Abstract  It has been postulated that proton transfer to beta-glycosides by some retaining beta-glycosidases takes place in the plane of the pyranoside ring. It is now hypothesised that a similarly oriented catalytically active acidic group in alpha-glycosidases could interact with glyconolactone derivatives, provided that these are sufficiently basic to overcome the effect of a less favourable geometry by an energetically more favourable interaction. In keeping with this hypothesis, D-gluconolactone, D-gluconolactam, the tetrazole 3, and the hydroximolactone 5 are weak inhibitors of yeast alpha-glucosidase, while the hydroximolactam 6 (pK(a) = 4.8) is a mixed-type (alpha=2) strong inhibitor (K-i = 2.9 mu M). A Similar inhibition is observed for the arylcarbamoyl derivative 9, while the (methylthio)methyl derivative 10 inhibits more weakly and in a purely competitive fashion. The mannonhydroximolactam 11 strongly inhibits jack bean a-mannosidase (K-i=0.15 mu M), while the gluco analogue 6 inhibits about 80 times more weakly, illustrating the dependence upon configuration. (C) 1997 Elsevier Science Ltd.

Abstract  O-Benzyl protected gluconolactone 1 reacts readily with 2-lithio derivatives of quinaldine, 2-methylquinoxaline, 2-methylbenzimidazole and N-protected derivatives, and 1-benzyloxymethyl-2-methylimidazole at low temperatures to afford as monoaddition products the corresponding D-gluco-2-heptuloses 2-5. The benzyl protective groups can be readily removed by hydrogenolysis as shown for the transformation of 4a into 8. Acylation reactions with 4a exhibited an interesting interplay between O- and N-acylation which is dependent on the nature of the acylating agent and on the reaction conditions. Reductive removal of the anomeric hydroxy group in 4a-c and 5 was readily performed via elimination products 18a-c and 23; their hydrogenation with Pd/C gave directly the O,N-deprotected C-beta-D-glucopyranosylmethyl derivatives 21 and 25, respectively.

Abstract  Pseudomonas putida U does not degrade D-glucose through the glycolytic pathway but requires (i) its oxidation to D-gluconic acid by a peripherally located constitutive glucose dehydrogenase (insensitive to osmotic shock), (ii) accumulation of D-gluconic acid in the extracellular medium, and (iii) the induction of a specific energy-dependent transport system responsible for the uptake of D-gluconic acid. This uptake system showed maximal rates of transport at 30 degrees C in 50 mM potassium phosphate buffer, pH 7.0. Under these conditions the K(m) calculated for D-gluconic acid was 6.7 microM. Furthermore, a different transport system, specific for the uptake of glucose, was also identified. It is active and shows maximal uptake rates at 35 degrees C in 50 mM potassium phosphate buffer, pH 6.0, with a K(m) value of 8.3 microM.

Abstract  6-Phosphoryl-beta-D-glucopyranosyl:6-phosphoglucohydrolase (P-beta-glucosidase, EC 3.2.1.86) has been purified from Fusobacterium mortiferum. Assays for enzyme activity and results from Western immunoblots showed that P-beta-glucosidase (M(r), 53,000; pI, 4.5) was induced by growth of F. mortiferum on beta-glucosides. The novel chromogenic and fluorogenic substrates, p-nitrophenyl-beta-D-glucopyranoside-6-phosphate (pNP beta Glc6P) and 4-methylumbelliferyl-beta-D-glucopyranoside-6-phosphate (4MU beta Glc6P), respectively, were used for the assay of P-beta-glucosidase activity. The enzyme hydrolyzed several P-beta-glucosides, including the isomeric disaccharide phosphates cellobiose-6-phosphate, gentiobiose-6-phosphate, sophorose-6-phosphate, and laminaribiose-6-phosphate, to yield glucose-6-phosphate and appropriate aglycons. The kinetic parameters for each substrate are reported. P-beta-glucosidase from F. mortiferum was inactivated by 6-phosphoglucono-delta-lactone (P-glucono-delta-lactone) derived via oxidation of glucose 6-phosphate. The pbgA gene that encodes P-beta-glucosidase from F. mortiferum has been cloned and sequenced. The first 42 residues deduced from the nucleotide sequence matched those determined for the N terminus by automated Edman degradation of the purified enzyme. From the predicted sequence of 466 amino acids, two catalytically important glutamyl residues have been identified, Comparative alignment of the amino acid sequences of P-beta-glucosidase from Escherichia coli and F. mortiferum indicates potential binding sites for the inhibitory P-glucono-delta-lactone to the enzyme from F. mortiferum.

