Unauthorized Horizontal Spread in the Laboratory Environment: The Tactics of Lula, a Temperate Lambdoid Bacteriophage of Escherichia coli

Rotman, Ella; Amado, Luciana; Kuzminov, Andrei

doi:10.1371/journal.pone.0011106

Cited by 25 publications

(51 citation statements)

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“…The Lula prophage was found to contaminate a significant fraction of E. coli laboratory strains, stealthily spreading in the laboratory environment-a highly unusual feat (75). In fact, Lula contamination is so pervasive that at the time of its initial sequence analysis, its tail fiber protein gene (gene 21) returned 99% identity to two human loci (LOC338829 and LOC392563; records of these human genes were later discontinued).…”

Section: Discussionmentioning

confidence: 99%

“…Until recently, however, no such creature was known for cultures of rapidly growing microbes, which, precisely because of their speed of growth, effectively deny such chances to a contaminating competitor. This has changed with a description of a temperate phage, Lula, that infects Escherichia coli, converts it into a lysogen, and efficiently spreads in the laboratory setting, stealthily contaminating laboratory strains without researchers' knowledge (75). Lula contamination is apparently widespread yet not broadly recognized, and, because of this combination, it can be a scourge in shared facilities that handle both contaminated cultures (lysogens) and noncontaminated cultures (nonlysogens), resulting in a frustratingly high frequency of lysis and growth inhibition of the latter "for no apparent reason."…”

mentioning

confidence: 99%

“…Lula contamination is apparently widespread yet not broadly recognized, and, because of this combination, it can be a scourge in shared facilities that handle both contaminated cultures (lysogens) and noncontaminated cultures (nonlysogens), resulting in a frustratingly high frequency of lysis and growth inhibition of the latter "for no apparent reason." Besides being superinfectious, Lula also changes the phenotype of cells in which it established itself as a lysogen, making them extra sensitive to any DNA damage (75), so its lysogenic conversion is not limited to a typical cross-resistance of lysogens to infection by lytic phages.…”

mentioning

confidence: 99%

“…This is a topic of critical importance for mammalian cell cultures, where viral cross-contamination among cell lines is pervasive, sometimes with fatal consequences for researchers (37). In a previous paper we analyzed Lula's characteristics that allow it to spread in the laboratory setting and concluded that these are (i) stealthy infectivity at 37°C (lysogenization instead of lytic development), allowing Lula infection to avoid detection, and (ii) cryptic lysogen productivity, yielding normally growing cultures of Lula lysogens carrying extremely high loads of infectious phage (75). The latter property is critically enhanced by Lula's stability in stationary-phase cultures (75).…”

mentioning

confidence: 99%

“…In a previous paper we analyzed Lula's characteristics that allow it to spread in the laboratory setting and concluded that these are (i) stealthy infectivity at 37°C (lysogenization instead of lytic development), allowing Lula infection to avoid detection, and (ii) cryptic lysogen productivity, yielding normally growing cultures of Lula lysogens carrying extremely high loads of infectious phage (75). The latter property is critically enhanced by Lula's stability in stationary-phase cultures (75). These characteristics could be the consequence of Lula's distinct genome organization relative to that of other temperate phages or could be due to specific genes unique to Lula.…”

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confidence: 99%

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Genome of Enterobacteriophage Lula/phi80 and Insights into Its Ability To Spread in the Laboratory Environment

