Characterization of bacteria with plant growth promotion and antagonistic activity associated to rhizosphere and phyllosphere of Platanus mexicana and Persea shiedeana trees natural hosts of ambrosial beetle

Abstract

Abstract It is well established that bacteria belonging to 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 pest, 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 over phytopathogenic fungus Fusarium sp., besides studying their lytic ability when confronted with cellulose, pectin, or chitin as carbon sources. Such strains were classified into Curtobacterium, Plantibacter, Bacillus, Brevibacterium, Carnobacterium, Staphylococcus, Erwinia, Serratia, Exiguobacterium and Yersinia genera. Every single strain revealed at least one of the evaluated characteristics. Yersinia sp. strain PsH3-014(14D) and Bacillus sp. strain Hay2-01H(7) stand out from the other strains due to their capacity to promote plant growth in A. thaliana seedlings as well as antagonist activity against of Fusarium sp.; moreover, 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 to degrade all three biopolymers tested (cellulose, pectin, and chitin). Further research could be directed towards the isolation and characterization of key enzymes produced by the referred strains, as well as further exploration of other metabolic capacities.