The social life of members of the sugarcane microbiome.

ADUSTO, LORENA; RUBIO, ANNA CAROLINA; DE CRISTOBAL, RICARDO EZEQUIEL; VINCENT, PAULA; ADLER, CONRADO

Tucumán

Congreso; SAMIGE; 2017

SAMIGE

Manipulation of soil and plant associated microbiomes holds great promise for contributing to a moreenvironmentally benign agriculture. Even though numerous microbial isolates have been proposed fortheir use in agriculture, the typical approach designed to fine-tune the plant physiology involves theuse of single microbial species. This approach clearly under-exploits the potential of microbiomes andhighlights the need of more information regarding the ability of members of such microbiomes tointeract with each other and with the plant. Distinctive microbial communities can be found at differentplant structures (i.e. roots, stems and leaves) and it is expected that a functional basis underlays thosespecific associations.In order to gain some insight into the functional and metabolic characteristics of thesugarcane-associated microbiome, we isolated bacteria from this niche and evaluated bacterialinteractions between members of the community. For that, plant stems were sampled with a corkborer, 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 selectedbased on differential colony morphologies and growth rates. A subset of phylogenetically differentisolates was selected after sequencing each isolate 16S rDNA. With this subset, which includedspecies belonging to the Acinetobacter, Agrobacterium, Beijerinckia, Kocuria, Microbacterium,Pantoea, Pseudomonas Rhizobium, Rothia and Sphingomonas genus, we performed pairwiseco-cultures on the same solid medium used for isolation. Microbial interactions were followed overtime and the type of interaction was documented. Even though the majority of pairwise co-culturesshowed no apparent interaction, several combinations revealed different types of interactions includinggrowth inhibition, commensal and mutualistic growth promotion, colony morphology changes, pigmentproduction and an unanticipated interaction consisting in growth inhibition of one of the isolates in theimmediate proximity to the other isolate but growth promotion at a distal position. Initial attempts toreveal the chemical nature behind some of the observed interactions indicate that siderophores mayplay a key role on them.