Enhancement of galactose uptake for bioethanol production from Eucheuma denticulatum hydrolysate using galactose-adapted yeasts.

Eucheuma denticulatum is a red macroalgae with a high carbohydrate content. The fermentable sugars from E. denticulatum were obtained through sequential thermal acid hydrolysis, enzymatic saccharification, and detoxification. Thermal acid hydrolysis of E. denticulatum was optimized under the condition of 10% (w/v) slurry content and 300 mM HNO3 at 121 â„ƒ for 90 min. The maximum monosaccharide concentration after thermal acid hydrolysis was 31.0 g/L with an efficiency (ETAH) of 44.7%. By further enzymatic hydrolysis of pretreated biomass solution under 20 U/mL Cellic CTec2 at 50 â„ƒ and 160 rpm for 72 h, the maximum monosaccharide concentration reached 79.9 g/L with an efficiency of 66.2% (ES). To remove 5-hydroxymethylfurfural (5-HMF), a fermentation inhibitor, absorption using 2% activated carbon was performed for 2 min. Ethanol fermentation was performed using wild-type and high galactose-adapted strains of Saccharomyces cerevisiae, Kluyveromyces marxianus, and Candida lusitaniae. As a result, galactose-adapted strains showed higher ethanol production than wild-type strains. Especially, the fermentation result by adaptively evolved S. cerevisiae produced the highest ethanol of 37.6 g/L and with YEtOH of 0.48 g/g. Moreover, the transcript level of MIG1 in the galactose-adapted strain was slightly lower than that in the wild-type strain. The application of adaptive evolution of microorganisms was efficient for bioethanol production.

Evaluation of gamma-aminobutyric acid (GABA) production by Lactobacillus plantarum using two-step fermentation.

Lactic acid bacteria (Lactobacillus plantarum KCTC 3103) were fermented to produce gamma-aminobutyric acid (GABA). The conditions of the modified synthetic medium were optimized as 5 g/L glucose, 10 g/L yeast extract, 100 g/L rice bran extract, and 1.0 g/L ascorbic acid for GABA production. Single-step fermentation of cell growth and GABA production with a modified synthetic medium was higher than those with an MRS medium. Two-step fermentation was evaluated by separating the cell growth and GABA production under a modified synthetic medium. The cell concentration of 1.65 g dcw/L produced by the modified synthetic medium was higher than that of 1.0 g dcw/L produced by the MRS medium at 36 h from the first step of two-step fermentation. The highest GABA production of L. plantarum KCTC 3103 was 0.67 g/L with monosodium glutamate addition at 60 h in the second step of fermentation. Two-step fermentation with the modified synthetic medium is suitable for GABA production because of its high GABA productivity and favorable cell growth.

Lead and mercury levels in repeatedly collected urine samples of young children: A longitudinal biomonitoring study.

Early life exposures to lead (Pb) and mercury (Hg) were reported to be associated with various adverse health outcomes. However, limited data was available for urinary Pb and Hg levels in young children and the proportion of children at risk by age, as well as inter- and intra-subject variations of urinary Pb and Hg levels. Therefore, we collected total 491 urine samples from 241 children by urine collection at birth and at intervals of 3 months until 27 months of age for each child (at 10 monitoring time points), measured urinary Pb and Hg levels, and then evaluated the proportion of children at risk by age and the intra-class correlation (ICC) of the urinary Pb and Hg levels. Both the urinary Pb and Hg levels were significantly different according to the monitoring time points (p < 0.0001 for both Pb and Hg). The number of children with Hg level over the Human BioMonitoring (HBM) I (7 µg/L) and II (25 µg/L) in the first urine at birth were 3 (2.2%) and 1 (0.7%), respectively, while the urinary samples at the other time points did not show Hg level over HBM I or HBM II. However, the exceedance rate for urinary Pb based on HBM values was not calculated due to unavailable HBM values. On the other hands, the proportion of the children with Pb and Hg levels over the reference value derived on the 95th percentile of representative samples (RV95) (1.7 µg/L for Canadian Pb and 0.4 µg/L for German Hg) was relatively high, ranging from 20.0% to 100.0% for Pb and from 13.6% to 100.0% for Hg. The ICC of the repeated measurements from birth to 27 months was 0 for Pb and 0.89 for Hg, while the ICC after the exclusion of the first urine at birth was 0.13 for Pb and 0.47 for Hg. Furthermore, the Pb and Hg exposures were consistent among the high-exposure group for Pb and among all population for Hg. Our data showed Korean children were exposed to relatively high levels of Pb and Hg. However, our Pb and Hg levels in children were based on only urine samples without urinary correction and without consideration of the levels in any other bio-samples such as bloods. Therefore, to explore the Pb and Hg exposures using urine samples warrant further investigation with large sample size considering urinary correction and other bio-samples in the future.

