Antibiotics such as tetracycline, streptomycin, and bacitracin are small organic molecules that are synthesized by particular species of bacteria. Microbiologists have hypothesized that the reason why certain bacteria make antibiotics is to kill other species that occupy the same environment. Bacteria that produce an antibiotic may be able to kill competing species. Eliminating competitors provides more resources for the antibiotic-producing bacteria. In addition, bacteria that have the genes necessary for antibiotic biosynthesis contain genes that confer resistance to the same antibiotic. For example, tetracycline is made by the soil bacterium Streptomyces aureofaciens. Besides the genes that are needed to make tetracycline, S. aureofaciens also has genes that confer tetracycline resistance; otherwise, it would kill itself when it makes tetracycline. In recent years, however, many other species of bacteria that do not synthesize tetracycline have acquired the genes that confer tetracycline resistance. For example, certain strains of E. coli carry tetracycline-resistance genes, even though E. coli does not synthesize tetracycline. When these genes were analyzed at the molecular level, it was found that they are evolutionarily related to the genes in S. aureofaciens. This observation indicates that the genes from S. aureofaciens have been transferred to E. coli.A. What form of genetic transfer (i.e., conjugation, transduction, or transformation) is the most likely mechanism of interspecies genetic transfer?B. Because S. aureofaciens is a nonpathogenic soil bacterium and E. coli is a bacterium found in the intestinal tract, do you think the genetic transfer was direct, or do you think it may have occurred in multiple steps (i.e., from S. aureofaciens to other bacterial species and then to E. coli)?
Bacterial Genomics
The study of the morphological, physiological, and evolutionary aspects of the bacterial genome is referred to as bacterial genomics. This subdisciplinary field aids in understanding how genes are assembled into genomes. Further, bacterial or microbial genomics has helped researchers in understanding the pathogenicity of bacteria and other microbes.
Transformation Experiment in Bacteria
In the discovery of genetic material, the experiment conducted by Frederick Griffith on Streptococcus pneumonia proved to be a stepping stone.
Plasmids and Vectors
The DNA molecule that exists in a circular shape and is smaller in size which is capable of its replication is called Plasmids. In other words, it is called extra-chromosomal plasmid DNA. Vectors are the molecule which is capable of carrying genetic material which can be transferred into another cell and further carry out replication and expression. Plasmids can act as vectors.
Antibiotics such as tetracycline, streptomycin, and bacitracin are small organic molecules that are synthesized by particular species of bacteria. Microbiologists have hypothesized that the reason why certain bacteria make antibiotics is to kill other species that occupy the same environment. Bacteria that produce an antibiotic may be able to kill competing species. Eliminating competitors provides more
A. What form of genetic transfer (i.e., conjugation, transduction, or transformation) is the most likely mechanism of interspecies genetic transfer?
B. Because S. aureofaciens is a nonpathogenic soil bacterium and E. coli is a bacterium found in the intestinal tract, do you think the genetic transfer was direct, or do you think it may have occurred in multiple steps (i.e., from S. aureofaciens to other bacterial species and then to E. coli)?
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