Abstract  Bacteria isolated from cultures of 4 different strains of the diatom Pseudo-nitzschia multiseries following numerous transfers in a defined medium were identified as mainly Moraxella and Alteromonas sp. These bacteria apparently form a characteristic suite of microorganisms living in a symbiotic relationship with the diatom. The bacterial isolates from each of the P. multiseries strains divided metabolically into 2 groups; those that produced significant amounts of acid from carbohydrates and those that grew readily at the expense of amino acids. The specific acid forming bacteria isolated from each diatom species grown in the presence of glucose produced gluconic acid/gluconolactone in quantity and released it to the surrounding medium. For growth of the diatom a salinity of 33 ppt was more favorable than 26 or 38 ppt; sorbitol varied with the salinity and thus might be an osmolyte. Glucose was present in significant quantities in the diatom grown at all 3 salinities. Nonaxenic growth of the diatom was stimulated considerably by the presence of proline alone and to approximately the same level when it was combined with glucose or sodium acetate, but not when glycine was substituted for the proline. Stimulation of the growth of the diatom by the presence of proline was considered to be a function of the associated bacteria. Glycine combined with sodium acetate was slightly inhibitory to the growth of the diatom but both glycine plus sodium acetate and glycine plus glucose combinations were markedly inhibitory to the growth of the associated bacteria. The possible role of all of these features in the initiation of a bloom of Pseudo-nitzschia multiseries, especially in an inshore environment enriched by organic nitrogen, and the consequent production of domoic acid is discussed.

Abstract  Electrodeposited Fe group: W and Mo alloys have the potential to replace hard Cr coatings for use in engineering applications where wear and corrosion resistance are needed. Electrochemical studies have concentrated in the past on Ni-W alloy deposition, but now interest in Co-W alloys has developed as they possess lower coefficients of friction when in contact with another metal. The most attractive coating composition is in the range 14-20 at.% W, if controlled deposition promotes crystalline alloys of high hardness, rather than softer amorphous alloys containing >20 at.% W. This paper employs ammonia free baths with low concentrations of cobalt and sodium tungstate and varying additions of sodium gluconate to produce alloys at close to 50% efficiency. Voltammetry, UV and visible spectrometry, and potentiostatic deposition have been performed on such baths, whilst XRD, SEM and TEM observations have been made on the deposits. This aims to optimise the process and to understanding the relationships between bath contents, electrochemical kinetics and alloy composition. Efficient deposition of coatings with hardness values up to 1000 kgf mm(-2) occurred from a bath containing a high concentration of gluconate. Such deposits arise from concentrations of Co-W-gluconate complexes which promote the formation of nanoscale alloy grains. Current densities up to 2.75 A dm(-2) in the agitated bath promoted deposition kinetics to form these highly orientated structures. These kinetics produced nano-segregation of W which may be assisted by the migration of Co-W clusters to boundary sites during the growth of the deposit. (C) 2010 Elsevier Ltd. All rights reserved.

Abstract  Phosphorus burns are a rarely encountered chemical burn, typically occurring in battle, industrial accidents, or from fireworks. Death may result even with minimal burn areas. Early recognition of affected areas and adequate resuscitation is crucial. Amongst our 2765 admissions between 1984 and 1998, 326 patients had chemical burns. Seven admissions were the result of phosphorus burns. Our treatment protocol comprises 1% copper sulfate solution for neutralization and identification of phosphorus particles, copious normal saline irrigation, keeping wounds moist with saline-soaked thick pads even during transportation, prompt debridement of affected areas, porcine skin coverage or skin grafts for acute wound management, as well as intensive monitoring of electrolytes and cardiac function in our burns center. Intravenous calcium gluconate is mandatory for correction of hypocalcemia. Of the seven, one patient died from inhalation injury and the others were scheduled for sequential surgical procedures for functional and cosmetic recovery. Cooling affected areas with tap water or normal saline, prompt removal of phosphorus particles with mechanical debridement, intensive monitoring, and maintenance of electrolyte balance are critical steps in initial management. Fluid resuscitation can be adjusted according to urine output. Early excision and skin autografts summarize our phosphorus burn treatment protocol.

