Abstract  Zinc is both an essential and potentially toxic metal. It is widely believed that oral zinc supplementation can reduce the effects of the common cold; however, there is strong clinical evidence that intranasal (IN) zinc gluconate (ZG) gel treatment for this purpose causes anosmia, or the loss of the sense of smell, in humans. Using the rat olfactory neuron cell line, Odora, we investigated the molecular mechanism by which zinc exposure exerts its toxic effects on olfactory neurons. Following treatment of Odora cells with 100 and 200μM ZG for 0-24h, RNA-seq and in silico analyses revealed up-regulation of pathways associated with zinc metal response, oxidative stress, and ATP production. We observed that Odora cells recovered from zinc-induced oxidative stress, but ATP depletion persisted with longer exposure to ZG. ZG exposure increased levels of NLRP3 and IL-1β protein levels in a time-dependent manner, suggesting that zinc exposure may cause an inflammasome-mediated cell death, pyroptosis, in olfactory neurons.

Abstract  A new caffeoylgluconic acid derivative, trans-caffeoyl-6-O-D-gluconic acid methyl ester (1), together with two known compounds named trans-caffeoyl-6-O-D-glucono-γ-lactone (2) and trans-caffeoyl-6-O-D-gluconic acid (3), was isolated from the nearly ripe fruits of Evodia rutaecarpa (Juss.) Benth.. These compounds were isolated by various separation methods associated with the UPLC-Q-TOF-MS technique. Their structures were elucidated on the basis of extensive spectroscopic methods.

Abstract  The effect of pH on the pore-forming ability of two Bacillus thuringiensis toxins, Cry1Ac and Cry1C, was examined with midgut brush border membrane vesicles isolated from the tobacco hornworm, Manduca sexta, and a light-scattering assay. In the presence of Cry1Ac, membrane permeability remained high over the entire pH range tested (6.5 to 10.5) for KCl and tetramethylammonium chloride, but was much lower at pH 6.5 than at higher pHs for potassium gluconate, sucrose, and raffinose. On the other hand, the Cry1C-induced permeability to all substrates tested was much higher at pH 6.5, 7.5, and 8.5 than at pH 9.5 and 10.5. These results indicate that the pores formed by Cry1Ac are significantly smaller at pH 6.5 than under alkaline conditions, whereas the pore-forming ability of Cry1C decreases sharply above pH 8.5. The reduced activity of Cry1C at high pH correlates well with the fact that its toxicity for M. sexta is considerably weaker than that of Cry1Aa, Cry1Ab, and Cry1Ac. However, Cry1E, despite having a toxicity comparable to that of Cry1C, formed channels as efficiently as the Cry1A toxins at pH 10.5. These results strongly suggest that although pH can influence toxin activity, additional factors also modulate toxin potency in the insect midgut.

Abstract  Previously, we identified the uncharacterized predicted membrane protein PA2663 of Pseudomonas aeruginosa PAO1 as a virulence factor using a poplar tree model; PA2663 was induced in the poplar rhizosphere and, upon inactivation, it caused 20-fold lower biofilm formation (Attila et al., Microb Biotechnol, 2008). Here, we confirmed that PA2663 is related to biofilm formation by restoring the wild-type phenotype by complementing the PA2663 mutation in trans and investigated the genetic basis of its influence on biofilm formation through whole-transcriptome and -phenotype studies. Upon inactivating PA2663 by transposon insertion, the psl operon that encodes a galactose- and mannose-rich exopolysaccharide was highly repressed (verified by RT-PCR). The inactivation of PA2663 also repressed 13 pyoverdine genes, which eliminated the production of the virulence factor pyoverdine in P. aeruginosa. The inactivation of PA2663 also affected other quorum-sensing-related phenotypes in that it repressed the Pseudomonas quinolone signal (PQS) genes, which abolished PQS production, and repressed lasB, which decreased elastase activity sevenfold. Genes were also induced for motility and attachment (PA0499, PA0993, PA2130, and PA4549) and for small molecule transport (PA0326, PA1541, PA1632, PA1971, PA2214, PA2215, PA2678, and PA3407). Phenotype arrays also showed that PA2663 represses growth on D: -gluconic acid, D: -mannitol, and N-phthaloyl-L: -glutamic acid. Hence, the PA2663 gene product increases biofilm formation by increasing the psl-operon-derived exopolysaccharides and increases pyoverdine synthesis, PQS production, and elastase activity while reducing swarming and swimming motility. We speculate that PA2663 performs these myriad functions as a novel membrane sensor.

