Transfer of genetic information … In Hansenula polymorpha recombinant strains, up to 100 copies were generated. Chapter 14 Lecture Notes: Microbial Genetics – Recombination and Plasmids I. In an early template for future synthetic phage design the filamentous phage Pf3 was modified to treat Pseudomonas aeruginosa infection in a mouse model.50 An export protein gene of Pf3 was replaced with a gene encoding the BglII restriction endonuclease, with the reasoning that (1) this gene replacement renders Pf3 non-replicative thereby introducing a containment strategy, (2) the phage can be stably propagated in a host containing the BglII methylase gene and (3) the BglII would catalyze double strand breaks in genomic DNA of the target strain for killing. Even in the case of successful killing of a target strain, the rapid lysis of a large number of bacteria and the concomitant release of endotoxins and superantigens may result in a strong infammatory response and an unfavourable clinical outcome. Transformation is the process of DNA uptake by the bacteria from the surrounding environment. The bacteria are grown on an agar medium with antibiotics to check for transformed cells. Due to this, the phage genome sometimes carries the bacterial genome with it and integrates it into the genome of the recipient cell. It has been a model system for the study of bacterial metabolism, the cell division process, cell wall biosynthesis, chemotaxis, Brenner's Encyclopedia of Genetics (Second Edition), Somatic Cell Genetics of Higher Plants: Appraising the Application of Bacterial Systems to Higher Plant Cells Cultured in Vitro, Although higher plant cells may have more in common with the fungi or the blue-green algae than with bacteria, we have chosen to compare them with the nonfilamentous bacteria, the Eubacteriales. Bacteria deploy numerous anti-phage systems, principle ones being the innate immunity of restriction-modification and the adaptive immunity of CRISPR/CAS, but conversely so have phage counter-evolved multiple strategies to defeat these systems such as using non-canonical nucleotides in their DNA, having fewer restriction sites or hyper methylating their genomes and delivering proteins that inhibit restriction enzymes or enhance methylating enzymes of the host. We use cookies to help provide and enhance our service and tailor content and ads. Prokaryotic genome (Bacterial): consist of a single copy (Haploid) ciruclar DNA molecule. Cancer cells are characterized by genomic instability and one cause of this instability is an imbalance of DNA damage signaling and repair. The high genetic diversity of the E. coli genome is also reflected by the large variation in DNA content between different strains [4–6] and by the distribution or genomic location (insertion site) of different virulence determinants [7, 8]. For example, inherited defects in MMR predispose carriers to hereditary nonpolyposis colon cancer and inherited defects in BRCA1 and BRCA2, which are important in HR, predispose carriers to breast and ovarian. Remaining targets for phage engineering are generic to many biologics, such as stability and response of the immune system. Copyright © 2020 Elsevier B.V. or its licensors or contributors. The genetics of bacteria is very different from that of higher organisms. That is, a donor cell transfers genes to a recipient cell rather than two cells sharing genetic information to generate progeny as in higher organisms. PowerPoint lecture on Microbial Genetics used in an actual college microbiology classroom. It has been suggested that tigecycline's tighter binding to the ribosome does not allow displacement by the RPPs. There are three different types of horizontal transmission for the transfer of genetic information. Plasmids may have either a high copy number or low copy number. Furthermore, phage can only infect bacteria expressing the correct receptor, so there is a tropism to the transfer of DNA.A.S. Importantly, however, in Acinetobacter baumannii, the AdeABC efflux pump, a well-characterized multidrug efflux pump, readily removes tigecycline from the intracellular space. He is a member of the Danish Medical Research Council and on its executive board from 1988 to 1991. Pathogenic E. coli cause various diseases in humans, including several types of diarrhea, urinary tract infections, sepsis, and meningitis (Table I). These studies were very exciting because they indicated for the first time that inhibition of PARP could be selectively toxic to at least a subset of tumors. Further the broad host range combined with CRISPR arrays targeting several antibiotic resistance or virulence genes could allow the use of presumptive phage therapy, that is before pathogen identification. Interestingly this study also demonstrated that the BRCA1 methylation that silenced breast cancer UACC3199 cell line was also sensitive to PARP inhibition suggesting a wider role for these agents in non-BRCA mutated cancers, and there is emerging clinical evidence to confirm this with the observation by Gelmon et al. Expression of the genes encoding this variety of virulence factors is often modulated in response to a series of environmental cues such as temperature, ion concentrations, osmolarity, iron levels, pH, carbon source availability, growth phase, and oxygen levels [25]. View Notes - Bacterial Genetics Notes .pdf from BIOLOGY 141 at Emory University. Transduction is the process of transfer of genes from the recipient to the donor through bacteriophage. Mogens Kilian is professor of medical microbiology at the University of Aarhus (since 1991). DNA replication, genetic characters, their changes & transfer to next generations. The killing of P. aeruginosa by Pf3R relies on the phage host range to provide specificity of targeting as BglII restriction sites would be expected to be present in essentially all bacterial genomes. In Eastern Europe phage therapy became common place and several renowned treatment centers exist to this day, for example, in Georgia and Poland. Don't show me this again. Aside from a minimal number of relevant references to other systems, we find sufficient examples that illustrate diverse selection schemes among studies of two groups of gram-negative bacteria: the coliform bacteria and the fluorescent pseudomonads, soil bacteria. By continuing you agree to the use of cookies. Although higher plant cells may have more in common with the fungi or the blue-green algae than with bacteria, we have chosen to compare them with the nonfilamentous bacteria, the Eubacteriales. Characteristics a) Much smaller than the chromosome (<1/20th the size), ranging in size from 200 kb to 2 kb. The donor and the recipient strand both contain a single strand of the F-plasmid. Cellular DNA is subject to a variety of insults from endogenous (eg, oxygen radicals formed as part of normal metabolism) and exogenous (eg, UV) sources on a continuous basis. This is one of over 2,200 courses on OCW. