Fig 2.
Nuclease activity in strains of V. fischeri. (A) Strains lacking xds (i.e., xds and xds-dns) were unable to degrade DNA in DNase agar after 24 hours at 28°C, but expression of xds in trans in the xds single mutant (xds+) restored nuclease activity. Strains used are as follows: ES114, dns (Δdns::FRT), xds (xds::miniTn5), xds+ (xds + pVSV105 xds cmR), xds dns (xds::miniTn5Δdns::FRT), dns+ (Δdns::FRT PnrdR dns). (B) After 6 days, a halo could be visualized around the xds mutant. Strains are as follows: Δxds Δdns (KV8865), xds (xds::miniTn5), xdsΔdns (xds::miniTn5Δdns::FRT), and Δxds (KV8811). (C) Nuclease activity in cells grown with shaking in lysogeny broth salt (LBS) to an OD600 of either 0.5 or 1.0. Cell-free culture supernatants were mixed with DNaseAlert reagents to measure nuclease activity. Each bar represents the average of five replicates (with standard error); these results are representative of three separate experiments. Different letters indicate statistically significant differences based on analysis of variance (ANOVA; P-value < 0.05).