Abstract  Low total blood calcium concentration after calving has been demonstrated to be a risk factor for reduced neutrophil function. The objective of this study was to evaluate whether administration of an injectable calcium supplement product soon after calving increased neutrophil oxidative burst or phagocytosis capacity. Cows (n = 27) from 4 farms were blocked by parity and randomly assigned to receive either calcium gluconate (35% wt/vol) in combination with calcium glucoheptonate (10% wt/vol; Theracalcium, Vétoquinol Canada Inc., Lavaltrie, Quebec, Canada) or a placebo within 12 h after calving and again 24 h later. Each dose of 120 mL was injected subcutaneously over 2 sites. Total serum calcium concentration, neutrophil oxidative burst, and neutrophil phagocytosis capacity were measured from coccygeal blood samples before (time 0) and 72 h after first treatment. There was no difference between treatment groups in lactation number, total calcium concentration, oxidative burst, or phagocytosis at time of enrollment. There was no effect of treatment on oxidative burst or phagocytosis by neutrophils. This preliminary study does not support an effect of supplemental calcium to improve neutrophil oxidative burst or phagocytosis capacity of low-parity parturient cows.

Abstract  Due to stricter environmental legislation and implementation of the "waste valorization" concept, recycling of dairy effluent, whey, has drawn a considerable attention. The main constituent of whey is lactose, which is responsible for high biological oxygen demand (BOD) and chemical oxygen demand (COD) values. Therefore, without going to its direct disposal into aquatic system, synthesis of nutraceuticals from lactose is considered a commendable challenge. Lactose-derived nutraceuticals, such as galacto-oligosaccharide (GOS), lactulose, lactitol, lactosucrose, lactobionic acid, gluconic acid, lactone, and tagatose, have been synthesized through different chemical and biochemical reactions, such as hydrolysis, transgalactosylation, oxidation, reduction, isomerization, and hydrogenolysis, considering raw whey or isolated lactose as feedstock. Pure biocatalyst (enzyme) and inorganic catalyst have been used for the synthesis of lactose-based nutraceuticals by different types of operations, such as conventional batch and continuous bioreactors with free catalyst, continuous packed bed bioreactor with immobilized catalyst, moving bed reactor, and membrane-assigned bioreactor. Moreover, in many cases, lactose-based nutraceuticals (lactic acid, lactosucrose, lactobionic acid, gluconic acid, and tagatose) have been synthesized by microbial fermentation process. Free microbial cell in batch and continuous fermentor and whole cell immobilized packed bed bioreactor have been used for this purpose. This review presents and compares different process-related technological aspects for synthesis of lactose-derived nutraceuticals from whey.

Abstract  Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc° = −34 ± 6 kJ mol–1, and ΔSassoc° = −55 ± 9 J mol–1 K–1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10–7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol–1, and ΔSassoc° = 42 ± 7 J mol–1 K–1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d-saccharate becomes spontaneously supersaturated with both d-gluconate and d-saccharate calcium salts, from which only calcium d-saccharate slowly precipitates. Calcium d-saccharate is suggested to act as a stabilizer of supersaturated solutions of other calcium hydroxycarboxylates with endothermic complex formation through a heat-induced shift in calcium complex distribution with slow equilibration upon cooling.

Abstract  Background: In this study, the performance of aerobic batch fermentation with Aspergillus niger producing sodium gluconate under different oxygen supply levels through adjusting the agitation rate were investigated. The response of glucose metabolism in A. niger to different oxygen uptake rate (OUR) levels has been studied in the present work. Results: Metabolic flux analysis demonstrated that the high oxygen supply condition was favorable for cell growth and initial sodium gluconate synthesis during the early fermentation phases. However, during the late stable phase, metabolic flux analysis indicated that a high yield of sodium gluconate production could be achieved at a medium OUR level of 55 2.5 mmol L-1 h(-1) as less flux was required for glucolysis and the TCA cycle. With a two-stage OUR control strategy, the final sodium gluconate yield of the batch fermentation was enhanced and reached 93.7% (mol vs mol), which was higher than those obtained using a high oxygen supply level throughout the whole fermentation process. Conclusions: Metabolic flux analysis was successfully used in the present work, and the two-stage OUR control strategy increased the yield of sodium gluconate production to 93.7%.

Abstract  D-glucosaminic acid (2-amino-2-deoxy-D-gluconic acid), a component of bacterial lipopolysaccharides and a chiral synthon, is easily prepared on a multigram scale by air oxidation of D-glucosamine (2-amino-2-deoxy-D-glucose) catalysed by glucose oxidase.

