Streptococcus lactis atlas pages 159 161 the genus

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Streptococcus lactis (Atlas Pages 159-161) The Genus Streptococcus (“Strep”) contains Gram Positive Aerotolerant Anaerobic Cocci (G= berries) arranged in Chains. The Colonies are round and White and very, very small. The Genus can be separated into five (5) Groups: • The Viridans Group (L= green) includes Streptococci that produce Alpha Hemolysins (G= blood breakers) , which are Exotoxins that lyse Red Blood Cells and partially break-down Hemoglobin. The partial Breakdown of Hemoglobin produces a green Color around Colonies grown on Blood Agar, hence the “Viridans” Name. Streptococcus mutans , the causative Agent of Cavities, is a Example. • The Enterococci (L= gut) includes Streptococci that inhabit the Human Intestine. Some produce Alpha Hemolysins. Streptococcus faecalis is an Example. • The Pneumococci are Streptococci that produce Alpha Hemolysins but that do not form Chains. Approximately 80% of Pneumonia Cases are caused by Streptococcus pneumoniae . • The Pyogenic Group (G= pus producers) are nasty little Beasts that produce Beta Hemolysins (Exotoxins that lyse Red Blood Cells and completely break-down Hemoglobin). The complete Breakdown of Hemoglobin produces a Zone of Clearing around Colonies grown on Blood Agar. Streptococcus pyogenes is one of the few Bacteria that can invade the Tissues of the Pharynx. It causes Strep Throat, Puerperal Fever, Scarlet Fever and Rheumatic Fever. • The Dairy Group are Streptococci that do not produce Hemolysins. Streptococcus lactis (now named Lactococcus lactis ) is used in the Production of Buttermilk, Yogurt and Cheese. We will not be isolating Streptococcus lactis -- it’s easy to grow and maintain but its Isolation from Dairy Products is a nuisance -- however, it will be an Unknown for the Biochemical Identification of Bacteria. Streptococcus lactis is on YGC Agar. The Colonies are very, very small and White, surrounded by a surprisingly large Zone of Clearing.
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Lab 1 Page 15 Human Flora (Bacteria found on or in Humans) You ʼ ll be isolating these Bacteria from “Patient” Swab Plates. Human Flora also fairly easy to isolate but a bit more difficult to purify. TSome of them are anything but Harmless, which is why we ʼ re not isolating any of them from you. Skin Bacteria Micrococcus luteus Micrococcus luteus is a Gram Positive Obligate Aerobe found on the Skin of Mammals (as well as in the Soil and in Water). They are very common Contaminants in MIC 101 (where they generally fall into an open Petri Plate from your Skin or Hair). The easiest Way to isolate Micrococcus sp. is to simply open a Petri Plate for about 15 Minutes. Micrococcus luteus is Non-Pathogenic. Micrococcus luteus is on YGC Agar. Micrococcus sp. can be White (and so look like Staphyloccus epidermidis ), Yellow or Red (and so look like small Drops of Blood). Our Micrococcus luteus is Yellow ( Luteum is Latin for Yellow).
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