Permeability optimization and performance evaluation of hot aerosol filters made using foam incorporated alumina suspension

Porous ceramic samples were prepared from aqueous foam incorporated alumina suspension for application as hot aerosol filtering membrane. The procedure for establishment of membrane features required to maintain a desired flow condition was theoretically described and experimental work was designed to prepare ceramic membranes to meet the predicted criteria. Two best membranes, thus prepared, were selected for permeability tests up to 700 degrees C and their total and fractional collection efficiencies were experimentally evaluated. Reasonably good performance was achieved at room temperature, while at 700 degrees C, increased permeability was obtained with significant reduction in collection efficiency, which was explained by a combination of thermal expansion of the structure and changes in the gas properties. (C) 2008 Elsevier B.V. All rights reserved.

Removal of selected metals from drinking water using modified powdered block carbon

This paper presents the possible alternative removal options for the development of safe drinking water supply in the trace elements affected areas. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causes various adverse effects on living bodies. Performance of three filter bed method was evaluated in the laboratory. Experiments have been conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe/Fe(3)C (iron/iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon (PBC), powder carbon steel and ball ceramic in the ion-sorption columns as a cleaning process. The PBC modified is a satisfactory and practical sorbent for trace elements (arsenite and chromate) dissolved in water.

Three filter beds for arsenite and chromate removal

Arsenic (As) and chromium (Cr) are two of the most toxic pollutants introduced into natural waters from a variety of sources, and they cause various adverse effects on living bodies when their concentrations exceed permissible limits. Laboratory experiments have been conducted to investigate the sorption of As and Cr on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of As and Cr species for iron/iron carbide (Fe/Fe3C) sites is the key factor in controlling the removal of the elements. The method is based on the use of powder carbon steel, powdered block carbon, and ball ceramic in the ion-sorption columns as a cleaning process. The presence of carbon steel in a system that contains As3+ and Cr6+ might have a potential effect.

Trace elements removal from water using modified activated carbon

This paper present the possible alternative options for the remove of trace elements from drinking water supplies in the trace. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causing various adverse effects on living bodies. The performance of three filter bed methods was evaluated in the laboratory. Experiments were conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe / Fe3C (iron / iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon, powder carbon steel and ceramic spheres in the ion-sorption columns as a cleaning process. The modified powdered block carbon is a satisfactory and economical sorbent for trace elements (arsenite and chromate) dissolved in water due to its low unit cost of about $23 and compatibility with the traditional household filtration system.

Purification and Characterization of a Trypsin Inhibitor from Plathymenia foliolosa Seeds

A novel trypsin inhibitor (PFTI) was isolated from Plathymenia foliolosa (Benth.) seeds by gel filtration chromatography on a Sephadex G-100, DEAE-Sepharose, and trypsin-Sepharose columns. By SDS-PAGE, PFTI yielded a single band with a M(r) of 19 kDa. PFTI inhibited bovine trypsin and bovine chymotrypsin with equilibrium dissociation constants (K(i)) of 4 x 10(-8) and 1.4 x 10(-6) M, respectively. PFTI retained more than 50% of activity at up to 50 degrees C for 30 min, but there were 80 and 100% losses of activity at 60 and 70 degrees C, respectively. DTT affected the activity or stability of PFTI. The N-terminal amino acid sequence of PFTI showed a high degree of homology with various members of the Kunitz family of inhibitors. Anagasta kuehniella is found worldwide; this insect attacks stored grains and products of rice, oat, rye, corn, and wheat. The velvet bean caterpillar (Anticarsia gemmatalis) is considered the main defoliator pest of soybean in Brazil. Diatraea saccharalis, the sugar cane borer, is the major pest of sugar cane crops, and its caterpillar-feeding behavior, inside the stems, hampers control. PFTI showed significant inhibitory activity against trypsin-like proteases present in the larval midguts on A. kuehniella and D. saccharalis and could suppress the growth of larvae.

The introduction of the Salmonella/microsome mutagenicity assay in a groundwater monitoring program

The objective of this study was to verify the possible inclusion of the Salmonella/microsome mutagenicity assay in a groundwater monitoring program as a complementary assay to assess water quality. Groundwater samples belonging to seven wells from different types of aquifers were analyzed. Three different methods for sample preparation were used: membrane filtration; liquid-liquid and XAD-4 extraction. The filtered samples were tested using TA98, TA100, YG1041 and YG1042 and the water extracts only with TA98 and TA100. No mutagenic activity was observed in any of the 16 filtered samples tested. Out of the 10 samples analyzed using XAD-4 extraction, five showed mutagenic activity with potency ranging from 130 to 1500 revertants/L. Concerning the liquid-liquid extraction, from the 11 samples analyzed, 3 showed mutagenicity. The XAD-4 extraction was the most suitable sample preparation. TA98 without S9 was found to be the most sensitive testing condition. The wells presenting water samples with mutagenic activity belonged to unconfined aquifers, which are more vulnerable to contamination. The data suggest that Salmonella/microsome assay can be used as an efficient screening tool to monitor groundwater for mutagenic activity. (C) 2009 Elsevier B.V. All rights reserved.

