Olive Pruning: Waste or Growth Media? Expanding the Metabolic Potential of Phyllospheric Rhodococcus sp. 24CO

Rhodococcus sp. 24CO, isolated from the olive phyllosphere, can accumulate significant amounts of neutral lipids, making it a promising candidate for biomass production from olive pruning waste. The strain efficiently converts this residue to neutral lipids, achieving a yield of over 20% of the cellular dry weight (CDW). This indicates that olive leaves, a by-product of the olive oil industry, could become a valuable resource for both the economy and the environment. Genome analysis revealed various metabolic pathways for converting carbon sources to neutral lipids, while phenotypic studies showed that the strain is selective about its carbon sources, thriving on specific monosaccharides and polyols found in olive leaves. Notably, fructose and mannitol were rapidly metabolized, leading to a content of stored triacylglycerides of up to 47% and 28% of the CDW, respectively. The strain also exhibited oleagenicity under high nitrogen availability when grown on mannitol. Finally, potential oleagenicity determinants were explored through an omics comparison.