phage induces a change in the phenotype of the infected bacteria that is not part of a usual phage cycle. Changes can often involve the external membrane of the cell by making it impervious to other phages or even by increasing the pathogenic capability of the bacteria for a host. In this way, temperate bacteriophages also play a role in the spread of virulence factors, such as exotoxins and exoenzymes, amongst bacteria. This change then stays in the genome of the infected bacteria and is copied and passed down to daughter cells. Bacterial survival Lysogenic conversion has shown to enable biofilm formation in Bacillus anthracis Strains of B. anthracis cured of all phage were unable to form biofilms, which are surface-adhered bacterial communities that enable bacteria to better access nutrients and survive environmental stresses. In addition to biofilm formation in B. anthracis, lysogenic conversion of Bacillus subtilis, Bacillus thuringiensis, and Bacillus cereus has shown an enhanced rate or extent of sporulation. Sporulation produces endospores, which are metabolically dormant forms of the bacteria that are highly resistant to temperature, ionizing radiation, desiccation, antibiotics, and disinfectants. Bacterial virulence Non-virulent bacteria have also been shown to transform into highly virulent pathogens through lysogenic conversion with the virulence factors carried on the lysogenic prophage. Virulence genes carried within prophages as discrete autonomous genetic elements, known as morons, confer an advantage to the bacteria that indirectly benefits the virus through enhanced lysogen survival. Examples: Corynebacterium diphtheriae produces the toxin of diphtheria only when it is infected by the phage β. In this case, the gene that codes for the toxin is carried by the phage, not the bacterium. Vibrio cholerae is a non-toxic strain that can become toxic, producing cholera toxin, when it is infected with the phage CTXφ. Shigella dysenteriae, which produces dysentery has toxins that fall into two major groups, Stx1 and Stx2, whose genes are considered to be part of the genome of lambdoid prophages. Streptococcus pyogenes, produce a pyrogenic exotoxin, obtained by lysogenic conversion, which causes fever and a scarlet-red rash, scarlet fever. Certain strains of Clostridium botulinum, which causes botulism, express botulinum toxin from phage-tranduced genes. Preventing lysogenic induction Strategies to combat certain bacterial infections by blocking prophage induction (the transition from the lytic cycle to the lysogenic cycle) by eliminating in vivo induction agents have been proposed. Reactive oxygen species (ROS), such as hydrogen peroxide, are strong oxidizing agents