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When he added nasal mucus, he found that the mucus inhibited the bacterial growth. [15] Surrounding the mucus area was a clear transparent circle (1 cm from the mucus), indicating the killing zone of bacteria, followed by a glassy and translucent ring beyond which was an opaque area indicating normal bacterial growth. In the next test, he used ...
Many species of bacteria are subject to lysis by the enzyme lysozyme, found in animal saliva, egg white, and other secretions. [1] Phage lytic enzymes produced during bacteriophage infection are responsible for the ability of these viruses to lyse bacterial cells. [2]
Lysozyme (EC 3.2.1.17, muramidase, N-acetylmuramide glycanhydrolase; systematic name peptidoglycan N-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycoside hydrolase that catalyzes the following process:
Double-stranded DNA phage lysins tend to lie within the 25 to 40 kDa range in terms of size. A notable exception is the streptococcal PlyC endolysin, which is 114 kDa. PlyC is not only the biggest and most potent lysin, but also structurally unique since it is composed of two different gene products, PlyCA and PlyCB, with a ratio of eight PlyCB subunits for each PlyCA in its active conformation.
Virulent bacteriophages multiply in their bacterial host immediately after entry. After the number of progeny phages reach a certain amount, they cause the host to lyse or break down, therefore they would be released and infect new host cells. [20] The process of host lyses and release is called the lytic cycle. Lytic cycle is a cycle of viral ...
In a series of experiments at the University of Berlin, he found that sugar was fermented by yeast extracts even when there were no living yeast cells in the mixture. [14] He named the enzyme that brought about the fermentation of sucrose "zymase". [15] In 1907, he received the Nobel Prize in Chemistry for "his discovery of cell-free fermentation".
Lysogens can remain in the lysogenic cycle for many generations but can switch to the lytic cycle at any time via a process known as induction. [8] During induction, prophage DNA is excised from the bacterial genome and is transcribed and translated to make coat proteins for the virus and regulate lytic growth. [8] Lysogenic Cycle [9]
The RM system was first discovered by Salvatore Luria and Mary Human in 1952 and 1953. [1] [2] They found that a bacteriophage growing within an infected bacterium could be modified, so that upon their release and re-infection of a related bacterium the bacteriophage's growth is restricted (inhibited; also described by Luria in his autobiography on pages 45 and 99 in 1984). [3]