Preventive Effects of Neuroprotective Agents in a Neonatal Rat of Photothrombotic Stroke Model.

Neonatal ischemic stroke has a higher incidence than childhood stroke. Seizures are the first sign for the need for clinical assessment in neonates, but many questions remain regarding treatments and follow-up modalities. In the absence of a known pathophysiological mechanism, only supportive care is currently provided. Stroke-induced microglia activation and neuroinflammation are believed to play a central role in the pathological progression of neonatal ischemic stroke. We induced a photothrombotic infarction with Rose Bengal in neonatal rats to investigate the effects of pre- and post-treatment with Aspirin (ASA), Clopidogrel (Clop), and Coenzyme Q10 (CoQ10), which are known for their neuroprotective effects in adult stroke. Pre-stroke medication ameliorates cerebral ischemic injury and reduces infarct volume by reducing microglia activation, cellular reactive oxygen species (ROS) production, and cytokine release. Post-stroke administration of ASA, Clop, and CoQ10 increased motor function and reduced the volume of infarction, and the statistical evidence was stronger than that seen in the pre-stroke treatment. In this study, we demonstrated that ASA, Clop, and CoQ10 treatment before and after the stroke reduced the scope of stroke lesions and increased behavioral activity. It suggests that ASA, Clop, and CoQ10 medication could significantly have neuroprotective effects in the neonates who have suffered strokes.

Optimization of hyper-thermal acid hydrolysis and enzymatic saccharification of Ascophyllum nodosum for ethanol production with mannitol-adapted yeasts.

In this study, Ascophyllum nodosum was studied as a biomass for ethanol production. A. nodosum was degraded to monosaccharide by hyper-thermal (HT) acid hydrolysis and enzymatic saccharification and analyzed using response surface methodology (RSM) and the Michaelis-Menten equation. Maximum monosaccharide concentrations of 20.3 g/L glucose and 7.0 g/L mannitol were obtained from HT acid hydrolysis and enzymatic saccharification from 8%(w/v) of A. nodosum. Fermentation was conducted using Pichia stipitis and P. angophorae adapted to high mannitol concentrations. Neither non-adapted P. stipitis and P. angophorae nor adapted P. stipitis could ferment all mannitol in the A. nodosum hydrolysate. Adapted P. angophorae produced the highest ethanol concentration among various yeasts, with ethanol production reaching 13.6 g/L with an ethanol yield (YEtOH) of 0.50. Optimization of HT acid hydrolysis and enzymatic saccharification, in combination with the use of adapted yeast, could enhance overall A. nodosum ethanol fermentation yields.

Ethanol production from water hyacinth (Eichhornia crassipes) hydrolysate by hyper-thermal acid hydrolysis, enzymatic saccharification and yeasts adapted to high concentration of xylose.

Water hyacinth (Eichhornia crassipes) was used as a feedstock for ethanol production. The optimal hyper-thermal (HT) acid hydrolysis conditions were 8% (w/v) slurry content, 200 mM H2SO4, at 160 °C for 20 min and enzymatic saccharification for 48 h using an enzyme mixture of 20 units/mL Viscozyme L and Cellic C Tec2. After pretreatment, 48.2 g/L monosaccharides were obtained. Fermentation was conducted with wild and adapted Saccharomyces cerevisiae, Pichia stipitis and Candida lusitaniae. Wild-type S. cerevisiae, P. stipitis, and C. lusitaniae produced 15.3, 19.5 and 22.7 g/L of ethanol, respectively. Adaptive evolution was carried out on 6% (w/v) xylose. S. cerevisiae, P. sipitis and C. lusitaniae adapted to xylose produced 15.3, 21.4 and 23.9 g/L of ethanol with YEtOH of 0.32, 0.44 and 0.49, respectively. These results indicate that water hyacinth has potential as a feed stock for ethanol.

