Shiow-Ling Lee

Optimization of medium composition for the production of glucosyltransferase by Aspergillus niger with response surface methodology

Abstract Aspergillus niger CCRC 31494 produced an extracellular glucosyltransferase (EC 2.4.1.24) with a high transglucosylating activity. For production of glucosyltransferase by A. niger, yeast extract was the best nitrogen source after cultivation for 7 days. Addition of minerals to the medium showed no significant increase in the production of glucosyltransferase. A significant decrease in the production of glycosyltransferase was obtained when the initial pH of the medium was adjusted at 3 or 4. The concentration of inoculated spores of 5.8 × 106 or 1 × 107 per ml medium caused the higher production of glucosyltransferase. The central composite experimental design (CCD) and response surface methodology (RSM) were employed to derive a statistical model for the effects of maltose and yeast extract on the production of glucosyltransferase by A. niger. An initial concentration of 4.5% maltose and 6.6% yeast extract have been found optimum to maximize the production of glucosyltransferase. In addition, the time course of glucosyltransferase production by A. niger in the optimized medium composition was also described.

Production and Molar Yield of 2-Phenylethanol by Pichia fermentans L-5 as Affected by Some Medium Components

In this study, the effects of carbon sources and various levels of sucrose (0-30%) yeast extract (0-1.25%) and phenylalanine (0-0.2%) on the production of 2-phenylethanol by Pichia fermentans L-5 were investigated. Results revealed that among the 11 carbon sources tested, glycerol and sucrose were suitable carbon sources for P. fermentans L-5 resulting in production of higher amounts of 2-phenylethanol. In the medium that contained 18% sucrose, P. fermentans L-5 produced the highest amount of 2-phenylethanol, 283.4 mg/l with a molar yield of 0.77, was noted among the various levels of sucrose tested. Increasing the amount of phenylalanine added to the culture medium to 1.0% resulted in increased production of phenylethanol. Enhanced production of 2-phenylethanol, 453.1 mg/l by P. fermentans L-5 with a molar yield of 0.71 for phenylethanol was obtained in the medium containing 18% sucrose, 0.25% yeast extract and 0.1% phenylalanine after 16 h of fermentation.

l-Mimosine blocks cell proliferation via upregulation of B-cell translocation gene 2 and N-myc downstream regulated gene 1 in prostate carcinoma cells

L-Mimosine, an iron chelator and a prolyl 4-hydroxylase inhibitor, blocks many cancer cells at the late G1 phase. B-cell translocation gene 2 (Btg2) regulates the G1/S transition phases of the cell cycle. N-myc downstream regulated gene 1 (Ndrg1) is a differentiation-inducing gene upregulated by hypoxia. We evaluated the molecular mechanisms of L-mimosine on cell cycle modulation in PC-3 and LNCaP prostate carcinoma cells. The effect of L-mimosine on cell proliferation of prostate carcinoma cells was determined by the [3H]thymidine incorporation and flow cytometry assays. L-Mimosine arrested the cell cycle at the G1 phase in PC-3 cells and at the S phase in LNCaP cells, thus attenuating cell proliferation. Immunoblot assays indicated that hypoxia and L-mimosine stabilized hypoxia-inducible factor-1α (HIF-1α) and induced Btg2 and Ndrg1 protein expression, but downregulated protein levels of cyclin A in both PC-3 and LNCaP cells. L-Mimosine treatment decreased cyclin D1 protein in PC-3 cells, but not in LNCaP cells. Dimethyloxalylglycine, a pan-prolyl hydroxylase inhibitor, also induced Btg2 and Ndrg1 protein expression in LNCaP cells. The transient gene expression assay revealed that L-mimosine treatment or cotransfection with HIF-1α expression vector enhanced the promoter activities of Btg2 and Ndrg1 genes. Knockdown of HIF-1α attenuated the increasing protein levels of both Btg2 and Ndrg1 by hypoxia or L-mimosine in LNCaP cells. Our results indicated that hypoxia and L-mimosine modulated Btg2 and Ndrg1 at the transcriptional level, which is dependent on HIF-1α. L-Mimosine enhanced expression of Btg2 and Ndrg1, which attenuated cell proliferation of the PC-3 and LNCaP prostate carcinoma cells.

