Biosynthesis and Antimicrobial Activity of Pseudodesmin and Viscosinamide Cyclic Lipopeptides Produced by Pseudomonads Associated with the Cocoyam Rhizosphere.

cyclic lipopeptides (CLPs) are encoded non-ribosomally by biosynthetic gene clusters (BGCs) and possess diverse biological activities. In this study, we conducted chemical structure and BGC analyses with antimicrobial activity assays for two CLPs produced by strains isolated from the cocoyam rhizosphere in Cameroon and Nigeria. LC-MS and NMR analyses showed that the sp.

Cyclic lipopeptide-producing Pseudomonas koreensis group strains dominate the cocoyam rhizosphere of a Pythium root rot suppressive soil contrasting with P. putida prominence in conducive soils.

Pseudomonas isolates from tropical environments have been underexplored and may form an untapped reservoir of interesting secondary metabolites. In this study, we compared Pseudomonas and cyclic lipopeptide (CLP) diversity in the rhizosphere of a cocoyam root rot disease (CRRD) suppressive soil in Boteva, Cameroon with those from four conducive soils in Cameroon and Nigeria. Compared with other soils, Boteva andosols were characterized by high silt, organic matter, nitrogen and calcium.

Fluorescent Pseudomonas and cyclic lipopeptide diversity in the rhizosphere of cocoyam (Xanthosoma sagittifolium).

Cocoyam (Xanthosoma sagittifolium (L.)), an important tuber crop in the tropics, is severely affected by the cocoyam root rot disease (CRRD) caused by Pythium myriotylum. The white cocoyam genotype is very susceptible while the red cocoyam has some field tolerance to CRRD.

Phenazines and biosurfactants interact in the biological control of soil-borne diseases caused by Pythium spp.

In this study, the putative role of phenazines and rhamnolipid-biosurfactants, antagonistic metabolites produced by Pseudomonas aeruginosa PNA1, was tested in the biological control of Pythium splendens on bean (Phaseolus vulgaris L) and Pythium myriotylum on cocoyam (Xanthosoma sagittifolium L Schott). A rhamnolipid-deficient and a phenazine-deficient mutant of PNA1 were used either separately or jointly in plant experiments. When the mutants were applied separately, no disease-suppressive effect was observed, although both mutants still produced one of the antagonistic compounds (phenazines or rhamnolipids).

Intraspecific variability of Pythium myriotylum isolated from cocoyam and other host crops.

Intraspecific variability within 51 isolates of Pythium myriotylum from cocoyam (Xanthosoma sagittifolium) and other host crops was analysed using optimum growth temperature, esterase banding patterns, AFLPs, rDNA-ITS sequencing, and virulence to cocoyam. P. myriotylum isolates virulent to cocoyam could easily be differentiated from other isolates of P.