Production of second-generation biodiesel using low-quality date fruits.

This study focused on the valorization of the date syrup obtained from low-quality date fruits to be used as a low-cost alternative medium for producing single cell oil (SCO) by Rhodotorula glutinis PTCC5256, which could further be converted into biodiesel. The higher C/N ratio of date syrup (C/N 70) led to restricting the formation of cell biomass and enhancing the biosynthesis of SCO. The maximal cell biomass and lipid productivities were obtained 72 mg/L/h and 17 mg/L/h by C/N ratios of 20 and 70, respectively. Although the obtained biodiesel met the international standards for cold filter plugging point (4.92 °C), iodine value (87.22 g I2/100 g oil), cetane number (52.26), higher heating value (40.19 MJ/kg), cloud point (6.29 °C), pour point (0.00 °C), density (878 kg/m3), kinematic viscosity (4.30 mm2/s) and oxidation stability (7.87 h), its weak cold-flow properties might limit its application in cold areas in comparison with diesel fuel.

Author Correction: Biosurfactant Production by Lactic Acid Bacterium Pediococcus dextrinicus SHU1593 Grown on Different Carbon Sources: Strain Screening Followed by Product Characterization.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Biosurfactant Production by Lactic Acid Bacterium Pediococcus dextrinicus SHU1593 Grown on Different Carbon Sources: Strain Screening Followed by Product Characterization.

The present study focused on producing and characterizing a type of biosurfactant (BS) derived from lactic acid bacteria (LAB) and its potential applications in pharmaceutical and food industries due to the preference of employing nonpathogenic organisms in bioprocesses. To this aim, several screening approaches were applied to identify an efficient BS-producing strain from a set of LAB, and Pediococcus dextrinicus SHU1593 was selected as the most operative one. The BS produced by P. dextrinicus was isolated and structurally characterized as a lipoprotein with an approximately equal ratio of lipids (~52% (w/w)) and proteins (47% (w/w)). It reduced the surface tension (ST) of phosphate-buffered saline (PBS) from 72.80 ± 0.10 to 39.01 ± 0.32 mN/m. The results also indicated the potential of developing low-cost strategies aimed at the production of efficient LAB-derived BSs which are structurally and quantitatively similar to the ones obtained from conventional media. Finally, given the physical and functional characterization (i.e. critical micelle concentration (CMC), emulsification index (%E24), stability, as well as antimicrobial and anti-adhesive activities) of the BS produced in the present study, it can be introduced as a promising candidate to be employed in plenty of areas in pharmaceutical and food industries.

Enhanced biosurfactant production with low-quality date syrup by Lactobacillus rhamnosus using a fed-batch fermentation.

Novel strategies toward the use of low-cost media to produce food-grade microbial products have been considerably attended in recent years. In this study, date syrup obtained from low-quality date fruits was implemented for biosurfactant production by the probiotic bacterium, Lactobacillus rhamnosus PTCC 1637. The most level of biosurfactant was achieved through fermentation in a bioreactor with a lactose feeding phase, up to 24 h. Critical micelle concentration of the cell-bound biosurfactant was found to be 6.0 mg/ml with a minimum surface tension value of 39.00 mN/m and a maximum emulsifying index of 42%. The spectrum of Fourier transform infrared spectroscopy taken from the cell-bound biosurfactant suggests that it should be a multi-component mixture of protein and polysaccharides associated with phosphate groups. The results indicated the potential for developing strategies toward the low-cost production of food-grade biomaterials by probiotic microorganisms.