Abstract  This study reported a high titer gluconic acid fermentation using dry dilute acid pretreated corn stover (DDAP) hydrolysate without detoxification. The selected fermenting strain Aspergillus niger SIIM M276 was capable of inhibitor degradation thus no detoxification on pretreated corn stover was required. Parameters of gluconic acid fermentation in corn stover hydrolysate were optimized in flasks and in fermentors to achieve 76.67 g/L gluconic acid with overall yield of 94.91%. The sodium gluconate obtained from corn stover was used as additive for extending setting time of cement mortar and similar function was obtained with starch based sodium gluconate. This study provided the first high titer gluconic acid production from lignocellulosic feedstock with potential of industrial applications.

Abstract  Thirteen cases of feline primary hyperaldosteronism were diagnosed based on clinical signs, serum biochemistry, plasma aldosterone concentration, adrenal imaging and histopathology of adrenal tissue. Two cases presented with blindness caused by systemic hypertension, whilst the remaining 11 cases showed weakness resulting from hypokalaemic polymyopathy. Elevated concentrations of plasma aldosterone and adrenocortical neoplasia were documented in all cases. Seven cases had adrenal adenomas (unilateral in five and bilateral in two) and six had unilateral adrenal carcinomas. Three cases underwent medical treatment only with amlodipine, spironolactone and potassium gluconate; two cases survived for 304 and 984 days until they were euthanased because of chronic renal failure, whilst the third case was euthanased at 50 days following failure of the owner to medicate the cat. Ten cases underwent surgical adrenalectomy following a successful stabilisation period on medical management. Five cases remain alive at the time of writing with follow-up periods of between 240 and 1803 days. Three cases were euthanased during or immediately following surgery because of surgical-induced haemorrhage. One cat was euthanased 14 days after surgery because of generalised sepsis, whilst the remaining cat was euthanased 1045 days after surgery because of anorexia and the development of a cranial abdominal mass. It is recommended that primary hyperaldosteronism should be considered as a differential diagnosis in middle-aged and older cats with hypokalaemic polymyopathy and/or systemic hypertension and should no longer be considered a rare condition.

Abstract  BACKGROUND: The high level of maternal mortality and morbidity as a result of complications due to childbirth is unacceptable. The impact of quality medicines in the management of these complications cannot be overemphasized. Most of those medicines are sensitive to environmental conditions and must be handled properly. In this study, the quality of oxytocin injection, misoprostol tablets, magnesium sulfate, and calcium gluconate injections was assessed across the six geopolitical zones of Nigeria.

METHOD: Simple, stratified random sampling of health facilities in each of the political zones of Nigeria. Analysis for identification and content of active pharmaceutical ingredient was performed using high-performance liquid chromatography procedures of 159 samples of oxytocin injection and 166 samples of misoprostol tablets. Titrimetric methods were used to analyze 164 samples of magnesium sulfate and 148 samples of calcium gluconate injection. Other tests included sterility, pH measurement, and fill volume.

RESULTS: Samples of these commodities were procured mainly from wholesale and retail pharmacies, where these were readily available, while the federal medical centers reported low availability. Approximately, 74.2% of oxytocin injection samples failed the assay test, with the northeast and southeast zones registering the highest failure rates. Misoprostol tablets recorded a percentage failure of 33.7%. Magnesium sulfate and Calcium gluconate injection samples recorded a failure rate of 6.8% and 2.4%, respectively.

CONCLUSION: The prevalence of particularly of oxytocin and misoprostol commodities was of substandard quality. Strengthening the supply chain of these important medicines is paramount to ensuring their effectiveness in reducing maternal deaths in Nigeria.

Abstract  Background: Aliphatic (poly)hydroxy carboxylic acids [(P)HCA] occur in natural, e.g. soils, and in technical (waste disposal sites, nuclear waste repositories) compartments . Their distribution, mobility and chemical reactivity, e.g. complex formation with metal ions and radionuclides, depend, among others, on their adsorption onto mineral surfaces. Aluminium hydroxides, e.g. gibbsite [α-Al(OH)3], are common constituents of related solid materials and mimic the molecular surface properties of clay minerals. Thus, the study was pursued to characterize the adsorption of glycolic, threonic, tartaric, gluconic, and glucaric acids onto gibbsite over a wide pH and (P)HCA concentration range. To consider specific conditions occurring in radioactive wastes, adsorption applying an artificial cement pore water (pH 13.3) as solution phase was investigated additionally.

