Silver nanoparticle-deposited whey protein isolate amyloid fibrils as catalysts for the reduction of methylene blue.

The unique structural characteristics and superior biocompatibility make the protein nanofibers promising immobilization platforms/substrates for catalysts/enzymes. Metal nanoparticles have been employed as the catalysts in industries due to their excellent catalytic activity and stability, whereas their high surface energy leads to nanoparticle aggregation, thereby hampering their catalytic performance. Here, amyloid fibril (AF) derived from whey protein isolate (WPI) was chosen as the support of silver nanoparticles (AgNP) and utilized for the catalytic reduction of methylene blue (MB). The one-dimensional amyloid-based hybrid materials (AgNP/WPI-AF) were first synthesized via chemical or photochemical route. The characterization of AgNP/WPI-AF by UV-vis spectrophotometry and electron microscopy revealed that the sizes of AgNP on WPI-AF's surface ranged from 2 to 30 nm. Next, the catalytic performances of AgNP/WPI-AF prepared by various routes for MB degradation were investigated. Additionally, the kinetic data were analyzed using two different models and the apparent rate constants and thermodynamic parameters were further determined accordingly. Moreover, the reusability of AgNP/WPI-AF was assessed by monitoring the percentage removal of MB over consecutive filtering cycles. Our results indicated that Langmuir-Hinshelwood-type mechanism better described the catalytic MB reduction using AgNP/WPI-AF. This work provides a nice example of application of nanoparticle-amyloid fibril composite materials for catalysis.

Green synthesis of gold nanoparticle/gelatin/protein nanogels with enhanced bioluminescence/biofluorescence.

Here we report the green synthesis of gelatin/protein hybrid nanogels containing gold nanoparticles (AuNPs) that collectively exhibit metal-enhanced luminescence/fluorescence (MEL/MEF). The gelatin/protein nanogels, prepared by genipin cross-linking of preformed gelatin/protein polyion complexes (PICs), exhibited sizes ranging between 50 and 200 nm, depending on the weight ratio of gelatin and protein. These nanogels serve as reducing and stabilizing agents for the AuNPs, allowing for nucleation in a gel network that exhibits colloidal stability and MEL/MEF. AuNP/gelatin/HRP and AuNP/gelatin/LTF nanogels presented an ~11-fold enhancement of bioluminescence in an HRP-luminol system and a ~50-fold fluorescence enhancement when compared to free LTF in cell uptake experiments. These hybrid nanogels show promise for optically enhanced diagnosis and other therapeutic applications.

Exploring the effects of methylene blue on amyloid fibrillogenesis of lysozyme.

The 129-residue lysozyme has been shown to form amyloid fibrils in vitro. While methylene blue (MB), a compound in the phenothiazinium family, has been shown to dissemble tau fibril formation, its anti-fibrillogenic effect has not been thoroughly characterized in other proteins/peptides. This study examines the effects of MB on the in vitro fibrillogenesis of lysozyme at pH 2.0 and 55 °C. Our results demonstrated that, upon 7-day incubation, the plateau ThT fluorescence of the sample was found to be ~8.69% or ~2.98% of the control when the molar ratio of lysozyme to MB was at 1:1.11 or 1:3.33, respectively, indicating that the inhibitory potency of MB against lysozyme fibrillogenesis is positively correlated with its concentration. We also found that MB is able to destabilize the preformed lysozyme fibrils. Moreover, molecular docking and molecular dynamics simulations results revealed that MB's mechanism of fibril formation inhibition may be triggered by binding with lysozyme's aggregation-prone region. Results reported here provide solid support for MB's effect on amyloid fibrillogenesis. We believe the additional insights gained herein may pave way to the discovery of other small molecules that may have similar action toward amyloid fibril formation and its associated diseases.

An efficient Photobioreactors/Raceway circulating system combined with alkaline-CO2 capturing medium for microalgal cultivation.

High efficiency of microalgal growth and CO2 fixation in a Photobioreactors (PBRs)/Raceway circulating (PsRC) system combined with alkaline-CO2 capturing medium and operation was established and investigated. Compared with a pH 6 medium, the average biomass productivity of Chlorella sp. AT1 cultured in a pH 11 medium at 2 L min-1 circulation rate for 7 days increased by about 2-fold to 0.346 g L-1 d-1. The maximum amount of CO2 fixation and CO2 utilization efficiency of Chlorella sp. AT1 could be obtained at a PBRs to Raceway ratio of 1:10 in an indoor-simulated PsRC system. A similar result was also shown in an outdoor PsRC system with a 10-ton scale for microalgal cultivation. Under the appropriate circulation rate, the stable growth performance of Chlorella sp. AT1 cultured by long-term semi-continuous operation in the 10-ton outdoor PsRC system was observed, and the total amount of CO2 fixation was approximately 1.2 kg d-1 with 50% CO2 utilization efficiency.

