Animals ; Humans ; Hydrogen Sulfide ; metabolism ; Inflammation ; metabolism

OBJECTIVETo study the characteristics of a bioflocculant named MBF7 produced by Penicillum strain HHE-P7 and the effects of cultivation conditions on bioflocculant production.

METHODSThe chemical group in the bioflocculant molecules was shown by Fourier transform infrared (FTIR) spectra, and the average molecular weight of MBF7 was estimated by gel permeation chromatography. The effects of medium components on bioflocculant production and flocculating activity were studied.

RESULTSPhospho-, amino-, hydroxyl, and carboxyl groups were the major fractions of MBF7, and the molecule weight was about 3.0x10(5) Da. In addition, the carbon and nitrogen sources favorable for the bioflocculant production were glucose and yeast extract respectively. When the initial pH of the medium was adjusted to 5.0, high flocculant efficiency could be achieved.

CONCLUSIONThe bioflocculant MBF7 is a new macromolecule with high flocculating efficiency for Kaolin suspension, and could be produced under appropriate culture conditions.

Culture Media ; Hydrogen-Ion Concentration ; Penicillium ; metabolism

OBJECTIVETo investigate the influence of a broad range of environmental conditions on initial rates of hydrogen peroxide produced by Streptococcus oralis (S. oralis).

METHODSFor each rate measurement, 1 ml aliquots of 10(12) cells/L mid-logarithmic phase S. oralis in TSBY were centrifuged and respectively washed by phosphate buffer containing 0.01-10 mmol/L glucose or sucrose, phosphate buffer with 5.0-7.5 pH or Bis-Tris buffer containing 0.01-100 mmol/L Ca(2+), 0.01-100 mmol/L F(-) or 0.01-100 mmol/L HFPO(3)(-). After S. oralis was cultured in respective buffer for 10, 20 and 30 min at 37 degrees C, the concentration of hydrogen peroxide in supernatant was assayed spectrophotometrically in 96-well micro-plate by ABTS-HRP at A(405).

RESULTSSynthesis rate of hydrogen peroxide by S. oralis was 7.48 micromol/L per minute without carbohydrate, the synthesis rate of hydrogen peroxide by S. oralis increased with 0.01-10 mmol/L glucose and 0.01-10 mmol/L sucrose, but there was no statistically significant difference in synthesis rate among the carbohydrate groups. The rates of H2O2 synthesis were inhibited in the buffer at pH 5.0-6.0, compared with pH 7.0 (P < 0.05). Ca(2+) had little influence on the rate of H2O2 synthesis. IC(50) of H2O2 synthesis rates by S. oralis responded to FHPO(3)(-) and F(-) were 12.65 mmol/L and 1.90 mmol/L respectively.

CONCLUSIONSEnvironmental conditions may influence the synthesis rate of H2O2 by S. oralis.

Culture Media ; chemistry ; Glucose ; Hydrogen Peroxide ; metabolism ; Hydrogen-Ion Concentration ; Metals, Heavy ; Streptococcus oralis ; metabolism

OBJECTIVETo investigate the characteristics of Zn2+ biosorption and the release of cations during the process of Zn2+ biosorption by intact cells of Saccharomyces cerevisiae.

METHODSThe batch adsorption test was used to study the biosorption equilibrium and isotherm. Zn2+ concentration was measured with atomic adsorption spectrophotometer (AAS) AAS 6 Vario.

RESULTSWhen the initial concentration of Zn2+ ranged between 0.08 and 0.8 mmol/L, the initial pH was natural (about 5.65), the sorbent concentration was about 1 g/L and the capacity of Zn2+ biosorption was from 74.8 to 654.8 micromol/g. The pH value increased by 0.55-1.28 and the intracellular cations (K+, Mg2+, Na+, Ca2+) of the cells were released during the process of Zn2+ biosorption.

CONCLUSIONIon exchange was one of the mechanisms for Zn2+ biosorption. The biomass of Saccharomyces cerevisiae is a potential biosorbent for the removal of Zn2+ from aqueous solution. More work needs to be done before putting it into practical application.

