Inhibition of Quorum Sensing-Controlled Virulence Factors and Biofilm Formation in Pseudomonas aeruginosa by Culture Extract from Novel Bacterial Species of Paenibacillus Using a Rat Model of Chronic Lung Infection

Table 1

Quorum sensing inhibitory effects of Paenibacillus sp. culture extract on the virulence factors and biofilm formation of Pseudomonas aeruginosa.

Test (concentration)	Virulence factors			Biofilm formation
	LasA protease activity^a	LasB elastase activity^b	Pyoverdin production^c	Test clinical isolate P. aeruginosa^d	Control biofilm-forming isolate P. aeruginosa (ATCC 27853)^d
	OD ± SD	OD ± SD	OD ± SD	OD ± SD	OD ± SD
With extract (1 mg/mL)	0.151 ± 0.013	88.333 ± 4.410	2261.000 ± 43.920	0.216 ± 0.073	0.124 ± 0.003
With extract (4.5 mg/mL)	0.091 ± 0.014	75.667 ± 8.090	2093.333 ± 95.614	0.149 ± 0.057	0.225 ± 0.004
Without extract (−control)	0.247 ± 0.004	167.000 ± 3.464	3775.667 ± 20.251	0.254 ± 0.003	0.539 ± 0.052
2(5H)-Furanone (+control)	0.062 ± 0.019	59.333 ± 9.244	1808.667 ± 139.190	0.105 ± 0.004	0.121 ± 0.001

LasA activity is expressed as the reduction at OD₆₀₀ per hour per μg of total protein.
^bElastase activity is expressed as the absorbance at OD₄₉₅ per μg of protein.
^cPyoverdin production is expressed as the fluorescence at OD₄₆₅ per μg of protein.
^dBiofilm formation is expressed as the adherence index at OD₅₇₀.
^dOD > 0.24 = positive biofilm former isolate.
^dOD > 0.12–<0.24 = weak biofilm former isolate.
^dOD < 0.12 = negative biofilm former isolate.
Values are expressed as the standard error mean ± S.E.M.
Significant value is .