Figure 5: Quantitative analysis of cluster density. Cell density analysis was performed as described in Methods. Cell density decreased in response to independent treatment with any of the three PEGs or bacterial strains. When treated with PEG 3350 and the two commensal bacterial strains, there was an increase in cell density. Cell density recovery was most persevered when treated with PEG 8000 and HS4. PEG 20,000 did not preserve cell density when cells were treated with any of the three bacterial strains. Standard Student’s t-test was applied to the samples and the were obtained for samples treated with PEG 8000 and HS4 indicated by an asterisk (*).