genotypic analysis
bacterial growth
bacterial growth cont.


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

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