5. •This is the minimum nutritional requirements
for growth and multiplication of bacteria .
•This includes water which varies from 75 to 90
percent of the total weight , a source of carbon,
a source of nitrogen and some inorganic salts.
6. The microbial cell is made up of several elements
such as carbon, oxygen, hydrogen, nitrogen,
sulfur, phosphorus, potassium, calcium,
magnesium, and iron.
These are also known as Macro elements or
Macronutrients because these elements are
required in high amounts by the microbes
.
7. MACRONUTRIENTS
Nitrogen is needed for the synthesis of such molecules as amino
acids, DNA, RNA and ATP . Depending on the organism, nitrogen,
nitrates, ammonia, or organic nitrogen compounds may be used as a
nitrogen source.
Sulfur is needed to synthesizes sulfur-containing amino acids and
certain vitamins. Depending on the organism, sulfates, hydrogen
sulfide, or sulfur-containing amino acids may be used as a sulfur
source.
Phosphorus is needed to synthesize phospholipids , DNA, RNA,
and ATP . Phosphate ions are the primary source of phosphorus.
8. Potassium, magnesium, and calcium These are required for
certain enzymes to function as well as additional functions.
Iron is required by microbes for the function of their
cytochromes and enzymes. However, little free iron is available
in environments, due to its insolubility.
Many bacteria have evolved siderophores, organic molecules
that chelate or bind ferric iron with high affinity
9.
10. Bacteria show a great deal of variation in their
requirements for gaseous oxygen. Most can be placed in one
of the following groups:
•Obligate aerobes are organisms that grow only in the
presence of oxygen. They obtain their energy through
aerobic respiration .
• Microaerophils are organisms that require a low
concentration of oxygen (2% to 10%) for growth. They
obtain their energy through aerobic respiration .
OXYGEN
11. • Obligate anaerobes are organisms that grow only in the absence
of oxygen. They obtain their energy through anaerobic respiration
or fermentation .
• Aerotolerant anaerobes, cannot use oxygen to transform energy
but can grow in its presence. They obtain energy only by
fermentation also called obligate fermenters.
• Facultative anaerobes grow with or without oxygen. They obtain
their energy through aerobic respiration if oxygen is present, but
use fermentation or anaerobic respiration if it is absent. Most
bacteria are facultative anaerobes.
12. Trace elements are elements required in very
minute amounts, and like potassium,
magnesium, calcium, and iron, they usually
function as cofactors in enzyme reactions.
They include sodium, zinc, copper,
molybdenum, manganese, and cobalt ions.
TRACE ELEMENTS OR MICRONUTRIENTS
13. •They are involved in biological functions in several
ways.
•For example, zinc (Zn2+) is present at the active site
of several enzymes.
•Manganese (Mn2+) involved in catalysis of the
transfer of phosphate group.
•Mo (Mo2+) is essential for nitrogen fixation.
14. ELECTRONS
They are required, they have three main functions,
which are
• The movement of electrons through electron
transport chains.
• During other oxidation-reduction reactions they
provide energy for use in cellular work.
• Electrons also are needed to reduce molecules
during biosynthesis.
15. GROWTH FACTOR
•Some organic compounds are important for microbial
growth but cannot be synthesized by few microbes,
they are known as growth factors.
•Amino acids (building blocks of protein),
•Purines and Pyrimidines (building blocks of nucleic
acid)
•Vitamins (enzyme cofactors)
16. NUTRITIONAL REQUIREMENTS
Organisms having complex nutritional requirements and
they can be grouped according to their
•Energy Source
•Carbon Source
Energy source
1. Phototrophs use radiant energy (light) as their primary
energy source.
2. Chemotrophs use the oxidation and reduction of
chemical compounds as their primary energy source.
17. Carbon source
Autotrophs : require only carbon dioxide as a
carbon source. An autotroph can synthesize organic
molecules from inorganic nutrients.
