Products derived from genetically engineered microorganisms

In Chapter 12 we saw how recombinant DNA technology can be used to genetically modify microorganisms so that they produce commercially important proteins such as human insulin. This is done by incorporating the gene for the desired protein into an PRODUCTS DERIVED FROM GENETICALLY ENGINEERED MICROORGANISMS 419 PRODUCTS DERIVED FROM GENETICALLY ENGINEERED MICROORGANISMS 419 Figure 17.7 A continuous flow stirred tank reactor. Parameters such as pH and concentrations of specific metabolites are...

Basidiomycota

This large group of some 25 000 species contains the true mushrooms and toadstools as well as other familiar fungi such as puffballs and bracket fungi. In fact the great majority of the fungi that we see in fields and woodlands belong to the Basidiomycota. They are of great economic importance in the breakdown of wood and other plant material (Chapter 16). The group derives its common name of the club fungi from the way that the spore-bearing hyphae involved in reproduction are swollen at the...

Airborne transmission influenza

Tied And Penetrated

Influenza is a disease of the respiratory tract caused by members of the Orthomyx-oviridae. Transmission occurs as a result of inhaling airborne respiratory droplets from an infected individual. Infection by the influenza virus results in the destruction of epithelial cells of the respiratory tract, leaving the host open to secondary infections from bacteria such as Haemophilus influenzae and Staphylococcus aureus. It is these secondary infections that are responsible for the great majority of...

Expression vectors

Sometimes, the aim of a cloning experiment is not just to obtain large amounts of a specific gene, but for the gene to be expressed. This involves using the host cell as a sort of 'factory', to manufacture the specific protein encoded by the cloned gene. One of the earliest applications of genetic engineering was the production of human insulin in E. coli (Figure 12.10). Insulin is needed in considerable quantities for the treatment of diabetics for years it was obtained from the pancreas of...

Phylum Chlamydiae

Formerly grouped with the Rickettsia (see above), these non-motile obligate parasites of birds and mammals are now assigned a separate phylum comprising only five genera, of which Chlamydia is the most important. Like the Rickettsia, members of the Chlamydiae have extremely small cells, and very limited metabolic capacities, and depend on the host cell for energy generation. Unlike that group, however, they are not dependent on an arthropod vector for transmission from host to host. Chlamydia...

Glossary

Acid-fast stain a procedure for assessing the ability of an organism to retain hot carbol fuchsin stain when rinsed with acidic alcohol. Acidophilic 'acid-loving' a term applied to organisms that show optimal growth in acid conditions pH lt 5.5 . Activated sludge treatment a method of wastewater treatment involving aeration in tanks that have been seeded with a mixed microbial sludge. Activation energy the energy required to initiate a chemical reaction. Active site the part of an enzyme...

Acids bases and pH

Only a minute proportion of water molecules, something like one in every 5 x 108, is present in its dissociated form, but as we have already seen, the H and OH- ions play an important part in cellular reactions. A solution becomes acid or alkaline if there is an imbalance in the amount of these ions present. If there is an excess of H , the solution becomes acid, whilst if OH- predominates, it becomes alkaline. The pH of a solution is an expression of the molar concentration of hydrogen ions In...

Airborne transmission strep throat

Streptococcal pharyngitis, commonly known as strep throat, is one of the commonest bacterial diseases of humans, being particularly common in children of school age. The primary means of transmission is by the inhalation from coughs and sneezes of respiratory droplets containing Streptococcus pyogenes p-haemolytic type A streptococci , although other routes kissing, infected handkerchiefs are possible. The primary symptoms are a red and raw throat and or tonsils , accompanied by headaches and...

Ascomycota

Reproduction Ascomycota

The Ascomycota are characterised by the production of haploid ascospores through the meiosis of a diploid nucleus in a small sac called an ascus. For this reason they are sometimes called the sac fungi or cap fungi. Many of the fungi that cause serious plant diseases such as Dutch elm disease and powdery mildew belong to this group. They include some 30 000 species, among them yeasts, food spoilage moulds, brown fruit rotting fungi and truffles. Note that the latter, often regarded as the most...

Chlorophyta

Asexual Reproduction Chlorophyta

The green algae have always attracted a lot of interest because, as a group, they share a good deal in common with the higher plants in terms of ultrastructure, metabolism and photosynthetic pigments, pointing to the likelihood of a common ancestor. They possess both chlorophyll a and b and certain carotenoids, store carbohydrate in the form of starch, and generally have a rigid cell wall containing cellulose. The starch is stored in structures called pyrenoids, which are found within...

Phylum Firmicutes The low GC Grampositive bacteria

The low GC Gram-positive bacteria form volume 3 of the second edition of Bergey. The spore-forming Gram-positive bacteria include two large genera, Clostridium and Bacillus. Although not particularly close in phylogenetic terms, they are both capable of propagation by endospores. Clostridium species are obligate anaerobes, and common inhabitants of soil. Sugars are fermented to various end-products such as butyric acid, acetone or butanol. Lacking an electron transport system, they obtain all...

Chemical bonds

Carbon Dioxide Ionic Bond

The force that causes two or more atoms to join together is known as a chemical bond, and several types are found in biological systems. The interaction between sodium and chloride ions shown in Figure 2.4 is an example of ionic bonding, where the transfer of an electron from one party to another means that both achieve a complete outer electron shell. There is an attractive force between positively and negatively charged ions, called an ionic bond. Certain elements form ions with more than a...

Box 52 The most probable number MPN method

Most Probable Number Microbiology Method

In the example below, three sets of five tubes of broth were inoculated with 10 ml, 1 ml and 0.1 ml of a water sample. The tubes were incubated to allow any bacteria present to multiply in number, and were scored as 'growth' dark shading or 'no growth' no shading . The cell density statistically most likely to give rise to the result obtained 5-3-1 is then looked up on a set of MPN tables. The table only part shown indicates that there is a 95 probability that the sample fell within the range...

How do we know Microbiology in perspective to the golden age and beyond

Swan Necked Flask

We have learnt an astonishing amount about the invisible world of microorganisms, particularly over the last century and a half. How has this happened The penetrating insights of brilliant individuals are rightly celebrated, but a great many 'breakthroughs' or 'discoveries' have only been made possible thanks to some frequently unsung development in microbiological methodology. For example, on the basis that 'seeing is believing', it was only when we had the means to see microorganisms under a...