Effect of Topical Application of Chlorogenic Acid on Excision Wound Healing in Rats

This study was undertaken to evaluate the therapeutic effects of topical chlorogenic acid on excision wounds in Wistar rats. A 1 % (w/w) chlorogenic acid or silver sulfadiazine ointment was applied topically once a day for 15 days on full-thickness excision wounds created on rats. The 1 % (w/w) chlorogenic acid ointment had potent wound healing capacity as evident from the wound contraction on the 15th post-surgery day, which was similar to that produced by 1 % (w/w) silver sulfadiazine ointment. Increased rates of epithelialization were observed in the treated rats. It also improved cellular proliferation, increased tumor necrosis factor-α levels during the inflammatory phase (12 h, 24 h, 48 h, and 72 h post-wounding) of wound healing, upregulated transforming growth factor-β1 and elevated collagen IV synthesis in the chlorogenic acid-treated group. The results also indicated that chlorogenic acid possesses potent antioxidant activity by increasing superoxide dismutase, catalase, and glutathione, and decreasing lipid peroxidation. In conclusion, these results demonstrate that topical application of chlorogenic acid can accelerate the process of excision wound healing by its ability to increase collagen synthesis through upregulation of key players such as tumor necrosis factor-α and transforming growth factor-β1 in different phases of wound healing as well as by its antioxidant potential.

Wound repair and anti-inflammatory potential of Lonicera japonica in excision wound-induced rats

BackgroundLonicera japonica Thunb. (Caprifoliaceae), a widely used traditional Chinese medicinal plant, is used to treat some infectious diseases and it may have uses as a healthy food and applications in cosmetics and as an ornamental groundcover. The ethanol extract of the flowering aerial parts of L. japonica (LJEE) was investigated for its healing efficiency in a rat excision wound model.MethodsExcision wounds were inflicted upon three groups of eight rats each. Healing was assessed by the rate of wound contraction in skin wound sites in rats treated with simple ointment base, 10% (w/w) LJEE ointment, or the reference standard drug, 0.2% (w/w) nitrofurazone ointment. The effects of LJEE on the contents of hydroxyproline and hexosamine during healing were estimated. The antimicrobial activity of LJEE against microorganisms was also assessed. The in vivo anti-inflammatory activity of LJEE was investigated to understand the mechanism of wound healing.ResultsLJEE exhibited significant antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Candida albicans, and Candida tropicalis. The ointment formulation prepared with 10% (w/w) LJEE exhibited potent wound healing capacity as evidenced by the wound contraction in the excision wound model. The contents of hydroxyproline and hexosamine also correlated with the observed healing pattern. These findings were supported by the histopathological characteristics of healed wound sections, as greater tissue regeneration, more fibroblasts, and angiogenesis were observed in the 10% (w/w) LJEE ointment-treated group. The results also indicated that LJEE possesses potent anti-inflammatory activity, as it enhanced the production of anti-inflammatory cytokines that suppress proinflammatory cytokine production.ConclusionsThe results suggest that the antimicrobial and anti-inflammatory activities of LJEE act synergistically to accelerate wound repair.

Production of γ-decalactone from ricinoleic acid by immobilized cells of Sporidiobolus salmonicolor

Abstract Sporidiobolus salmonicolor CCRC 21975 was immobilized in κ-carrageenan, chitosan, agarose or calcium alginate. Due to the detrimental effects of high temperature attained during the gelling processes of κ-carrageenan and agarose as well as the toxicity of chitosan to the test organism, immobilization of S. salonicolor with these matrices for the production of γ-decalactone was inadequate. Neither viable cells nor production of γ-decalactone could be detected in media after 4 days cultivation of S. salmonicolor immobilized with κ-carrageenan or chitosan. Fewer viable cells and little γ-decalactone production was found in media with agarose-immobilized cells. In contrast, no significant reduction in the viable population was noted during immobilization procedures using alginate. Alginate-immobilized S. salmonicolor cells showed less susceptibility to ricinoleic acid toxicity and produced more γ-decalactone than did free cells. Time courses of γ-decalactone production by S. salmonicolor also revealed that immobilized cells produced a maximum γ-decalactone yield of ca. 131·8 mg l −1 after 5 days fermentation, compared with a maximum of ca. 107·5 mg l −1 for free cells.

Optimized production of biodiesel from waste cooking oil by lipase immobilized on magnetic nanoparticles.

