OLIVE PRUNING WASTE CONVERSION INTO VALUE-ADDED LIPIDS BY Rhodococcus

SANDOVAL NE; ARIAS N; GALLEGOS, A. L.; PALMERI A; ALVAREZ, HM; LANFRANCONI MP

Congreso; XVII Congreso Argentino de Microbiología General; 2022

Phyllosphere is an understudied environment whose stressful conditions such as UV exposition, temperature fluctuations and dryness make it a promising place to find microorganisms with potential biotechnology capacities. A bacterial strain, named 24CO, was isolated from leaves of Olive Tree var. frantoio, showing the capacity to accumulate neutral lipids. Our goal was to taxonomically identify and characterize its ability to synthesize these compounds. Whole-genome sequence was determined by Illumina technology, assembled with SPAdes and annotated with RAST. In order to assign this strain phylogenetically, classic essential genes, e.g., 16S rDNA, rpoD and gyrB were analyzed. All of them gave the highest identity with Rhodococcus globerulus, however the values obtained were not conclusive to assign 24CO to this species. A similar result was obtained with different comparative tools such as ANI, GGDC and TYGS. The in-silico reconstruction of Kennedy pathway involved in triacylglycerol (TAG) biosynthesis showed that the route is complete, with 7 putative copies of wax synthase/diacylglycerol acyltransferase, the key enzyme involved in the process. Besides, 24CO seems to have the ability to synthesize and accumulate polymeric neutral lipids from sugars, as we found putative copies of phaC, phaA, and an alternative to phaB that bypass this step and involve two enzymes. Furthermore, phaJ and fabG genes coding for enzymes involved in PHA biosynthesis from fatty acids were also found. We further explored the physiological behavior of strain 24CO assessing growth and accumulation of neutral lipids with different carbon sources. The strain was able to grow and accumulate TAG on gluconate, fructose, glucose, glycerol and xylose, turning it into an oleaginous strain depending on the carbon source tested. Fatty acids were mainly even-numbered (C16, C18, C18:1). Current studies are being conducted to define the isolate as a new species and deepen the metabolic characterization of the strain grown on different substrates.