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Short answer Toxicity of salt depends on contact time. 50 g NaCl per liter kills nearly all bacteria in 2 days. 100 g NaCl/L may do a quite thorough job in 30 minutes. Background Body odor is caused by bacteria that feed on the fluids produced by the apocrine glands, mainly present under the arm pits and other areas with abundant hair follicles. Bacteria in ...


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Yes there are many such mechanisms. One of the simplest, but perhaps most easily overlooked, is metabolism. Conjugation requires ATP. In environments with low levels of nutrients, heterotrophs might not have enough "extra" ATP to fuel the conjugation process. Note that both donor and recipient need to expend ATP in conjugation. The donor needs to make ...


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It's because E.coli BL21(DE3) are competent cells. The competent is the key here as the cells were chemically treated so the transfection can be performed by heat-shock with high efficiency. This means these bacteria are quite fragile, due to the chemical treatment, and therefore are very sensitive to both mechanical and thermal shocks. Pre-heating the ...


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As to why they don't recognize RNA-DNA heteroduplexes (which are present during transcription, for example), I suspect that the methylation which protects bacterial genomic dsDNA (see the DNA modifying enzyme section of this Columbia University lecture for more info) also protects RNA-DNA hybrids, as the genomic DNA would still be methylated. Note that most ...


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This is a matter of pragmatism in the culture process. Taking 100 colonies instead of 1 increases the inoculation volume by a factor of 100, which then saves you perhaps 2 hours of bacterial growth time before your culture reaches the OD you want. However, mutations and loss of plasmid in culture, while unlikely, are possible, especially if the bacteria ...


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While all colonies on a selective media SHOULD contain a resistance gene, that's a long way from them containing the plasmid you want. A typical cloning experiment will insert a gene of interest into a empty vector backbone to make an intact plasmid. The backbone usually contains some antibiotic resistance gene. If your gene of interest is not correctly ...



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