Inhibition of Bacterial Growth by Bacteriophage as distinct from Lytic Action

Abstract

SUMMARY:Certain races of streptococcal phage with a normal lytic action on some strains of streptococci were found to be adsorbed on, and to inhibit the growth of, other strains, without the occurrence of lysis or multiplication of the phage. One race of phage inhibited the growth of several streptococcal strains which had hitherto been considered unrelated to one another on the basis of their reactions to lytic phages. Cultures which recovered from temporary inhibition by phage contained variants which were resistant both to inhibition and to lysis by phages which attacked the original strain. This resistance is, however, short-lived as compared with the resistance of variants obtained through the action of a lytic phage.The typical interaction between bacteriophage and bacterium is that in which adsorption of phage is followed after an interval by lysis of the bacterium and a many-fold increase in number of phage particles. The, majority of workers now visualize phage as a bacterial parasite which grows in or on the bacterial cell, ultimately causing lysis with liberation of phage particles. There are, however, other types of association between phage and! bacterium to which this picture does not apply. For instance there are the cases where bacteria are lysogenic, or where resistant organisms support the growth of an associated phage. Another association which is not followed! by lysis or phage reproduction has also been observed. Rakieten & Rakieten (1937) and Rakieten & Tiffany (1938) observed that staphylococcus phages were absorbed on strains of Bacillus subtilis and of enterococci without apparent effect on the growth of these organisms. Andrewes & Elford (1932) and Adams (1949) reported observations on 'citrate sensitive' coli phages which, in the absence of calcium, attached themselves to bacteria, prevented bacterial multiplication, but did not cause lysis. Felix (1949) reported that with certain salmonella adsorption of phage was not always followed by lysis.We have encountered in the group of lactic streptococci some instances of phage adsorption without subsequent lysis. Certain phage races which exert a lytic effect on some strains of streptococci are adsorbed by other strains without any lytic effect and when present in relatively high concentration the adsorbed phage inhibits the growth of the adsorbing organisms. It appears that adsorption takes place as usual but that subsequent growth of the phage, normally leading to lysis, is blocked. This blockage also results. apparently in interference with the metabolism of the bacterium. MATERIALS AND METHODS Cultures.The eight bacterial cultures used were strains of Streptococcw cremoris as used in commercial cheese manufacture. They had been isolated in this Institute over about 17 years, and were selected on the bases of acid-

Partial purification and some properties of øC2(W) lysin, a lytic enzyme produced by phage-infected cells ofStreptococcus lactisC2

“…The results of this study provide further evidence for the difference in the thermal lability of lactic streptococcal phages and their lysins and may explain why some early studies of the nascent phenomenon (Collins, 1952;Whitehead et al 1952) did not find evidence for a lytic agent other than particulate phage.…”

Plaque Morphology of Certain Streptomycete Phages

“…The effect may be caused by a proteinaceous agent, similar to colicin, pyocin, or bacteriocin, released from the maintenance host by phage-induced lysis. This reaction is also reminiscent of a phenomenon reported by Andrewes andElford (1932) andWhitehead et al (1952) that certain phages can adsorb onto and kill cells or inhibit growth without penetrating and multiplying in the host.…”

Contrasting genomic patterns and infection strategies of two co‐existing Bacteroidetes podovirus genera

“…lytic versus lysogenic, is critical to determine, as it alters the ecological impact of phage‐host interactions. For example, lytic phage infection turns hosts into a phage factory and ultimately kills them (Whitehead et al ., ), while temperate phages spend time in the lysogenic cycle where their genome remains either extrachromosomal or integrated into the host genome (Bertani and Bertani, ; Jiang and Paul, ), potentially improving the host's fitness (Anderson et al ., ). This can include growth improvement as seen in Escherichia coli when temperate phage lambda is integrated (Edlin et al ., ) and resistance to superinfection, as seen for lambda‐like phages infecting Salmonella (Bossi et al ., ).…”