Biohydrogen production by dark fermentation of glycerol using Enterobacter and Citrobacter Sp

Glycerol is an attractive substrate for biohydrogen production because, in theory, it can produce 3 mol of hydrogen per mol of glycerol. Moreover, glycerol is produced in substantial amounts as a byproduct of producing biodiesel, the demand for which has increased in recent years. Therefore, hydrogen production from glycerol was studied by dark fermentation using three strains of bacteria: namely, Enterobacter spH1, Enterobacter spH2, and Citrobacter freundii H3 and a mixture thereof (1:1:1). It was found that, when an initial concentration of 20 g/L of glycerol was used, all three strains and their mixture produced substantial amounts of hydrogen ranging from 2400 to 3500 mL/L, being highest for C. freundii H3 (3547 mL/L) and Enterobacter spH1 (3506 mL/L). The main nongaseous fermentation products were ethanol and acetate, albeit in different ratios. For Enterobacter spH1, Enterobacter spH2, C. freundii H3, and the mixture (1:1:1), the ethanol yields (in mol EtOH/mol glycerol consumed) were 0.96, 0.67, 0.31, and 0.66, respectively. Compared to the individual strains, the mixture (1:1:1) did not show a significantly higher hydrogen level, indicating that there was no synergistic effect. Enterobacter spH1 was selected for further investigation because of its higher yield of hydrogen and ethanol. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013     

Carcass traits and meat quality of Nellore cattle fed different non-fiber carbohydrates sources associated with crude glycerin

Crude glycerin, a potential energy source for ruminant animals, has been evaluated, mainly, in diets with high starch content. However, a limit number of studies have evaluated the inclusion of crude glycerin in low starch diets. This study aimed to evaluate the effects of the association of crude glycerin with corn grain or citrus pulp on carcass traits and meat quality of Nellore bulls (n=30, 402±31 kg initial weight). The treatment consisted of: CON=control, without crude glycerin; CG10=10% of crude glycerin and corn grain; CG15=15% of crude glycerin and corn grain; CP10=10% of crude glycerin and citrus pulp; CP15=15% of crude glycerin and citrus pulp. The performance parameters and carcass traits were not affected by treatments (P>0.05). The inclusion of crude glycerin decreased yellow color intensity and increased fatty acids pentadecanoic and heptadecenoic in meat (P<0.05), without affecting neither the concentration of polyunsaturated fatty acids nor the relationship of saturated and unsaturated fatty acids. The association of crude glycerin with corn or citrus pulp has no adverse effects on carcass characteristics and meat quality.     

Overexpression of ACC gene from oleaginous yeast Lipomyces starkeyi enhanced the lipid accumulation in Saccharomyces cerevisiae with increased levels of glycerol 3-phosphate substrates

The conversion of acetyl-CoA to malonyl-CoA by acetyl-CoA carboxylase (ACC) is the rate-limiting step in fatty acid biosynthesis. In this study, a gene coding for ACC was isolated and characterized from an oleaginous yeast, Lipomyces starkeyi. Real-time quantitative PCR (qPCR) analysis of L. starkeyi acetyl-CoA carboxylase gene (LsACC1) showed that the expression levels were upregulated with the fast accumulation of lipids. The LsACC1 was co-overexpressed with the glycerol 3-phosphate dehydrogenase gene (GPD1), which regulates lipids biosynthesis by supplying another substrates glycerol 3-phosphate for storage lipid assembly, in the non-oleaginous yeast Saccharomyces cerevisiae. Further, the S. cerevisiae acetyl-CoA carboxylase (ScACC1) was transferred with GPD1 and its function was analyzed in comparison with LsACC1. The results showed that overexpressed LsACC1 and GPD1 resulted in a 63% increase in S. cerevisiae. This study gives new data in understanding of the molecular mechanisms underlying the regulation of fatty acids and lipid biosynthesis in yeasts.     

Co‐utilization of acidified glycerol pretreated‐sugarcane bagasse for microbial oil production by a novel Rhodosporidium strain

Acidified glycerol pretreatment is very effective to deconstruct lignocellulosics for producing glucose. Co‐utilization of pretreated biomass and residual glycerol to bioproducts could reduce the costs associated with biomass wash and solvent recovery. In this study, a novel strain Rhodosporidium toruloides RP 15, isolated from sugarcane bagasse, was selected and tested for coconversion of pretreated biomass and residual glycerol to microbial oils. In the screening trails, Rh. toruloides RP 15 demonstrated the highest oil production capacity on glucose, xylose, and glycerol among the 10 strains. At the optimal C:N molar ratio of 140:1, this strain accumulated 56.7, 38.3, and 54.7% microbial oils based on dry cell biomass with 30 g/L glucose, xylose, and glycerol, respectively. Furthermore, sugarcane bagasse medium containing 32.6 g/L glucose from glycerol‐pretreated bagasse and 23.4 g/L glycerol from pretreatment hydrolysate were used to produce microbial oils by Rh. toruloides RP 15. Under the preliminary conditions without pH control, this strain produced 7.7 g/L oil with an oil content of 59.8%, which was comparable or better than those achieved with a synthetic medium. In addition, this strain also produced 3.5 mg/L carotenoid as a by‐product. It is expected that microbial oil production can be significantly improved through process optimization.     

