genotypic analysis
what is MLST
multilocus sequence typing
definition of bacterial growth
increase in cell #
first step
selection of site for septum formation using MinCDE proteins
2 doubling time factors
is generation time identical for all bacteria
what is principle of MLST
the allelic profile can be the identification marker
strains are clustered based upon total sequence identity between all the loci investigated
(species and subspecies level allelic profiles)
most common form of bacterial growth
binary fission: cell division where a cell grows to twice its original size and then divides to form two cells
how does MinCDE protein complex establish site of septum
fxn of minCDE is to inhibit polymerization of Z ring
assay: use flourescent scope to boserve CDE labeled with flouro dye
minCDE oscillates from 1 end to other and back, staying slightly longer at the ends. this builds a concentration gradient of the protein complex and the midpoint forms at the lowest concentration point
MLST procedure
1. isolate DNA
2. amplify DNA 6-7 genes
3. sequence DNA
4. compare and note alleles
5. build distance tree based on allelic profile = (sum of specific alleles for 6-7 genes)
5 steps in binary fission
1. DNA replication
2. cell elongation
3. septum formation
4. completion of septum with formation of distinct walls
5. cell separation
second step
assembly of Z ring
FtsZ protein fxn is to polymerize to form z ring structure and
constriction of cell after cell wall and membrane are complete at septum (step 5)
limitations of
MLST
choose 6-7 genes, but select genes may not evolve quickly enough to distinguish between strains
what is cytokinesis
the process in which the cytoplasm of a single cell is divided to form 2 daughter cells
third step
linkage of Z ring to cytoplasmic membrane
Zip A protein serves as anchor that attaches Z ring to cell membrane
what is species concept in microbiology
species are basic unit of taxonomy
asexual prokaryotes are same species if greater than/equal to 97% identity 16srRNA sequence. (95% = same genus, between 95 and 97 is same genus, diff species)
OR there is greater than/equal to 70% DNA-DNA hybridization
divisome definition
a contractile ring of polypeptides involved in bacterial cell division
fourth step
asembly of the cell wall synthesizing machinery (transpeptidase, autolysin, bactoprenol)
what is generation
all of the offspring that are at the same stage of descent from a common ancestor
5th step
constriction of cell and septum formation using FtsZ protein
what is generation or doubling time
the time required for a population of cells to double in number
fxn of FtsA protein
provides energy with ATPase
what is growth rate
# of doubling per hour
if FtsZ gene knocked out, what is seen under scope
mutant phenotype of bacteria, elongated cells, multiple chromosomes