Characterization of plant growth promoting and antagonistic bacteria associated with the rhizosphere and phyllosphere of Platanus mexicana and Persea shiedeana trees natural hosts of ambrosia beetle.

Abstract

Abstract It is well known that bacteria belonging to the microbiota of plants, contribute to the better development of their hosts by different mechanisms, such as, growth promotion, nutrient facilitation, stimulation of plant defenses, antagonizing pathogens or pests, and some of them are also, some microorganisms show enzymatic activities with biotechnological application in the agricultural and industrial sector. In the present study we identified and characterized fourteen bacterial strains isolated from the rhizosphere and phyllosphere of Platanus mexicana and Persea schiedeana trees; the aim of this research was to evaluate bacterial biological activities over plant growth promotion on Arabidopsis thaliana seedlings and antagonistic activity against the phytopathogenic fungus Fusarium sp., besides studying their lytic ability when confronted with cellulose, pectin, or chitin as carbon sources. These strains were classified into the genera Curtobacterium, Plantibacter, Bacillus, Brevibacterium, Carnobacterium, Staphylococcus, Erwinia, Serratia, Exiguobacterium and Yersinia. Each individual strain exhibited revealed at least one of the characteristics evaluated. Yersinia sp. strain PsH3-014(14D) and Bacillus sp. strain Hay2-01H(7) stand out from the other strains due to their ability to promote plant growth in A. thaliana seedlings as well as their antagonistic activity against of Fusarium sp. In addition, PsH3-014(14D) also degrades pectin and chitin, while Hay2-01H (7) degrades cellulose and pectin. In contrast, Carnobacterium gallinarum strain Chi2-3Ri was detrimental for the development of Arabidopsis seedlings but it can degrade cellulose. Erwinia sp. strain Hay2-1H was the only strain capable of degrading all three biopolymers tested (cellulose, pectin, and chitin). Further research could be directed towards the isolation and characterization of key enzymes produced by the these strains, as well as further exploration of other metabolic capacities.