in nodules on legumes)

3. Food production – cheese, butter, yogurt and pickled products

4. Drug and chemical production thru genetic engineer-

ing (growth hormones, insulin, antibiotics)

5. Can digest small oil spills, remove poisons from water

4. Help digest food and production of vitamin K in digestive tract

Pathogens – disease causing agents Examples : pneumonia, diptheria,

typhoid, leprosy, strep and staph infection

harm organisms by:1 direct attack (tuberculosis)2. releasing harmful toxins (poisons)

ie. salmonella and botulism, strep, diptheria

Protection against Bacteria:

1. barriers (skin, mucous membranes)2. white blood cell attack3. vaccine-weakened or killed bacteria

that stimulate the body to produce

antibodies4. antibiotics -penicillin - discovered by

Alex Fleming in 1929

Growth and Reproduction Asexual reproduction – binary fission –

produces identical daughter cells  Conjugation – genes are passed from one

cell to another thru pili

- new combinations of genes results in greater

diversity  Endospores form in unfavorable conditions

– protects DNA foryears

 

Double Bonus: Bacteria Eat Pollution, Generate Electricity Scientists have long studied bacteria that can clean up toxic waste

by eating it. Other bacteria have been employed to produce electricity.

Now scientists have found a two-for-one deal in bacteria that will eat toxic chemicals 24/7 and make electricity to boot.

"The bacteria are capable of continuously generating electricity at levels that could be used to operate small electronic devices," says Charles Milliken of the Medical University of South Carolina, who conducted the research with colleague Harold May. "As long as the bacteria are fed fuel they are able to produce electricity 24 hours a day."

The new study involved Desulfitobacteria, already known for their ability to breakdown and detoxify some of the most problematic environmental pollutants, including PCBs and some chemical solvents.

"These bacteria are very diverse in their metabolic capabilities, including the food that they can consume. That means that these bacteria can convert a large number of different food sources into electricity," says Milliken. "The technology could be used to assist in the reclamation of wastewaters, thereby resulting in the removal of waste and generation of electricity."

The bacteria perform their useful tasks while in spore form, a dormant stage of growth that can handle extreme heat, radiation and lack of water -- all useful traits for an organism that might be employed in some of the worst manmade environments.

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