Abstract  Spatial organization of multiple enzymes at specific positions for a controlled reaction cascade has attracted wide attention in recent years. Here, we report the construction of a biomimetic enzyme cascade organized on DNA triangle prism (TP) nanostructures to enable the efficient catalytic production of nitric oxide (NO) on a single microbead. Two enzymes, glucose oxidase (GOx) and horseradish peroxidase (HRP), were assembled at adjacent locations on a DNA TP nanostructure by using DNA-binding protein adaptors with small interenzyme distances. In the cascade, the first enzyme, GOx, converts glucose into gluconic acid in the presence of oxygen. The produced H2 O2 intermediate is rapidly transported to the second enzyme, HRP, which oxides hydroxyurea into NO and other nitroxyl species. The pH near the surface of the negatively charged DNA nanostructures is believed to be lower than that in the bulk solution; this creates an optimal pH environment for the anchored enzymes, which results in higher yields of the NO product. Furthermore, the multienzyme system was immobilized on a microbead mediated by a DNA adaptor, and this enabled the efficient catalytic generation of gas molecules in the microreactor. Therefore, this work provides an alternative route for the biomimetic generation of NO through enzyme cascades. In particular, the dynamic binding capability of the DNA sequence enabled the positions of the protein enzyme and the DNA nanostructure to be reversed, which allowed the cascade catalysis to be modulated.

Abstract  The purification and characterization of a novel extracellular beta-glucosidase from Paecilomyces thermophila J18 was studied. The beta-glucosidase was purified to 105-fold apparent homogeneity with a recovery yield of 21.7% by DEAE 52 and Sephacryl S-200 chromatographies. Its molecular masses were 116 and 197 kDa when detected by SDS-PAGE and gel filtration, respectively. It was a homodimeric glycoprotein with a carbohydrate content of 82.3%. The purified enzyme exhibited an optimal activity at 75 degrees C and pH 6.2. It was stable up to 65 degrees C and in the pH range of 5.0-8.5. The enzyme exhibited a broad substrate specificity and significantly hydrolyzed p-nitrophenyl-beta- d-glucopyranoside ( pNPG), cellobiose, gentiobiose, sophorose, amygdalin, salicin, daidzin, and genistin. Moreover, it displayed substantial activity on beta-glucans such as laminarin and lichenan, indicating that the enzyme has some exoglucanase activity. The rate of glucose released by the purified enzyme from cellooligosaccharides with a degree of polymerization (DP) ranging between 2 and 5 decreased with increasing chain length. Glucose and glucono-delta-lactone inhibited the beta-glucosidase competitively with Ki values of 73 and 0.49 mM, respectively. The beta-glucosidase hydrolyzed pNPG, cellobiose, gentiobiose, sophorose, salicin, and amygdalin, exhibiting apparent Km values of 0.26, 0.65, 0.77, 1.06, 1.39, and 1.45 mM, respectively. Besides, the enzyme showed transglycosylation activity, producing oligosaccharides with higher DP than the substrates when cellooligosaccharides were hydrolyzed. These properties make this beta-glucosidase useful for various biotechnological applications.

Abstract  Polygalacturonase produced by Streptomyces lydicus was purified to homogeneity by ultrafiltration and a combination of ion exchange and gel filtration chromatographic procedures. The purified enzyme was an exo-polygalacturonase with a molecular weight of 43 kDa. It was optimally active at 50 degrees C and pH 6.0. The enzyme was stable from pH 4.0 to 7.0 and at or below 45 degrees C for 90 min. K(m) value for polygalacturonic acid was 1.63 mg/mL and the corresponding V(max) was 677.8 microM min(-1) mg(-1). The inhibition constant (K(i)) for gluconic acid d-lactone was 20.75 mM. Purified enzyme had been inhibited by N-bromosuccinimide, while l-tryptophan could induce enzyme activity, indicating the involvement of tryptophan at the active site.