Results: The sorption of gluconic acid at pH 4, 7, 9, and 12 was best described by the "two-site" Langmuir isotherm, combining "high affinity" sorption sites (adsorption affinity constants [Formula: see text] > 1 L mmol-1, adsorption capacities < 6.5 mmol kg-1) with "low affinity" sites ([Formula: see text] < 0.1 L mmol-1, adsorption capacities ≥ 19 mmol kg-1). The total adsorption capacities at pH 9 and 12 were roughly tenfold of that at pH 4 and 7. The S-shaped pH sorption edge of gluconic acid was modelled applying a constant capacitance model, considering electrostatic interactions, hydrogen bonding, surface complex formation, and formation of solved polynuclear complexes between Al3+ ions and gluconic acid. A Pearson and Spearman rank correlation between (P)HCA molecular properties and adsorption parameters revealed the high importance of the size and the charge of the adsorbates.

Conclusions: The adsorption behaviour of (P)HCAs is best described by a combination of adsorption properties of carboxylic acids at acidic pH and of polyols at alkaline pH. Depending on the molecular properties of the adsorbates and on pH, electrostatic interactions, hydrogen bonding, and ternary surface complexation contribute in varying degrees to the adsorption process. Linear distribution coefficients Kd between 8.7 and 60.5 L kg-1 (1 mmol L-1 initial PHCA concentration) indicate a considerable mineral surface affinity at very high pH, thus lowering the PHCA fraction available for the complexation of metal ions including radionuclides in solution and their subsequent mobilization.

Abstract  Aromatic precursors are precisely in the skin of grapes and nearby cells, and therefore there is a greater expression of the varietal aromas and aromatic precursors when the wine passes through this skin contact, as well as changes in product color. The aim of this study was to evaluate the physical and chemical characteristics of Chardonnay wine that has gone through different periods of skin contact. Chardonnay grapes, grown in vineyards located in the town of Bage, in Campanha Gaucha, were de-stemmed, crushed and a sulfur dioxide (50 mg/L-1) was addeded. The experimental design was a 4 x 3 factorial of 4 treatments with 3 repetitions: T1, the wine obtained directly from pressing machine; T2, skin contact for 2 days; T3, skin contact for 4 days and T4, skin contact for 6 days. After the end of malolactic fermentation wines went under -2 degrees C for the tartaric stabilization. There were analyzed the variables alcohol, total acidity, volatile acidity, total polyphenols, glycerol, gluconic acid and 420, 520 and 620 colors by infrared spectroscopy method by Fourier transform and the means were compared by 5% Tukey test. There was a significant differencein variables alcohol, volatile acidit, glucanic acid and color index of 420 nm (yellow).

Abstract  The choice for this paper was determine by the necessity to identify some practical and objective ways to evaluate the energetic and effort capacity at sport horses, which serve to measure the period and intensity of training and to appreciate the effects of training over the level of physic preparation.

Biologic material used for researches was represented by 15 sport horses from Dinamo Club-Bucharest, animals which come from the effective of Jegalia and Cislau studs.

The method used for researches consists in transformation of glucose, under glucozo-oxidases action in gluconic acid and oxygenate water.

The blood glucose value, at horses used in complete trial competition, oscillated depending on trial' type and increased obviously after effort. The differences between the glucose values before and after effort were very significant for steeple chase and jumping trials and insignificant for cross country. (C) 2016 Published by Elsevier B.V.

Abstract  Alcohol dehydrogenase D (AdhD) is a monomeric thermostable alcohol dehydrogenase from the aldo-keto reductase (AKR) superfamily of proteins. We have been exploring various strategies of engineering the activity of AdhD so that it could be employed in future biotechnology applications. Driven by insights made in other AKRs, we have made mutations in the cofactor-binding pocket of the enzyme and broadened its cofactor specificity. A pre-steady state kinetic analysis yielded new insights into the conformational behavior of this enzyme. The most active mutant enzyme concomitantly gained activity with a non-native cofactor, nicotinamide mononucleotide, NMN(H), and an enzymatic biofuel cell was demonstrated with this enzyme/cofactor pair. Substrate specificity was altered by grafting loop regions near the active site pocket from a mesostable human aldose reductase (hAR) onto the thermostable AdhD. These moves not only transferred the substrate specificity of hAR but also the cofactor specificity of hAR. We have added alpha-helical appendages to AdhD to enable it to self-assemble into a thermostable catalytic proteinaceous hydrogel. As our understanding of the structure/function relationship in AdhD and other AKRs advances, this ubiquitous protein scaffold could be engineered for a variety of catalytic activities that will be useful for many future applications.

