Hi Dr. Tuqa
Bacterial genomes are remarkably stable from one generation to the next but are plastic on an evolutionary time scale, substantially shaped by horizontal gene transfer, genome rearrangement, and the activities of mobile DNA elements. This implies the existence of a delicate balance between the maintenance of genome stability and the tolerance of genome instability.
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3957733/&ved=2ahUKEwiRz-Sd-ZfpAhXNCuwKHQ5tC6sQFjAKegQIBBAB&usg=AOvVaw2WZKxYyiCBGJ2-DbIMoQ6a
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1317469/&ved=2ahUKEwjN8JyfgpjpAhUQ3qQKHRhIArwQFjAKegQIARAK&usg=AOvVaw0l0kVVj-ECozsJJX0vBfbA
the protein being expressed upsets the bacterium without being lethal, it will grow but find a way to lose the gene. Plasmid may be retained with mutated gene or gene excised, Kanr may even be incorporated into
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https://www.researchgate.net/deref/https%3A%2F%2Fwww.google.com%2Furl%3Fsa%3Dt%26source%3Dweb%26rct%3Dj%26url%3Dhttps%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC3957733%2F%26ved%3D2ahUKEwiRz-Sd-ZfpAhXNCuwKHQ5tC6sQFjAKegQIBBAB%26usg%3DAOvVaw2WZKxYyiCBGJ2-DbIMoQ6a
Hi dear
Concern plasmid it May be lost from bacterial isolates due external effectors looks like physical or chemical agents leading to absence of Some traits like Antibiotic and heavy metals resistance
BR
Hi Dr.
can see this
Article Effects of Long-Term Storage on Plasmid Stability in Bacillu...
Genetic charecters of isolates remain stable if preserve under freezing at -70.
It depends upon how you are storing it. If storage is in stabs at room temperature, then it is possible to pick up variants although I would not expect all the cells to have mutated, just a subpopulation. There is some slow growth in stabs.
If storage is at -70C then there should be no changes. If the cells are not growing and replicating, there should be no changes. Note that when you freeze away a large population of cells there are going to be preexisting mutations in that population, just like you would find in any culture. But there won't be changes due to storage at ultra low temperatures.
If bacteria stored under deep freeze conditions (-80), it will remain genetically stable over time.
Hi Dr. This differs in time and quality according to the methods and conditions of storage
sure, both genotypic and phenotypic features of organisms change overtime specially when they put under pressure.
I always make fresh glycerol stocks from the primary culture and use them for 2-3 months, before subculturing and making another batch and store it ..
Newly acquired plasmids are frequently lost due to fitness ... of IncQ plasmids as agents of bacterial gene transfer in nature. ... 2: Time courses of plasmid evolution in E. coli.
Yes, Assist Lec.Tuqa Abdul Kareem Hameed, it could happen. The thing is these prokaryotic organisms don't like carrying around vast circular DNA segments (plasmids) for no reason. At various time points (think of replication, transcription and translation) they cost them various resources like their energy currency ATP, nucleotides and multiple enzymes (polymerase, helicase, etc.), which they could have avoided if they didn't have them in the first place. But they still carry it around because it equips them with additional features like antibiotic resistance and bacteriocin. But, in the absence of stress conditions (like antibiotic resistance), they can lose their plasmids, and this is why it is recommended to store bacterial samples with some selective pressure. There have been multiple reports on bacterial plasmid loss; I will link a few:
- Bacterial fitness and plasmid loss: the importance of culture conditions and plasmid size https://www.nrcresearchpress.com/doi/abs/10.1139/w98-020#.XrGsFqgzZPY
- The kinetics of plasmid loss
Article The kinetics of plasmid loss
- Enhanced plasmid loss in bacterial populations exposed to the antimicrobial compound irgasan delivered from interpenetrating polymer network silicone hydrogels
Article Enhanced plasmid loss in bacterial populations exposed to th...
Hi, the following link of paper might be helpful for your understanding. You can study via -https://aem.asm.org/content/aem/71/12/7778.full.pdf
Thanks.
Whenever you will get any bacterial species either from clinical settings or from the environmental source, kindly follow the following steps
1. After porper identification, sub-culture it in an appropriate media.
2. On next day, inoculate one single colony in tryptic soy broth under antibiotic pressure. Selection of antibiotic will depend upon your plasmid preference. If your organism is an MDR, use any broad-spectrum candidate.
3. Make glycerol stock (600ul of culture + 400ul of autoclaved 50% glycerol) and store it at -80 degree freezer.
Genomic variation could occur during long-term preservation.
The following paper might be helpful for you:
Article Genetic variation during long-term preservation of bacteria ...
Well,
Plasmid loss in the form of segregational instability and plasmid copy number reduction in nonselective environments are important to the understanding of the evolution of the bacteria-plasmid associations and the appreciation of the potential for altering the genetic properties of a clone maintained or subcultured on a standard medium.Smith
Regards
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