et al. 2012

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The novel temperate bacteriophage Lula, contaminating laboratory Escherichia coli strains, turned out to be the well-known lambdoid phage phi80. Our previous studies revealed that two characteristics of Lula/phi80 facilitate its spread in the laboratory environment: cryptic lysogen productivity and stealthy infectivity. To understand the genetics/genomics behind these traits, we sequenced and annotated the Lula/phi80 genome, encountering an E. coli-toxic gene revealed as a gap in the sequencing contig and analyzing a few genes in more detail. Lula/phi80's genome layout copies that of lambda, yet homology with other lambdoid phages is mostly limited to the capsid genes. Lula/phi80's DNA is resistant to cutting with several restriction enzymes, suggesting DNA modification, but deletion of the phage's damL gene, coding for DNA adenine methylase, did not make DNA cuttable. The damL mutation of Lula/phi80 also did not change the phage titer in lysogen cultures, whereas the host dam mutation did increase it almost 100-fold. Since the high phage titer in cultures of Lula/phi80 lysogens is apparently in response to endogenous DNA damage, we deleted the only Lula/phi80 SOS-controlled gene, dinL. We found that dinL mutant lysogens release fewer phage in response to endogenous DNA damage but are unchanged in their response to external DNA damage. The toxic gene of Lula/phi80, gamL, encodes an inhibitor of the host ATP-dependent exonucleases, RecBCD and SbcCD. Its own antidote, agt, apparently encoding a modifier protein, was found nearby. Interestingly, Lula/phi80 lysogens are recD and sbcCD phenocopies, so GamL and Agt are part of lysogenic conversion.T he laboratory setting is, by design, an inhospitable environment, as very few species are capable of overcoming the researcher-imposed barriers for growth, multiplication, and spread. The well-known examples of organisms successfully propagating in the laboratory environment are mycoplasmas (76) and HeLa cells (39), both of which cross-contaminate mammalian cell cultures and spread through the laboratories around the world with appalling ease (48). Part of their success is their rapid growth and hardiness, giving them the ability to outgrow and outlive any laboratory strain competitors. Until recently, however, no such creature was known for cultures of rapidly growing microbes, which, precisely because of their speed of growth, effectively deny such chances to a contaminating competitor. This has changed with a description of a temperate phage, Lula, that infects Escherichia coli, converts it into a lysogen, and efficiently spreads in the laboratory setting, stealthily contaminating laboratory strains without researchers' knowledge (75). Lula contamination is apparently widespread yet not broadly recognized, and, because of this combination, it can be a scourge in shared facilities that handle both contaminated cultures (lysogens) and noncontaminated cultures (nonlysogens), resulting in a frustratingly high frequency of lysis and growth inhibition of the latter "for no ap...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Genome of Enterobacteriophage Lula/phi80 and Insights into Its Ability To Spread in the Laboratory Environment

et al. 2012

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Adding Functions to Biomaterial Surfaces through Protein Incorporation

et al. 2016

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The concept of biomaterials has evolved from one of inert mechanical supports with a long-term, biologically inactive role in the body into complex matrices that exhibit selective cell binding, promote proliferation and matrix production, and may ultimately become replaced by newly generated tissues in vivo. Functionalization of material surfaces with biomolecules is critical to their ability to evade immunorecognition, interact productively with surrounding tissues and extracellular matrix, and avoid bacterial colonization. Antibody molecules and their derived fragments are commonly immobilized on materials to mediate coating with specific cell types in fields such as stent endothelialization and drug delivery. The incorporation of growth factors into biomaterials has found application in promoting and accelerating bone formation in osteogenerative and related applications. Peptides and extracellular matrix proteins can impart biomolecule- and cell-specificities to materials while antimicrobial peptides have found roles in preventing biofilm formation on devices and implants. In this progress report, we detail developments in the use of diverse proteins and peptides to modify the surfaces of hard biomaterials in vivo and in vitro. Chemical approaches to immobilizing active biomolecules are presented, as well as platform technologies for isolation or generation of natural or synthetic molecules suitable for biomaterial functionalization.

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Coping with inadvertent lysis of Escherichia coli cultures: Strains resistant to lysogeny and infection by the stealthy lysogenic phage Φ80

Srinivas

Cronan

2019

Biotech & Bioengineering

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Phage Φ80 can infect Escherichia coli in a stealthy manner and persist by forming lysogens. Such Φ80 lysogens are fairly common and often go undetected unless the host is grown at temperatures below 37°C. Since low growth temperatures are required for growing temperature-sensitive mutants and often preferred for large-scale applications such as protein production, Φ80-resistant strains would be useful. We report the construction of E. coli strains that cannot be efficiently lysogenized or infected by bacteriophage Φ80. These strains contain combinations of deletions or mutations in the bacterial attachment site for Φ80 integration and/or deletions in the genes required for phage absorption to the host outer membrane. These strains should help contain and prevent Φ80 infection of E. coli cultures in a laboratory or industrial setting. K E Y W O R D S contamination, fhuA, lysis, lysogen, phage, tonA, tonB, Φ80

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Unauthorized Horizontal Spread in the Laboratory Environment: The Tactics of Lula, a Temperate Lambdoid Bacteriophage of Escherichia coli

Cited by 25 publications

References 39 publications

Genome of Enterobacteriophage Lula/phi80 and Insights into Its Ability To Spread in the Laboratory Environment

Genome of Enterobacteriophage Lula/phi80 and Insights into Its Ability To Spread in the Laboratory Environment

Adding Functions to Biomaterial Surfaces through Protein Incorporation

Coping with inadvertent lysis of Escherichia coli cultures: Strains resistant to lysogeny and infection by the stealthy lysogenic phage Φ80

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