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL:, URL:, URL:, URL:, URL:, URL:, URL:, URL:, URL:, URL:, David P. Clark, ... Michelle R. McGehee, in, Disruption of Protease Genes in Microbes for Production of Heterologous Proteins, New and Future Developments in Microbial Biotechnology and Bioengineering, Industrial Biotechnology and Commodity Products, Comprehensive Biotechnology (Third Edition). These factors induce actin rearrangements and activation of particular signal transduction pathways that result in disease [23]. This is carried out by temperate bacteriophage which undergoes the lysogenic cycle. Conjugation is carried out in several steps: 1. C. DNA Replication 1. Plasmids, and sometimes bacterial chromosomes, are transferred between two cells during bacterial mating. Bacteria can acquire DNA (i.e., new genes) in 3 basic ways: 1) Transformation • uptake and retention of external DNA molecules 2) Conjugation • direct transfer of DNA from one bacterium to another 3) Transduction • the transfer of DNA between bacteria by a virus Among many honors, Luria received a Nobel Prize for Physiology and Medicine in 1969, sharing it with Max Delbrück and Alfred Hershey. Bacterial transformation is the transfer of free DNA released from a donor bacterium into the extracellular environment that results in assimilation and usually an expression of the newly acquired trait in a recipient bacterium.. The use of phages has several advantages over antibiotics, primarily the potential to target specific strains and thereby leave the beneficial microbial community intact, and also the ability to overcome resistance by use of complementing phage cocktails, ‘training’ phages on selected host strains or simply isolating new phages against a pathogen. The cells that survive and grow are transformed cells. Extensive use of tetracyclines in humans and in the veterinary field as growth promoters led to widespread selection and dissemination among bacteria of genetic determinants encoding ribosomal protection proteins (RPP) and major facilitator superfamily (MFS) drug efflux pump-mediated resistance mechanisms.5 Most of these acquired tetracycline resistance genes reside on transposons, conjugative transposons and/or integrons which permit horizontal resistance transfer from one species to another and between unrelated genera.5 Resistance to first- and second-generation tetracyclines is now relatively common among bacteria causing respiratory tract infections such as pneumococci. Bacterial Genetics; A significant portion of bacterial genetics, the study of bacteria, have been devoted to medical and industrial purposes. Major advances in bacterial genetics have been made with Escherichia coli K12; consequently, some people tend to equate bacterial genetics with E. coli. Long-circulating phage mutants were obtained by a serial passage technique58 and were found to be mutated in the major capsid protein. B. Dec 15, 2020 - Bacterial genetics MBBS Notes | EduRev is made by best teachers of MBBS. The bacterial chromosome is a long circle of deoxyribonucleic acid (DNA) that is attached to the membrane of the cell. Conjugation does involve cell contact. In this way phage could be readily deployed for treatments, without a new platform having to be isolated ad hoc for each pathogen. Only the bacteria containing the antibiotic resistance gene will grow in the presence of antibiotic. The virus enters the bacteria and integrates its genome within the host cell DNA. EIEC behaves as Shigella, in that it contains the same virulence factors (e.g., type III secretion system, invasins, and intracellular spread mechanism) that are responsible for producing a dysentery-like disease [21]. Bacterial infections that cause human illness can be prevented by vaccines or can be cured by antibiotics. Overview: Microbial Model Systems. They discovered that the F-factor can move between E.coli cells and proposed the concept of conjugation. Science Prof Online (SPO) is a free science education website that provides fully-developed Virtual Science Classrooms, science-related PowerPoints, articles and images. Later a single amino acid change, also in a capsid protein, introduced by direct genetic manipulation resulted in a 13,000 to 16,000-fold increased capacity for the phage to remain in the mouse circulatory system.59 Other parameters to improve phage as therapeutic agents, such as production, formulation and route of administration probably fall outside the scope of SB activities, but the lessons learned from previous work with native phages will also apply to SB engineered phages. EHEC produces a Shiga-like toxin (similar to that found in Shigella dysenteriae) that seems to be involved in causing the hemolytic uremic syndrome in a proportion of cases [22]. Range from 580-4600 Kbp Many bacteria contain extra chromosomal DNA materials as apart of genome called plasmid and transposons. Virulence gene expression is determined by a consensus response to a mixture of these different biochemical and physical parameters that allows the bacterial cell to identify and exploit a particular extracellular or intracellular niche. This opens the way for improved genetic engineering of bacteria.