Nisin expression production from Lactococcus lactis in milk whey medium

BACKGROUND: Nisin is a commercially available bacteriocin produced by Lactococcus lactis ATCC 11454 and used as a natural agent in the biopreservation of food. In the current investigation, milk whey, a byproduct from dairy industries was used as a fermentation substrate for the production of nisin. Lactococcus lactis ATCC 11454 was developed in a rotary shaker (30 degrees C/36 h/100 rpm) using two different media with milk whey (i) without filtration, pH 6.8, adjusted with NaOH 2 mol L-1 and without pH adjustment, both autoclaved at 121 degrees C for 30 min, and (ii) filtrated (1.20 mu m and 0.22 mu m membrane filter). These cultures were transferred five times using 5 mL aliquots of broth culture for every new volume of the respective media. RESULTS: The results showed that culture media composed of milk whey without filtration supplied L. lactis its adaptation needs better than filtrated milk whey. Nisin titers, in milk whey without filtration (pH adjusted), was 11120.13 mg L-1 in the second transfer, and up to 1628-fold higher than the filtrated milk whey, 6.83 mg.L-1 obtained in the first(t) transfer. CONCLUSIONS: Biological processing of milk byproducts (milk whey) can be considered a profitable alternative, generating high-value bioproducts and contributing to decreasing river disposals by dairy industries. (C) 2008 Society of Chemical Industry.

Partial characterization of proteins from baru (Dipteryx alata Vog) seeds

BACKGROUND: Baru (Dipteryx alata Vog.) is a fruit distributed throughout the Brazilian savanna and contains a seed with a high protein content, whose properties have been rarely explored. The purpose of this study was to characterize this protein, especially by isolation and quantifying its fractions and measuring some of its molecular properties. RESULTS: Baru seeds contain 244 g kg(-1) protein on a dry weight basis. Solubility profiles showed a preponderance of globulins. This fraction dominated the seed composition, with 61.7 wt% of the total soluble proteins. Albumins and glutelins accounted for 14 and 3.3 wt%, respectively. SDS-PAGE resolution of albumin and globulin showed main bands with molecular weights of 84 kDa and 64,66 and 73 kDa, respectively. The total protein of the flour and the globulin showed values of in vitro digestibility of 85.59% and 90.54%, relative to casein. Total globulin produced only one chromatographic peak, both on Sepharose CL-6B gel filtration and on DEAE-cellulose ion-exchange columns, eluted at a concentration of 0.12 mol L(-1) NaCl. CONCLUSION: The baru seed had high protein content with large quantities of storage proteins. The chromatographic and solubility profiles indicate the predominance of a fraction with characteristics of a legumin-type protein. (C) 2011 Society of Chemical Industry

Deconstructing Tick Saliva NON-PROTEIN MOLECULES WITH POTENT IMMUNOMODULATORY PROPERTIES

Dendritic cells (DCs) are powerful initiators of innate and adaptive immune responses. Ticks are blood-sucking ectoparasite arthropods that suppress host immunity by secreting immunomodulatory molecules in their saliva. Here, compounds present in Rhipicephalus sanguineus tick saliva with immunomodulatory effects on DC differentiation, cytokine production, and costimulatory molecule expression were identified. R. sanguineus tick saliva inhibited IL-12p40 and TNF-alpha while potentiating IL-10 cytokine production by bone marrow-derived DCs stimulated by Toll-like receptor-2, -4, and -9 agonists. To identify the molecules responsible for these effects, we fractionated the saliva through microcon filtration and reversed-phase HPLC and tested each fraction for DC maturation. Fractions with proven effects were analyzed by micro-HPLC tandem mass spectrometry or competition ELISA. Thus, we identified for the first time in tick saliva the purine nucleoside adenosine (concentration of similar to 110pmol/mu l) as a potent anti-inflammatory salivary inhibitor of DC cytokine production. We also found prostaglandin E(2) (PGE(2) similar to 100 nM) with comparable effects in modulating cytokine production by DCs. Both Ado and PGE(2) inhibited cytokine production by inducing cAMP-PKA signaling in DCs. Additionally, both Ado and PGE(2) were able to inhibit expression of CD40 in mature DCs. Finally, flow cytometry analysis revealed that PGE(2), but not Ado, is the differentiation inhibitor of bone marrow-derived DCs. The presence of non-protein molecules adenosine and PGE(2) in tick saliva indicates an important evolutionary mechanism used by ticks to subvert host immune cells and allow them to successfully complete their blood meal and life cycle.