Abstract  Progress in miniature chip-design raises demands for implantable power sources in health care applications such as continuous glucose monitoring of diabetic patients. Pioneered by Adam Heller, miniaturized enzymatic biofuel cells (mBCs) convert blood sugars into electrical energy by employing for example glucose oxidase (GOx) on the anode and bilirubin oxidase on the cathode. To match application demands it is crucial to increase lifetime and power output of mBCs. The power output has been limited by the performance of GOx on the anode. We developed a glucose oxidase detection assay (GODA) as medium-throughput screening system for improving GOx properties by directed protein evolution. GODA is a reaction product detection assay based on coupled enzymatic reactions leading to NADPH formation which is recorded at 340 nm. The main advantage of the assay is that it detects the production of d-gluconolactone instead of the side-product hydrogen peroxide and enables to improve bioelectrochemical properties of GOx. For validating the screening system, a mutagenic library of GOx from Aspergillus niger (EC 1.1.3.4) was generated and screened for improved activity using Saccharomyces cerevisiae as host. Directed evolution resulted in a GOx mutant I115V with 1.4-1.5-fold improved activity for beta-d-glucose (Vmax from 7.94 to 10.81 micromol min(-1) mg(-1); Km approximately 19-21 mM) and oxygen consumption kinetics correlate well [Vmax (O2) from 5.94 to 8.34 micromol min(-1) mg(-1); Km (O2) from 700 to 474 microM]. The developed mutagenic protocol and GODA represent a proof-of-principle that GOx can be evolved by directed evolution in S. cerevisiae for putative use in biofuel cells.

Abstract  This is the first report on the degradation of poly(3-hydroxybutyrate) (PHB), and its copolymers poly(3-hydroxyvalerate) P(3HB-co-10-20% HV) by Nocardiopsis aegyptia, a new species isolated from marine seashore sediments. The strain excreted an extracellular PHB depolymerase and grew efficiently on PHB or its copolymers as the sole carbon sources. The degradation activity was detectable by the formation of a transparent clearing zone around the colony on an agar Petri plate after 25 days, or a clearing depth under the colony in test tubes within 3 weeks. The previous techniques proved that the bacterium was able to assimilate the monomeric components of the shorter alkyl groups of the polymers. Nocardiopsis aegyptia hydrolyzed copolymers 10-20% PHBV more rapidly than the homopolymer PHB. The bacterial degradation of the naturally occurring sheets of poly(3-hydroxybutyrate), and its copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was observed by scanning electron microscopy (SEM). The samples were degraded at the surface and proceeded to the inner part of the materials. Clear morphological alterations of the polymers were noticed, indicating the degradative capability of the bacterium. Plackett-Burman statistical experimental design has been employed to optimize culture conditions for maximal enzyme activity. The main factors that had significant positive effects on PHB depolymerase activity of Nocardiopsis aegyptia were sodium gluconate, volume of medium/flask and age of inoculum. On the other hand, MgSO4 center dot 7H(2)O, KH2PO4, K2HPO4 and NH4NO3 exhibited negative effects. Under optimized culture conditions, the highest activity (0.664 U/mg protein) was achieved in a medium predicted to be near optimum containing (in g/L): PHB, 0.5; C6H11O7Na, 7.5; MgSO(4)center dot 7H(2)O, 0.35; K2HPO4, 0.35; NH4NO3, 0.5; KH2PO4, 0.35; malt extract, 0.5 and prepared with 50% seawater. The medium was inoculated with 1% (v/v) spore suspension of 7 days old culture. Complete clarity of the medium was achieved after 3 days at 30 degrees C.

