LECTURES IN MICROBIOLOGY. Microbial Nutrition and Growth. Sofronio Agustin Professor. LESSON 5. Lesson 5 Topics. Microbial Nutrition Environmental Factors Microbial Growth. Microbial Nutrition. Based on intake: (a) Macronutrients (CHONPS) (b) Micronutrients (trace elements)
(a) Macronutrients (CHONPS) (b) Micronutrients (trace elements)
(a) Organicnutrients- contain carbon
(b) Inorganicnutrients- simple atom or molecule without carbon
Bacteria are composed of different elements and molecules, with water (70%) and proteins (15%) being the most abundant.
(e.g. sugar, proteins and lipids)
Summary of different nutritional categories of microbes based energy and carbon sources
A cube of sugar will diffuse from a concentrated area into a more dilute region, until an equilibrium is reached.
Facilitated Diffusion: The Process
Fate of cells in different osmotic conditions - isotonic, hypotonic, and hypertonic solutions
(Ex. Permeases and protein pumps transport sugars, amino acids, organic acids, phosphates and metal ions)
Example of permease, group translocation and endocytosis
20 to 40 °C
(2) Carbon dioxide
All are toxic byproducts of metabolism neutralized by enzymes SOD (superoxide dismutase), peroxidase and catalase.
SOD, peroxidase and catalase
Anaerobic culture techniques: (a) anaerobic chamber, (b) anaerobic jar
Thioglycollate broth is used to demonstrate aerotolerance of bacteria.
Aerobes, facultative anaerobes, and obligate anaerobes can be detected using this medium.
Ex: Campylobacter jejuni
Ex: S. pneumoniae
withstands hypertonic conditions
Ex. Halobacterium sp. (Archaea)
Ex. Staphylococcus aureus
Influence microorganisms have on other microbes:
Organisms that live together in close nutritional relationships
as a form of commensalism
Rod-shaped bacteria undergoing binary fission
Growth curve in a bacterial culture.
(b) Viable plate count
(c) Membrane filtration
(d) Most probable number
(b) Metabolic assay
(c) Dry weight determinations
Serially diluted samples are plated out and bacterial count expressed in CFU/ml.
Membrane filtration and coliform counts.
Turbidimetric measurements as indicators of bacterial growth.
The greater the turbidity the larger the population density.