Table 3 Phage strains

T7+

Wild-type (Genbank V01146)

Control phage for some adaptations

[20]

T7v

T7 cloning vector, made as T7Select 415b-1 (Novagen) with the left end BclI fragment replaced by that of a phage carrying the C74 deletion (gene 0.3 is intact)

Used as backbone for gene insertions because of the cloning site and the ability to grow on hosts containing type I restriction modification (RM)

T7 ₀ in [15]

T7dsp+trx _10B

T7415-C74:trxAdspB. T7v with the E. coli trx A gene, T7 ϕ 10 promoter and A. actinomycetemcomitans CU1000 dsp B gene recombined in to the multiple cloning site between genes 10 and 11

Re-engineered version of T7DspB from [4] to grow on hosts with type I RM

This study

T7dsp+trx _10B/ dsp _10B

T7dsp+trx _10B grown on a host with pUC57-T7dspB to remove the trx A gene by recombination; not clonally isolated

Used to allow evolution of dispersin free of trx A

This study

T7dsp+1.2 _3.8

T7v but most of gene 3.8 replaced with T3 gene 1.2 (enabling growth on F plasmid-bearing strains) and the dsp B gene. Created by recombination with plasmid pMK-RQ-T7trxAdspB. The multiple cloning site in gene 10B is unaltered from T7v.

Used to create T7-1.2+dsp _3.8/dsp _3.8.

This study

T7dsp+1.2 _3.8/ dsp _3.8

T7-1.2+dsp _3.8 recombined with pMKRQ-T7dspB to create variation in the presence/absence of the 1.2 gene. Not purified.

Evolved in a chemostat to study evolution of the dsp gene.

This study

T7dsp _3.8P

The initial mix of T7-1.2+dsp _3.8/dsp _3.8 recombined against the chemostat-evolved population of T7-1.2+dsp _3.8/dsp _3.8 in which the dsp gene had been lost.

Multiple recombinations separated dsp from 1.2 and introduced any mutations from a chemostat adaptation that might be beneficial in the background of the phage. This polymorphic population was used to evaluate the effect of selection on the dsp transgene in serial transfer, short term biofilms and long term biofilms.

This study