RHEA JANE GAMIT
MARK JOY GABRINO
REYZON JAN CARLOS
In chemistry, pH is a measure of the acidity or basicity of an aqueous
solution. Solutions with a pH less than 7 are said to be acidic and solutions
with a pH greater than 7 are basic or alkaline. Pure water has a pH very
close to 7.
pH measurements are important
in medicine, biology, chemistry, agriculture, forestry, food
science, environmental science ,oceanography, civil
engineering, chemical engineering, nutrition, water treatment & water
purification, and many other applications.
Most bacteria grow best around
neutral pH values (6.5 - 7.0)
Some bacteria thrive in very acid
conditions and some can even tolerate
a pH as low as 1.0. Such acid loving
microbes are called acidophiles. Even
though they can live in very acid
environments, their internal pH is
much closer to neutral values.
Human blood has a normal pH of
about 7.41. The pH of urine has a wider
range. Normal ranges for urine pH are
from 4.5 to 8.
Most spoilage bacteria grow best near neutral pH
Acidity and alkalinity levels can also influence microbe growth. Most microbes
grow at a more neutral pH range between 6.5 and 7.5. Some microbes can grow
outside that pH range.
Yeast and moulds have much greater tolerance to acidic (lower) pH
The optimum pH range is usually quite narrow so that small changes in the pH can
have large effects on the growth rate of the organism
Thiobacillus acidophilus is an example
of a thermo-acidophile, meaning a
bacterium that likes both extremely hot
and extremely acidic environments. It
is found in acidic geyser basins in
Yellowstone National Park, as well as
Acetobacter aceti has modified its
proteins so that they aren’t harmed by
acidic environments. A study in applied
environmental microbiology found more
than 50 specialized proteins that had
evolved to help the bacterium deal with
Helicobacter pylori is the most
common chronic bacterial infection in
humans. Although most people who
have the infection have no symptoms or
problems with it, it can cause chronic
gastritis, most peptic ulcers, and gastric
adenocarcinoma and gastric lymphoma.
any organism that lives and thrives in an
alkaline environment, such as a soda lake
Vibrio cholerae is a Gram-negative,
comma-shaped bacterium. Some strains
of V. cholerae cause the
disease cholera. V. cholerae is
a facultative anaerobic organism and
has a flagellum one cell pole.
microalgae are microscopic algae,
in freshwater and marine systems. They
are unicellular species which exist
individually, or in chains or groups.
any organism that thrives in a relatively
Natronomonas pharaonis was isolated
from soda lakes where it has to cope
with two extreme conditions, high salt
concentrations and an alkaline pH of
11. It grows optimally in 3.5 M NaCl
and at pH 8.5
any organism that lives and thrives in an alkaline
environment, such as a soda lake; a form of
Oxygen is a natural element essential to all human life on Earth, as well as the lives
of other air-breathing mammals. But there are some living things on Earth, including
some organisms, that consider oxygen to be the enemy. While some forms of bacteria
need some oxygen to grow, others cannot grow if oxygen is present.
AEROBIC -aerobic organism or aerobe is an organism that can survive and grow
in an oxygenated environment.
ANAEROBIC - anaerobic organism or anaerobe is any organism that does not
require oxygen for growth. It may react negatively or even die if oxygen is present.
obligate aerobe- is an organism
that requires oxygen to grow.
facultative anaerobe- is
an organism that makes ATP
by aerobic respiration if oxygen is
present, but is capable of switching
to fermentation or anaerobic
respiration if oxygen is absent.
microaerophile - is
a microorganism that
requires oxygen to survive, but
requires environments containing
lower levels of oxygen than are
present in the atmosphere.
are microorganisms that are killed
by normal atmospheric
concentrations of oxygen
: Aerotolerant organisms-
considered an anaerobe since it does
not use oxygen to oxidize molecules
during energy production.