Bacteria: The good, bad and the ugly!
Bacteria are unicellular microorganisms and also prokaryotes (organisms in the kingdom
monera who have no distinct nucleus, no membrane-bound organelles, and DNA that
usually forms a single, circular chromosome). They come in different shapes such as
spheres, rods, and spirals. Some bacteria can move through the use of flagella (a small,
slender projection from the cell body that can be used in a whip-like fashion to propel the
cell body). Bacteria reproduce through binary fission, a type of asexual reproduction (a
form of reproduction that only involves one parent, and does not involve meiosis or
fertilization) where one cell divides into two cells of equal size. Under ideal conditions,
bacteria can reproduce extremely fast, and an entire population of bacteria can double in
9.8 minutes! Some bacteria can withstand extreme conditions; these are called
extremophiles and live in places with extreme pressure or even temperature such as the
bottom of the ocean or within a volcano. Bacteria can form something called an
endospore (a tough, dormant, non-reproductive structure formed by bacteria to withstand
environmental stress). These endospores can withstand radiation, extreme heat and
pressure, as well as chemical disinfectants and can remain able to live and grow for
millions of years! Endospores have even been released into space and survived! Bacteria
are an ancient lineage of organism that dates back 3.5 billion years. As you have already
heard, bacteria can be both extremely harmful and extremely helpful.
The Bad and the Ugly!
Bacteria can form a parasitic relationship (a relationship in which one organism benefits
while the other is harmed) with other organisms. This makes bacteria a pathogen (causes
disease or illness to its host). Bacteria can be a major cause of human death and are
responsible for diseases such as tetanus, syphilis, pneumonia, meningitis, food-borne
illness, leprosy, and even tuberculosis. Tuberculosis alone kills 2 million people a year!
Most of you have probably heard of the Bubonic Plague that wiped out ¼ of Europe’s
total population, making it the largest death toll from any non-viral break out of
infectious disease! Rats infected with bacteria caused the Bubonic plague. When fleas bit
the rats, the bacteria multiplied and plugged the fleas’ stomach causing them to starve.
The fleas then hungrily attack whatever they could, including humans, passing the
bacteria on to us! Mortality was as high as 95% in those infected and many times people
who were infected died the same day.
The plaque in your teeth is caused by bacteria and can damage your teeth if not
regularly removed through dentist visits and brushing. Bacterial diseases can harm
agriculture and even wipe out entire crops raising the prices and hurting farmers and
people dependent on that crop for their livelihood or food. Bacteria can infect farm
animals with salmonella and anthrax. Sometimes the helpful bacteria that usually live
inside the human body can become harmful if a person’s immunity is lowered or the
bacteria somehow move to an area of the body where they don’t belong. For example, the
bacteria that usually live harmlessly in our noses, if moved somewhere else in the body
can cause meningitis, pneumonia, and even sepsis, a condition where the body goes into
shock and the person can die. Anthrax along with other bacteria could be used in
biological warfare. Remember the endospores you read about earlier, well anthrax forms
these endospores and they can lethal if inhaled. Antiseptics (something that can sterilize
the skin before puncturing it) and antibiotics (used to treat bacterial infections) have
saved millions of lives. The overuse of antibiotics and antibacterial soaps is causing
bacteria to evolve resistant strains that make treating bacterial infections much more
difficult.
The Good Bacteria
Bacteria are extremely important. Remember without bacteria dead living matter and
wastes would just pile up cluttering our earth, nutrients wouldn’t be recycled and then
other organisms couldn’t use them, the food web would collapse and smaller organisms
such as zooplankton (microscopic, single-celled animal-like floating organisms) would
starve. But besides all of this, bacteria are helpful in so many other ways! Do you like to
eat pickles, yoghurt, cheese, bread or soy sauce? All of these require a fermentation (a
type of respiration that does not require oxygen, it is anaerobic) process, one similar to
that used to make beer and wine, and this process of fermentation requires bacteria! This
same process of fermentation can be used to make a more environmentally friendly fuel,
ethanol, from cornhusks. American farms are capable of producing plenty of corn so this
new fuel source could help relieve the oil crisis. Some cars are already being made that
run on 10% ethanol in order to make them more fuel-efficient.
Have you heard of the Exxon Valdez oil spill that occurred in Prince William
Sound off of Alaska that occurred in 1989? The oil tanker hit an offshore reef and lost 11
million gallons of oil into the water!!! This spill was very bad for the environment as
Prince William Sound was habitat to seals, sea otters, salmon, sea birds, and many other
organisms. Bacteria were used in a process called bioremediation (this process uses
microorganisms and their enzymes to turn an environment affected by contaminants
(such as oil) back to its original condition). Bacteria are capable of breaking down
molecules made up of hydrogen and carbon (hydrocarbons) that make up the oil. In some
areas clean up crews added nutrients to the water to encourage the growth of naturally
occurring bacteria to degrade the oil in the environment. Bacteria are also used in
bioremediation of toxic and chemical wastes.
Bacteria are important in bioengineering and biotechnology because their DNA is
used as the plasmid (small, circular DNA) in order to transfer genes from one organism
to another. This process is important to make necessary proteins such as growth hormone
for people with stunted growth or insulin for people with diabetes. Bacteria can also be
used in place of pesticides in agriculture and are considered environmentally friendly
since they have little or no effect on humans or wildlife. Bacteria are necessary for the
very important processes of nutrient cycling. Plants need the nutrient nitrogen to live, but
they can only use it in a specific form. Many plants cannot live without the bacteria that
live on their roots and fix nitrogen so that it is in an easily absorbable form. Without these
nitrogen-fixing bacteria in the soil and in the ocean (where they perform a similar
function for marine plant life) plants would die!
Now that you know you can’t live without bacteria, take this quiz to show your
appreciations!
Quick Bacteria Quiz
1. Bacteria are a type of unicellular microorganism called _______________.
YESPOORAKTR
2. Dormant structures bacteria can form that are able to withstand extreme
environmental stress and still live are called…
a. Extremeophiles
b. Anthrax
c. Endospores
d. Conjugation
3. Which of these products are capable of killing bacteria and are leading to the
evolution of resistant strains of bacteria that could cause treating bacterial
infections much more difficult in the future?
a. Antibiotics
b. Antibacterial soap
c. Antiseptic
d. All of the above
4. Bacteria were used to clean up Prince William Sound in a process called
______________________where the microorganisms broke up the
__________________ in the oil that was spilled by the Exxon Valdez oil tanker.
5. Which infectious disease below was not caused by a bacterial pathogen?
a. Tuberculosis
b. Hepatitis
c. Bubonic Plague
d. Meningitis
e. Anthrax