1,3-丙二醇发酵中甘油代谢及产物抑制作用

对微生物法甘油转化成1,3-丙二醇过程中代谢规律及代谢控制的相关酶作以简述,并着重分析了丁酸梭菌发酵生产中乙酸、丁酸等副产物对细胞的抑制作用,对未来的研究发展方向进行了展望。     

Purification,stabilization, and crystallization of a modular protein: Grb2

We report here the purification and the crystallization of the modular protein Grb2. The protein was expressed as a fusion with glutathione-S-transferase and purified by affinity chromatography on glutathione agarose. It was apparent from reverse phase chromatography that the purified protein was conformationally unstable. Instability was overcome by the addition of 100 mM arginine to the buffers. Because Grb2 appeared to be extremely sensitive to oxidation, crystallization experiments were performed with a dialysis button technique involving daily addition of fresh DTT to the reservoirs. The presence of 8 to 14% glycerol was necessary to obtain mono-crystals. These results are discussed in relation with the modular nature of Grb2. © 1996 Wiley-Liss, Inc.     

Ultrasound promoted green synthesis,anticancer evaluation,and molecular docking studies of hydrazines: a pilot trial

We reported herein an efficient, environmentally friendly synthesis of hydrazine carboxamides (6a–l) in a water-glycerol (6:4) solvent system using ultrasonic irradiation. Ultrasonicated reactions were found to be much faster and more productive than conventional synthesis. The prepared compounds (6a–l) were tested against nine panels of 60 cancer cell lines according to the National Cancer Institute (NCI US) protocol. N-(4-Chlorophenyl)-2-(2-oxoindolin-3-ylidene)hydrazine-1-carboxamide (6b) was discovered to be promising anticancer agents with higher sensitivity against CCRF-CEM, HOP-92, UO-31, RMPI-8226, HL-60(TB), and MDA-MB-468 with percent growth inhibitions (%GIs) of 143.44, 33.46, 33.21, 33.09, 29.81, and 29.55 respectively. Compounds (6a–l) tested showed greater anticancer activity than Imatinib, except for compound 6k. Compounds 6b and 6c were found to be lethal on the CCRF-CEM leukaemia cell line, with %GIs of 143.44 and 108.91, respectively. Furthermore, molecular docking analysis was performed to investigate ligand binding affinity at the active site of epidermal growth factor (EGFR).     

On the structure of hisH: protein structure prediction in the context of structural and functional genomics

We predict a structure of the glutamine amidotransferase subunit (hisH) of imidazole glycerol phosphate synthase (IGPS) which catalyzes the fifth step of the histidine biosynthesis in Escherichia coli. The model is constructed using an energy-based threading program augmented by a multiple sequence to structure profile analysis. In developing our model we identified a conserved core region within hisH and a variable domain which is the likely site of interaction with the synthase subunit (hisF) of IGPS. Information available from structural and functional genomics studies was used to improve the structure prediction, to discuss parallels between histidine biosynthesis and other amino acid and nucleotide metabolic pathways, and to better understand the protein-protein interactions between the hisH and hisF domains of IGPS. This work allows us to develop a preliminary model for the structure of the entire IGPS holoenzyme.     

Physical Changes of Amniotic Membranes Through Glycerolization for The Use as an Epidermal Substitute. Light and Electron Microscopic Studies

Our Department of Plastic and Reconstructive Surgery has routinely been using amnion preserved in glycerol for the treatment of debrided II° burns. This treatment is almost pain free and requires fewer changes of dressings and fewer anaesthetics. It also prevents overgrowing granulation tissue and lessens scarring. Since 1910 amnion has been used as biological wound dressing. Its advantages such as reduced loss of protein and electrolytes, fluids and energy as well as reducing the risk of infection and accelerated regeneration of the epithelium have been well documented in medical literature. In order to more closely examine the question of possible changes to the micro structure of the amnion through preservation and rehydration as well as the interaction between transplanted tissue and recipient, we have carried out several light and electron microscopic studies. Results showed that neither the treatment with glycerol, nor the pretransplantation rehydration eliminates the monolayer of surface epithelium of the amnion. Its complex architecture remains intact during the preservation process and is therefore suitable as a matrix for the growth of keratinocytes and thereby the healing process. In clinical use we found amnion to be an excellent wound dressing as it allows proper control of fluid, has sufficient permeability for gases, has good thermal properties, is impervious to micro-organisms and is free from toxic material. This revised version was published online in July 2006 with corrections to the Cover Date.