Acetone, butanol, and ethanol production from the green seaweed Enteromorpha intestinalis via the separate hydrolysis and fermentation.

Acetone, butanol, and ethanol (ABE) were produced following the separate hydrolysis and fermentation (SHF) method using polysaccharides from the green macroalgae Enteromorpha intestinalis as biomass. We focused on the optimization of enzymatic saccharification as pretreatments for the fermentation of E. intestinalis. Pretreatment was carried out with 10% (w/v) seaweed slurry and 270-mM H2SO4 at 121 °C for 60 min. Monosaccharides (mainly glucose) were obtained from enzymatic hydrolysis with a 16-U/mL mixture of Celluclast 1.5 L and Viscozyme L at 45 °C for 36 h. ABE fermentation with 10% (w/v) E. intestinalis hydrolysate was performed using the anaerobic bacteria Clostridium acetobutylicum with either uncontrolled pH, pH controlled at 6.0, or pH controlled initially at 6.0 and then 4.5 after 4 days, which produced ABE contents of 5.6 g/L with an ABE yield (YABE) of 0.24 g/g, 4.8 g/L with an YABE of 0.2 g/g, and 8.5 g/L with an YABE of 0.36 g/g, respectively.

Enhancement of bioethanol production from Gracilaria verrucosa by Saccharomyces cerevisiae through the overexpression of SNR84 and PGM2.

A total monosaccharide concentration of 47.0 g/L from 12% (w/v) Gracilaria verrucosa was obtained by hyper thermal acid hydrolysis with 0.2 M HCl at 140°C for 15 min and enzymatic saccharification with CTec2. To improve galactose utilization, we overexpressed two genes, SNR84 and PGM2, in a Saccharomyces cerevisiae CEN-PK2 using CRISPR/Cas-9. The overexpression of both SNR84 and PGM2 improved galactose utilization and ethanol production compared to the overexpression of each gene alone. The overexpression of both SNR84 and PGM2 and of PGM2 and SNR84 singly in S. cerevisiae CEN-PK2 Cas9 produced 20.0, 18.5, and 16.5 g/L ethanol with ethanol yield (YEtOH) values of 0.43, 0.39, and 0.35, respectively. However, S. cerevisiae CEN-PK2 adapted to high concentration of galactose consumed galactose completely and produced 22.0 g/L ethanol at a YEtOH value of 0.47. The overexpression of both SNR84 and PGM2 increased the transcriptional levels of GAL and regulatory genes; however, the transcriptional levels of these genes were lower than those in S. cerevisiae adapted to high galactose concentrations.

Correction to: Butanol and butyric acid production from Saccharina japonica by Clostridium acetobutylicum and Clostridium tyrobutyricum with adaptive evolution.

Unfortunately, the author name was wrongly published as Pailin Sukwang.instead of Pailin Sukwong.

Lipid and unsaturated fatty acid productions from three microalgae using nitrate and light-emitting diodes with complementary LED wavelength in a two-phase culture system.

In this study, Pavlova lutheri, Chlorella vulgaris, and Porphyridium cruentum were cultured using modified F/2 media in a 1 L flask culture. Various nitrate concentrations were tested to determine an optimal nitrate concentration for algal growth. Subsequently, the effect of light emitted at a specific wavelength on biomass and lipid production by three microalgae was evaluated using various wavelengths of light-emitting diodes (LED). Biomass production by P. lutheri, C. vulgaris, and P. cruentum were the highest with blue, red, and green LED wavelength with 1.09 g dcw/L, 1.23 g dcw/L, and 1.28 g dcw/L on day 14, respectively. Biomass production was highest at the complementary LED wavelength to the color of microalgae. Lipid production by P. lutheri, C. vulgaris, and P. cruentum were the highest with yellow, green, and red LEDs' wavelength, respectively. Eicosapentaenoic acid production by P. lutheri, C. vulgaris, and P. cruentum was 10.35%, 10.14%, and 14.61%, and those of docosahexaenoic acid were 6.09%, 8.95%, and 11.29%, respectively.