Hydrogen-Ion Concentration ; Saccharomyces cerevisiae ; metabolism ; Spectrophotometry, Atomic ; Zinc ; metabolism

OBJECTIVETo review the vasorelaxant effects of hydrogen sulfide (H(2)S) in arterial rings in the cardiovascular system under both physiological and pathophysiological conditions and the possible mechanisms involved.

DATA SOURCESThe data in this review were obtained from Medline and Pubmed sources from 1997 to 2011 using the search terms "hydrogen sulfide" and "vascular relaxation".

STUDY SELECTIONArticles describing the role of hydrogen sulfide in the regulation of vascular activity and its vasorelaxant effects were selected.

RESULTSH(2)S plays an important role in the regulation of cardiovascular tone. The vasomodulatory effects of H(2)S depend on factors including concentration, species and tissue type. The H(2)S donor, sodium hydrosulfide (NaHS), causes vasorelaxation of rat isolated aortic rings in a dose-dependent manner. This effect was more pronounced than that observed in pulmonary arterial rings. The expression of K(ATP) channel proteins and mRNA in the aortic rings was increased compared with pulmonary artery rings. H(2)S is involved in the pathogenesis of a variety of cardiovascular diseases. Downregulation of the endogenous H(2)S pathway is an important factor in the pathogenesis of cardiovascular diseases. The vasorelaxant effects of H(2)S have been shown to be mediated by activation of K(ATP) channels in vascular smooth muscle cells and via the induction of acidification due to activation of the Cl(-)/HCO(3)(-) exchanger. It is speculated that the mechanisms underlying the vasoconstrictive function of H(2)S in the aortic rings involves decreased NO production and inhibition of cAMP accumulation.

CONCLUSIONH(2)S is an important endogenous gasotransmitter in the cardiovascular system and acts as a modulator of vascular tone in the homeostatic regulation of blood pressure.

Animals ; Cardiovascular System ; metabolism ; Humans ; Hydrogen Sulfide ; metabolism ; Vasodilation ; physiology

Catalases are well studied enzymes that play critical roles in protecting cells against the toxic effects of hydrogen peroxide. The ubiquity of the enzyme and the availability of substrates made heme catalases the focus of many biochemical and molecular biology studies over 100 years. In human, this has been implicated in various physiological and pathological conditions. Advancement in proteomics revealed many of novel and previously unknown features of this mysterious enzyme, but some functional aspects are yet to be explained. Along with discussion on future research area, this mini-review compile the information available on the structure, function and mechanism of action of human catalase.
Catalase ; chemistry ; metabolism ; physiology ; Heme ; chemistry ; Humans ; Hydrogen Peroxide ; metabolism

A mixture of fructose and glucose was developed to simulate the hydrolysate of Jerusalem artichoke tubers, the fructose-based feedstock suitable for butanol production. With the initial pH of 5.5 without regulation during mixed-sugar fermentation, as high as 23.26 g/L sugars were remained unconverted, and butanol production of 5.51 g/L were obtained. Compared with either glucose or fructose fermentation, the early termination of mixed-sugar fermentation might be caused by toxic organic acids and the low pH. When the pH of the fermentation system was controlled at higher levels, it was found that sugars utilization was facilitated, but less butanol was produced due to the over-accumulation of organic acids. On the other hand, when the pH was controlled at lower levels, more sugars were remained unconverted, although butanol production was improved. Based on these experimental results, a stage-wise pH regulation strategy, e.g., controlling the pH of the fermentation system at 5.5 untill the OD620 reached 1.0, and then the pH control was removed, was developed, which significantly improved the fermentation performance of the system, with only 2.05 g/L sugars unconverted and 10.48 g/L butanol produced.
Acetone ; metabolism ; Butanols ; metabolism ; Fermentation ; Fructose ; metabolism ; Glucose ; metabolism ; Helianthus ; metabolism ; Hydrogen-Ion Concentration