Characterization of an extracellular ß-glucosidase from Dekkera bruxellensis for resveratrol production.

Polygonum cuspidatum is a widely grown crop with a rich source of polydatin (also called piceid) for resveratrol production. Resveratrol is produced from piceid via enzymatic cleavage of the sugar moiety of piceid. In this study, Dekkera bruxellensis mutants were selected based on their high p-nitrophenyl-ß-d-glucopyranoside and piceid conversion activities. The enzyme responsible for piceid conversion was a heterodimeric protein complex that was predominantly secreted to the extracellular medium and consisted of two subunits at an equal ratio with molecular masses of 30.5 kDa and 48.3 kDa. The two subunits were identified as SCW4p and glucan-ß-glucosidase precursor in D. bruxellensis. Both proteins were individually expressed in Saccharomyces cerevisiae exg1Δ mutants, which lack extracellular ß-glucosidase activity, to confirm each protein's enzymatic activities. Only the glucan-ß-glucosidase precursor was shown to be a secretory protein with piceid deglycosylation activity. Our pilot experiments of piceid bioconversion demonstrate the possible industrial applications for this glucan-ß-glucosidase precursor in the future.

Ability of an alkali-tolerant mutant strain of the microalga Chlorella sp. AT1 to capture carbon dioxide for increasing carbon dioxide utilization efficiency.

An alkali-tolerant Chlorella sp. AT1 mutant strain was screened by NTG mutagenesis. The strain grew well in pH 6-11 media, and the optimal pH for growth was 10. The CO2 utilization efficiencies of Chlorella sp. AT1 cultured with intermittent 10% CO2 aeration for 10, 20 and 30min at 3-h intervals were approximately 80, 42 and 30%, respectively. In alkaline medium (pH=11) with intermittent 10% CO2 aeration for 30min at 3-, 6- and 12-h intervals, the medium pH gradually changed to 10, and the biomass productivities of Chlorella sp. AT1 were 0.987, 0.848 and 0.710gL-1d-1, respectively. When Chlorella sp. AT1 was aerated with 10% CO2 intermittently for 30min at 3-h intervals in semi-continuous cultivation for 21days, the biomass concentration and biomass productivity were 4.35gL-1 and 0.726gL-1d-1, respectively. Our results show that CO2 utilization efficiency can be markedly increased by intermittent CO2 aeration and alkaline media as a CO2-capturing strategy for alkali-tolerant microalga cultivation.

Pilot scale repeated fed-batch fermentation processes of the wine yeast Dekkera bruxellensis for mass production of resveratrol from Polygonum cuspidatum.

Resveratrol has long been used as an ingredient in functional foods. Currently, Polygonum cuspidatum extract is the greatest natural source for resveratrol because of high concentrations of glycosidic-linked resveratrol. Thus, developing a cost-effective procedure to hydrolyze glucoside could substantially enhance resveratrol production from P. cuspidatum. This study selected Dekkera bruxellensis from several microorganisms based on its bioconversion and enzyme-specific activities. We demonstrated that the cells could be reused at least nine times while maintaining an average of 180.67U/L ß-glucosidase activity. The average resveratrol bioconversion efficiency within five rounds of repeated usage was 108.77±0.88%. This process worked effectively when the volume was increased to 1200L, a volume at which approximately 35mgL-1h-1 resveratrol per round was produced. This repeated fed-batch bioconversion process for resveratrol production is comparable to enzyme or cell immobilization strategies in terms of reusing cycles, but without incurring additional costs for immobilization.

Simultaneous microalgal biomass production and CO2 fixation by cultivating Chlorella sp. GD with aquaculture wastewater and boiler flue gas.

