Lecture 7: Bacterial Energetics and Nutrition

Microbial Nutrition

bacterial growth is dependent on an environment that is abundant in nutrients; nutrients allow them to divide faster

- poor nutrient availability can result in cell death

- micro and macronutrients

Micronutrients

trace elements

- Co, Cu, Mn, Zn

Macronutrients

major elements

- C, O, H, N, P, S

- necessary ions: Mg, Ca, Fe, K

Growth Factors

things required in small amounts for cell growth that they cannot make on their own

- vitamins; generally function as coenzymes, amino acids, purines, pyrimidines

Culture Media

supply of nutritional requirements for proper cultivation of microbes

- liquid, semi-solid, solid

- complex, defined/synthetic, selective, differential

Liquid Media

allows for continuous culture as microbes are in favorable conditions

- referred to as a broth

Semi-Solid Media

allows for motile bacteria to be able to move

- ex. motility indole ornithine (MIO); differential

Solid Media

allows for differentiation between colonies

- allows us to purify a culture; contain one microbe

- referred to as plates

Colony Morphology

physical appearance of bacteria grown on a solid media

- each colony is assumed to be the result of a single bacteria multiplying on the surface; different colored colonies are different bacteria

Complex Medium

generally unidentified chemicals or complex

- ex. nutrient broth, nutrient agar

- usually an extract of nutrients from an organism

Defined/Synthetic Medium

the chemical composition is known

- carbon source is known

Selective Medium

contains ingredients to inhibit the growth of a certain species and allows for the growth of others

- ex. MSA; selects for staphylococci

Differential Medium

contains ingredients that allow us to identify a specific chemical process

- ex. MSA; has a pH indicator

Microbial Cell Cycle Stages

B period, C period, D period

- known as Binary Fission

B Period

increases in size and mass and generates ATP

- building stage

- cell uses ATP to generate cell wall, amino acids, nucleotides, and lipids

C Period

chromosome replicates

D Period

cell walls divide

Mre B

shape determinign factor in prokaryotes