Summary notes – Prosthecae PDF

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Summary notes – Prosthecae

Prosthecae are semi-rigid extension of cell wall and cell membrane One bacteria may contains one or many prosthecae. Some prosthecae develop bud at the tip and hence helps in reproduction. Some prosthecate bacteria are: Caulibacter, Stella, Prosthecobacter, Hyphomicrobium Prosthecae increase surface area for nutrition absorption. It is usually formed in bacteria living in very dilute environment where concentration of nutrition is low. Helps in adhesion. Asexual reproduction by budding

It consists of glycan backbone formed by repeated unit of NAG (n-acetyl Glucosamine) and NAM (Nacetyl muramic acid) and the glycan backbone is cross linked by peptide bond. Peptidoglycan layer is present in cell wall of both gram positive as well as gram negative bacteria. However, gram positive have thick layer of peptidoglycan.

Teichoic acid is water soluble polymer of glycerol or ribitol phosphate present in gram positive bacteria. It constitutes about 50% of dry weight of cell wall. It is the major surface antigen of gram positive bacteria

Bacteria are primary decomposers – recycle nutrients back into the environment (sewage treatment plants) Winogradsky and M. Beijerinck studied soil microbes and their role in the biochemical cycles of sulfur, carbon, nitrogen etc. Insect Pest Control: some bacteria are used as bio-pesticides to control Insects pest. Eg. Bacillus thuringiensis Bioremediation: microbes are also used to clean up pollutants and toxic wastes. Eg. Pseudomonas putida; used to remove petroleum spill.

Vaccine activates immune response. Edward Jenner inoculated people with cowpox to protect against smallpox. Pasteur developed the rabies vaccine (1885). Von Behring and Kitasato (1890) produced toxoid vaccine against diphtheria and tetanus. Metchnikoff (1884) described role of phagocytic cell in defense. Microbes are used in economic and industrial purposes.

Biotechnology, fermentation technology, food and beverages etc are now established on large industrial scale for income. Patients right of procedure

Genetic engineering is used for the production of transgenic plants and animals. Animal and plant improvement by biotechnology for better production, resistant to environmental fluctuation. Molecular farming: transgenic animal or plant are used as bioreactor for mass production

Transformation is the process of introduction of derived DNA fragments from a donor bacteria into a recipient bacteria. It is one of the cornerstone of molecular genetics. It is the transfer of naked DNA from donor cell to recipient cell.

Most types of cell cannot take up DNA efficiently unless they have been exposed to special chemical or electrical treatment to make them more permeable. However, some types of bacteria are naturally transformable ie they can take DNA from environment without requiring special treatment. Bacteria that take up DNA are called competent. At least 40 species of naturally competent and transformable bacteria have been found.

The protein involved in transformation of these Gram +ve bacteria is a product of com In Bacillus subtilis , the com gene are organized into several operons. The product of com A and com K are involved in regulation of competence and other com E, com F and com G encodes structural protein for uptake of DNA. The first gene of com E operon, com EA encodes the protein that directly binds extracellulat double stranded DNA. The com F gene encodes the protein that translocate DNA into cell. for example; Com FA is an ATPase that translocate DNA into cell. The com G gene of comG operon encodes protein that form pseudopilus that helps to move DNA through channel. The com E, com F and com G operon are under transcriptional control of com K operon. Com K is a transcriptional factor that is regulated by com A Some other genes involved in transformation are nuc A gene that encodes nuclease enzyme which cuts extracellular dsDNA to single stranded,

Single strand binding protein and Rec A gene which helps in recombination of transforming DNA with chromosome of recipient bacteria.

A variety of Gran Negative bacteria are capable of competence. Some examples are Acenetobacter calcoaceticus, Helicobacter pylori, Neisseria spp, etc H. pylori and Neisseria spp require specific DNA sequences for binding of DNA so these species take up DNA from same species only. Gram-ve bacteria utilizes two different pathway for uptake of DNA

The term PSTC has been applied to some protein indicating their multiple role in Pilus formation, Secretion, Twitching motility and Competence. These proteins form structure needed to transport DNA across the cell wall and cell membrane. Many of these proteins that function in DNA uptake in H. influenza, Neisseria, Acinetobacter, Vibrio etc are related to com G...