Butanol and butyric acid production from Saccharina japonica by Clostridium acetobutylicum and Clostridium tyrobutyricum with adaptive evolution.

Optimal conditions of hyper thermal (HT) acid hydrolysis of the Saccharina japonica was determined to a seaweed slurry content of 12% (w/v) and 144 mM H2SO4 at 160 °C for 10 min. Enzymatic saccharification was carried out at 50 °C and 150 rpm for 48 h using the three enzymes at concentrations of 16 U/mL. Celluclast 1.5 L showed the lowest half-velocity constant (Km) of 0.168 g/L, indicating a higher affinity for S. japonica hydrolysate. Pretreatment yielded a maximum monosaccharide concentration of 36.2 g/L and 45.7% conversion from total fermentable monosaccharides of 79.2 g/L with 120 g dry weight/L S. japonica slurry. High cell densities of Clostridium acetobutylicum and Clostridium tyrobutyricum were obtained using the retarding agents KH2PO4 (50 mM) and NaHCO3 (200 mM). Adaptive evolution facilitated the efficient use of mixed monosaccharides. Therefore, adaptive evolution and retarding agents can enhance the overall butanol and butyric acid yields from S. japonica.

Effects of light-emitting diode (LED) with a mixture of wavelengths on the growth and lipid content of microalgae.

Integrations of two-phase culture for cell growth and lipid accumulation using mixed LED and green LED wavelengths were evaluated with the microalgae, Phaeodactylum tricornutum, Isochrysis galbana, Nannochloropsis salina, and Nannochloropsis oceanica. Among the single and mixed LED wavelengths, mixed LED produced higher biomass of the four microalgae, reaching 1.03 g DCW/L I. galbana, followed by 0.95 g DCW/L P. tricornutum, 0.85 g DCW/L N. salina, and 0.62 g DCW/L N. oceanica than single LED or fluorescent lights at day 10. Binary combination of blue and red LEDs could produce the high biomass and photosynthetic pigments in the four microalgae. The highest lipid accumulation during second phase with the exposure to green LED wavelengths was 56.0% for P. tricornutum, 55.2% for I. galbana, 53.0% for N. salina, and 51.0% for N. oceanica. The major fatty acid in the four microalgae was palmitic acid (C16:0) accounting for 38.3-47.3% (w/w) of the total fatty acid content.

Improved fermentation performance to produce bioethanol from Gelidium amansii using Pichia stipitis adapted to galactose.

This study employed a statistical method to obtain optimal hyper thermal acid hydrolysis conditions using Gelidium amansii (red seaweed) as a source of biomass. The optimal hyper thermal acid hydrolysis using G. amansii as biomass was determined as 12% (w/v) slurry content, 358.3 mM H2SO4, and temperature of 142.6 °C for 11 min. After hyper thermal acid hydrolysis, enzymatic saccharification was carried out. The total monosaccharide concentration was 45.1 g/L, 72.2% of the theoretical value of the total fermentable monosaccharides of 62.4 g/L based on 120 g dry weight/L in the G. amansii slurry. To increase ethanol production, 3.8 g/L 5-hydroxymethylfurfural (HMF) in the hydrolysate was removed by treatment with 3.5% (w/v) activated carbon for 2 min and fermented with Pichia stipitis adapted to high galactose concentrations via separate hydrolysis and fermentation. With complete HMF removal and the use of P. stipitis adapted to high galactose concentrations, 22 g/L ethanol was produced (yield 0.50). Fermentation with total HMF removal and yeast adapted to high galactose concentrations increased the fermentation performance and decreased the fermentation time from 96 to 36 h compared to traditional fermentation.

Hyper-thermal acid hydrolysis and adsorption treatment of red seaweed, Gelidium amansii for butyric acid production with pH control.

