3 - Bacterial nutrition and growth Flashcards
What is a macronutrient?
A nutrient that is required in significant amounts in the diet for all organisms
What is a micronutrient?
A nutrient that is only required in small amounts and are not required by all organisms
What is the difference between a complex media and a chemically defined media?
In a chemically defined media, you know the exact chemical composition of the media but in complex media you don’t
Give some mediums in which bacteria can be grown
On nutrient agar or in a liquid medium in a test tube or Erlenmeyer flask
What is a batch culture?
a closed-system microbial culture of fixed volume
What is binary fission?
When the cell replicates its genetic material, before splitting into two daughter cells.
What are the four main stages in binary fission?
DNA replication, cell elongation, septum formation and cell seperation
What is generation time?
time required for microbial cells to double in number
What are the four stages in a bacterial growth curve?
lag phase, log phase, stationary phase, death phase
What are viable but not cultivable bacteria?
Live bacteria that are unable to grow or divide, so can’t be cultured on conventional media but their existence can be proved by other methods
What is a total count of bacteria?
A non specific dye is used that stains all bacteria including live, viable, VBNC and dead bacteria
What is a viable count of bacteria?
A fluorescent dye is used that only dyes active cells (culturable, viable and VBNC)
What are some disadvantages of a total cell count?
It requires the use of a special counting slide and it does not differentiate between live and dead cells
What is a cultural count?
When a sample of bacteria is spread on an agar plate and left to grow and then the individual colonies are counted
What assumption is used in a cultural count?
That each culturable cell will grow and divide to yield one colony each