Abstract  Pears (Pyrus communis L cv. Conference) may develop core breakdown when stored under low oxygen or elevated carbon dioxide conditions. This physiological disorder is characterized by the development of brown spots due to oxidation of phenolic compounds, and eventually, cavities in the center of the fruit. Based on metabolic profiling of brown and sound tissue using GC-EI-TOF-MS, the hypothesis that this disorder is due to an imbalance between oxidative and reductive processes at the cellular level was investigated. Brown tissue was clearly characterized by a distinctive pattern in changes which included a decrease of malic acid and an increase in fumaric acid and gamma aminobutyric acid (GABA), which indicated a reduced metabolic activity at the level of the Krebs cycle and a putative block of the GABA shunt pathway. Increased gluconic acid concentration might be related to ascorbic acid degradation due to insufficient reducing equivalents or to an impaired pentose phosphate pathway. For the first time, GABA and gluconic acid have been shown to be metabolic markets for core breakdown. The concentrations of other compounds which are believed to be related to hypoxic stress response such as trehalose and putrescine were also considerably higher in brown tissue than in sound tissue. The concentration of some sugars which are typically found in xyloglucans also increased during brown development. possibly indicating cell wall breakdown due to enzymatic processes or chemical reactions of hydroxyl radicals. (C) 2008 Elsevier B.V. All rights reserved.

Abstract  Phylogenetic analysis was performed on a cellulose-producing strain, designated WE7T, isolated from contaminated coconut milk. The analysis utilized nearly complete 16S rRNA gene sequences, as well as concatenated partial sequences of the housekeeping genes dnaK, groEL and rpoB, and allowed identification of the strain as belonging to the genus Komagataeibacter. DNA-DNA correlation or average nucleotide identity analysis was performed between WE7T and its closest phylogenetic neighbours, and the resulting values were below the species level (<70 % and <95 %), suggesting that the strain represents a novel species in genus Komagataeibacter. Strain WE7T was coupled with Komagataeibacter species more tightly than with Gluconacetobacter species in a 16S rRNA gene sequence phylogenetic tree. Strain WE7T can be differentiated from closely related Komagataeibacter and Gluconacetobacter entanii species by the ability to grow on the carbon sources d-mannitol, sodium d-gluconate and glycerol, the ability to form acid by d-fructose, sucrose, d-mannitol, d-galactose and ethanol, and the ability to grow without acetic acid. The major fatty acid of WE7T is C18 : 1ω9c (52.3 %). The DNA G+C content of WE7T is 63.2 mol%. The name Komagataeibacter cocois sp. nov. is proposed, with the type strain WE7T (=CGMCC 1.15338T=JCM 31140T).

Abstract  Lipopolysaccharide (LPS), which can cause acute airway inflammatory reactions, constitutes one of the most common substances to establish acute lung injury (ALI) models in mice. Studies suggest that calcium gluconate offers the possibility of suppressing the immune response, and this study was intended to explore the effects of calcium gluconate on LPS-induced ALI in mice. Mice inhaled with LPS were intraperitoneally injected with calcium gluconate (12.5, 25, 50 mg/kg). IL-1β, IL-6 and TNF-α levels in bronchoalveolar lavage fluid (BALF) were determined by ELISA. The expression of signaling proteins, phosphorylation extracellular regulated protein kinases (p-ERK), was detected using Western Blot in lung tissues. In our study, the release of inflammatory cytokines IL-1β, IL-6 and TNF-α in BALF increased after inhalation of LPS. Post-treatment with calcium gluconate inhibited LPS-induced airway inflammatory injury and the release of inflammatory cytokines. In addition, LPS promoted the expression of signaling protein p-ERK while calcium gluconate was capable of reversing this change. Overall, calcium gluconate inhibits LPS-induced ALI in mice, which may take effects through the inhibition of ERK phosphorylation.