Kidney and cloaca function in the estuarine crocodile (Crocodylus porosus) at different salinities: Evidence for solute-linked water uptake

Kidney function and the role of the cloacal complex in osmoregulation was investigated in estuarine crocodile (Crocodylus porosus) exposed to three environmental salinities: hypo-, iso- and hyperosmotic to the plasma. Plasma homeostasis was maintained over the range of salinities. Antidiuresis occurred with increased salinity. Although urine from the kidneys retained an osmotic pressure between 77% and 82% of the plasma, over 93% and 98% of plasma chloride filtered at the glomeruli was reabsorbed during passage through the kidneys under hypo and hyperosmotic conditions, respectively, and only 64% in iso-osmotic water. The kidneys were the primary site of sodium reabsorption under hypo-and hyperosmotic conditions. Secondary processing of urine during storage in the cloaca varied with salinity. During post renal storage of urine, the difference in urine osmotic pressure increased from -26.1 +/- 15.5 to 35.66 +/- 9.29 mOsM with increased salinity, and potassium concentration of urine increased over 3-fold in C. porosus from freshwater. The almost complete reabsorption of both sodium and chloride under hyperosmotic conditions indicates the necessity for secretory activity by the lingual salt glands. The osmoregulatory response of the kidneys and cloacal complex to environmental salinity is both plastic and complementary. (C) 1998 Elsevier Science Inc.

A simplified, sequential, phosphorus fractionation method

Hedley er al. (1982) developed what has become the most widely used land modified), phosphorus (P) fractionation technique. It consists of sequential extraction of increasingly less phytoavailable P pools. Extracts are centrifuged at up to 25000 g (RCF) and filtered to 0.45 mu m to ensure that soil is not lost between extractions. In attempting to transfer this method to laboratories with limited facilities, it was considered that access to high-speed centrifuges, and the cost of frequent filtration may prevent adoption of this P fractionation technique. The modified method presented here was developed to simplify methodology, reduce cost, and therefore increase accessibility of P fractionation technology. It provides quantitative recovery of soil between extractions, using low speed centrifugation without filtration. This is achieved by increasing the ionic strength of dilute extracts, through the addition of NaCl, to flocculate clay particles. Addition of NaCl does not change the amount of P extracted. Flocculation with low speed centrifugation produced extracts comparable with those having undergone filtration (0.025 mu m). A malachite green colorimetric method was adopted for inorganic P determination, as this simple manual method provides high sensitivity with negligible interference from other anions. This approach can also be used for total P following digestion, alternatively non-discriminatory methods, such as inductively coupled plasma atomic emission spectroscopy, may be employed.

Expression, purification, and characterization of biol: A carbon-carbon bond cleaving cytochrome P450 involved in biotin biosynthesis in Bacillus subtilis

Pimelic acid formation for biotin biosynthesis in Bacillus subtilis has been proposed to involve a cytochrome P450 encoded by the gene biol. We have subcloned bioI and overexpressed the encoded protein, BioI. A purification protocol was developed utilizing ion exchange, gel filtration, and hydroxyapatite chromatography, Investigation of the purified BioI by UV-visible spectroscopy revealed spectral properties characteristic of a cytochrome P450 enzyme. BioI copurifies with acylated Escherichia coil acyl carrier protein (ACP), suggesting that in vivo a fatty acid substrate may be presented to BioI as an acyl-ACP. A combination of electrospray mass spectrometry of the intact acyl-ACP and GCMS indicated a range of fatty acids were bound to the ACP. A catalytically active system has been established employing E. coli flavodoxin reductase and a novel, heterologous flavodoxin as the redox partners for BioI. In this system, BioI cleaves a carbon-carbon bond of an acyl-ACP to generate a pimeloyl-ACP equivalent, from which pimelic acid is isolated after base-catalyzed saponification. A range of free fatty acids have also been explored as potential alternative substrates for BioI, with C16 binding most tightly to the enzyme. These fatty acids are also metabolized to dicarboxylic acids, but with less regiospecificity than is observed with acyl-ACPs. A possible mechanism for this transformation is discussed. These results strongly support the proposed role for BioI in biotin biosynthesis. In addition, the production of pimeloyl-ACP explains the ability of BioI to function as a pimeloyl CoA source in E. coli, which, unlike B. subtilis, is unable to utilize free pimelic acid for biotin production. (C) 2000 Academic Press.

