Microbiology Supplies ~ Stains

The most commonly utilised stain in microbiological laboratories is the Gram stain, developed by Danish Microbiologist Christian Gram in 1884. The Gram stain is used to classify bacteria on the basis of their forms, sizes, cellular morphologies, and Gram reactions in a clinical microbiology laboratory. It is additionally a critical test for the rapid presumptive diagnosis of infectious agents and serves to assess the quality of clinical specimens.

Interpretation of Gram-stained smears involves consideration of staining characteristics and cell size, shape, and arrangement. These characteristics may be influences by a number of variables, including culture age, media, incubation atmosphere, staining methods, and the presence of inhibitory substances. Similar considerations apply to the interpretation of smears from clinical specimens, and additional factors include different host cell types and possible phagocytosis.

Gram stain permits the separation of all bacteria into two large groups, those which retain the primary dye (gram-positive) and those that take the color of the counterstain (gram-negative). The primary dye is crystal violet and the secondary dye is usually either safranin O or basic fuchsin. Some of the more common formulations include: saturated crystal violet (approximately 1%), Hucker’s crystal violet, and 2% alcoholic crystal violet.

POCD Scientific will custom make Gram stains to your tried and tested recipes. We also have a complete range of bacteriological stains, including AFB (acid-fast bacilli) stains, stains for fungal elements, ova, cysts and parasites.

• Crystal Violet
• Carbol Fuchsin Concentrated and Dilute
• Grams Iodine
• Jensen’s Iodine
• Neutral Red
• Safranin
• Fluorescent stain for TB Auromine Rhodamine Stain
• Gomories Trichrome – Parasitology
• Trichrome Blue Stain – Parasitology
• Wheatons Trichrome – Parasitology
• Parasitology Stain Kit
• Ziehl Nelson
• Methylene Blue

Microbiology Supplies ~ reagents

Prepared using the highest quality materials to our own stringent quality standards. These reagents are stable, pre-filtered through a 3-stage filtration process to eliminate the occurrence of potentially confusing dye particulates on the slide. All reagents are supplied in polybottles fitted with dispenser nozzles to allow accurate application to slides and economic use of reagent.

• Acetone The contaminant-free purity of POCD Scientific Reagent Grade Acetone is perfect for the Microbiology lab.
• Acid Alcohol

Microbiology Supplies ~ Mountants

• Slidemount # 1 through 9 : Refractive index 1.515. This is acrylate/methacrylate based with Xylene as the solvent. Fast drying [touch dry in 3-4mins] and permanent [coverslips are difficult to remove]. The numbers relate to viscosity. No 1 is very thick and No 9 thin. Please note the most common viscosity is No 4, which is equivalent to Eukitt. However Ultramount No 9 has now been released, which is especially formulated for automatic cover-slipping machines.
• Aquamount – This is a water based mountant and is used for special staining techniques where the use of solvents removes the component being stained. This is not a permanent mountant. Otherwise known as Apathy's mountant.
• Citramount – No 4 and 7 : Is again Perspex based but with Citrolene as the solvent. If one is clearing with Histolene [our Xylene replacement solvent] then this mountant is better suited. Also available in our popular Safe-T-Mount squeeze tubes.

Microbiology Supplies ~ thumbnail History of Microbiology

In 1676, Antonie van Leeuwenhoek observed bacteria and other microorganisms, using a single-lens microscope of his own design. While Van Leeuwenhoek is often cited as the first to observe microbes, Robert Hooke made the first recorded microscopic observation, of the fruiting bodies of molds, in 1665. The first observation of microbes using a microscope is generally credited to the Dutch draper and haberdasher, Antonie van Leeuwenhoek, who lived for most of his life in Delft, Holland. It has, however, been suggested that a Jesuit priest called Athanasius Kircher was the first to observe micro-organisms.He was among the first to design magic lanterns for projection purposes, so he must have been well acquainted with the properties of lenses.

One of his book contains a chapter in Latin, which reads in translation – ‘Concerning the wonderful structure of things in nature, investigated by Microscope. Here, he wrote ‘who would believe that vinegar and milk abound with an innumerable multitude of worms.’ He also noted that putrid material is full of innumerable creeping animalcule. These observations antedate Robert Hooke’s Micrographia by nearly 20 years and were published some 29 years before van Leeuwenhoek saw protozoa and 37 years before he described having seen bacteria.

The field of bacteriology (later a subdiscipline of microbiology) was founded in the 19th century by Ferdinand Cohn, a botanist whose studies on algae and photosynthetic bacteria led him to describe several bacteria including Bacillus and Beggiatoa. Cohn was also the first to formulate a scheme for the taxonomic classification of bacteria and discover spores. Louis Pasteur and Robert Koch were contemporaries of Cohn’s and are often considered to be the father of Microbiology and medical microbiology, respectively.

Pasteur is most famous for his series of experiments designed to disprove the then widely held theory of spontaneous generation, thereby solidifying microbiology’s identity as a biological science. Pasteur also designed methods for food preservation (pasteurization) and vaccines against several diseases such as anthrax, fowl cholera and rabies. Koch is best known for his contributions to the germ theory of disease, proving that specific diseases were caused by specific pathogenic micro-organisms. He developed a series of criteria that have become known as the Koch's postulates. Koch was one of the first scientists to focus on the isolation of bacteria in pure culture resulting in his description of several novel bacteria including Mycobacterium tuberculosis, the causative agent of tuberculosis.

While Pasteur and Koch are often considered the founders of microbiology, their work did not accurately reflect the true diversity of the microbial world because of their exclusive focus on micro-organisms having direct medical relevance. It was not until the late 19th century and the work of Martinus Beijerinck and Sergei Winogradsky, the founders of general microbiology (an older term encompassing aspects of microbial physiology, diversity and ecology), that the true breadth of microbiology was revealed. Beijerinck made two major contributions to microbiology: the discovery of viruses and the development of enrichment culture techniques.

While his work on the Tobacco Mosaic Virus established the basic principles of virology, it was his development of enrichment culturing that had the most immediate impact on microbiology by allowing for the cultivation of a wide range of microbes with wildly different physiologies. Winogradsky was the first to develop the concept of chemolithotrophy and to thereby reveal the essential role played by micro-organisms in geochemical processes. He was responsible for the first isolation and description of both nitrifying and nitrogen-fixing bacteria.

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