A microalgal strain, Chlorella sp. GD, cultivated in aquaculture wastewater (AW) aerated with boiler flue gas, was investigated. When AW from a grouper fish farm was supplemented with additional nutrients, the microalgal biomass productivity after 7days of culture was 0.794gL-1d-1. CO2 fixation efficiencies of the microalgal strains aerated with 0.05, 0.1, 0.2, and 0.3vvm of boiler flue gas (containing approximately 8% CO2) were 53, 51, 38, and 30%, respectively. When the microalgal strain was cultured with boiler flue gas in nutrient-added AW, biomass productivity increased to 0.892gL-1d-1. In semi-continuous cultures, average biomass productivities of the microalgal strain in 2-day, 3-day, and 4-day replacement cultures were 1.296, 0.985, and 0.944gL-1d-1, respectively. These results demonstrate the potential of using Chlorella sp. GD cultivations in AW aerated with boiler flue gas for reusing water resources, reducing CO2 emission, and producing microalgal biomass.

Cultivation of Chlorella sp. GD using piggery wastewater for biomass and lipid production.

The development of a culture system for Chlorella sp. GD to efficiently produce biomass and oil for biodiesel production was investigated. Chlorella sp. GD was cultivated with 0%, 25%, 50%, 75% and 100% piggery wastewater (diluted by medium) at 300 µmol m(-2) s(-1), a 2% CO2 aeration rate of 0.2 vvm and 26±1°C; after a 10-day culture in batch cultures, the maximum specific growth rate and biomass productivity of the microalga obtained in 100% piggery wastewater were 0.839 d(-1) and 0.681 g L(-1) d(-1), respectively. The highest lipid content and lipid productivity were 29.3% and 0.155 g L(-1) d(-1) at 25% wastewater, respectively. In semi-continuous cultures, the biomass and lipid productivities with 25-75% wastewater ratios were greater than 0.852 and 0.128 g L(-1) d(-1), respectively. These results show that Chlorella sp. GD grows efficiently in piggery wastewater, and that a stable growth performance was achieved for long-term microalgal cultivation in a semi-continuous culture.

Deactivation of isoamylase and ß-amylase in the agitated reactor under supercritical carbon dioxide.

The current research examines the impact of agitation on deactivation of isoamylase and ß-amylase under supercritical carbon dioxide (SC-CO2). Our experimental results showed that the activity of either enzyme decreased with increasing pressure or speed of agitation. The degree of enzymatic deactivation caused by pressure became more prominent in the presence of agitation, suggesting that the agitation plays an important role in enzymatic deactivation in SC-CO2 environment. Moreover, the enzymatic deactivation behavior associated with agitation and pressure was further quantitatively analyzed using a proposed inactivation kinetic model. Our analysis indicated that isoamylase and ß-amylase exhibited significantly different relationships between the inverse of percentage residual activity and the product of number of revolution per time and time elapsed under pressurized carbon dioxide. We believe that the outcome from this work may provide a better understanding of the effects of agitation and pressure in enzyme deactivation behavior under SC-CO2.

The protective effects of a fermented substance from Saccharomyces cerevisiae on carbon tetrachloride-induced liver damage in rats.

BACKGROUND & AIMS: The aim of this study was to investigate the effect of a fermented substance from Saccharomyces cerevisiae (FSSC) on the liver fibrosis induced by chronic carbon tetrachloride (CCl(4)) administration in rats. METHODS: Rats were divided randomly into four groups: control, CCl(4), and two FSSC groups. Except for rats in the control group, all rats were orally administered CCl(4) twice a week for 8 weeks. Rats in the FSSC groups were treated daily with FSSC (0.5 or 1.5 g/kg) through gastrogavage for the entire experimental period. RESULTS: CCl(4) caused liver damage, as characterized by increases in levels of plasma transaminase, hepatic malondialdehyde, and hydroxyproline, in addition to increases in spleen and liver weights and decreases in plasma albumin levels. Compared with CCl(4) group, FSSC (1.5 g/kg) treatment significantly decreased the spleen (P<0.01) and liver (P<0.01) weights, the activities of transaminase (P<0.05), and levels of hepatic malondialdehyde (P<0.05) and hydroxyproline (P<0.01); however, the treatment increased plasma albumin level (P<0.05). The pathological results also showed that FSSC (1.5 g/kg) suppressed hepatic inflammation, steatosis and necrosis. Data for hepatic fibrosis were expressed as the mean percentage of the total hepatic area in the tissue sections. FSSC (1.5 g/kg) treatment significantly decreased the hepatic fibrosis (12.8+/-1.2 and 6.4+/-0.7 in CCl(4) and FSSC group, respectively, P<0.001). RT-PCR analysis showed that FSSC (1.5 g/kg) treatment decreased the expression of methionine adenosyltransferase 2A (P<0.01), collagen (alpha1)(I) (3.15+/-0.05 and 1.52+/-0.04 in CCl(4) and FSSC groups, respectively, P<0.001), and transforming growth factor-beta1 (2.50+/-0.05 and 1.21+/-0.04 in CCl(4) and FSSC groups, respectively, P<0.001), apart from increasing the expression of methionine adenosyltransferase 1A (P<0.05). CONCLUSION: These results showed that FSSC protects the liver against CCl(4) damage in rats.