Abstract  Our study aimed to elucidate the plant growth-promoting characteristics and the structure and composition of Sphingomonas sp. LK11 genome using the single molecule real-time (SMRT) sequencing technology of Pacific Biosciences. The results revealed that LK11 produces different types of gibberellins (GAs) in pure culture and significantly improves soybean plant growth by influencing endogenous GAs compared with non-inoculated control plants. Detailed genomic analyses revealed that the Sphingomonas sp. LK11 genome consists of a circular chromosome (3.78 Mbp; 66.2% G+C content) and two circular plasmids (122,975 bps and 34,160 bps; 63 and 65% G+C content, respectively). Annotation showed that the LK11 genome consists of 3656 protein-coding genes, 59 tRNAs, and 4 complete rRNA operons. Functional analyses predicted that LK11 encodes genes for phosphate solubilization and nitrate/nitrite ammonification, which are beneficial for promoting plant growth. Genes for production of catalases, superoxide dismutase, and peroxidases that confer resistance to oxidative stress in plants were also identified in LK11. Moreover, genes for trehalose and glycine betaine biosynthesis were also found in LK11 genome. Similarly, Sphingomonas spp. analysis revealed an open pan-genome and a total of 8507 genes were identified in the Sphingomonas spp. pan-genome and about 1356 orthologous genes were found to comprise the core genome. However, the number of genomes analyzed was not enough to describe complete gene sets. Our findings indicated that the genetic makeup of Sphingomonas sp. LK11 can be utilized as an eco-friendly bioresource for cleaning contaminated sites and promoting growth of plants confronted with environmental perturbations.

Abstract  INTRODUCTION: Micronutrient deficiencies are one of the most important public health issues worldwide and iron (Fe) deficiency anemia is the most prevalent micronutrient deficiency. Iron deficiency often coexists with calcium deficiency and iron and calcium supplementation often overlap. This has led to investigations into the interaction between these two minerals, and whether calcium may inhibit iron absorption in the gut.

OBJECTIVE: To determine the effect of various calcium salts on non-heme iron bioavailability in fasted women of childbearing age.

METHODS: A randomized and single blinded trial was conducted on 27 women of childbearing age (35-45 years old) divided into 2 groups (n1 = 13 and n2 = 14, respectively). On four different days, after an overnight fast, they received 5 mg of Fe as FeSO4 (labeled with 55Fe or 59Fe) with 800 mg of elemental calcium in the form of either calcium chloride, calcium gluconate, calcium citrate, calcium carbonate, calcium lactate, calcium sulfate or calcium phosphate. Calcium chloride was used as the control salt in both groups. Iron was labeled with the radioisotopes 59Fe or 55Fe, and the absorption of iron was measured by erythrocyte incorporation of radioactive Fe RESULTS: 800 mg of elemental calcium as calcium citrate produced a significant decrease in non-heme iron bioavailability (repeated measures ANOVA, F = 3.79, p = 0.018).

CONCLUSION: Of the various calcium salts tested, calcium citrate was the only salt that decreased non-heme iron bioavailability relative to the calcium chloride control when taken on an empty stomach. These results suggest that inhibition of non-heme iron absorption in fasted individuals is dependent upon the calcium salt in question and not solely dependent on the presence of calcium.

Abstract  The mycotoxin patulin is produced in colonized tissue by Penicillium expansum during storage of apples and is significantly affected by environmental factors that contribute to its accumulation. Few reports have, however, examined the effect of natural intrinsic factors associated with the fruit on the production of patulin. Here, we find that with advancing maturity, Golden Delicious apples show increased concentrations of total soluble solids (TSS) from 14 to 17% associated with the increased expression of the global transcription factor involved in regulation of secondary metabolite biosynthesis in filamentous fungi, laeA expression and patulin accumulation. However, the apple cultivar Granny Smith, with similar TSS values but differing in pH levels and malic acid concentrations, showed reduced expression levels of laeA and the patulin biosynthesis gene cluster (pat genes) and patulin accumulation, suggesting a complexity of host factors contribution to patulin accumulation during P. expansum colonization. To start elucidating these apple intrinsic factors, we examined their in vitro impact on laeA and pat gene expression concomitant with patulin synthesis. Increasing sucrose concentrations from 15 to 175 mM repressed laeA and pat gene expression and patulin production. However, this affect was modified and often reversed and sometimes accentuated by changes in pH, or the addition of malic acid or the major apple phenolic compounds, chlorogenic acid and epicatechin. While the increase in malic acid from 0 to 1% increased laeA and pat gene expression, the decrease in pH from 3.5 to 2.5 reduced their expression. Also the increased laeA and pat genes expressions at increasing epicatechin concentrations from 0 to 1 mM, was reversed by increasing sucrose concentrations, all together suggesting the complexity of the interactions in vivo.

