Table 1.

In vitro antagonism against Phytophthora capsici and production of antifungal metabolites by Pseudomonas isolates from the rhizospheres of different plants

Isolates	Species	Origin	In vitro inhibitiona		Biosurfactantb	P solubilizationc	ICd	HCNe	Siderophoref	phlDg	Proteaseh
6ba6	P. fluorescens	Broad bean	100.0	a	+++	+	+	++	+++	+	++
6ba2	Pseudomonas sp.	Broad bean	100.0	a	+++	-	+	+++	+++	+	++
6ba3	Pseudomonas sp.	Broad bean	90.4	b	++	++	+	++	+++	+	+
6t14	Pseudomonas sp.	Radish	86.7	b	++	+	+++	+	+++	+	-
3ss9	P. fluorescens	Strawberry	71.1	c	+++	+	+	+++	++	+	+
6L10	P. fluorescens	Cabbage	57.8	d	+++	++	++	+++	++	+	++
ke	P. fluorescens	Strawberry	56.7	d	++	++	+	+++	++	+	+
3k9	P. fluorescens	Strawberry	51.8	e	+++	+	+	+++	++	+	+
6L14	P. fluorescens	Cabbage	50.6	e	++	+	+	+++	++	+	++
mbj	P. fluorescens	Strawberry	49.3	e	++	++	+	+++	++	+	+
3tg8	Pseudomonas sp.	Strawberry	38.6	f	++	++	++	+	++	+	-

^aMean percent inhibition (relative to the radius of hyphal growth of P. capsici in control) in dual culture assay; values followed by the same letter are not significantly different, according to Tukey’s HSD test at P = 0.05

^bBiosurfactant production, according to Siegmund and Wagner (1991): (+++ >20 mm-wide blue zone; ++ 10−20 mm-wide blue zone; − absent)

^cInorganic phosphate solubilization, based on plate assay on TCP medium (De Freitas et al., 1997): (++ 10−20 mm-wide clear zone; + 5−10 mm-wide clear zone; − absent)

^dIndolic compounds (IC) production, assayed by the colorimetric method of Patten and Glick (2002): (+++ > 1 μg/mL; ++ 0.5−1 μg/mL, + 0.1−0.5 μg/mL; − absent)

^eHydrogen cyanide activity, based on color change of filter paper, according to Bakker and Schippers (1987) :(+++ strong; ++ moderate; + weak; − absent)

^fSiderophores, according to Schwyn and Neilands (1987): (+++ >20 mm-wide orange zone; ++ 10−20 mm-wide orange zone; + 5−10 mm-wide orange zone; − absent)

^gDetection of the phlD gene (629-bp product) by PCR (McSpadden Gardener, 2001)

^hProtease activity, determined by plate assay of Krachel et al. (2002): (+++ >10 mm-wide clear zone; ++ 5−10 mm-wide clear zone; + <5 mm-wide clear zone, − absent)