Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Biochemistry I
Transcript
Biochemistry I Labs 22,23,24 Exoenzymes – Lab 22 Bacteria make enzymes to digest macromolecules outside of the cell The smaller sub units of the enzymatic reaction are then able to be transported across the cell membrane This capacity is a characteristic of many Gram Positive bacteria Hydrolysis of starch Starch is composed of glucose molecules connected by glycosidic linkages When the glycosidic linkages are broken, individual sugar molecules are produced Linkages are broken in the presence of Water and the enzyme amylase Hydrolysis of Gelatin When water and an enzyme are added to a protein, the peptide bond in proteins are broken, producing individual amino acids Gelatin Hydrolysis in the tube Carbohydrates and Sugars Glycolysis Sugar fermentation- Carbohydrate metabolism Fermentation Phenol red – pH indicator is red in a neutral environment and yellow is the result of an acidic pH Gas – Gas is a by - product of the fermentation reaction - www.jlindquist.net/generalmicro /dfnewgfbpage.html Triple Sugar Iron a. metabolize lactose and/or sucrose b. conduct fermentation to produce acid c. produce gas during fermentation d. generate H2S. TSI Results Results BUTT COLOR/CO NDITION Cod e Lett er Interpretation Example RED R no fermentation, the bacterium is an obligate aerobe Example red butt Y some fermentation has occurred, acid Example has been produced, it is a facultative yellow anaerobe. butt GAS FORMED YG Seen as cracks in the agar, bubbles, or the entire slant may be pushed out of the tube. (Caution: these gassy fermenters may have bacteria close to the opening.) Example yellow butt with gas BLACK "+" H2S has been produced Example black butt YELLOW SLANT BUTT H2S COMMENTS Shigella dysenteriae R Y Salmonella typhimurium R YG + Causes food poisoning Salmonella typhi R Y + Causes typhoid fever Aerobacter aerogenes Y YG Similar to Klebsiella,but nonrespiratory Escherichia coli Y YG Most common of GIflora Citrobacter freundii Y YG + one of "paracolon" group (nonpathogenic) Proteus vulgaris Y YG + Causes GU infections, highly motile Klebsiella pneumoniae Y R or YG Pneumonia in debilitated patients (nosocomial) Pseudomonas aeruginosa R R GI inhabitant, causes wound, GU infections Alcaligenes faecalis R R GI inhabitant, opportunistic pathogen of GU Causes food infection dysentery