Heterotrophs : require organic forms of carbon. A
Heterotroph cannot synthesize organic molecules
from inorganic nutrients.
18. Combining their nutritional patterns, all organisms in
nature can be placed into one of four separate groups:
based on their Carbon and Energy Source.
•Photoautotrophs,
• Photoheterotrophs
• Chemoautotrophs
•Chemoheterotrophs
Based on their Energy, Carbon and Electron source they
can be grouped into the following
20. UPTAKE OF NUTRIENTS
In order to support its’ activities, a cell must bring in
nutrients from the external environment across the cell
membrane. In microbes several different transport
mechanisms exist.
Passive Diffusion or Simple diffusion
•Allows for the passage across the cell membrane of simple
molecules and gases, such as CO2, O2, and H2O. In this case,
there is higher concentration of the substance outside of
the cell than there is inside the cell.
21. Facilitated Diffusion
• Here the concentration of the substance is higher outside the cell,
but differs with the use of carrier proteins (sometimes called
permeases). These proteins are embedded within the cell
membrane and provide a channel or pore across the membrane
barrier, allowing for the passage of larger molecules.
Active Transport
• Many types of nutrient uptake require that a cell be able to
transport substances against a concentration gradient . A
metabolic energy is utilized for the transport of the substance
through carrier proteins embedded in the membrane. This is
known as active transport.
22.
23. •Primary Active
Transport
This involves the use of
chemical energy, such
as ATP, to drive the
transport. One example
is the ABC system,
which utilizes ATP-
Binding Cassette
transporters.
24. Secondary active transport
utilizes energy from a proton motive force (PMF). A PMF is an ion
gradient that develops when the cell transports electrons during
energy-conserving processes. Positively charged protons accumulate
along the outside of the negatively charged cell.
There are three different types of transport events for simple transport:
uniport, symport, and antiport
Uniporters transport a single substance across the membrane, either
in or out.
Symporters transport two substances across the membrane at the
same time, typically a proton paired with another molecule.
Antiporters transport two substances across the membrane as well,
but in opposite directions. As one substance enters the cell, the other
substance is transported out.
26. Group Translocation
•This is a distinct type of active transport, using energy
from an energy-rich organic compound that is not ATP.
•Group translocation also differs from both simple transport
and ABC transporters in that the substance being
transported is chemically modified in the process
27.
28. • Microbial Nutrition is the minimum nutritional requirements for growth and
multiplication of bacteria
• Bacteria show a great deal of variation in their requirements for gaseous oxygen. Most
can be placed in one of the following groups: obligate aerobes, microaerophils, obligate
anaerobes, aerotolerant anaerobes, or facultative anaerobes.
• Bacteria can be grouped according to their energy source as phototrophs or chemotrophs.
• Bacteria can be grouped according to their carbon source as autotrophs or heterotrophs.
• Combining their nutritional patterns, all organisms in nature can be placed into one of
four separate groups: photoautotrophs, photoheterotrophs, chemoautotrophs, and
chemoheterotrophs.
• Bacteria also need a nitrogen source, various minerals, and water for growth.
• Organisms having complex nutritional requirements and needing many growth factors
are said to be fastidious
SUMMARY
29. STUDY QUESTIONS
• What are the different terms associated with microbial
nutritional types?
• How can these terms be combined to define the nutritional types
of microbes in terms of their sources of carbon, electrons, and
energy?
• What are macroelements and why are they important to a cell?
• What are growth factors and what is their significance to a cell?
• Why is iron uptake important for a cell? What is used to
accomplish this?
30. What is the importance of nutrient uptake for a cell?
What are the common features of nutrient uptake by bacteria?
What is transported into a bacteria cell by passive diffusion and how
does this affect a bacterial cell?
Explain diffusion (passive and facilitated) and active transport.
What are the 3 types of active transport?
Be able to diagram each processes.
What is required for each of these processes?
How are they similar, how are they different?
