"Serial passage of bacteria can result in increased genomic diversity of derivative strains relative to the parental strain"
Article In Vitro Serial Passage of Staphylococcus aureus: Changes in...
Is there any text that mentions the effect of the type of media on the degree of this occurrence, for example, the effect of MacConkey on Gram-negative and Mannitol salt agar on Gram-positive?
Depends for how many generations you are maintaining the strain. Like all laboratory adapted strains you will find some evolutionary adaptation to the media of choice over time.
What is the microorganism in question? If it grows well on MacConkey and is in pure culture - no. Do you ask how many passages from isolation when you purchase an ATCC strain?
That said, USP does specify no more than 5 transfers from ATCC product for preservative challenge testing - but not aware of supporting data.
Passing bacterial strains through MacConkey agar is not disastrous for research purposes. MacConkey agar is a selective and differentiating medium that only grows gram-negative bacteria and further differentiates them based on their lactose metabolism. It is commonly used in clinical microbiology for the isolation and identification of gram-negative organisms. Therefore, using MacConkey agar can be a valuable tool in differentiating and isolating bacterial species from samples, particularly gram-negative bacteria. It is important to consider the specific research objectives and the characteristics of the bacterial strains being studied when selecting the appropriate growth medium.
First 2 potentially yes, as media compounds can induce or repress the expression of some genes so you might get different results depending on what media you choose to perform the tests on. As long as you do an overnight culture in the correct media before plating on the desired media there should be no long term problems. PCR detection will be unaffected. Also plasmids are known to carry enzymes involved in antimicrobial resistance and substrate metabolism.
Robert Adolf Brinzer I was speaking about mutations instead of phenotypic variations. It's my bad, i think should rewrite the question for clarity.
Mahmoud Gharieb
No. It does not. Not antimicrobial susceptibility, biochemical physiology, PCR. Please understand, it is common in clinical and industrial settings to isolate Gram negative bacteria using selective media followed by such further investigation using other appropriate media and technique.
Why do you think mutation rate would be induced on MacConkey vs any enrichment medium- if the bug grows well so is not inhibited by bile salts, crystal violet etc.
If bugs were that vulnerable, clinical and indsutrial micro and taxonomy would be a total mess.
Yes, the type of culture media used for serial passage of bacterial strains can influence the mutations that occur.
Different types of culture media can influence the mutations that occur in bacterial strains through various mechanisms:
1. Nutrient composition: Culture media with different nutrient compositions can affect the metabolic state of bacteria. Nutrient limitation or excess can induce stress conditions that increase the likelihood of mutations.
2. Chemical components: Culture media may contain specific chemicals or compounds that can act as mutagens or affect DNA replication fidelity, leading to an altered mutation rate.
3. Selective pressure: Some culture media contain antibiotics or other selective agents. This can promote the emergence of mutations that confer resistance to those agents.
4. Growth conditions: Factors such as temperature, pH, and oxygen levels in the culture media can influence mutation rates by affecting DNA replication fidelity, DNA repair processes, and the generation of reactive oxygen species.
5. Induced stress conditions: Certain media formulations may induce specific stress conditions (e.g., oxidative stress, osmotic stress), which can trigger genetic changes in bacteria.
It's important to note that the specific mutations that arise also depend on the genetic background of the bacteria, their inherent mutation rates, and the presence of mutagenic agents (both natural and added) in the culture media.
Overall, the variations in culture media can create different growth conditions and selective pressures, thereby influencing the types and frequencies of mutations that occur in bacterial strains.
good luck
Djihad chenna
Certainly, the possibility of mutations may be influenced by the unique conditions or compositional differences in the culture media. These variations have the potential to impact the selective pressures acting on the bacteria. For instance, when a medium lacks essential nutrient or contains antibiotics and/or toxic compounds, bacteria may undergo mutations as an adaptive response to ensure survival.
No - serial passage per se does cause mutation any more than any culture that reproduces. Any viable isolate undergoes constant serial culture - else it ceases to exist. Mutations are constant and most are lethal.
Article Mutation—The Engine of Evolution: Studying Mutation and Its ...
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