BIS 2C Lecture Notes - Lecture 7: Teixobactin, Antibiotics, Penicillin
27 Apr 2018
School
Department
Course
Antibiotics
Penicillium fungus, discovered in 1928 by Fleming on accident
Proved useful for killing bacterial pathogens
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Isolated compound but low yield/ sensitive to stomach acid
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Research increased during WW2 and were able to get better strains for
fungus which were commercialized
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Most antibiotics found in 40-50s until now when we have a discovery void
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After release of penicillin, resistance by bacteria was developed quickly and
previously effective bacteria were no longer viable; needed constant feed of new
antibiotics
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Tried to stop resistance but none of the methods have worked
Pharmacological: dosage change
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Biochemical: alter the action of the antibiotics
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Genomics: alter DNA of antibiotics
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Target: different part of bacteria must be targets
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Recently, teixobactin is newest antibiotic that has no detectable resistance
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Resistance occurs by evolution
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Linear Inheritance or Vertical Transmission
Primary form of cell division/reproduction in prokaryotes is binary fission which
is process of cloning
Occurs rapidly; within minutes new clones made
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Environment can influence strongly (for archaea and bacteria0
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Antibiotic Resistance/Genetic Variation
Mutations occur during cell division which might give new trait like resistance to
antibiotics which will spread in pop
Since there is a selection factor by antibiotics, the resistant strains succeed
for reproduction while unlucky die out
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Mutations/selections happens quickly because haploid nature only requires one
allele to phenotype
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Introduction of Genetic Variation via Other Methods
Mutations/ Selection
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Plasmids: another small piece of genetic material/DNA
Can be passed to daughter cells randomly
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Much different than DNA of chromosomes
Fewer quantity of genes
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Non essential but can have advantageous effects
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Take energy to produce so if not in stressful environment, becomes non
beneficial
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Multiple functions: fertility, metabolism, resistance, virulence
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Lateral (horizontal) Gene transfer - can transfer to different species, and domains
Three ways
Conjugation: use of pili to transfer genes from donor to close
recipient; connections very brief
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Transformation: incorporation of DNA from the environment
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Transduction: use of virus(bacteriophage) to inject bacteria with
DNA, kill host, and then use DNA of both viral and host mix to
succeed and infect others.
§
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Three functions: Metabolic, antibiotic, virulence
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If larger change then probably not by this
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Sexual Repro vs LGT
Between different species with LGT
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Multiple ways for LGT, one of sex
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Both involved recombination
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Biotechnology and LGT
Use gene splicing to put in foreign DNA into the bacteria and then use the
bacteria transformed to infect cells for desired traits
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Impact of LGT
May cause problems in phylogenetic trees b/c some genes may show up similar in
different organism that are not similar at all just because they received this
sequence of DNA
Can look at core set of genes that are never passed on by LGT for better
phylogeny (ribosomal DNA)
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May look like convergent DNA
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*Large changes not due to LGT, convergent DNA causes large changes*
Prokaryote Reproduction (7)
Friday, January 19, 2018
12:08 PM
Document Summary
Penicillium fungus, discovered in 1928 by fleming on accident. Isolated compound but low yield/ sensitive to stomach acid. Research increased during ww2 and were able to get better strains for fungus which were commercialized. Most antibiotics found in 40-50s until now when we have a discovery void. After release of penicillin, resistance by bacteria was developed quickly and previously effective bacteria were no longer viable; needed constant feed of new antibiotics. Tried to stop resistance but none of the methods have worked. Target: different part of bacteria must be targets. Recently, teixobactin is newest antibiotic that has no detectable resistance. Primary form of cell division/reproduction in prokaryotes is binary fission which is process of cloning. Environment can influence strongly (for archaea and bacteria0. Mutations occur during cell division which might give new trait like resistance to antibiotics which will spread in pop. Since there is a selection factor by antibiotics, the resistant strains succeed for reproduction while unlucky die out.
