Growth - increase in size of the population
as well as of individual cells
Binary fission, a form of asexual reproduction
in which cells replicates their chromosomal DNA
as they increases in size, form a septum between
the chromosome copies, then separate (divides into
two cells of roughly equal size
Generation time is the length of time required
for a microbial population to double
Generation time = time/number
of generations ... G = t/n
G typically varies from 5 min to 12 h in actively growing
cultures
Number of cells present at a given time depends on the number
present at the beginning of the culture (N0) and the
number of generations (n) as follows: N = N0 x 2n
Measuring microbial growth by increases
in:
mass - a broth culture of cells can
be grown, then dehydrated and the dry weight
of the cells determined by weighing them
number of cells in a broth culture,
three approaches can be taken:
direct count - cells are counted
using a Neubauer chamber (which allows
one to count the number of cells in
a known volume of fluid)
viable count - cells are diluted
and plated on a suitable culture medium,
then the number of resulting colonies
counted
total count - the number of
cells can be estimated by determining
the turbidity of the culture using a
colorimeter