Being kept in one place, the resulting cells have accumulated to form a visible patch. What Can Grow on a Nutrient Agar Plate? BacteriaĮach distinct circular colony should represent an individual bacterial cell or group that has divided repeatedly.
A lobate margin has rounded finger-like growths that spread outward. A curled margin appears as wave-like layers spreading outward. A filiform margin has small branch like growth that spreads outward. Bacteria can grow with a bumpy edge called undulate. The margin growth of a bacteria describes how the edges of the colony appear under a microscope and can appear: with a smooth rounded edge called entire. The elevation of bacteria describes how they grow upwards: raised in a shallow dome shape, convex growth in a steep dome shape, flat growth parallel to the ground, umbonate growth with a small raised bump in the center, and crateriform growth has a raised profile with a concave dip in the center. The bacterias form describes how they spread in a petri dish and can be: circular (covering the whole dish) irregular (spreading out in a non-uniform pattern), filamentous (spreading out like roots towards the outer edge), and rhizoid (spreading out like branches with main segments splitting into smaller segments). Refer to the diagram below for illustrated examples of form, elevation, and margin: (2)Ĭommon physical characteristics of bacteria colonies are listed and separated into 3 categories. Please note that 3 additional elements of morphology should be examined only in a supervised laboratory setting: consistency, emulsifiability, and odor. Chromogenesis (pigmentation) - For example, white, buff, red, purple, etc.Opacity - For example, transparent (clear), opaque, translucent (almost clear, but distorted vision, like looking through frosted glass), iridescent (changing colors in reflected light), etc.Surface - How does the surface of the colony appear? For example, smooth, glistening, rough, dull (opposite of glistening), rugose (wrinkled), etc.Margin - What is the magnified shape of the edge of the colony?.Elevation - What is the cross sectional shape of the colony? Turn the Petri dish on end.Form - What is the basic shape of the colony? For example, circular, filamentous, etc.There are 10 times more bacteria in our guts than there are cells in our body.Although bacterial and fungi colonies have many characteristics and some can be rare, there are a few basic elements that you can identify for all colonies: (1) thermophilus and Bifidobacterium bifidus. Other bacteria found in yoghurt are Lactobacillus acidophilus or casei, Streptococcus salivarius subsp. bulgaricus to produce lactic acid, which acts on milk protein to give yoghurt its texture and its characteristic acidic taste. Yogurt is made from the fermentation of the lactose in milk by the rod-shaped bacteria Lactobacillus delbrueckii subsp. You will be able to see the bacteria even without using the stain.īacteria can be found isolated, in pairs (diplo), in clusters or in threads (strepto), and they can have different shapes like rods (bacilli), sphere (coccus) etc. Bacteria will appear small even at the highest magnification. View in the compound microscope at 4 x or 10 x initially, before moving to higher magnification.Remove excess solution around the coverslip with a paper towel or tissue. Wear gloves and do NOT allow children to handle methylene blue solution. Place a small drop of methylene blue solution on a microscope slide (optional).Take a very small drop of yogurt with the toothpick and smear it for 2 to 3 seconds on the slide.Methylene blue solution (0.5 to 1%) Optional.Yogurt with live culture (eg: Actimel, Activia, Yakhult).
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