17HOW BACTERIA OBTAIN ENERGY Like all organisms, bacteria need a constant supply of energy to perform all their life activities. This energy is supplied by the process of respiration and fermentation.Respiration is the process that involves oxygen and breaks down food molecules to release energy.Fermentation, on the other hand, enables cells to carry out energy production without oxygen.
18BACTERIAL RESPIRATION Aerobic bacteria (Obligate aerobes)They require free oxygen to carry out cellular respirationObligate anaerobesThey do not require free oxygen for cellular respiration.Obligate anaerobesThey cannot live in the presence of O2Facultative anaerobesThey can live in either the presence or absence of O2
19HOW BACTERIA OBTAIN ENERGY AUTOTROPHIC BACTERIAPhotosynthetic bacteriaChemosynthetic bacteriaBacteria that synthesize food by the using the energy obtained from inorganic compounds (such as hydrogen sulfide, nitrites, sulfur and iron) rather than from light are called chemotrophic autotrophs.Ex: Nitrosomonas is an example of a chemotrophic autotroph that uses ammonia and oxygen to produce energy.Bacteria that trap the energy of sunlight in a manner similar to green plants are called phototrophic autotrophs.Ex: Cyanobacteria and some photosynthetic Eubacteria.
20HOW BACTERIA OBTAIN ENERGY HETEROTROPHIC BACTERIASaprobesThey feed on the remains of dead plants and animals and ordinarily do not cause disease.They release digestive enzymes into the organic matter. The enzymes break down the large food molecules into smaller ones, which are absorbed by bacterial cells.ParasitesThey live in or on living organisms, absorbing nutrients directly from their hosts.Parasites can cause disease.
23Growth Curve of a Bacterial Culture Lag phase: At the beginning there are not much individuals in the population and growth is slow. (adaptation time for the environment)Exponential phase: Bacteria are dividing rapidly.Stationary phase: The reproductive rate equals death rate.Death phase: The bacteria are dying off faster than they are reproducing.
24ENDOSPOREEndospores form when conditions for bacterial growth are unfavorable. In this state bacteria can survive for years and withstand extreme conditions like freezing, boiling, or dry environments. Once conditions become favorable, endospore becomes active.
25PROKARYOTIC KINGDOMS Archaebacteria Eubacteria They live in extremely hostile environments – volcanic hot springs, salt lakes and seas, and black organic mud at the bottom of marshes and swamps. Their cell walls lack the carbohydrate peptidoglycan.Most bacteria are members of this kingdom. Their cell walls have peptidoglycan. Disease-causing bacteria and the cyanobacteria are in this group.
28Archaebacteria In very salty water: example: the Great Salt Lake Strongly alkaline or acidic water: example: Pools in Yellowstone National ParkIn very hot water: example: pools in Yellowstone National ParkNear deep sea vents where hot water accompanies volcanic eruptionsIn no oxygen (anoxic) environments: example: lake bottoms.
30Figure . Methanococcus jannischiiwas originally isolated from a sample taken from a "white smoker" chimney at an oceanic depth of 2,600 meters on the East Pacific Rise. It can be grown in a mineral medium containing only H2 and CO2 as sources of energy and carbon for growth within a temperature range of 50 to 86 degrees. Cells are irregular cocci that are motile due to two bundles of polar flagella inserted near the same cellular pole.
32IMPORTANCE OF BACTERIA Bacteria are used in the production of a wide variety of foods and beverages, such as cheese, yogurt, buttermilk, and sourcream.Some bacteria are used to make pickles and sauerkraut,and some make vinegar from wine.Some bacteria have been usefulin synthesizing drugs and chemicals through techniques of genetic engineering.
33IMPORTANCE OF BACTERIA Some bacteria remove waste products and poisons from water.Some bacteria can help to mine minerals from the ground.Bacteria are also used in industry. One type of bacteria can digest petroleum, which makes them helpful in cleaning up small oil spills.Sewage treatmentOil spill treatment.
34IMPORTANCE OF BACTERIA Our intestines are inhabited by large numbers of bacteria, including E. coli. In the intestines, the bacteria are provided with a warm safe home, plenty of food, and free transportation. We, in turn, get help in digesting our food. These bacteria also make a number of vitamins that we cannot produce on our own. So both we and the bacteria benefit from this symbiotic relationship.Animals such as cattle are also dependent upon the symbiotic relationship they have with the bacteria in their intestines.Bacteria living in the digestive systems of such animals can make these enzymes, thus allowing the animals to digest their food properly.
36An electron micrograph shows bacteria at work breaking down food in the human digestive tract. A colored transmission electron micrograph of Streptococcus bacteria attached to a human tonsil cell.
37Heterocysts are special cells found in some filamentous genera; these specialised cells contain the "nitrogen-fixing" enzyme complexThe photograph above shows Rhizobium sp. in the root nodules of a bean plant.