PinPlasdagar mannaol, LAB PRACTICAL STUDY GUIDE The Lab Practical will be on Tue
ID: 135618 • Letter: P
Question
PinPlasdagar mannaol, LAB PRACTICAL STUDY GUIDE The Lab Practical will be on Tuesday July 24.2018 7PM. T The format will be fill in the blank and short answer 1. Define these terms: microbial cuilture medium microbial colony bactericidal antibiotic mixed versus pure culture stock culture eptic differential vs. selective medium sterilization disinfection otal magnification (be able to calculate this) 2. KNow THE FOLLOWING ?TEMS FOR EACH TYPE OF MEDIA LISTED BELOW. Know what each type of media is used to test . Know what a positive vs. negative reaction looks like, and what the result means in terms of enzymes . present (if applicable) and chemical reactions taking place. . (where applicable) For what kinds of organisms are they selective or differential? Le. macconkeys, mannitol salt agar (where applicable) Know what reagents must be added to the media in order to determine a positive or negative result. I have added an example below using starch agar. These are some of the questions I would ask myself What reagent is added to a starch plate to test for the reaction? What is the enzyme that breaks down starch or you could say what is this media testing for?, etc. . Example # 1: Starch agar can be used to determine if an organism produces the enzyme amylase, which hydrolyzes starch. A positive result for amylase production/starch hydrolysis would be depicted as a clearing around the organism (on the agar plate) after iodine (which is a reagent) is added to the plate. Example #2: Simmons citrate agar tests for the production of the enzyme citrase by microbes. A positive cesuft would be depicted in the agar turning blue (the agar was originally green and due to a pH change, the agar will turn blue if citrase is produced). Example #3: MacConkey's agar will select for gram negative organisms (ie. enterics, coliform bacteria). This means NO gram positive organisms will grow on a MAC plate. MAC plates can also tel us if the gram-negative organisms that grew are LACTOSE fermenters (non-pathogenic organisms) or Lactose non-fermenters (pathogenic organisms). If you see red-pinkish colonies then that organism is a lactose fermenter/non-pathogenic organism (like E. coll) . Skim Milk Agar . SIM tube . Durham tube (know the purpose of this tube) .Blood agar .Simmons citrate agar . Thioglycollate: be able to tell whether an organism is an obligate aerobe, obligate anaerobe, or facultative anaerobe based on where it is growing in the tube. Know what these terms mean. Mannitol salt agar MacConkey's agar Nitrate broth Starch agar . Gelatin Sugar fermentation tubes (Do not confuse these with the triple sugar iron tubes)Explanation / Answer
Ans 1...
A...microbial culture...it is a method by which microbial organism are multilied.a culture medium is provided to them in optimum condition in which they reproduce and multiply
B...Medium....It is the medium which is provided to the organism for its cultuere or growth.it may be solid liquid or semi solid.it has nutrients required for growth of cell.
C.. microbial colony...colony is like a clone of bacteria.when a single mother cell originates into multiple organism of same type giving rise to a visible mass it's celled colony
D...mixed vs pure culture.
Mixed culture has more than one species of micro organism
Pure culture has only one type of micro organism . actually pure culture is derived from mixed culture.
Ans 2...a...skim milk agar...it is used for cultivation and enumertaion of the micro organism encountered in dairy industry.its ingredients are SM powder,tryptone,yeast extract dextrose,Agar .
It is used for demonstration of caogulation and proteolysis of cascein.
Addition of SM powder to any nutrient rich medium creates favourable condition for growth of organism which are encountered in milk.
B....SIM tube...SIM stands for Sulphide indonale motility
As the name suggest it test the ability of an organism to
Reduce sulphur
Pruduce indole
Motility in agar
It is used to differentiate diffrent members of enterobactericie family of bacteria
It is a semi solid medium containing protein ,iron ,sulphur in the form of sodium thiosulfate and small amount of agar.
C....Durham Tube...Durham Tube are used to detect the production of gas by an organism .they are small.test tube which are filled with solution in which we want to grow the microorganisms and then we check by bubbles at the top that wheter there is gas production or not
D...Blood agar...blood agar is a type of enriched media.these are prepared to meet the nutritional requirements of fastidious organism like streptococcus isolation by addition of blood.we can also see pattern of haemolysis in blood agar