Directed evolution of mammalian cytochrome P450 enzymes involved in xenobiotic metabolism

Directed evolution of cytochrome P450 enzymes represents an attractive means of generating novel catalysts for specialized applications. Xenobiotic-metabolizing P450s are particularly well suited to this approach due to their inherent wide substrate specificity. In the present study, a novel method for DNA shuffling was developed using an initial restriction enzyme digestion step, followed by elimination of long parental sequences by size-selective filtration. P450 2C forms were subjected to a single round of shuffling then coexpressed with reductase in E. coli. A sample (54 clones) of the resultant library was assessed for sequence diversity, hemo- and apoprotein expression, and activity towards the substrate indole. All mutants showed a different RFLP pattern compared to all parents, suggesting that the library was free from contamination by parental forms. Haemoprotein expression was detectable in 45/54 (83%) of the mutants sampled. Indigo production was less than or comparable to the activities of one or more of the parental P450s, but three mutants showed indirubin production in excess of that seen with any parental form, representing a gain of function. In conclusion, a method is presented for the effective shuffling of P450 sequences to generate diverse libraries of mutant P450s containing a high proportion of correctly folded hemoprotein, and minimal contamination with parental forms.

Combined in-fermenter extraction and cross-flow microfiltration for improved inclusion body processing

In this study we demonstrate a new in-fermenter chemical extraction procedure that degrades the cell wall of Escherichia coli and releases inclusion bodies (IBs) into the fermentation medium. We then prove that cross-flow microfiltration can be used to remove 91% of soluble contaminants from the released IBs. The extraction protocol, based on a combination of Triton X-100, EDTA, and intracellular T7 lysozyme, effectively released most of the intracellular soluble content without solubilising the IBs. Cross-flow microfiltration using a 0.2 mum ceramic membrane successfully recovered the granulocyte macrophagecolony stimulating factor (GM-CSF) IBs with removal of 91% of the soluble contaminants and virtually no loss of IBs to the permeate. The filtration efficiency, in terms of both flux and transmission, was significantly enhanced by infermenter Benzonase(R) digestion of nucleic acids following chemical extraction. Both the extraction and filtration methods exerted their efficacy directly on a crude fermentation broth, eliminating the need for cell recovery and re-suspension in buffer. The processes demonstrated here can all be performed using just a fermenter and a single cross-flow filtration unit, demonstrating a high level of process intensification. Furthermore, there is considerable scope to also use the microfiltration system to subsequently solubilise the IBs, to separate the denatured protein from cell debris, and to refold the protein using diafiltration. In this way refolded protein can potentially be obtained, in a relatively pure state, using only two unit operations. (C) 2004 Wiley Periodicals Inc.

Purification and biochemical characterization of a thermostable extracellular glucoamylase produced by the thermotolerant fungus Paecilomyces variotii

An extracellular glucoamylase produced by Paecilomyces variotii was purified using DEAE-cellulose ion exchange chromatography and Sephadex G-100 gel filtration. The purified protein migrated as a single band in 7% PAGE and 8% SDS-PAGE. The estimated molecular mass was 86.5 kDa (SDS-PAGE). Optima of temperature and pH were 55 degrees C and 5.0, respectively. In the absence of substrate the purified glucoamylase was stable for 1 h at 50 and 55 degrees C, with a t(50) of 45 min at 60 degrees C. The substrate contributed to protect the enzyme against thermal denaturation. The enzyme was mainly activated by manganese metal ions. The glucoamylase produced by P. variotii preferentially hydrolyzed amylopectin, glycogen and starch, and to a lesser extent malto-oligossacarides and amylose. Sucrose, p-nitrophenyl alpha-D-maltoside, methyl-alpha-D-glucopyranoside, pullulan, alpha- and beta-cyclodextrin, and trehalose were not hydrolyzed. After 24 h, the products of starch hydrolysis, analyzed by thin layer chromatography, showed only glucose. The circular dichroism spectrum showed a protein rich in alpha-helix. The sequence of amino acids of the purified enzyme VVTDSFR appears similar to glucoamylases purified from Talaromyces emersonii and with the precursor of the glucoamylase from Aspergillus oryzae. These results suggested the character of the enzyme studied as a glucoamylase (1,4-alpha-D-glucan glucohydrolase).