PSYCH207 Lecture Notes - Lecture 6: Microorganism, Pasteurization, Glutaraldehyde
30 Nov 2016
School
Department
Course
Professor
Fundamentals of Microbiology (Biology 240)
Course notes
Dr. Laura A. Hug
Topic 6: Cultivation and Control
Learning Objectives: Following this topic, you should have an understanding of how
bacteria are cultured and the difference between defined and complex growth media.
You should also understand methods of eliminating viruses preventing their growth.
Before we learn about cell growth, it is necessary to briefly consider metabolism and
nutrition. For cells to grow, they must convert chemical compounds into cellular matter.
Nutrients from outside the cell are transformed into new cell material. This process is
called anabolism or biosynthesis. The cell requires energy for biosynthesis, as well as
for other processes (e.g. transport, motility). Energy is often derived from the oxidation
of chemical compounds, in a process called catabolism.
All cells require macronutrients to build macromolecules. These include carbon,
nitrogen, phosphorus, sulfur and oxygen. Some may also need certain micronutrients
Nutrients are incorporated into the cell through the process of assimilation.
Different types of microorganisms assimilate nutrients from different sources.
Autotrophs acquire carbon from inorganic sources, while heterotrophs acquire it from
organic sources.
Microbes also need an energy source. Phototrophs capture energy from light, while
chemotrophs capture it through oxidizing various compounds.
Electrons are required by microbes for the completion biochemical reactions.
Organotrophs and lithotrophs gain electrons from organic and inorganic molecules,
respectively.
See Figure 6.1
Different factors can affect microbial growth:
Nutrient Type
Nutrient Concentration (Figure 6.3)
Presence of Oxygen
pH Level (Figure 6.5)
Osmotic Pressure and Water Availability
Temperature (Figure 6.7)
Culture Media
Defined: the exact chemical composition is known -- purified ingredients are
used
Complex: the exact chemical composition is not known
Document Summary
Learning objectives: following this topic, you should have an understanding of how bacteria are cultured and the difference between defined and complex growth media. You should also understand methods of eliminating viruses preventing their growth. Before we learn about cell growth, it is necessary to briefly consider metabolism and nutrition. For cells to grow, they must convert chemical compounds into cellular matter. Nutrients from outside the cell are transformed into new cell material. The cell requires energy for biosynthesis, as well as for other processes (e. g. transport, motility). Energy is often derived from the oxidation of chemical compounds, in a process called catabolism. These include carbon, nitrogen, phosphorus, sulfur and oxygen. Nutrients are incorporated into the cell through the process of assimilation. Different types of microorganisms assimilate nutrients from different sources. Autotrophs acquire carbon from inorganic sources, while heterotrophs acquire it from organic sources. Phototrophs capture energy from light, while chemotrophs capture it through oxidizing various compounds.
