ACC Deaminase from <i>Lysobacter gummosus</i> OH17 Can Promote Root Growth in <i>Oryza sativa</i> Nipponbare Plants

Although <i>Lysobacter</i> species are a remarkable source of natural compounds with antibacterial and antifungal activities, the ability of these bacteria to produce plant growth promoters remains practically unknown. In this work, the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) has been isolated from the secretions of <i>Lysobacter gummosus</i> OH17, indicating the presence of an ACC deaminase, which was shown to be encoded in the gene <i>peg_1256</i>. The recombinant enzyme could not only deaminate ACC to provide 2-oxobutanoic acid but also catalyzed the amination of the 2-oxobutanoic acid, demonstrating, for the first time, that ACC deaminases can produce ACC. After the treatment of rice <i>Oryza sativa</i> Nipponbare plants with OH17 ACC deaminase, the ethylene production levels were 44% higher in comparison with the control experiments, allowing significant improvements in root, 10%, and stem, 14%, growth