PORTAGE LEARNING: MODULE 4 QUESTIONS AND ANSWERS (100% PASS)

Growth media - Answer a liquid or solid formulated to support microbial growth. Media contains - Answer essential nutrients to provide the microbe with a source of carbon/energy, which, in turn, encourages its expansion. Nutrient composition often includes - Answer a rich source of sugars, amino acids, and vitamins. Such media can also be referred to as - Answer nutrient broth and is commonly used to grow microbes in a suspension. Most common nutrient broth - Answer LB media - lysogeny broth LB media is - Answer a nutritionally rich liquid known for its ability to grow a vast array of microbes Selective media would be used when a researcher wants to - Answer establish conditions where various types of bacteria will grow, while others will not When is differential media used - Answer when a researcher wants to establish conditions where several types of microbes can be grown simultaneously while being able to distinguish one type from another Selective media - Answer allows for only the growth of certain microbes and, by extension, restricts the growth of all others. Selective media approach - Answer Such an approach can be accomplished in a variety of ways including using limiting amounts of nutrients, varying degrees of pH (being either very acidic or very basic media), or various chemical additives that limit unwanted microbial growth (i.e. antibiotics). Selective media is often used in medical laboratories for the cultivation of human pathogens such as - Answer Neisseria meningitides - causative agent of meningitis Because Neisseria meningitides is a relatively s - Answer low-growing organism, other bacteria, mold, or fungi often outgrow the sample—remember medical samples often contain numerous unknown microbes! —therefore, additives are included in the growth media to specifically inhibit such foreign microbes and ensure the isolated growth of Neisseria meningitides. Differential media does what - Answer distinguishes between two, often related, microbes. Example of differential media - Answer two microbes Escherichia coli and Salmonella are both Gram-negative but can be distinguished by the presence (or absence) of lactose fermentation. If grown on the same differential media, What does E. coli do - Answer E. coli ferments lactose and turns the culture red What does Salmonella do - Answer In contrast, Salmonella does not ferment lactose, and the culture remains white/tan in color. Enriched media - Answer is used to grow fastidious microorganisms— What does fastidious mean - Answer organisms with complex growth requirements such that if absent will not grow. Thus, enriched medias contain the - Answer essential nutrients required for the growth of this subset of microorganisms. Medias can be a combination of selective, differential, and enriched. Solid growth media, - Answer often contained within a sterile petri dish, is in its simplest form liquid growth media that has had a hardening agent added. The addition of - Answer a polysaccharide derived from seaweed [algae] extract creates a solid medium called agar. Agar is used to create - Answer a solid, smooth surface on which microbes can grow As they grow, microbes form - Answer colonies take on the appearance of individual isolated dots.