To evaluate the ability of microbial mix-culture fermenting syngas into ethanol, we studied the microbial mix-cultures A-fm 4, G-fm 4, Lp-fm 4 and B-fm 4 obtained by enrichment and compared with Clostridium autoethanogenum DSM10061 with 10% and 25% inoculation size. The results show that, with 10% inoculation size, the ethanol production of A-fm 4, G-fm 4, Lp-fm 4, B-fm 4 and C. autoethanogenum were 349.15, 232.16, 104.25, 79.90 and 26.99 mg/L respectively. With 25% inoculation size, the ethanol production were 485.81, 472.73, 348.58, 272.52 and 242.15 mg/L respectively. Higher inoculation size will increase the production of ethanol. The tested mix-culture exhibited a significant yield advantage compared with the maximum production of C. autoethanogenum reported in the literature (259.64 mg/L). This research provided a practical method to improve ethanol production from syngas.
Bacteria ; classification ; metabolism ; Clostridium acetobutylicum ; metabolism ; Ethanol ; isolation & purification ; metabolism ; Fermentation ; Gases ; metabolism ; Hydrogen ; metabolism

OBJECTIVEThis review discusses the current status and progress in studies on the roles of hydrogen sulfide (H(2)S) in regulation of neurotoxicity, neuroprotection, and neuromodulator, as well as its therapeutic potential for neurodegenerative disorders.

DATA SOURCESThe data used in this review were mainly from Medline and PubMed published in English from 2001 to August 2011. The search terms were "hydrogen sulfide", "neuron", and "neurodegenerative disorders".

STUDY SELECTIONArticles regarding the regulation of neuronal function, the protection against neuronal damage and neurological diseases, and their possible cellular and molecular mechanisms associated with H(2)S were selected.

RESULTSThe inhibited generation of endogenous H(2)S is implicated in 1-methy-4-phenylpyridinium ion, 6-OHDA, and homocysteine-triggered neurotoxicity. H(2)S elicits neuroprotection in Alzheimer's disease and Parkinson's disease models as well as protecting neurons against oxidative stress, ischemia, and hypoxia-induced neuronal death. H(2)S offers anti-oxidant, anti-inflammatory and anti-apoptotic effects, as well as activates ATP-sensitive potassium channels and cystic fibrosis transmembrane conductance regulator Cl- channels. H(2)S regulates the long-term potentiation (LTP) and GABAB receptors in the hippocampus, as well as intracellular calcium and pH homeostasis in neurons and glia cells.

CONCLUSIONSThese articles suggest that endogenous H(2)S may regulate the toxicity of neurotoxin. H(2)S not only acts as a neuroprotectant but also serves as a novel neuromodulator.

Animals ; Humans ; Hydrogen Sulfide ; metabolism ; Nervous System ; metabolism ; Neuroprotective Agents ; metabolism ; Neurotoxins ; metabolism ; Neurotransmitter Agents ; metabolism

5-aminovalanoic acid (5AVA) can be used as the precursor of new plastics nylon 5 and nylon 56, and is a promising platform compound for the synthesis of polyimides. At present, the biosynthesis of 5-aminovalanoic acid generally is of low yield, complex synthesis process and high cost, which hampers large-scale industrial production. In order to achieve efficient biosynthesis of 5AVA, we developed a new pathway mediated by 2-keto-6-aminohexanoate. By combinatory expression of L-lysine α-oxidase from Scomber japonicus, α-ketoacid decarcarboxylase from Lactococcus lactis and aldehyde dehydrogenase from Escherichia coli, the synthesis of 5AVA from L-lysine in Escherichia coli was achieved. Under the initial conditions of glucose concentration of 55 g/L and lysine hydrochloride of 40 g/L, the final consumption of 158 g/L glucose and 144 g/L lysine hydrochloride, feeding batch fermentation to produce 57.52 g/L of 5AVA, and the molar yield is 0.62 mol/mol. The new 5AVA biosynthetic pathway does not require ethanol and H₂O₂, and achieved a higher production efficiency as compared to the previously reported Bio-Chem hybrid pathway mediated by 2-keto-6-aminohexanoate.
Nylons ; Lysine/metabolism* ; Hydrogen Peroxide/metabolism* ; Metabolic Engineering ; Plastics/metabolism* ; Fermentation ; Escherichia coli/metabolism* ; Aminocaproates/metabolism*