Rhodococcus bacteria as a promising source of oils from olive mill wastes

HERRERO O. MARISA; VILLALBA MARÍA SOLEDAD; LANFRANCONI MARIANA; ALVAREZ HÉCTOR MANUEL

WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY

SPRINGER

Año: 2018 vol. 34 p. 1 - 10

0959-3993

The accumulation of triacylglycerols (TAG) is a common feature among actinobacteria belonging to Rhodococcus genus.Some rhodococcal species are able to produce significant amounts of those lipids from different single substrates, such asglucose, gluconate or hexadecane. In this study we analyzed the ability of different species to produce lipids from olive oilmill wastes (OMW), and the possibility to enhance lipid production by genetic engineering. OMW base medium preparedfrom alperujo, which exhibited high values of chemical oxygen demand (127,000 mg/l) and C/N ratio (508), supported goodgrowth and TAG production by some rhodococci. R. opacus, R. wratislaviensis and R. jostii were more efficient at producingcell biomass (2.2?2.7 g/l) and lipids (77?83% of CDW, 1.8?2.2 g/l) from OMW than R. fascians, R. erythropolis and R.equi (1.1?1.6 g/l of cell biomass and 7.1?14.0% of CDW, 0.1?0.2 g/l of lipids). Overexpression of a gene coding for a fattyacid importer in R. jostii RHA1 promoted an increase of 2.2 fold of cellular biomass value with a concomitant increase inlipids production during cultivation of cells in OMW. This study demonstrates that the bioconversion of OMW to microbiallipids is feasible using more robust rhodococal strains. The efficiency of this bioconversion can be significantly enhancedby engineering strategies.