Exopolysaccharides and abiotic stress tolerance in bacterial isolates from “sabiá” nodules

Abstract

Several microorganisms produce polysaccharides, deemed to protect the bacteria from several environmental stresses. This paper aims to evaluate the protective effect of exopolyssacharides to different abiotic stresses in bacterial isolates from “sabiá” (Mimosa caesalpiniifolia) nodules. 303 fast growing isolates were qualitatively evaluated for exopolyssacharide production and tested in vitro for tolerance to two levels of acidity, joint aluminum and acidity, three salinity levels; 11 antibiotics and three herbicides. Most isolates resisted media acidity, acidity with aluminum, salinity, and ampicillin, cefotaxime, gentamicin and vancomycin antibiotics and 2,4D herbicide, while being sensitive to ciprofloxacin, chloramphenicol, streptomycin, kanamycin, nalidixic acid, rifampicin and tetracycline antibiotics and paraquat and glyphosate herbicides. There was no connection between exopolyssacharide production and abiotic stress tolerance.