Optimization and economic evaluation of ultrasound extraction of lutein from Chlorella vulgaris

The main carotenoid in Chlorella vulgaris is lutein. The ultrasound alone or together with enzymatic pretreatment for the extraction of lutein from C. vulgaris was optimized using response surface methodology (RSM) to improve the extraction process. The optimal ultrasound extraction condition was: ultrasound frequency, 35 kHz; ultrasound intensity, 56.58 W/cm²; extraction temperature, 37.7°C; extraction time, 5 h; and ratio of solvent to solid, 31 mL/g, where the lutein recovery was 3.16 ± 0.03 mg/g wet C. vulgaris. The optimal enzymatic pretreatment was: reaction time, 2 h; enzyme concentration, 1.23% (v/w); pH, 4.5, and temperature 50°C. The optimal ultrasound extraction with enzymatic pretreatment was: ultrasound frequency, 35 kHz; ultrasound intensity, 56.58 W/cm²; extraction temperature, 37.7°C; extraction time, 162 min; and ratio of solvent to solid, 35.6 mL/g wet C. vulgaris, where the extraction yield of lutein was 3.36 ± 0.10 mg/g wet C. vulgaris. This was much higher than for ultrasound treatment alone. The surface areas of microalga cells treated by ultrasound with/without enzymatic pretreatment increased significantly, which might contribute to the increase in lutein yield. There were no significant differences in structure, color, and antioxidant activity of lutein between the ultrasound and conventional methods. The highest cost of the crude and lutein was obtained by the ultrasound with enzymatic pretreatment due to the complex process and liquid waste in the enzymatic pretreatment process, but the ultrasound treatment alone was the lowest. Therefore, ultrasound extraction is the most economical method for the extraction of microalgal lutein.     

Survival of rat functional dental pulp cells in vascularized tissue engineering chambers

Regenerative endodontics aims to preserve, repair or regenerate the dental pulp tissue. Dental pulp stem cells, have a potential use in dental tissue generation. However, specific requirements to drive the dental tissue generation are still obscured. We established an in vivo model for studying the survival of dental pulp cells (DPC) and their potential to generate dental pulp tissue. DPC were mixed with collagen scaffold with or without slow release bone morphogenic protein 4 (BMP-4) and fibroblast growth factor 2 (FGF2). The cell suspension was transplanted into a vascularized tissue engineering chamber in the rat groin. Tissue constructs were harvested after 2, 4, 6, and 8 weeks and processed for histomorphological and immunohistochemical analysis. After 2 weeks newly formed tissue with new blood vessel formation were observed inside the chamber. DPC were found around dentin, particularly around the vascular pedicle and also close to the gelatin microspheres. Cell survival, was confirmed up to 8 weeks after transplantation. Dentin Sialophosphoprotein (DSPP) positive matrix production was detected in the chamber, indicating functionality of dental pulp progenitor cells. This study demonstrates the potential of our tissue engineering model to study rat dental pulp cells and their behavior in dental pulp regeneration, for future development of an alternative treatment using these techniques.     

Direct bioconversion of rice residue from canteen waste into lipids by new amylolytic oleaginous yeast Sporidiobolus pararoseus KX709872

The new amylolytic oleaginous red yeast, Sporidiobolus pararoseus KX709872, produced both α-amylase (540?±?0.09?mU/mL) and amyloglucosidase (23?±?0.00?mU/mL) and showed good ability to directly convert rice residue from canteen waste to biomass and lipids. Effects of medium composition and cultivation conditions on growth and lipid accumulation for strain KX709872 were investigated under shaking flask and upscaling levels. At C?:?N ratio of 25?:?1, pH 5.45, 22.36°C, and 199.40?rpm for 7 days, volumetric production of biomass and lipids, lipid content, and lipid productivity reached 17.69?±?0.44, 8.35?±?0.19?g/L, 49.48?±?0.41% (w/w), and 1.67?±?0.11?g/L/day, respectively. Production of lipids was also implemented in 5.0-L stirred tank bioreactor with 2.5?L of optimized medium at 300?rpm and 3.0 vvm for 5 days. Volumetric production of biomass and lipids, lipid content, and lipid productivity were 16.33?±?0.49, 8.75?±?0.13?g/L, 56.61?±?0.04% (w/w), and 2.19?±?0.03?g/L/day, respectively. Meanwhile, the fatty acids of lipids from strain KX709872 had high oleic acid content (60?62%) which was similar to those of vegetable oils, indicating that these lipids are promising as an alternative biodiesel feedstock. Moreover, the biodiesel derived from lipids of strain KX709872 had properties satisfying the criteria of ASTM D6751 and EN 14214 standards.     

