Burkholderia thailandensis E264 as a promising safe rhamnolipids’ producer towards a sustainable valorization of grape marcs and olive mill pomace

Abstract

Within the circular economy framework, our study aims to assess the rhamnolipid production from winery and olive oil residues as low-cost carbon sources by nonpathogenic strains. After evaluating various agricultural residues from those two sectors, Burkholderia thailandensis E264 was found to use the raw soluble fraction of nonfermented (white) grape marcs (NF), as the sole carbon and energy source, and simultaneously, reducing the surface tension to around 35 mN/m. Interestingly, this strain showed a rhamnolipid production up to 1070 mg/L (13.37 mg/g of NF), with a higher purity, on those grape marcs, predominately Rha-Rha C14-C14, in MSM medium. On olive oil residues, the rhamnolipid yield of using olive mill pomace (OMP) at 2% (w/v) was around 300 mg/L (15 mg/g of OMP) with a similar CMC of 500 mg/L. To the best of our knowledge, our study indicated for the first time that a nonpathogenic bacterium is able to produce long-chain rhamnolipids in MSM medium supplemented with winery residues, as sole carbon and energy source. Key points • Winery and olive oil residues are used for producing long-chain rhamnolipids (RLs). • Both higher RL yields and purity were obtained on nonfermented grape marcs as substrates. • Long-chain RLs revealed stabilities over a wide range of pH, temperatures, and salinities

Economical Di-Rhamnolipids Biosynthesis by Non-Pathogenic Burkholderia thailandensis E264 Using Post-Consumption Food Waste in a Biorefinery Approach

“…Furthermore, RLs production yields with FWH substrates were elevated by 1.6 times (34 mg/g) the amount obtained with standard glycerol medium (21 mg/g). These observations are in the higher range as RLs yields reported with other agro-industrial feedstocks are: CSL (16.5 mg/g), CSL + OMW (23 mg/g), NF (13.37 mg/g), and OMP (15 mg/g) [11][12][13].…”

“…Another study used the supplementation of raw soluble fractions of agricultural residues from the white winemaking process and olive oil extraction for the biosynthesis of RLs from B. thalandensis. The derived nonfermented grape marcs (NF) and olive pomace residues (OMP) both resulted in RL production reaching 1.07 g/L and 0.3 g/L, respectively [13]. However, nitrate salts and minerals were added as a supplement to fulfill the required nitrogen and micronutrients during fermentation.…”

“…Generally, RLs can be produced from a variety of hydrophilic (glucose, glycerol) [8] and hydrophobic substrates such as fatty acids (heptadecanoic acid, oleic acid) [10] and oils (canola oil) [8]. Residual substrates like waste cooking oil (WCO) and agricultural residues have also been proposed as alternatives for RLs biosynthesis [11][12][13].…”

White wine grape pomace as a suitable carbon source for lipid and carotenoid production by fructophilic Rhodorotula babjevae

“…The surface tension of the cell-free culture medium was measured at the beginning and at the end of the experiments to assess the impact of secreted glycolipids (Chebbi et al, 2021). A Sigma 702 (KSV) force tensiometer apparatus was used, with a platinum Du Noüy ring.…”