Get close but not too close. Microbial interactions between two sugarcane endophytic isolates

RUBIO, ANNA CAROLINA; FARIZANO, JUAN VICENTE; FASCIO, CÉSAR JUSTINIANO; VINCENT, PAULA ANDREA; ZENOFF, ANA MARÍA; POMARES, MARÍA FERNANDA; CARAM DI SANTO, MARÍA CAROLINA; DE CRISTOBAL, RICARDO EZEQUIEL; ESPINOSA-URGEL MANUEL; ADLER, CONRADO

Congreso; SAIB; 2022

Microorganisms interact with their host and with each other, establishing dynamic microbial community structures and functions. Microbial interactions take place at a chemical level, through the production of diffusible metabolites or by mechanisms involving direct contact. In this work, we study the interaction between two sugarcane endophytic isolates classified as BECA 336 and BECA 335 after genome sequencing. The two isolates were spotted on solid medium using a distance pattern that allowed observing growth effects at different ranges. When the two isolates were in close proximity, BECA 336 inhibited BECA 335. On the contrary, at greater distances BECA 336 stimulated BECA 335 growth. In silico analysis and in vitro assays appeared to indicate that growth-stimulating effect is mediated at least in part by the siderophore enterobactin, produced by BECA 336. The attempt of purification of the active compound using HPLC-UV-MS demostrated that the part of the extract that presented activity could correspond to DHBA-L-Ser. While growth stimulation showed an intensity gradient consistent with the diffusion of a metabolite, inhibition displayed an irregular pattern that rules out this possibility. Inhibition was enhanced under conditions favoring BECA 336 motility suggesting that the phenotype might be contact dependent. Unraveling how microorganisms interact may pave the way for the understanding of microbial community assembly.