The production of l-phenylalanine is conventionally carried out by fermentations that use glucose or sucrose as the carbon source. This work reports on the use of glycerol as an inexpensive and abundant sole carbon source for producing l-phenylalanine using the genetically modified bacterium Escherichia coli BL21(DE3). Fermentations were carried out at 37°C, pH 7.4, using a defined medium in a stirred tank bioreactor at various intensities of impeller agitation speeds (300–500 rpm corresponding to 0.97–1.62 m s⁻¹ impeller tip speed) and aeration rates (2–8 L min⁻¹, or 1–4 vvm). This highly aerobic fermentation required a good supply of oxygen, but intense agitation (impeller tip speed ~1.62 m s⁻¹) reduced the biomass and l-phenylalanine productivity, possibly because of shear sensitivity of the recombinant bacterium. Production of l-phenylalanine was apparently strongly associated with growth. Under the best operating conditions (1.30 m s⁻¹ impeller tip speed, 4 vvm aeration rate), the yield of l-phenylalanine on glycerol was 0.58 g g⁻¹, or more than twice the best yield attainable on sucrose (0.25 g g⁻¹). In the best case, the peak concentration of l-phenylalanine was 5.6 g L⁻¹, or comparable to values attained in batch fermentations that use glucose or sucrose. The use of glycerol for the commercial production of l-phenylalanine with E. coli BL21(DE3) has the potential to substantially reduce the cost of production compared to sucrose- and glucose-based fermentations.

Mulch films increase soil temperature, maintain soil moisture, improve water and fertilizer absorption, and reduce weed growth. This work studied a mulching film made using polyvinyl alcohol (PVA) and lignin extracted from empty fruit bunches (EFBs). The mulch films were investigated for opaqueness, biodegradation, water-solubility, absorption, and mechanical properties. Life cycle assessment (LCA) and cost estimate analysis were conducted. The composite mulch film-PVA solution was blended with 6% EFB lignin in dimethyl sulfoxide (DMSO) solution using five different amounts (0, 20, 40, 60, or 80 wt% lignin). The results showed that increasing the amount of lignin increased the film’s water solubility, moisture content, and biodegradability. At the same time, water absorption tended to decrease. Consequently, the light transmittance of the film was reduced, which had a positive effect on preventing soil weed growth. Tests of the mechanical properties showed that 60% lignin in the PVA film had the highest tensile strength (16.293 MPa). According to the LCA studies and cost estimation, the lignin-mixed PVA film had the lowest impact and was cheaper than the commercial mulching film. The results suggested that it is possible to blend polyvinyl alcohol polymer with lignin to improve biodegradability up to 25.47% by soil burial and 32% by water solubility.