Archive for the ‘Microbiology’ Category

How are Fungi Dispersed?

Posted 28 Mar 2010 — by admin
Category Microbiology

Microorganisms like fungi are eukaryotic organisms that could be found in air, water and soil. They can be harmful or harmless. They are often called the “garbage disposers” because they feed on rotting, organic matter in the environment.

Fungi dispersal mechanisms differ in some ways for each of the five (5) phyla. In order to understand this, we have first to know the characteristics of a fungus and the different phyla classified under it.

The classifications of the phyla according to their methods of reproduction are: Zygomycotina, Chytridiomycotina, Ascomycotina, Basidiomycotina, and Deuteromycotina.

The first two are considered as lower fungi and are aseptate. The next two are the higher fungi, while the last phyla are considered the fungi Imperfecti which are very useful in the medical field as sources of antibiotics.

Since they do not have an apparent means of locomotion like pseudopodia, cilia and flagella, they are, in other words, “dispersed” into the environment.

What are the mechanisms of fungal dispersion?

1. Fungi causing bread molds and food spoilage usually belong to the class Zymycotina. These are dispersed through their filaments or hyphae which extend over the surface of the material it is growing on. It is through spore formation that it reproduces.

We commonly call these fungi growth on food and water as molds.

They are dispersed when they got blown by air, or through fungi infected water, or get transferred through contact with the mold itself.

2. Some fungi, like the mushroom, (yes the mushroom is a fungi, not a plant), are dispersed from their spores, which may travel through air, soil or water, or in direct contact from one medium to another. This would also bring about a new growth, just like a plant seed.

Some mushrooms are edible and some are not. The edible ones are even considered as special dishes in some countries. The non-edible ones produce toxins, like in Ergot poisoning, where mold-contaminated wheat are ingested by man. The condition would start from nausea, high fever, convulsions, gangrene and eventually death.

3. Dispersal of fungi that are present in human infections, like Candia albicans, Blastomyces dermatitidis or Aspergillus species is done through skin to skin contact.

4. Yeasts are found in food (skins of fruits, vegetables), soil and water. They are very useful in the manufacture of alcoholic beverages because they break down sugars to cause fermentation.

Opportunistic yeasts are also found in humans. They live harmlessly in the skin, mouth and genitor-urinary tract and only cause disease when there is a decrease in the indigenous bacteria in these organs.

They can be dispersed through inhalation of contaminated air or soil. They could also enter through wounds.

Dispersal of the yeast could be done also through dried feces of both birds and bats. When these contaminated materials are blown by air or come in contact with food, the yeast are further spread into the environment.

In conclusion, fungi could be dispersed through budding, spore dispersal, contaminated water, soil and direct contact. It must be noted that these organisms could be both beneficial and pathogenic and these should be considered when treating fungi related conditions.

Identification of Neisseria gonorrhea

Posted 03 Mar 2010 — by admin
Category Laboratory Procedures, Microbiology

Neisseria gonorrhea is the causative agent of gonorrhea a sexually transmitted disease (STD). They are coffee-bean shaped cocci occurring in pairs. They are gram-negative, intracellular diplococci and they are stained using gram staining.

Identification of Neisseria gonorrhea is easy with a simple smear.

Materials needed

Clean and dry glass slide

Applicator stick with cotton

Grams stain

Personal protective equipment

Procedure

Step 1

Wear your personal protective equipment (PPE), gloves, masks and laboratory gown. Neisseria gonorrhea could infect the eyes and your throat. They could cause gonorrheal blindness and throat infections if not diagnosed immediately.

Step 2

With an applicator stick, collect the specimen from the cervical or vaginal area. Sometimes the doctor collects the specimen during his examination.

Step 3

Make a smear of the secretion on the clean and dry glass slide, not too thick or too thin. Identification of Neisseria gonorrhea is facilitated when the simple smear is properly prepared.

Step 4

Allow to air dry or through exposure to direct flame. This will allow the smear to stick to the slide and not washed off during staining.

Step 5

Place in a staining rack and add crystal violet until all the smear is exposed to the stain. The time will depend upon the staining kit’s instructions. The time varies with newly developed kits.

Step 6

Wash the slide and add acid alcohol to decolorize. The gram-positive bacteria will take up the crystal violet while the gram-negative bacteria like Neisseria gonorrhea will decolorize.

Step 7

Wash with distilled water and add safranin. The gram-negative bacteria will take up this stain and will be colored pink. While the gram positive bacteria will be stained purple or violet, taking up the color of crystal violet.

Step 8

Wash again with distilled water and allow to dry.

Step 9

Focus in the microscope using the low power objective (LPO), then shift to the high power objective (HPO) or shift straight to the oil immersion objective (OIO). When using the OIO, place a drop of oil into the slide to be able to see clearly.

Step 10

Following a four field meander, scan the slide for the presence of gram-negative intracellular, diplococci. You should scan the whole slide, as you may not see them immediately. A large amount of pus cells is usually one indication of the infection. Do not report however as positive unless you have observed the diploccoci in the smear itself. Step 10 Record and report your findings.

Step 11

Dispose of your materials properly.

The Anatomy of a Virus

Posted 25 Feb 2010 — by admin
Category Microbiology

The morphological appearance of a virus is so beautiful that you would not expect this seemingly harmless and visually attractive entity to be a deadly, virulent microorganism.

This minute organism, first discovered by Dmitri Iwanowski in 1892, is a universal microbe present in a variety of hosts, including us – the Homo sapiens. Contrary to common knowledge; however, not all viruses are disease causing, some of them also have beneficial effects on their hosts.

So what is the anatomy of a virus? What is its bodily structure?

1. Viruses have a size ranging from 10 to 300 nm (nanometers).

The largest is the Ebola virus which is, more or less, 1 um (micrometer) in length. To help you visualize its size, 1 inch is 25399999.999999996 nm; and 1 inch in micrometers is 25400.

They can only be seen under an electron microscope which usually utilizes unstained preparations of viruses under a dark background.

2. A virus is composed of either a DNA or RNA, but not both.

This DNA or RNA is the type of the nucleic acid genome present in all viruses. Viruses depend on their host’s ribosomal synthesis because they could not synthesize their own ribosomes; this property makes them unique from all other organisms.

Living cells are composed of both RNA plus a DNA, which multiply through binary fission, mitosis or meiosis, while viruses cannot replicate on their own, they need a host to be able to do this.

3. A virus is surrounded by a capsid.

This is a protein coat made up of several protein units called capsomeres. This maybe helical (coiled tubes), spherical, polyhedral (various sides), enveloped, or a combination of any of these shapes. That is why they look captivating under the microscope.

4. Some viruses have outer coverings made up of lipids and polysaccharides.

These are also called enveloped viruses. Lipids are commonly called fats, and polysaccharides are complex carbohydrates.

5. Some may have sheaths, tails or tail fibers.These are usually found in bacterial viruses.

6. They have a core protein.

This protein comprises the interior of the virus could interact with the cytoplasm of the host cell where the virus may alter them and produce toxins and become harmful, or remain harmless and exercises no detrimental effect.
The anatomy of a virus therefore is one of great variety and interest. It can be influenced entirely by the host’s specific biochemical characteristics or cellular components.