Padronização de extração de DNA de bacteriófago

Abstract

Bacterial resistance to conventional antibiotics has become increasingly recurrent, becoming a serious problem for public health. This has been a stimulus for the study of new forms of treatment, either with other antimicrobial substances, or with alternative therapies, such as phage therapy. This is taken as a form of biological control, using bacteriophages which are viruses that specifically infect bacterial cells. This work used the bacteriophage model T4 in the infection of the bacterium Escherichia coli strain B4. Thus, the virus was cultured in the host bacterium and, after removal of the bacterial DNA and RNA, the virus was concentrated using polyethylene glycol / NaCl. The virus was then lysed using proteinase K / SDS and the DNA was phenol / chloroform extracted, followed by precipitation with sodium acetate / isopropanol. After centrifugation, the precipitate was washed with 70% ethanol, resuspended in Tris-EDTA buffer and subjected to agarose gel electrophoresis. This protocol was based on two other protocols tested, with changes in PEG concentration and incubation, and change in incubation time for precipitation with sodium acetate and isopropanol. Using the protocol C obtained after the changes, DNA with molecular mass above 20 Kbp was observed. Thus, it will be possible to obtain DNA from other bacteriophages, for characterization and evaluation of their potential in bacterial cell lysis.