Identification Via Dna Fingerprinting

Introduction

DNA fingerprinting, also known as genetic fingerprinting or DNA profiling, is a technique which can compare DNA samples (Lackie, 2010). DNA fingerprinting first developed and used in 1980s, and it is able to determine the possible genetic relationship between individuals or establishing an individual’s identity (Colman, 2015).

There are two parts in the DNA sequence for a eukaryotic cell, coding sequence (exons) which are segments of genes, and non-coding sequence (introns) (Jin, et al., 2016). Different individuals have different cleavage of DNA, which would result in different sets of restriction fragments with the assist of the restriction enzymes (Hine & Martin, 2015). The existing restriction sites would then be deleted and some new sites would be created, therefore random base changes would happen in the non-coding sequence, and this DNA-DNA hybridization technique is called restriction fragment length polymorphism (RFLP) (Hine & Martin, 2015).

In the research of the treating antibiotic resistant golden staph (MRSA) using bacteriophages, one culture was contaminated by mud accidently. All the MASA in that culture died, while the culture had already been autoclaved. DNA that were able to extract were just enough as an unknown sample for fingerprinting. In order to find out the identity for the unknown bacteriophage, three DNA samples were extracted from the three most abundant strains. The strain X is confirmed to be ΦTCH60. The strain ΦTCH60 is a kind of phage which has elongated heads with the genes encoding Panton-valentine leucocidin (PVL) (Chen, et al., 2013). The strain Y which is found to be SPA-26 is an induced phage, it was clinically isolated from Staphylococcus aureus. The phage SPA-26 includes 63 frames coding by double-stranded 41,270 bp DNA (Rahman, et al., 2011). For treatment combined with SPA-26, there are a clear biofilm removal effect and induced structural changes showed in the biofilm matrix, and a decreasing trend of bacteria number can also be found (Rahman, et al., 2011). The strain Z, ΦSH19, is a bacteriophage that was isolated from pig intestinal content (Hooton, et al., 2011). It is a phage in the Myoviridae Family with the characteristics of an icosahedral head and a contractile tail (Hooton, et al., 2011).

Virulent bacteriophages are used as biological control agents in order to fighting against pathogens. For the traditional treatment for Staphylococcus aureus, there is a high rick if device-related infections (DVIs) for diagnosing and treating in the hospitals (Chopra, et al., 2015). To reduce DVIs, the effectiveness of fighting against biofilm bacteria is restricted (Chopra, et al., 2015). Biofilm often adhere to damaged tissue because of its multi-layered structure with sessile cells and outer extracellular matrix (Chopra, et al., 2015). Therefore, it is hard to treat the biofilm bacteria using antibiotics as the extracellular