Pseudomonas diversity in western Algeria: role in the stimulation of bean germination and common bean blight biocontrol

The aim of this work was to determine the functional diversity of soil bacteria belonging to the Pseudomonas genus, to study their effects on bean (Phaseollus vulgaris L) seed germination and their biocontrol potential of common bean blight. Bacteria were isolated and identified based on physiological and biochemical characters and BOX-PCR. Followed by qualitative and/or quantitative analysis of their secondary metabolites. 50 soil bacteria were affected to the two groups of fluorescent (72%) and non-fluorescent Pseudomonads (28%). The UPGMA (Unweighted Pair Group Method with Arithmetic Mean) showed five phenons of carbon sources assimilation; at the time that BOX-PCR profiling resulted in five clusters characterized by 29 different haplotypes. (66%) isolates induced phosphate solubilization; (24%) were HCN producers, (21%) showed IAA production and all isolates had produced siderophores. In vitro antibacterial activity against Xapf showed 26.67 and 24 mm of inhibition zone using the two isolates P. grimontii P25 and P. cepatia P7, respectively. Similarly, the same isolates significantly reduced Xapf-bean common blight intensity, while their co-inoculation was less effective. The isolate P. cepatia P7 was highly effective on seed germination and root growth properties, then P. grimontii P25. Thus, the selected isolates could play a crucial bean growth promotion and bean common blight biocontrol as alternative to chemicals for crop yield enhancement.