Bacterial growth and morphology observation experiment
Bacterial growth and morphology observation experiment
Observe the bacterial colonies:
Observation methods generally available to the naked eye for observation, will be placed in front of a flat dish culture of natural light or incandescent light, from different angles to observe the colony, if the colony is too small, available magnifying glass observation.
Observation of the colony: to understand the various characteristics of the colony, in order to determine how to further identify the colony. The various characteristics of the colony and their descriptions are as follows:
Size: diameter in millimeters (mm).
Shape; dotted, round, filamentous, irregular, rhizomatous, pike-like.
Protuberance: flattened, bulging, raised, occipital, button-like, umbilical.
Margins: smooth, wavy, earlobe-like, jagged, filiform, curly.
Color: white, yellow, black, yellowish, orange, etc.
Surface: shiny, dull, other.
Transparency: opaque, translucent, transparent, other.
Viscosity: creamy, viscous, filmy and friable.
Operation method
Bacterial growth and morphology observation experiment
Principle
Observation of bacterial colonies: observation methods generally available to the naked eye for observation, will be placed in front of a flat dish culture of natural light or incandescent light, from different angles to observe the colonies, if the colonies are too small, can be observed with a magnifying glass. Move 1. Observation of colonies: Understand the various characteristics of the colony in order to determine how the colony can be further identified. The various characteristics of the colony and its description are as follows: For more product details, please visit Aladdin Scientific website.
Size: diameter in millimeters (mm).
Shape; dot-drop, round, filamentous, irregular, rhizomatous, pike-like.
Protuberance: flattened, bulging, raised, occipital, button-like, umbilical.
Margins: smooth, wavy, earlobe-like, jagged, filiform, curly.
Color: white, yellow, black, yellowish, orange, etc.
Surface: shiny, dull, other.
Transparency: opaque, translucent, transparent, other.
Viscosity: creamy, viscous, filmy and friable.
2. Reaction of the colony on agar medium used for identification of bacteria:
(l) hemolysis on blood agar:
Alpha hemolysis: the blood medium around the colony becomes green ringed, and the shape of red blood cells is intact.
β hemolysis: due to the lysis of red blood cells, the blood around the colony forms a completely clear and transparent ring.
Gamma hemolysis: the medium around the colony remains unchanged and the red blood cells are not lysed or have no defects.
Double ring: a second circle of partial hemolysis outside the halo of complete lysis around the colony.
(2) Pigments produced on agar medium: green pus pigment, fluorescent pigment (fluorescein), etc.
(3) Odors: Some bacteria produce odors from their metabolic activities on flat media that, in combination with traits on liquid media, help in the identification of bacteria. Bacteria with special odors include: Pseudomonas spp. (grape juice odor), Aspergillus spp. (burnt chocolate odor), Streptococcus spp. (moldy odor), Clostridium spp. (fecal odor, rotting odor), and Melanobacterium spp. (pungent odor).
Bacterial morphology:
Bacteria have three basic forms, namely spherical, rod and spiral, called cocci, bacilli and spirochetes, respectively.
I. Coccidioides: spherical or nearly spherical (such as bean-shaped, kidney-shaped or spearhead-shaped), with a diameter of about l μm. According to the mode of division of bacterial cells and the division of the bacterium after the complete separation of the inter-bacterial body and the arrangement of the different ways, and is divided into:
1, staphylococcus: bacterial cells in a number of different planes of division, after the split irregularly stacked like a bunch of grapes, such as Staphylococcus aureus.
In addition, some cocci in two mutually perpendicular plane division, after the division of four bacteria arranged in a square, known as quadruple cocci. There are also cocci in three mutually perpendicular plane, along the upper and lower, left and right, before and after the direction of the division, after the division of eight bodies adhering to the package, known as the eight stacks of cocci. These two kinds of bacteria are not pathogenic.
2, diplococcus: split in a plane, after splitting the two bodies into a double arrangement, such as Neisseria meningitidis, Streptococcus pneumoniae, Neisseria gonorrhoeae.
3、Streptococcus: split in a plane, after the split of the bacterial body adhesion into a chain, such as hemolytic streptococcus.
2, bacillus:
Bacilli are rod-shaped or bulbous. In bacteria, bacilli are the most diverse, with great differences in length, size and thickness. Large bacilli, such as Bacillus anthracis, are 3-10 μm long, medium-sized bacilli, such as Escherichia coli, are 2-3 μm long, and small bacilli, such as Brucella, are only 0.6-1.5 μm long. Most bacilli are straight, such as Bacillus anthracis, while some are branching, such as Mycobacterium tuberculosis, and some are "eight" or fenestrated, such as Corynebacterium diphtheriae. These features can be used as a basis for diagnosis.
Third, spirochetes:
Spirochetes: the bacilli are curved in a spiral shape and can be divided into two categories:
l, Vibrio: bacterial body length 2-3 μm, only one bend, arc-shaped or comma-like, such as Vibrio cholerae.
2, spirochetes: the body length of 3-6 μm, there are several bends, such as the rat bite fever spirochetes.