Abstract  This study aimed to evaluate the effects of different concentration methods (nanofiltration and evaporation) and heat treatments on the gel properties of milk protein concentrate (MPC). The MPC gels were produced using glucono-δ-lactone (GDL) as an acidifier with different preheat treatments (30 min at 80°C and 5 min at 92°C). We then evaluated the effect of preheat treatments on MPC gel properties, including storage modulus (G'), loss tangent (tan δ), firmness, whey separation, and microstructure. The results indicated that without preheating, evaporation (EP)-MPC had higher G' and firmness, and lower tan δ and whey separation than nanofiltration (NF)-MPC. These results suggest that EP-MPC produced a better acid-induced gel than NF-MPC when no preheat treatments were performed. After preheating, however, except for a very small difference in the final G' (EP-MPC was higher), the 2 MPC did not differ significantly in firmness, final tan δ, or whey separation. Additionally, compared with the gel of unheated MPC, both preheat-treated gels (NF-MPC and EP-MPC) achieved increased G' and firmness and decreased tan δ and whey separation. The preheat-treated MPC also displayed a more flexible-stranded network. These findings demonstrate that, given a suitable heating treatment, NF-MPC compares favorably with EP-MPC in achieving desired gel properties.

Abstract  Floral nectar plays important roles in the interaction between animal-pollinated plants and pollinators. Its components include water, sugars, amino acids, vitamins, and proteins. Growing empirical evidence shows that most of the proteins secreted in nectar (nectarines) are enzymes that can tailor nectar chemistry for their animal mutualists or reduce the growth of microorganisms in nectar. However, to date, the function of many nectarines remains unknown, and very few plant species have had their nectar proteome thoroughly investigated. Mucuna sempervirens (Fabaceae) is a perennial woody vine native to China. Nectarines from this species were separated using two-dimensional gel electrophoresis, and analyzed using mass spectrometry. A L-gulonolactone oxidase like protein (MsGulLO) was detected, and the full length cDNA was cloned: it codes for a protein of 573 amino acids with a predicted signal peptide. MsGulLO has high similarity to L-gulonolactone oxidase 5 (AtGulLO5) in Arabidopsis thaliana, which was suggested to be involved in the pathway of ascorbate biosynthesis; however, both MsGulLO and AtGulLO5 are divergent from animal L-gulonolactone oxidases. MsGulLO was expressed mainly in flowers, and especially in nectary before blooming. However, cloning and gene expression analysis showed that L-galactonolactone dehydrogenase (MsGLDH), a vital enzyme in plant ascorbate biosynthesis, was expressed in all of flowers, roots, stems, and especially leaves. MsGulLO was purified to near homogeneity from raw MS nectar by gel filtration chromatography. The enzyme was determined to be a neutral monomeric protein with an apparent molecular mass of 70 kDa. MsGulLO is not a flavin-containing protein, and has neither L-galactonolactone dehydrogenase activity, nor the L-gulonolactone activity that is usual in animal GulLOs. However, it has weak oxidase activity with the following substrates: L-gulono-1,4-lactone, L -galactono-1,4-lactone, D-gluconic acid-δ-lactone, glucose, and fructose. MsGulLO is suggested to function in hydrogen peroxide generation in nectar but not in plant ascorbate biosynthesis.

