Helpful Bacteria Most bacteria are harmless to humans Many are useful Aid in digestion Provide nutrients for plants by breaking down dead material by decomposition Provide drugs and hormones Provide some types of food ID: 482231
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Slide1
Helpful and Harmful BacteriaSlide2
Helpful Bacteria
Most bacteria are harmless to humans.
Many are useful:
Aid in digestion
Provide nutrients for plants by breaking down dead material by decomposition
Provide drugs and hormones
Provide some types of food.Slide3
Yoghurt
This is made by the action of a particular type of bacteria on milk.
Lactobacillus
bulgaricus
and Streptococcus
thermophilus
These bacteria change milk sugar (lactose) into lactic acid.
The acid gives yoghurt its characteristic sour flavour and also causes the curd to separate from the milk.Slide4
Yoghurt
The resulting yoghurt is thick and creamy.
When it is eaten, the bacteria colonise the intestinal tract where it is thought that they aid the process of digestion.Slide5
Nutrient Cycles
Decomposers break down dead plant and animal material into simpler chemicals, releasing essential nutrients into the soil.
These nutrients can then be used for plant growth.Slide6
The Nitrogen Cycle
Atmospheric nitrogen can be fixed by lightning or certain nitrogen fixing bacteria called
Rhizobium
.
These
Rhizobium
live in a
mutualistic
relationship in the root nodules of leguminous plants such as lupins, gorse and clover.
Also some free-living soil bacteria “fix” nitrogen.Slide7
The Nitrogen Cycle
Denitrifying bacteria break down nitrates to nitrogen, thus returning it to the reservoir in the air.
This is known as
Denitrification
.Slide8
The Nitrogen CycleSlide9
The Carbon CycleSlide10
Harmful BacteriaSlide11
Harmful Bacteria
Micro-organisms that cause disease are called Pathogens.
An infectious disease is one that can be passed on from person to person.Slide12
Catching Diseases
Contaminated food and water.
Salmonella spp, Clostridium botulinum
Through the air
Sneezing or coughing
Staphylococcus and Streptococcus
Skin contact
Particularly through broken skin
Staphylococcus sppSlide13
Catching Diseases
Contact with infected materials like towels and handkerchiefs
Contact with body fluids
E.g. blood, semen, salivaSlide14
Harmful Bacteria
Pathogenic bacteria make people feel sick by getting into the body and producing enzymes which break down body tissues or by excreting very strong poisons called toxins.Slide15
Bacterial Diseases
Diptheria
-
Corynebacterium
diphtheriae
Syphillis
-
Treponema
pallidum
Tetanus -
Clostridium
tetani
Typhoid -
Salmonella typhi
Tuberculosis -
Mycobacterium
tuberculosis
Sore throat -
Streptococcus
Salmonella –
Salmonella
spp Slide16
Bacterial Diseases
Meningitis -
Neisseria
meningitidis
Whooping cough -
Bordetella
pertussis
Cholera -
Vibrio
Cholerae
Gonorrhoea –
Neisseria Gonorrhoeae
Chlamydia –
Chlamydia
trachomatis
Plague -
Y
ersinia pestis
Pneumonia -
Streptococcus pneumoniaeSlide17
Harmful Bacteria
When people are sick, samples of their tissues, blood, or faeces may be taken and placed onto agar plates to see if the samples grow bacterial cultures.
This will determine if a particular type of bacteria is causing the illness and will help the doctor prescribe an antibiotic drug to kill the bacteria.