Change in nuclear DNA content and pollen size with polyploidisation in the sweet potato (Ipomoea batatas,Convolvulaceae) complex

• Genome size evolution and its relationship with pollen grain size has been investigated in sweet potato (Ipomoea batatas), an economically important crop which is closely related to diploid and tetraploid species, assessing the nuclear DNA content of 22 accessions from five Ipomoea species, ten sweet potato varieties and two outgroup taxa.
• Nuclear DNA amounts were determined using flow cytometry. Pollen grains were studied using scanning and transmission electron microscopy.
• 2C DNA content of hexaploid I. batatas ranged between 3.12–3.29 pg; the mean monoploid genome size being 0.539 pg (527 Mbp), similar to the related diploid accessions. In tetraploid species I. trifida and I. tabascana, 2C DNA content was, respectively, 2.07 and 2.03 pg. In the diploid species closely related to sweet potato e.g. I. ×leucantha, I. tiliacea, I. trifida and I. triloba, 2C DNA content was 1.01–1.12 pg. However, two diploid outgroup species, I. setosa and I. purpurea, were clearly different from the other diploid species, with 2C of 1.47–1.49 pg; they also have larger chromosomes. The I. batatas genome presents 60.0% AT bases.
• DNA content and ploidy level were positively correlated within this complex. In I. batatas and the more closely related species I. trifida, the genome size and ploidy levels were correlated with pollen size. Our results allow us to propose alternative or complementary hypotheses to that currently proposed for the formation of hexaploid Ipomoea batatas.

     

Rhodomyrtone Modulates Innate Immune Responses of THP-1 Monocytes to Assist in Clearing Methicillin-Resistant Staphylococcus aureus

Background

The increasing resistance of Staphylococcus aureus to conventional antibiotics poses a major health problem. Moreover, S. aureus can survive within phagocytes, thus evading some antibiotics and the innate immune response. Rhodomyrtone, a bioactive compound from the leaves of Rhodomyrtus tomentosa, possesses potent antibacterial activity against methicillin-resistant S. aureus (MRSA). This study was to investigate the immunomodulatory effects of rhodomyrtone on THP-1 monocytes in response to MRSA.

Methods

THP-1 monocytes were stimulated with heat-killed MRSA, followed by treatment with rhodomyrtone. The cell pellets were prepared to detect pro-inflammatory molecules using real-time PCR. The supernatants were collected to assess nitric oxide production using Griess assay. Assays for phagocytosis and bacterial killing by THP-1 monocytes were performed to determine if they were affected by rhodomyrtone.

Results

Expression of pro-inflammatory molecules including IL-1β, TNF-α, IL-6, and iNOS was enhanced in THP-1 monocytes stimulated with high doses of heat-killed MRSA (10⁸ to 10⁹ cfu/ml). In contrast, monocytes stimulated with MRSA at lower doses (10⁶ to 10⁷ cfu/ml) did not induce the expression of these cytokines. However, rhodomyrtone significantly increased the expression of pro-inflammatory mediators, IL-6 and iNOS in monocytes stimulated with heat-killed MRSA at low doses, and displayed some anti-inflammatory activity by reducing TNF-α expression in monocytes stimulated with heat-killed MRSA at high doses. Treatment with rhodomyrtone also significantly up-regulated the expression of the key pattern recognition receptors, TLR2 and CD14, in THP-1 monocytes stimulated with heat-killed MRSA at 10⁶ to 10⁹ cfu/ml, while heat-killed MRSA alone did not induce the expression of these molecules. The ability of rhodomyrtone to eliminate MRSA from the monocytes was observed within 24 h after treatment.

Conclusion

Rhodomyrtone enhanced the expression of pattern recognition receptors by monocytes in response to MRSA. Increased expression of these receptors might improve MRSA clearance by modulating pro- and anti-inflammatory cytokine responses.