Engineered ACC deaminase-expressing free-living cells of Mesorhizobium loti show increased nodulation efficiency and competitiveness on Lotus spp.

VALERIA CONFORTE; MARIELA ECHEVERRÍA; CINTIA SÁNCHEZ; RODOLFO UGALDE; ANA MENÉNDEZ; VIVIANA LEPEK

JOURNAL OF GENERAL AND APPLIED MICROBIOLOGY

MICROBIOL RES FOUNDATION

Año: 2010 vol. 56 p. 331 - 338

0022-1260

Ethylene inhibits the establishment of symbiosis between rhizobia and legumes. Several rhizobia species express the enzyme ACC deaminase, which degrades the ethylene precursor 1-cyclopropane-1-carboxilate (ACC), leading to reductions in the amount of ethylene evolved by the plant. M. loti has a gene encoding ACC deaminase, but this gene is under the activity of the NifA-RpoN-dependent promoter; thus, it is only expressed inside the nodule. The M. loti structural gene ACC deaminase (acdS) was integrated into the M. loti chromosome under a constitutive promoter activity. The resulting strain induced the formation of a higher number of nodules and was more competitive than the wild-type strain on Lotus japonicus and L. tenuis. These results suggest that the introduction of the ACC deaminase activity within M. loti in a constitutive way could be a novel strategy to increase nodulation competitiveness of the bacteria, which could be useful for the forage inoculants industry.