Inhibitory effect of olive oil on fibrosis induced by carbon tetrachloride in rat liver.

BACKGROUND & AIMS: In this study, the inhibitory effect of olive oil on liver fibrosis induced by carbon tetrachloride (CCl(4)) has been investigated in rats. METHODS: Rats were divided randomly into four groups: control, CCl(4), and two olive oil groups. Except for rats in the control group, all rats were orally administered CCl(4) twice a week for 8 weeks. Rats in the olive oil groups were treated daily with olive oil (2 or 10 ml/kg) through gastrogavage for the entire experimental period. RESULTS: RT-PCR analysis showed that CCl(4) increased the hepatic mRNA expressions of lipopolysaccharide binding protein, CD14, Toll-like receptor-4, NADPH oxidase, nuclear factor-kappa beta, collagen (alpha1) (I), collagen (alpha1) (III), and transforming growth factor beta1. The expression of these mRNAs could be decreased by olive oil treatment. In addition, Western blot analysis also supported these results. CCl(4)-induced liver damage, as characterized by the increase in hepatic malondialdehyde and hydroxyproline levels. Olive oil treatment decreased the hepatic malondialdehyde and hydroxyproline levels. Histological evaluations showed that olive oil could attenuate the liver fibrosis, necrosis, and expression of smooth muscle alpha-actin that are induced by CCl(4). CONCLUSION: It is speculated that the phenolic compounds in olive oil significantly reduced CCl(4)-induced hepatic fibrosis in rats.

Protective effect of a fermented substance from Saccharomyces cerevisiae on liver injury in mice caused by acetaminophen.

The protective effect of a fermented substance from Saccharomyces cerevisiae (FSSC) on liver injury caused by acetaminophen (AAP) was studied in mice. Mice were pretreated with FSSC (0.5-2.0 g/kg, p.o.) for 4 d, and on the fourth day, the mice received an overdose of AAP (500 mg/kg, i.p.). Subsequently, they were sacrificed at 7 h, and blood was drawn from the abdominal vein and liver samples were collected. Histological and biochemical examinations revealed that the administration of AAP caused liver injury in the mice, including increases in plasma alanine aminotransferase and asparate aminotransferase activities and decreases in the hepatic reduced form of glutathione (GSH) content and antioxidant enzyme activities. Prior to AAP treatment, the mice pretreated with FSSC showed significantly reduced levels of alanine aminotransferase (ALT) and aspirate aminotransferase (AST) activity. Liver histology in the FSSC-pretreated mice was significant. In these mice, pretreatment with FSSC also served to reduce hepatic GSH depletion and the inhibition of antioxidant enzyme activity caused by AAP overdose. In conclusion, oral administration of FSSC significantly reduced AAP-induced hepatic injury in the mice.

Maleimide and maleic anhydride derivatives from the mycelia of Antrodia cinnamomea and their nitric oxide inhibitory activities in macrophages.

On cultivation of the fungus Antrodia cinnamomea (BCRC 36799) on a medium, the mycelium was extracted and evaluated for nitric oxide (NO) inhibitory activity. Bioactivity-directed fractionation led to the isolation of two new maleimide derivatives, antrocinnamomins A (1) and B (2), and two new maleic anhydride derivatives, antrocinnamomins C (3) and D (4), along with three known compounds, 3-isobutyl-4-[4-(3-methyl-2-butenyloxy)phenyl]furan-2,5-dione (5), 3-isobutyl-4-[4-(3-methyl-2-butenyloxy)phenyl]-1H-pyrrole-2,5-dione (6), and 3-isobutyl-4-[4-(3-methyl-2-butenyloxy)phenyl]-1H-pyrrol-1-ol-2,5-dione (7). Structural elucidation of compounds 1-4 was carried out by spectroscopic data. Compound 1 displayed significant inhibitory effect on nitric oxide (NO) production.