Production and Qualitative Analysis of Secondary Metabolites of Staphylococcus Bacteria having Antibiotic Activity

Author Name(s): *Sara Pakseresht, Ahmed Waleed Majeed
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Antibiotics are one of the most important commercially exploited secondary metabolites produced by the bacteria and employed in a wide range. Most of the antibiotic producers used today are the soil microbes and the antibiotics are the secondary metabolites of these cells. With the increasing applications of these commercially available antibiotics they are becoming more expensive and hence it is the time to discover a more cost effective method for their production. The current work aims to use the soil bacteria in the field of antibiotic production due to their abundant availability. The work involves the isolation of the bacteria from the selected area and the production of pure cultures. As all the bacteria are not capable of antibiotic secondary metabolite production, the isolates would be subjected for the initial screening for the sensitivity to the test antibiotic ampicillin. Here ampicillin is selected as the test or reference antibiotic to which the activity of the metabolites produced is compared. Ampicillin resistant strains were selected as ampicillin is the referenced antibiotic. The antibiotic production was further confirmed by Zone of Inhibition test in comparition with the commercial ampicillin. Once the bacteria capable of antibiotic secondary metabolite production are isolated its identification is done based on Biochemical tests. Finally the antibiotic metabolites are produced which can be further purified.


Antibiotic, Soil Bacteria, Isolation, Production


Antibiotics are chemical compounds used to kill or inhibit the growth of infectious organisms. All antibiotics share the property of selective toxicity. They are more toxic to an invading organism than they are to an animal or human host. Penicillin is the most well-known antibiotic and has been used to fight many infectious diseases, including syphilis, gonorrhea, tetanus, and scarlet fever. Another antibiotic, streptomycin, has been used to combat tuberculosis. Antibiotics can be classified in several ways. The most common method classifies them according to their action against the infecting organism. Some antibiotics attack the cell wall; some disrupt the cell membrane; and the majority inhibits the synthesis of nucleic acids and proteins, the polymers that make up the bacterial cell. Most antibiotics act by selectively interfering with the synthesis of one of the large-molecule constituents of the cell–the cell wall or proteins or nucleic acids. Some, however, act by disrupting the cell membrane. Many antibiotics operate by inhibiting the synthesis of various intracellular bacterial molecules, including DNA, RNA, ribosomes, and proteins. The synthetic sulfonamides are among the antibiotics that indirectly interfere with nucleic acid synthesis.
The production of a new antibiotic is lengthy and costly. First, the organism that makes the antibiotic must be identified and the antibiotic tested against a wide variety of bacterial species. Then the organism must be grown on a scale large enough to allow the purification and chemical analysis of the antibiotic and to demonstrate that it is unique. This is a complex procedure because there are several thousand compounds with antibiotic activity that have already been discovered, and these compounds are repeatedly rediscovered. After the antibiotic has been shown to be useful in the treatment of infections in animals, larger-scale preparation can be undertaken.
The use of antibiotics is limited because bacteria have evolved defenses against certain antibiotics. One of the main mechanisms of defense is inactivation of the antibiotic. This is the usual defense against penicillin and chloramphenicol, among others. An antibiotic is a selective poison. It has been chosen so that it will kill the desired bacteria, but not the cells in body. Antibiotics work to kill bacteria. Bacteria are single-cell organisms. If bacteria make it past our immune systems and start reproducing inside our bodies, they cause disease. We want to kill the bacteria to eliminate the disease. Each different type of antibiotic affects different bacteria in different ways. For example, an antibiotic might inhibit a bacterium’s ability to turn glucose into energy, or its ability to construct its cell wall. When this happens, the bacterium dies instead of reproducing. At the same time, the antibiotic acts only on the bacterium’s cell-wall-building mechanism, not on a normal cell’s.


The current work aimed to identify the ability of the commonly found soil bacteria to resist to the antibiotics and the use of these bacteria in the industrial production of the antibiotic secondary metabolites. The organism that was isolated was first subjected for antibiotic sensitivity against the reference antibiotic ampicillin. The organisms were further subjected for Gram’s staining and biochemical tests for their identification. The bacteria were found to be staphylococcus aureus. This bacterium was further employed for the production of W= standard Ampicillin, C = Test Broth, E= Sterile water antibiotic metabolites that can inhibit the growth of the selected bacteria. Here we have selected the ampicillin sensitive bacteria as the target species. The efficacy of the bacteria was tested based on zones of inhibition. This was further compared with the commercially available ampicillin. It was concluded that these secondary metabolites can be used in place of ampicillin as they exhibit equivalent inhibitory activity. The work has to be further extended by increasing the number of target organisms and the antibiotic range.

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