Optimal hyper-thermal (HT) acid hydrolysis conditions for Gelidium amansii were determined to be 12% (w/v) seaweed slurry content and 144 mM H2SO4 at 150 °C for 10 min. HT acid hydrolysis-treated G. amansii hydrolysates produced low concentrations of inhibitory compounds and adsorption treatment using 3% activated carbon. An adsorption time of 5 min was subsequently used to remove the inhibitory 5-hydroxymethylfurfural from the medium. A final maximum monosaccharide concentration of 44.6 g/L and 79.1% conversion from 56.4 g/L total fermentable monosaccharides with 120 g dw/L G. amansii slurry was obtained from HT acid hydrolysis, enzymatic saccharification, and adsorption treatment. This study demonstrates the potential for butyric acid production from G. amansii hydrolysates under non-pH-controlled as well as pH-controlled fermentation using Clostridium acetobutylicum KCTC 1790. The activated carbon treatment and pH-controlled fermentation showed synergistic effects and produced butyric acid at a concentration of 11.2 g/L after 9 days of fermentation.

Bioethanol production from Gracilaria verrucosa using Saccharomyces cerevisiae adapted to NaCl or galactose.

This study examined the pretreatment, enzymatic saccharification, and fermentation of the red macroalgae Gracilaria verrucosa using adapted saccharomyces cerevisiae to galactose or NaCl for the increase of bioethanol yield. Pretreatment with thermal acid hydrolysis to obtain galactose was carried out with 11.7% (w/v) seaweed slurry and 373 mM H2SO4 at 121 °C for 59 min. Glucose was obtained from enzymatic hydrolysis. Enzymatic saccharification was performed with a mixture of 16 U/mL Celluclast 1.5L and Viscozyme L at 45 °C for 48 h. Ethanol fermentation in 11.7% (w/v) seaweed hydrolysate was carried out using Saccharomyces cerevisiae KCTC 1126 adapted or non-adapted to high concentrations of galactose or NaCl. When non-adapted S. cerevisiae KCTC 1126 was used, the ethanol productivity was 0.09 g/(Lh) with an ethanol yield of 0.25. Ethanol productivity of 0.16 and 0.19 g/(Lh) with ethanol yields of 0.43 and 0.48 was obtained using S. cerevisiae KCTC 1126 adapted to high concentrations of galactose and NaCl, respectively. Adaptation of S. cerevisiae KCTC 1126 to galactose or NaCl increased the ethanol yield via adaptive evolution of the yeast.

Efficient utilization of Eucheuma denticulatum hydrolysates using an activated carbon adsorption process for ethanol production in a 5-L fermentor.

A total monosaccharide concentration of 37.8 g/L and 85.9% conversion from total fermentable monosaccharides of 44.0 g/L from 110 g dw/L Eucheuma denticulatum slurry were obtained by thermal acid hydrolysis and enzymatic saccharification. Subsequent adsorption treatment to remove 5-hydroxymethylfurfural (5-HMF) using 5% activated carbon and an adsorption time of 10 min were used to prevent a prolonged lag phase, reduced cell growth, and low ethanol production. The equilibrium adsorption capacity (q e) of HMF (58.183 mg/g) showed high affinity to activated carbon comparing to those of galactose (2.466 mg/g) and glucose (2.474 mg/g). The efficiency of cell growth and ethanol production with activated carbon treatment was higher than that without activated carbon treatment. Fermentation using S. stipitis KCTC7228 produced a cell concentration of 3.58 g dw/L with Y X/S of 0.107, and an ethanol concentration of 15.8 g/L with Y P/S of 0.48 in 96 h.

Increases of Catalase and Glutathione Peroxidase Expressions by Lacosamide Pretreatment Contributes to Neuroprotection Against Experimentally Induced Transient Cerebral Ischemia.

Lacosamide is a new antiepileptic drug which is widely used to treat partial-onset seizures. In this study, we examined the neuroprotective effect of lacosamide against transient ischemic damage and expressions of antioxidant enzymes such as Zn-superoxide dismutase (SOD1), Mn-superoxide dismutase (SOD2), catalase (CAT) and glutathione peroxidase (GPX) in the hippocampal cornu ammonis 1 (CA1) region following 5 min of transient global cerebral ischemia in gerbils. We found that pre-treatment with 25 mg/kg lacosamide protected CA1 pyramidal neurons from transient global cerebral ischemic insult using hematoxylin-eosin staining and neuronal nuclear antigen immunohistochemistry. Transient ischemia dramatically changed expressions of SOD1, SOD2 and GPX, not CAT, in the CA1 pyramidal neurons. Lacosamide pre-treatment increased expressions of CAT and GPX, not SOD1 and 2, in the CA1 pyramidal neurons compared with controls, and their expressions induced by lacosamide pre-treatment were maintained after transient cerebral ischemia. In brief, pre-treatment with lacosamide protected hippocampal CA1 pyramidal neurons from ischemic damage induced by transient global cerebral ischemia, and the lacosamide-mediated neuroprotection may be closely related to increases of CAT and GPX expressions by lacosamide pre-treatment.

