Confidence intervals (95% CIs) for best-fit model parameter values.

<p>Confidence intervals (95% CIs) for best-fit model parameter values.</p

Effect of catalase on CIR resistance.

<p><b>a</b>: Growth of DR and DR<i>kat</i>^- under 36 Gy/h, or without CIR. Dilutions of DR and DR<i>kat</i>^- are indicated. <b>b</b>: Growth restoration of DR<i>kat</i>^- under 36 Gy/h by catalase, added to the central area of a TGY plate that was pre-inoculated with DR<i>kat</i>^- cells. Dilutions (log₁₀ based) of inoculated DR<i>kat</i>^- are indicated.</p

Comparison of observed and model-predicted growth-inhibitory critical CIR dose rates for microorganisms grown under aerobic conditions.

<p><b>a</b>: Bacteria. <b>b</b>: Fungi. Green diamonds: <i>highest</i> tested dose rate at which <i>any</i> growth was observed. Red squares: <i>lowest</i> tested dose rate at which <i>no</i> growth was observed. Blue curves: best-fit model predictions. Black points: uncertainty range of model predictions. Model-based predictions at cell concentrations higher than those tested had very large uncertainties for EC2 and SC and, therefore, the prediction curves were truncated at cell concentrations slightly above 0 dilution for these organisms.</p

A schematic representation of the effects of cell concentration on microbial resistance to CIR.

<p>A schematic representation of the effects of cell concentration on microbial resistance to CIR.</p

Microbial cooperation under CIR.

<p><b>a</b>: Growth of EC1 in the presence or absence of 36 Gy/h for 2 days, either in pure culture or mixed in 1:1 co-culture with DR. <b>b</b>: As for panel A, but with DR<i>kat</i>^- substituting for DR. The y-axis shows clonogenically viable cell concentrations normalized to 1 ml: the actual numbers of viable cells are 200 times smaller because only 5 μl of each species were used in these experiments. Dashed lines indicate cell concentrations under the assumption of no net proliferation.</p

Aerobic growth of microorganisms under CIR.

<p><b>a:</b> Bacteria. <b>b:</b> Clonogenic survival of bacteria under CIR. For the corresponding CIR study under microaerobic conditions, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189261#pone.0189261.s002" target="_blank">S1 Fig</a>. In this and the following figure, dilutions shown in panels <b>a</b> and <b>c</b> are on a log₁₀ scale and represent order of magnitude changes in initial cell concentration. The bars shown in panel <b>b</b> are based on CFU counts normalized to 1 ml: the actual numbers of viable cells are 200 times smaller because only 5 μl of each species were used in these experiments. At 94 Gy/h, individual colonies could not always be reliably identified, and therefore the bars at this dose rate represent estimates. Abbreviations: No IR = no irradiation; sealed = microaerobic. Red arrows indicate cases where 10-fold reduction in cell concentration completely extinguished growth at a given dose rate. <b>c:</b> Fungi.</p

ORAC of TGY harvested with or without bacterial growth.

<p><b>a</b>: The net AUC (net area under the fluorescence decay curve) is an integrative value of total fluorescence during antioxidant reaction in the presence of the indicated sample. <b>b:</b> Linear regression for log-transformed ratios of net AUC for samples with indicated bacteria to samples without bacteria, vs. log-transformed time. Red lines = regression best fits, blue lines = 95% confidence intervals. Y-axis values >0 suggest that the indicated microorganisms increased the ORAC of the medium; values <0 suggest the opposite—microorganisms decreased the ORAC.</p

Quantification of responses to AIR and CIR for fungi.

<p>Logistic regression intended to predict growth at 36 Gy/h based on log₁₀[D₁₀]. D₁₀ = AIR dose which kills 90% of population. Growth at 36 Gy/h was a binary variable (0 = no growth, 1 = growth). Blue circles indicate raw data; Black squares indicate summary data for log₁₀[D₁₀] quartiles, where x-axis shows median log₁₀[D₁₀] values for each quartile and y-axis shows fractions of fungi which grew under 36 Gy/h; Red curve = best-fit model predictions.</p