| Summary: | <i>Rahnella aquatilis</i> AZO16M2, was characterized for its phosphate solubilization capacity to improve the establishment and survival of <i>Musa acuminata</i> var. Valery seedlings under ex-acclimation. Three phosphorus sources (Rock Phosphate (RF), Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> and K<sub>2</sub>HPO<sub>4</sub>) and two types of substrate (sand:vermiculite (1:1) and Premix N°8) were selected. The factorial analysis of variance (<i>p</i> < 0.05) showed that <i>R. aquatilis</i> AZO16M2 (OQ256130) solubilizes Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> in solid medium, with a Solubilization Index (SI) of 3.77 at 28 °C (pH 6.8). In liquid medium, it was observed that <i>R. aquatilis</i> produced 29.6 mg/L soluble P (pH 4.4), and synthesized organic acids (oxalic, D-gluconic, 2-ketogluconic and malic), Indole Acetic Acid (IAA) (33.90 ppm) and siderophores (+). Additionally, acid and alkaline phosphatases (2.59 and 2.56 µg pNP/mL/min) were detected. The presence of the pyrroloquinoline-quinone (PQQ) cofactor gene was confirmed. After inoculating AZO16M2 to <i>M. acuminata</i> in sand:vermiculite with RF, the chlorophyll content was 42.38 SPAD (Soil Plant Analysis Development). Aerial fresh weight (AFW), aerial dry weight (ADW) and root dry weight (RDW) were superior to the control by 64.15%, 60.53% and 43.48%, respectively. In Premix N°8 with RF and <i>R. aquatilis</i>, 8.91% longer roots were obtained, with 35.58% and 18.76% more AFW and RFW compared with the control as well as 94.45 SPAD. With Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>, values exceeded the control by 14.15% RFW, with 45.45 SPAD. <i>Rahnella aquatilis</i> AZO16M2 favored the ex-climatization of <i>M. acuminata</i> through improving seedling establishment and survival.
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