Lysis

About: Lysis is a research topic. Over the lifetime, 6072 publications have been published within this topic receiving 216978 citations.

Killing and Lysis of Gram-negative Bacteria Through the Synergistic Effect of Hydrogen Peroxide, Ascorbic Acid, and Lysozyme

Abstract: A mixture of hydrogen peroxide and ascorbic acid has been found to generate an antibacterial mechanism which is active against gram-negative bacteria. It results in bacterial death and renders the organism sensitive to lysis by lysozyme. Under the conditions used, horseradish peroxidase did not augment the antibacterial effect. It is suggested that the effector mechanism involves the generation of short-lived free radicals which disturb the integrity of the cell wall. This effect alone might kill bacteria by interfering with selective permeability, but in the presence of lysozyme a further bactericidal activity is accomplished by complete disruption of the cell. It is proposed that a transient antibacterial system such as that described could exist within phagocytic cells. Free radicals would be formed through the interaction of certain oxidizable substances and hydrogen peroxide, which is produced during the enhanced metabolic activity that accompanies ingestion of bacteria. Such a system would help to explain why macrophages, which are apparently devoid of preformed bactericidins, are nonetheless very efficient in killing most phagocytosed bacteria.

Effects of Bacteriophages on the Population Dynamics of Four Strains of Pelagic Marine Bacteria.

Abstract: Viral lysis of specific bacterial populations has been suggested to be an important factor for structuring marine bacterioplankton communities. In the present study, the influence of bacteriophages on the diversity and population dynamics of four marine bacterial phage-host systems was studied experimentally in continuous cultures and theoretically by a mathematical model. By use of whole genome DNA hybridization toward community DNA, we analyzed the dynamics of individual bacterial host populations in response to the addition of their specific phage in continuous cultures of mixed bacterial assemblages. In these experiments, viral lysis had only temporary effects on the dynamics and diversity of the individual bacterial host species. Following the initial lysis of sensitive host cells, growth of phage-resistant clones of the added bacteria resulted in a distribution of bacterial strains in the phage-enriched culture that was similar to that in the control culture without phages after about 50-60 h incubation. Consequently, after a time frame of 5-10 generations after lysis, it was the interspecies competition rather than viral lysis of specific bacterial strains that was the driving force in the regulation of bacterial species composition in these experiments. The clonal diversity, on the other hand, was strongly influenced by viral activity, since the clonal composition of the four species in the phage-enriched culture changed completely from phage-sensitive to phage-resistant clones. The model simulation predicted that viral lysis had a strong impact on the population dynamics, the species composition, and the clonal composition of the bacterial community over longer time scales (weeks). However, according to the model, the overall density of bacteria in the system was not affected by phages, since resistant clones complemented the fluctuations caused by viral lysis. Based on the model analysis, we therefore suggest that viral lysis can have a strong influence on the dynamics of bacterial populations in planktonic marine systems.

Isolation of deoxyribonucleic acid and ribosomal ribonucleic acid from bacteria.

Abstract: 1. Nucleic acids were released from Escherichia coli by lysing with tri-iso-propylnaphthalene sulphonate and 4-aminosalicylate and then extracting with a phenol-cresol mixture. 2. Nucleic acids were similarly released from Bacillus subtilis after initial treatment with lysozyme. 3. DNA was sedimented after careful precipitation with m-cresol or 2-butoxyethanol (0.1-0.12vol.) in the presence of 20% sodium benzoate. 4. Contaminating ribosomal RNA was removed by precipitation in the presence of 4m-sodium chloride or by extracting DNA with an acetate-butyrate mixture, in which RNA is insoluble. 5. The DNA from B. subtilis has a transforming ability of 0.3-0.6% for the tryptophan marker. 6. Ribosomal RNA was then precipitated with rapidly labelled RNA by the addition of an equal volume of 2-butoxyethanol. 7. There was good separation of the nucleic acids from protein and polysaccharides.

Method for the lysis of Gram-positive, asporogenous bacteria with lysozyme.

Abstract: A method developed for the lysis of oral streptococci that employed the action of lysozyme suspended in dilute tris(hydroxymethyl)aminomethane-hydrochloride buffer containing polyethylene glycol has been adapted for use with lactobacilli, actinomycetes, propionibacteria, and pediococci Most of the cellular deoxyribonucleic acid was liberated from many strains of bacteria usually thought to be lysozyme resistant The major observations were as follows: (i) supplementation of the growth medium with L-threonine, L-lysine, or both frequently produced cells that were more susceptible to lysis by lysozyme; (ii) glucose-containing media produced cells that were more easily lysed than those from cultures grown on other substrates; (iii) polyethylene glycol not only served as an osmotic stabilizer, it also enhanced the extent of lysis; and (iv) dilute tris(hydroxymethyl)aminomethane buffer was superior to the buffer systems most commonly employed in published muramidase-based lysis techniques Stationary-phase cells of Lactobacillus casei and Streptococcus mutans were more easily lysed than those isolated from log-phase cultures The method as detailed in this report should be generally applicable for the lysis of gram-positive, asporogenous bacteria