8.0) to illustrate the spatial arrangement of each sample community relative to each other. Two-sample t-test performed using sigma plot v.11.0, were applied to viable count data to determine whether the effects of the antimicrobials in microcosms were significant, relative to unexposed microcosms. Moreover, statistical comparisons of individual vs. paired and paired vs. combinatorial exposure data (viability and count data) were performed to evaluate potential enhanced activities of HDPs in pairs or combination, relative to their individual effects on aggregation and differential counts. Table 2

(microscopy) presents data for the effect of HDPs on bacterial viability and aggregation frequency, in comparison with unexposed microcosms. Viability analyses using BacLight™ LIVE/DEAD bacterial-viability kit indicated that decreases (P < 0.05) in viability occurred (except paired HNPs and hβD 3) and MG-132 datasheet aggregation (except HNP 1, HNP 2, paired histatins and LL37) in HDP-exposed microcosms. Statistical analyses did not reveal significant enhancement or decrease in antimicrobial effect between HDPs used in various combinations. Differential culture data are shown in Table 2. All HDP exposures (single,

paired and combined) with the EPZ 6438 exception of His 5 caused statistically significant (P < 0.05) decrease in the numbers of Gram-negative anaerobes, in comparison with control microcosms. Although of relatively low abundance in the unexposed microcosms, counts of lactobacilli decreased

significantly Y-27632 2HCl (P < 0.05) to below detectable levels following exposure to majority of HDPs (except HNP 2, paired HNPs and hβD 1). On the other hand, His 5 exposure caused a significant increase (P < 0.05) in lactobacilli. Counts of streptococci increased with exposure to HNP 1, hβD 1, hβD 3, His 5 and LL37, whereas they decreased in the presence of paired HNPs and hβD 1 with 3. In general, singular HDP exposures increased total streptococci, whilst paired exposures decreased counts for this genus. Counts of streptococci were not significantly altered by exposure to all eight HDPs. Plaques that developed in the presence of HDPs generally had increased levels of facultative anaerobes (except paired HNPs, hβD 1, hβD 1 with 2, hβD 2 with 3 and paired histatins) and elevated total anaerobes (except paired HNPs, hβD 1, hβD 2, hβD 1 with 2, hβD 2 with 3, paired histatins and LL37). Facultative anaerobe counts, however, decreased significantly (P < 0.05) following the introduction of hβD 2. Comparative statistical analyses of individual vs. paired exposures demonstrated putative enhancement of antimicrobial activity for paired hβDs, HNPs and histatins, relative to their individual effects on counts of streptococci, and similar effects for HNPs were observed for facultative and total anaerobes. Dendrogram analysis (Fig.