Open AccessIsolation and Characterization of Cold-Tolerant Hyper-ACC-Degrading Bacteria from the Rhizosphere, Endosphere, and Phyllosphere of Antarctic Vascular Plants
Author(s) -
Macarena A. Araya,
Tamara Valenzuela,
Nitza G. Inostroza,
Fumito Maruyama,
Milko A. Jorquera,
Jacquelinne J. Acuña
Publication year - 2020
Publication title -
microorganisms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.858
H-Index - 17
ISSN - 2076-2607
DOI - 10.3390/microorganisms8111788
Subject(s) - phyllosphere , rhizosphere , biology , bacteria , botany , abiotic component , microbiology and biotechnology , ecology , genetics
1-Aminociclopropane-1-carboxylate (ACC)-degrading bacteria having been widely studied for their use in alleviating abiotic stresses in plants. In the present study, we isolated and characterized ACC-degrading bacteria from the rhizosphere, phyllosphere, and endosphere of the Antarctic vascular plants Deschampsia antarctica and Colobanthus quitensis . One hundred and eighty of the 578 isolates (31%) were able to grow on minimal medium containing ACC, with 101 isolates (23, 37, and 41 endosphere-, phyllosphere- and rhizosphere-associated isolates, respectively) identified as being genetically unique by enterobacterial repetitive intergenic consensus (ERIC)-PCR. Subsequently, freeze/thaw treatments and ice-recrystallization-inhibition (IRI) activity assays were performed, the results of which revealed that 77 (13%) of cold-tolerant isolates exhibited putative ACC deaminase activity. Significant ( p ≤ 0.05) differences in IRI activity were also observed between the studied plant niches. Surprisingly, all the cold-tolerant isolates showed ACC deaminase activity, independent of the plant niches, with 12 isolates showing the highest ACC deaminase activities of 13.21-39.56 mmol α KB mg protein -1 h -1 . These isolates were categorized as 'cold-tolerant hyper-ACC-degrading bacteria', and identified as members of Pseudomonas , Serratia, and Staphylococcus genera. The results revealed the occurrence of cold-tolerant hyper-ACC-degrading bacteria in diverse plant niches of Antarctic vascular plants, that could be investigated as novel microbial inoculants to alleviate abiotic stresses in plants.