Microbial cellsDr Muhammad Imran

Who was 1st , 2nd and 3rd…. Why

• Archaea

• Eubacteria

• Eukaryotes

Established industrial microbes

Check table 4.1 of the book to look for molecules/compounds these organisms can be used

Gram negative

Oxidizing environment

Structure of peptidoglycan

• Alternating residues of β-(1,4) linked N-acetylglucosamine and N-acetylmuramic acid + short peptide

E. Coli• Cycle is about 20 min under ideal condition• 0.3-1.0 um wide and 1-3 um long• 7-8 nm outer membrane…non-selective and

selective porins….600-700 Da……5000Da• Pilli for attachement• Peptidoglycan is 2-3 nm thick and 1-3 layers• Periplasmic space…12-15 nm filled with• alkaline phosphatase, nucleases and proteases,

also penicillinase

Innermembrane and cytoplasm• Transporters and exporters, ion channels

• Lactose permease etc

• Reducing environment pH 7.6-7.8

• 4600 kbp DNA circular in nucleoid region

• Plasmids…F, R and col plamids• Polysaccharide glycogen

Gram positive

Baccillus subtilisB. subtilis has become widely used for the production of industrial enzymes, particularly amylases and proteases.

B. subtilis has also proved very useful for the manufacture of fine chemicals, especially nucleosides, vitamins and aminoacids, and some strains are used in crop protectionagainst fungal pathogens.

This bacterium is also a valuable cloning host for the production of heterologous proteins.

Features

• 4188 kbp genome• All are catalase +ve• 0.5-2.5 um wide and 1.2-10 um long• Few are pathogenic Bacillus anthracis• Baccillus are generally safe otherwise

20–50 nm thick and simply composed of 20–25 layers of peptidoglycan, associated with some lipid, protein and teichoic acid

Yeast a unicellular Fungi (S. cerevisiae)

Benefits

• Phosphorylation

• Glycosylation

• Secretion

• Simple and fast growth cycle like E. coli

• Well established physiology and genetics

Nutritional needs

• Reduced carbon source…..acetate

• Ammonium salt

• Minerals

• Viatmins; pantothenic acid and thiamine