PubMed · 15658414
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Junki Takamatsu. 2004. [Factor X].. https://pubmed.ncbi.nlm.nih.gov/15658414/
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Commercial cellulase preparations are potentially effective for processing biomass feedstocks in order to obtain bioethanol. In plant cell walls, cellulose fibrils occur in close association with xylans (monocotyls) or xyloglucans (dicotyls). The enzymatic conversion of cellulose/xylans is a complex process involving the concerted action of exo/endocellulases and cellobiases yielding glucose and xylanases yielding xylooligomers and xylose. An overview of commonly measured cellulase-, cellobiase-, and xylanase-activity, using respectively filter paper, cellobiose, and AZCL-dyed xylan as a substrate of 14 commercially available enzyme preparations from several suppliers is presented. In addition to these standardized tests, the enzyme-efficiency of degrading native substrates was studied. Grass and wheat bran were fractionated into a water unsoluble fraction (WUS), which was free of oligosaccharides and starch. Additionally, cellulose- and xylan-rich fractions were prepared by alkaline extraction of the WUS and were enzymatically digested. Hereby, the capability of cellulose and xylan conversion of the commercial enzyme preparations tested was measured. The results obtained showed that there was a large difference in the performance of the fourteen enzyme samples. Comparing all results, it was concluded that the choice of an enzyme preparation is more dependent on the characteristics of the substrate rather than on standard enzyme-activities measured.
Mast cells are highly responsive cells that are capable of secreting a variety of inflammatory mediators, including histamine, heparin, serine proteases, leukotrienes, prostaglandins, and thromboxanes. Studies from several laboratories have demonstrated that mast cells have the capacity to produce a variety of cytokines in response to various stimuli. Characterization of the cytokine profiles in mast cells has routinely been determined by the performance of individual enzyme-linked immunosorbent assays. This process is expensive, time-consuming, and requires a great deal of material to characterize multiple cytokines. In this chapter, we describe a multiplex cytokine assay to detect 17 cytokines simultaneously in 50 microL of culture supernatant derived from stimulated human cord blood-derived mast cells.
Zero valent iron (ZVI) is a reactive media commonly utilized in permeable reactive barriers (PRBs). Sulfate reducing bacteria are being considered for the immobilization of heavy metals in PRBs. The purpose of this study was to evaluate the potential of ZVI as an electron donor for sulfate reduction in natural mixed anaerobic cultures. The ability of methanogens to utilize ZVI as an electron-donor was also explored since these microorganisms often compete with sulfate reducers for common substrates. Four grades of ZVI of different particle sizes (1.120, 0.149, 0.044, and 0.010 mm diameter) were compared as electron donor in batch bioassays inoculated with anaerobic bioreactor sludge. Methanogenesis was evaluated in mineral media lacking sulfate. Sulfate reduction was evaluated in mineral media containing sulfate and the specific methanogenic inhibitor, 2-bromoethane sulfonate. ZVI contributed to significant increases in methane production and sulfate reduction-compared to endogenous substrate controls. The rates of methane formation or sulfate reduction were positively correlated with the surface area of ZVI. The highest rates of 0.310 mmol CH4 formed/mol Fe0.day and 0.804 mmol SO4(2-) reduced/mol Fe0.day were obtained with the finest grade of ZVI (0.01 mm). The results demonstrate that ZVI is readily utilized as a slow-release electron donor for methanogenesis and sulfate reduction in anaerobic sludge; and therefore, has a promising potential in bioremediation applications.