THE SOCIAL LIFE OF MEMBERS OF THE SUGARCANE MICROBIOME

ADUSTO, LR; RUBIO MOLINA, AC; DE CRISTÓBAL RE; VINCENT P.A; ADLER CONRADO

San Miguel de Tucumán

Congreso; Congreso Argentino de Microbiología General SAMIGE; 2017

Asociación Civil de Microbiología General

Manipulation of soil and plant associated microbiomes holds great promise for contributing to a more environmentally benign agriculture. Even though numerous microbial isolates have been proposed for their use in agriculture, the typical approach designed to fine-tune the plant physiology involves the use of single microbial species. This approach clearly under-exploits the potential of microbiomes and highlights the need of more information regarding the ability of members of such microbiomes to interact with each other and with the plant. Distinctive microbial communities can be found at different plant structures (i.e. roots, stems and leaves) and it is expected that a functional basis underlays those specific associations.In order to gain some insight into the functional and metabolic characteristics of the sugarcane-associated microbiome, we isolated bacteria from this niche and evaluated bacterial interactions between members of the community. For that, plant stems were sampled with a cork borer, plant tissue was ground and subsequently plated in a culture medium containing salts, aminoacids and sucrose. After 5 days of incubation at 30° C, sugarcane endophytes were selected based on differential colony morphologies and growth rates. A subset of phylogenetically different isolates was selected after sequencing each isolate 16S rDNA. With this subset, which included species belonging to the Acinetobacter, Agrobacterium, Beijerinckia, Kocuria, Microbacterium, Pantoea, Pseudomonas Rhizobium, Rothia and Sphingomonas genus, we performed pairwise co-cultures on the same solid medium used for isolation. Microbial interactions were followed over time and the type of interaction was documented. Even though the majority of pairwise co-cultures showed no apparent interaction, several combinations revealed different types of interactions including growth inhibition, commensal and mutualistic growth promotion, colony morphology changes, pigment production and an unanticipated interaction consisting in growth inhibition of one of the isolates in the immediate proximity to the other isolate but growth promotion at a distal position. Initial attempts to reveal the chemical nature behind some of the observed interactions indicate that siderophores may play a key role on them.