Abstract  The traditional way of producing wine is through the use of Saccharomyces cerevisiae in order to convert glucose and fructose into alcohol. In the case of red wines, after this alcoholic fermentation lactic bacteria Oenococus oeni is used to stabilize wine from a microbiological point of view by converting malic acid into lactic acid that it is not a microbiological substract. The yeast species Schizosaccharomyces pombe was traditionally considered spoilage yeast. Nevertheless, during the last decade it started to be used due to its unique malic acid deacidification ability to reduce the harsh acidity of wines from northern Europe, by converting malic acid to ethanol and CO2 without producing lactic acid as lactic bacteria does. Additionally, during the last years, S. pombe has started to be used to solve the problems of modern winemaking industry such as increasing food quality or food safety. Some of those new uses, different from its traditional malic acid deacidification, are: high autolytic polysaccharides release, gluconic acid reduction, urease activity that make impossible ethyl carbamate (toxic compound) formation, high pyruvic acid production, that is related to color improvement, and removing lactic bacteria subtracts while avoiding biogenic amines (toxic compounds such as histamine) formation.

Abstract  Bacterial response to environmental stimuli is essential for survival. In response to fluctuating environmental conditions, the physiological status of bacteria can change due to the actions of transcriptional regulatory machinery. The synthesis and accumulation of polyhydroxyalkanoates (PHAs) are one of the survival strategies in harsh environments. In this study, we used transcriptome analysis of Pseudomonas putida KT2440 to gain a genome-wide view of the mechanisms of environmental-friendly biopolymers accumulation under nitrogen-limiting conditions during conversion of metabolically different carbon sources (sodium gluconate and oleic acid). Transcriptomic data revealed that phaG expression is associated with medium-chain-length-PHAs' synthesis not only on sodium gluconate but also on oleic acid, suggesting that PhaG may play a role in this process, as well. Moreover, genes involved in the β-oxidation pathway were induced in the PHAs production phase when sodium gluconate was supplied as the only carbon and energy source. The transition from exponential growth to stationary phase caused a significant expression of genes involved in nitrogen metabolism, energy supply, and transport system. In this study, several molecular mechanisms, which drive mcl-PHAs synthesis, have been investigated. The identified genes may provide valuable information to improve the efficiency of this bioprocess and make it more economically feasible.

Abstract  The synthesis of a range of analogues of the migrastatin macrolide core has been achieved from tri-O-acetyl-D-glucal in order to facilitate structure-activity studies. Efficient macrolactone formation was achieved in the presence of a reactive olefin, by increasing steric hindrance in the olefin environment. Acyclic analogues of migrastatin, structurally related to dorrigocin A, have also been prepared from D-glucal. The dorrigocin A analogues were prepared using the combination of the cross metathesis of ethyl 6-heptenoate with a glycal derivative and a subsequent allylic rearrangement-alkene isomerisation reaction (Perlin reaction). A synthetic route is thus provided that will enable dorrigocin A analogues to be prepared in parallel to migrastatin analogues in the search for novel anti-cancer and anti-arthritic therapeutics. Biological evaluation of one migrastatin and one dorrigocin A sugar derived analogue show that they inhibit proliferation and serum-induced migration of tumour and synovial cells at higher concentrations than evodiamine. Dorrigocin A analogues displayed similar potency to analogues of the migrastatin core.

Abstract  A new efficient and rapid experimental method and product isolation procedure as well as easy recyclable reaction media is expected to contribute to the development of a green strategy for the synthesis of furan diol from D-glucal. We determine the best conditions of reaction, minimizing the toxicity and finding an environmentally more acceptable process, using [Bmim][MSO4]/InCl3 center dot 3H(2)O as a new solvent system under extremely mild conditions, providing high yields with a dramatic enhancement of reaction rate. (c) 2007 Elsevier Ltd. All rights reserved.

Abstract  Microwave-assisted organic synthesis (MAOS) of D-gluconic acid can be efficiently done by oxidation of D- glucose with bromine water, upon irradiation with microwave ( MW). It was also used for the conversion of D-gluconic acid to ethyl D-gluconate, D-glucono-1,4- and 1,5-lactones, gluconyl hydrazide, and gluconyl phenylhydrazide in yields comparable to those obtained by conventional methods, but in much shorter times. A convenient microwave- mediated condensation of D- gluconic acid with o-phenylenediamines provided the respective acyclonucleoside benzimidazole in short time and good yield.

