medium is known as a culture. • The substances & environment which is provided to the microorganisms for their growth is called as media. • Culture media are contained in test tubes, flasks, or Petri dishes . • Media are extremely varied in nutrient content & consistency & can be specially formulated for a particular purpose. INTRODUCTION By Mf
water-based solutions that do not solidify at temperatures above freezing & that tend to flow freely when the container is tilted. These media termed broths, milks, or infusion, are made by dissolving various solutes in distilled water. Growth occurs throughout the container & can then present a dispersed cloudy or particulate appearance. Examples: • Luria broth • Nutrient broth By Mf
(agar or gelatin) that thickens the media but does not produce a firm substrate. This media is used to determine the motility of bacteria & to localize a reaction at a specific site. Example: • Both motility test medium & Sulfide Indole Motility (SIM) contain a small amount of agar. The medium is stabbed carefully in the center & later observed for the pattern of growth around the stab line. By Mf
can form discrete colonies & are advantages for isolating & sub-culturing bacteria & fungi. They come in two forms: 1. Liquefiable 2. Nonliquefiable By Mf
contain a solidifying agent that is thermoplastic include agent such as agar (complex polysaccharide isolated from the red alga Gelidium) agar is solid at room temperature & it melts (liquefies) at 100˚C Non-liquefiable solid media have less versatile applications than agar media because they are not thermoplastic include materials such as rice grains (used to grow fungi), cooked meat media (good for anaerobes), & potato slices all of these media start out solid & remain solid after heat sterilization By Mf
chemically defined are termed as synthetic media. These media contain highly pure organic & inorganic compounds that vary little from one source to another & have a molecular content specified by means of an exact formula. Examples: • Glucose-salt agar • Inorganic synthetic broth By Mf
are termed as nonsynthetic media. It contain at least one ingredient that is not chemically definable. Most of these substances are extracts of animals, plants, or yeasts including such materials as ground-up cells, tissues, secretions, milk, yeast extract, soybean digests, peptone. Examples: • Nutrient broth • Blood agar • EMB agar By Mf
broad a spectrum of microbes as possible. They are nonsynthetic & contain a mixture of nutrients that could support the growth of pathogens & nonpathogens alike. Examples: • Nutrient agar • Nutrient broth • Brain-heart infusion • Trypticase soy agar General purpose media By Mf
or special growth factors) that allow certain species to grow. Examples: •Streptococcus pneumoniae is cultured on blood agar, which is made by adding sterile sheep, horse or rabbit blood to a sterile agar base •Neisseria can grow on Thayer-Martin medium or chocolate agar, which is essentially cooked blood agar. By Mf
the growth of certain microbes thereby encourages the growth of desired microbe. These type of media are very important in primary isolation of a specific type of microorganism from samples containing a highly mixed population. Examples: • Mannitol Salt Agar (MSA) • MacConkey agar • Eosin-Methylene Blue (EMB) agar By Mf
microorganisms, but it is designed to highlight differences among these microorganisms. Its ability of differentiation is due to the type of agents added. Examples: • Sulfide Indole Motility (SIM) agar • Xylose Lysine Deoxycholate (XLD) agar • Triple Sugar Iron (TSI) agar By Mf
or cystine) that absorbs oxygen or slows the penetration of oxygen in a medium thus reducing its availability. These media are important for growing anaerobic bacteria or determining oxygen requirements. Example: • Thioglycolate broth Reducing media By Mf
that have to be held for a period of time prior to clinical analysis or to sustain delicate species that die rapidly if not held under stable conditions. Example: • Stuart’s & Amies transport media contain salts, buffers & absorbants to prevent cell destruction by enzymes, pH changes & toxic substances but will not support growth. By Mf
the effectiveness of antimicrobial drugs & by drugs manufacturers to assess the effect of disinfectants, antiseptics, cosmetics & preservatives on the growth of microorganisms. By Mf