Portage Microbiology Module 4 Exam Questions and Correct Answers Latest Update

Portage Microbiology Module 4 Exam Questions and Correct Answers Latest Update growth media - Answers nutrient-rich environment for isolating and culturing microorganisms - liquid or solid LB media (lysogeny broth) - Answers Most common nutrient Broth Known for ability to grow vast array of microbes Selective Media - Answers allows for growth of specific microbes, while restricting the growth of other microbes often used to grow human pathogens, or slower growing microbes. The selectivity allows for discounting foreign unwanted microbes Differential Media - Answers allows growth of several types of microbes and displays visible differences among those microbes ex. both gram(-) ecoli v salmonella as ecoli ferments lactose and growth w lactose shows red, where salmonella remains white/tan Enriched Media - Answers used to grow fastidious orgs - complex growth requirements that will cease to grow if not exact. Agar - Answers Polysaccharide derived from seaweed extract Solid & smooth allowing growth of colonies in isolated dots Covering entire plate = lawn more agar = more firm/ LB agar - Answers Lysogeny broth (LB), a nutritionally rich medium, is primarily used for the growth of bacteria; LBagar capable of wide variety of micro'o's. LB is non-selective and non-differential. Trypticase Soy Agar - Answers TSA or TSAYE - identical in color to LBagar Multipurpose media w high variety Non-selective & non-differential Blood Agar - Answers BAPlates, derivative of TSA combined with mammalian blood, at [5-10%] BAP are red BAP rich, non-selective & are differential RBC allow for growth of fastidious micro'o's IE strep Allows for detection of HEMOLYTIC ACTIVITY BAP Hemolysis - Answers Alpha h- greenish-browish color, due to incomplete/partial lysis of RBC Beta h- capacity a microbe has to completely lyse RBC Gamma h- lack of hemolytic activity, resulting colonies often white/tan growing on red background of agar plate Columbia CNA agar - Answers Red color, enriched selective and differential Used for isolation of gram(+) bact Media suppresses growth of Gram(-) bact = contains antimicrobials colistin and nalidixic acid Chocolate Agar - Answers CHOC, or CBA Chocolate Blood Agar enriched, non-selective, non-differential derivative of BAP Plate contains RBC that have been lysed via heat PRIOR to plating (differs BAP as those are lysed on the plate) The cooking of RBC gives dark choc color Lysed red cells release various growth factors into media required for cultivation of fastidious, pathogenic bact. Enriched examples: Haemophilus influenzae and Neisseria Meningitidis -- gram (-) MacConkey Agar (MAC) - Answers -*Selective* for *gram-negative bacteria*. Inhibits the grow of gram-positive bacteria and fungi w crystal violet and bile salts Lactose and the pH indicator neutral red [acid indic]. added to differentiate bw lactose fermenters (lac+ ; red) and non-fermenters (lac- ; white/tan colonies). Base color of plate changes as the microbes consume nutrients in agar. Agar can be yellow (pH>8) in surrounding area of non-fermenting microbe. Agar may turn pink/red in region around lac+ microbe (pH<6.8) Ecoli (gram- and lac+) used to demonstate formation of pink colonies. MacConkey used primarily to isolate intestinal pathogenic microbes ex being Enterobacteriaceae fam Salmonella and Shingella Sorbitol-MacConkey Agar SMAC - Answers Variant of MAC, formulated to detect specific path strin of Escherichia coli O157:H7 Under eneteric condition ecoli ferments lactose and sorbitol; however O157:H7 is unable to ferment sorbitol. Therefore SMAC plates contain sorbitol (instead of lac) to differentiate non-pathogenic strains of ecoli (red;acidic) from pathogenic (white;neutral) Eosin Methylene Blue Agar (EMB) - Answers Red in color, classified as selective and differential. EMB contains eosin&mb restricting the growth of gram-positive bacteria Micro'o's differentiated by ability to ferment the lactose present in the media