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Abstract  This study examining factors contributing to the production or elimination of domoic acid (DA) in cultures of Pseudo-nitzschia multiseries showed that in axenic cultures doubling the silicate concentrations increased growth, but not DA levels. DA concentration for axenic cultures was increased by the addition of gluconolactone (GlcA), especially in cultures with increased silicon. In non-axenic cultures, there were similar increases in growth with increased silicon, but a reduction of DA production in the presence of GlcA. Detailed examinations confirmed these findings and also showed that in non-axenic cultures, glucose alone resulted in a reduction of DA while a combination of glucose with gluconolactone resulted in a complete elimination of DA. Subsequent trials with axenic P. multiseries cultures showed that additions of DA or DA plus glucose introduced at the early stationary growth phase and incubated for 5 d had no impact on DA concentrations. In contrast, a 6 d incubation of the associated bacteria separated from the non-axenic diatom cultures showed reductions of added DA concentrations ranging from 46 to 72 %, depending upon co-additives. The diatom does not use extracellular DA present in surrounding culture medium whereas bacteria associated with the diatom can utilize DA readily. Reductions in the production of DA by aging P. multiseries cultures appear to be the result of changing balances over time among bacteria associated with the diatom. These data coupled with results from other studies indicate that the amount of DA measured in P. multiseries cultures is a result of competitive interaction, i.e. a function of the diatom's production rate versus the extra-cellular utilization of DA by associated bacteria.

Abstract  An extracellular beta-glucosidase was purified 154-fold to electrophoretic homogeneity from the brown-rot basidiomycete Fomitopsis palustris grown on 2.0% microcrystalline cellulose. SDS-polyacrylamide gel electrophoresis gel gave a single protein band and the molecular mass of purified enzyme was estimated to be approximately 138 kDa. The amino acid sequences of the proteolytic fragments determined by nano-LC-MS/MS suggested that the protein has high homology with fungal beta-glucosidases that belong to glycosyl hydrolase family 3. The Kms for p-nitorophenyl-beta-D-glucoside (p-NPG) and cellobiose hydrolyses were 0.117 and 4.81 mM, and the Kcat values were 721 and 101.8 per sec, respectively. The enzyme was competitively inhibited by both glucose (Ki= 0.35 mM) and gluconolactone (Ki= 0.008 mM), when p-NPG was used as substrate. The optimal activity of the purified beta-glucosidase was observed at pH 4.5 and 70 degrees. The F. palustris protein exhibited half-lives of 97 h at 55 degrees and 15 h at 65 degrees, indicating some degree of thermostability. The enzyme has high activity against p-NPG and cellobiose but has very little or no activity against p-nitrophenyl-beta-lactoside, p-nitrophenyl-beta-xyloside, p-nitrophenyl-alpha-arabinofuranoside, xylan, and carboxymethyl cellulose. Thus, our results revealed that the beta-glucosidase from F. palustris can be classified as an aryl-beta-glucosidase with cellobiase activity.

Abstract  Electrodeposition of acid copper plating on mild steel substrate is tedious due to the galvanic displacement reaction of copper on mild steel. This can be avoided by using a proper complexing agent, because the complexing agent tuned the potential of noble direction to less noble direction by complex formation. In this paper, environment friendly electrodeposition of copper from non-cyanide electrolyte using sodium gluconate as complexing agent was investigated in alkaline medium. The effects of additives such as 1, 2, 3-benzotriazole, sodium lauryl sulphate, PEG 8000 and saccharin were studied. These additives are found to reduce the grain size, grain boundaries and improve surface morphology of the copper deposits. Also they improve the throwing power of the depositing electrolytes and hardness of deposits. The electrodeposited copper coatings were characterized by X-ray diffraction technique. XRD results indicate that the electrodeposited copper shows polycrystalline and face centered cubic structure. The crystal size was calculated by XRD and AFM analysis. Among these additives studied, the mixture of benzotriazole and sodium lauryl sulphate acts as the best additive. A uniform pore-free surface observed under SEM and AFM results reveal the grain refining brought about by the additives.