Biodiesel, a non-toxic and biodegradable fuel, has recently become a major source of renewable alternative fuels. Utilization of lipase as a biocatalyst to produce biodiesel has advantages over common alkaline catalysts such as mild reaction conditions, easy product separation, and use of waste cooking oil as raw material. In this study, Pseudomonas cepacia lipase immobilized onto magnetic nanoparticles (MNP) was used for biodiesel production from waste cooking oil. The optimal dosage of lipase-bound MNP was 40% (w/w of oil) and there was little difference between stepwise addition of methanol at 12 h- and 24 h-intervals. Reaction temperature, substrate molar ratio (methanol/oil), and water content (w/w of oil) were optimized using response surface methodology (RSM). The optimal reaction conditions were 44.2 °C, substrate molar ratio of 5.2, and water content of 12.5%. The predicted and experimental molar conversions of fatty acid methyl esters (FAME) were 80% and 79%, respectively.

Curcumin provides potential protection against the activation of hypoxia and prolyl 4-hydroxylase inhibitors on prostate-specific antigen expression in human prostate carcinoma cells

SCOPE Prostate-specific antigen (PSA) is a well-known marker for diagnosing and monitoring prostate cancer. Curcumin, a yellow curry pigment, has been reported to enhance androgen receptor (AR) degradation. We examined the effects of curcumin on increasing PSA expression by hypoxia and prolyl hydroxylase inhibitors, L-mimosine and dimethyloxalylglycine (DMOG), in human prostate carcinoma LNCaP cells. METHODS AND RESULTS The 3H-thymidine incorporation assay revealed that either L-mimosine or DMOG treatments attenuated cell proliferation. Immunoblot and enzyme-linked immunosorbent assays (ELISA) indicated that both L-mimosine and DMOG have an effect similar to hypoxia, which stabilized hypoxia-inducible factor-1α (HIF-1α) and induced PSA gene expression. The results of the immunoblot and transient gene expression assays indicated that induction of the PSA expression by hypoxia is both HIF-1α- and AR-dependent. Immunoblot assays revealed that a curcumin treatment (10 μM) decreased the protein abundance of AR but did not significantly affect the protein levels of HIF-1α and vascular endothelial growth factor, which were induced by hypoxia. ELISA and transient gene expression assays indicated that curcumin blocked the activation of L-mimosine or DMOG treatment on PSA expression. CONCLUSIONS These results indicate that curcumin blocked the enhanced effect of PSA expression by L-mimosine and DMOG that induce hypoxia condition.

Effect of physical factors on the production of γ-decalactone by immobilized cells of Sporidiobolus salmonicolor

Abstract The effects of some physical factors, including preculture time, media initial pH and bead concentrations, on the production of γ-decalactone by immobilized Sporidiobolus salmonicolor CCRC 21975 within calcium alginate beads were investigated. Long-term reuse and stability of the immobilized preparation were also examined. Regardless of the preculture time, no significant difference in the production of γ-decalactone by immobilized S. salmonicolor cells was observed as long as the initial populations of the entrapped cells were the same. Calcium alginate-immobilized S. salmonicolor cells showed improved tolerance to perturbations in external pH and produced more γ-decalactone than did free cells. The patterns of changes in S. salmonicolor cells inside or outside the gel beads as well as production of γ-decalactone by immobilized S. salmonicolor did not vary significantly with bead concentration. Furthermore, after reuse of the calcium alginate-immobilized S. salmonicolor cells for 13 consecutive 4-day batch fermentations, no bead leakage was detected. The production of γ-decalactone in the 13th cycle was about 58.4% of that in the first cycle.

Fermentation with Aspergillus awamori enhanced contents of amino nitrogen and total phenolics as well as the low-density lipoprotein oxidation inhibitory activity of black soybeans.

A solid fermentation was performed on black soybeans with Aspergillus awamori. The effects of fermentation on the contents of total phenolics and amino nitrogen and on the inhibitory effect on low-density lipoprotein (LDL) oxidation of black soybeans were examined. Results revealed that fermentation significantly enhanced the LDL oxidation inhibitory activity and total phenolics and amino nitrogen contents of black soybeans. The increased content of amino nitrogen was closely related to the enhanced LDL oxidation inhibitory activity of fermented black soybeans and its water extract. Fermentation temperature and length affected the LDL oxidation inhibitory effect exerted by the prepared fermented black soybeans. The A. awamori-fermented black soybean prepared at 30 °C for 3 days exhibited the highest inhibitory effect on LDL oxidation. The bioactive principles related to the inhibitory effect on LDL oxidation in black soybeans, regardless of fermentation, could be most efficiently extracted with water rather than 80% methanol or 80% ethanol.