Occurrence and prenatal exposure to persistent organic pollutants using meconium in Korea: Feasibility of meconium as a non-invasive human matrix.

Prenatal exposure to persistent organic pollutants (POPs) is of great concern due to the vulnerability of fetus. Nineteen Polychlorinated biphenyls (PCBs), 18 organochlorine pesticides (OCPs) including DDTs, HCHs, chlordanes, and hexachlorobenzene, and 22 polybrominated diphenyl ethers (PBDEs) were measured in meconium samples from 72 newborn infants using high resolution gas chromatography/mass spectrometry. The median concentrations (on wet weight basis) of PCBs, OCPs, and PBDEs were 26.8pg/g, 66.7pg/g, and 2.32pg/g, respectively. Highly significant correlations were observed among the compounds of PCBs and OCPs, suggesting their similar sources and kinetic behaviors. BDE 47 had significant correlations with PCBs and OCPs, whereas BDE 209 was not correlated with any of the contaminants due to different exposure sources. The concentrations of p,p'-DDE, ß-HCH, and trans-nonaCHL between paired maternal blood-meconium and cord blood-meconium showed significant correlations, while PCBs and PBDEs were not significantly correlated in the paired samples. Maternal age and gestational age were demographic parameters affecting POP levels in meconium. Multiple regression analysis showed that the levels of several OCPs in cord and maternal serum were contributing factors governing the levels of these contaminants in meconium. Our results indicate that meconium can be utilized as a human matrix for prenatal exposure to several OCPs.

Potential of phosphoric acid-catalyzed pretreatment and subsequent enzymatic hydrolysis for biosugar production from Gracilaria verrucosa.

This study combined phosphoric acid-catalyzed pretreatment and enzymatic hydrolysis to produce biosugars from Gracilaria verrucosa as a potential renewable resource for bioenergy applications. We optimized phosphoric acid-catalyzed pretreatment conditions to 1:10 solid-to-liquid ratio, 1.5 % phosphoric acid, 140 °C, and 60 min reaction time, producing a 32.52 ± 0.06 % total reducing sugar (TRS) yield. By subsequent enzymatic hydrolysis, a 68.61 ± 0.90 % TRS yield was achieved. These results demonstrate the potential of phosphoric acid to produce biosugars for biofuel and biochemical production applications.

Evaluation of ethanol production and bioadsorption of heavy metals by various red seaweeds.

The objective of this study was to evaluate ethanol production and bioadsorption with four red seaweeds, Gelidium amansii, Gracilaria verrucosa, Kappaphycus alvarezii and Eucheuma denticulatum. To produce ethanol, thermal acid hydrolysis, enzymatic saccharification and fermentation was carried out. After pretreatment, 38.5, 39.9, 31.0 and 27.5 g/L of monosaccharides were obtained from G. amansii, G. verrucosa, K. alvarezii and E. denticulatum, respectively. Ethanol fermentation was performed with Saccharomyces cerevisiae KCCM 1129 adapted to 80 g/L galactose. The ethanol productions by G. amansii, G. verrucosa, K. alvarezii and E. denticulatum were 18.8 g/L with Y EtOH = 0.49, 19.1 g/L with Y EtOH = 0.48, 14.5 g/L with Y EtOH = 0.47 and 13.0 g/L with Y EtOH = 0.47, respectively. The waste seaweed slurries after the ethanol fermentation were reused to adsorb Cd(II), Pb(II) and Cu(II). Using langmuir isotherm model, Cu(II) had the highest affinity for waste seaweeds with the highest q max and electronegativity values among three heavy metals.