Bacterial Growth Essay Research Paper Bacterial GrowthBacteria — страница 2

found in water, soil, milk, foods, and certain insects. In spite of the fact that bacteria are harmful to the body, certain measures can be taken in order to inhibit their growth and reproduction. The most common form of bacteria fighting medicines are antibiotics. Antibiotics carry out the action which their Greek origin suggests: anti meaning against, and bios meaning life. In the early parts of the 20th century, a German chemist, Paul Ehrlich began experimentation using organic compounds to combat harmful organisms without causing damage to the host. The results of his experimentation began the study and use of antibiotics to fight bacteria. Antibiotics are classified in various ways. They can be arranged according to the specific action it has on the cell. For example,

certain antibiotics attack the cell wall, others concentrate on the cell membrane, but most obstruct protein synthesis. Another form of indexing antibiotics is by their actual chemical structure. Practically all antibiotics deal with the obstruction of synthesis of the cell wall, proteins, or nucleic acids. Some antibacterials interfere with the messenger RNA, consequently mixing up the bacterial genetic code. Penicillins act by inhibiting the formation of a cell wall. This antibiotic works most effectively against gram-positive streptococci, staphylococci (e.g. Micrococcus Luteus) as well as certain gram-negative bacteria. Penicillin is usually prescribed to treat syphilis, gonorrhea, meningitis, and anthrax. Tetracycline inhibits protein synthesis in pathogenic organism. This

antibiotic is obtained from the culture of Streptomyces. Streptomycin an antibiotic agent which is obtained from Streptomyces griseus. This antibiotic acts by limiting normal protein synthesis. Streptomycin is effective against E. Coli, gram-negative bacilli, as well as many cocci. Neomycin an antibiotic derived from a strain of Streptomyces fradiae. Neomycin effectively destroys a wide range of bacteria. Kanamycin an antibiotic substance derived from Streptomyces kanamycetius. Its antibacterial action is very similar to that of neomycin. Kanamycin works against many aerobic gram-positive and gram-negative bacteria, especially E. coli. Protracted use may result in auditory as well as other damages. Erythromycin is an antibiotic produced by a strain of Streptomyces erythreaus.

This antibiotic works by inhibiting protein synthesis but not nucleic synthesis. Erythromycin has inhibitory effects on gram-negative cocci as well as some gram-positive bacteria. Chloramphenicol is a clinically useful antibiotic in combating serious infections caused by certain bacteria in place of potentially hazardous means of solving the problem. In lab tests, it has been shown that this medicine stopped bacterial reproduction in a wide range of both gram-positive and gram-negative bacteria. The inhibition of cell reproduction caused by Chloramphenicol takes place through interference with protein synthesis. An experiment was conducted in order to determine which antibiotics are most effective in inhibiting bacterial growth. First, the different bacteria were placed on agar

inside petri dishes. Then, antibiotic discs were placed into the dishes. Each bacteria was exposed to every one of the antibiotics listed above. The bacteria used in the experiment were: Bacillus Cerus, Escerichia Coli, Seratia Marscens, and Micrococcus Luteus. After a 24 hour incubation period, the results were measured. In order to determine which antibiotic had the most effect their zones of inhibition were recorded. The zone of inhibition refers to the distance from the disc to the outermost section around the disc where no bacterial growth was present. The results can be seen on the graph and data chart. The following is a table showing the different zones of inhibition of each antibiotic in the bacteria

culture:TetracyclineChloramphenicolKanamycinNeomycinPenicillinStreptomycinErythromycinB. Cerus5.5956.61713E. Coli74.25.54.5no effect4.6no effectS. Marscensno effectno effect4.54no effect3no effectM. Luteus2322101123.511.519After analysis of the data obtained it is obvious that each antibiotic had a distinct effect on the growth of the different bacteria. The results of this experiment are very important, since they teach of how each bacteria reacts to different antibiotics. This is very valuable because it is the information which assists physicians in prescribing certain medications to cure diseases caused by bacteria. Bibliography1) Encart Encyclopedia 1994, CD-ROM. 2) McGraw-Hill Encyclopedia of Science and Technology, 1992. 3) Physicians Desk Reference, 1996. 328