Abstract  In order to maintain the quantity of ferrous ions, two eco-friendly chelating agents (CAs), i.e., sodium citrate (Citrate) and sodium gluconate (Glu), have been introduced into a traditional iron activated sodium persulfate (PS) system (Fe2+/PS). The results indicated that the PS/CA/Fe2+ oxidation could be an effective method for BDE209 removal. Effects of the chelating agents, reagents dosage, and pH were evaluated in batch experiments. Glu was observed to be more effective than citrate. In addition, the rate constants (k 1) of BDE209 removal indicated a quadratic curve relationship with initial persulfate concentrations (k 1 = -0.019 × [PS]02 + 0.031 × [PS]0 + 0.007, R 2 = 0.933, [PS]0 = 0.1-1.0 M) and a good linear relationship with initial ferrous contents (k 1 = 0.109 × [Fe2+]0 + 0.002, R 2 = 0.943). Furthermore, as a reducing agent, ascorbic acid (H2A) could enhance the degradation rate of BDE209, which might be because H2A accelerated the transformation process from Fe3+- to Fe2+-gluconate complexes.

Abstract  The mineral phosphate-solubilizing phenotype in bacteria is attributed predominantly to secretion of gluconic acid produced by oxidation of glucose by the glucose dehydrogenase enzyme and its cofactor, pyrroloquinoline quinone. This study analyzes pqqE gene expression and pqq promoter activity in the native phosphate-solubilizing bacterium Serratia sp S119 growing under P-limitation, and in the presence of root exudates obtained from peanut plants, also growing under P-limitation. Results indicated that Serratia sp. S119 contains a pqq operon composed of six genes (pqqA,B,C,D,E,F) and two promoters, one upstream of pqqA and other between pqqA and pqqB. PqqE gene expression and pqq promoter activity increased under P-limiting growth conditions and not under N-deficient conditions. In the plant-bacteria interaction assay, the activity of the bacterial pqq promoter region varied depending on the concentration and type of root exudates and on the bacterial growth phase. Root exudates from peanut plants growing under P-available and P-limiting conditions showed differences in their composition. It is concluded from this study that the response of Serratia sp. S119 to phosphorus limitation involves an increase in expression of pqq genes, and that molecules exuded by peanut roots modify expression of these phosphate-solubilizing bacterial genes during plant-bacteria interactions.

Abstract  Phosphorus is a plant nutrient which is rapidly made immobile and less available for plant use after addition to the soil as a soluble fertiliser. Phosphate-solubilising microorganisms may be able to improve the P nutrition of plants and thus stimulate plant growth. Penicillium radicum, a phosphate-solubilising fungus isolated from the rhizosphere of wheat roots, has shown promise in plant growth promotion. Its ability to solubilise inorganic phosphate was studied in vitro. The fungus was grown in liquid medium cultures containing either ammonium or nitrate as the sole source of N. Insoluble, or sparingly-soluble P (1000 mg P l(-1)) was supplied as calcium monohydrogen phosphate (CaHPO4), calcium orthophosphate (Ca-3(PO4)(2)), crystalline ferric phosphate (FePO4. 4H(2)O), crystalline aluminium phosphate (AlPO4), colloidal ferric phosphate or colloidal aluminium phosphate. The titratable: acidity, pH and concentrations of organic acids and soluble phosphate: were determined periodically during a 20 or 31 d incubation. Phosphate solubilisation was highest from CaHPO4 (475 mg P l(-1)), Ca-3(PO4)(2) (360 mg P l(-1)) and colloidal aluminium phosphate (207 mg P l(-1)). Phosphate solubilisation was generally higher when ammonium rather than nitrate was the sole source of N. Soluble phosphate concentrations in the culture medium were directly proportional to the titratable acidity and organic acid (principally gluconic acid) concentration and inversely related to pH. The main mechanism for phosphate solubilisation was acid production leading to a decrease in pH. Evidence from an abiotic study using HCl and gluconic acid to solubilise P also indicated that chelation of Al3+ by gluconic acid may have been a factor in the solubilisation of colloidal aluminium phosphate. (C) 1999 Elsevier Science Ltd. All rights reserved.

Abstract  Most acid soils have a high capacity to bind phosphorus (P) strongly on iron (Fe) and aluminum (Al) hydroxides, resulting in low P fertilizer use efficiency. Organic chelating agents form strong bonds with metals in soil and may reduce P binding with Fe and Al and increase fertilizer P use efficiency. Ethylenediamine tetraacetic acid (EDTA), hydroxyethyl ethylenediamine triacetic acid (HEEDTA), gluconic acid, and citric acid were tested to determine their influence on water-soluble P (WSP), Mehlich-1 P, and Mehlich-3 P in a loam and sand fertilized with P and incubated for 49 days. Soil P sorption capacity (PSC) was estimated from an oxalate extraction of Fe and Al, and chelates were applied at rates of 90% of the PSC. EDTA and HEEDTA were also applied at 0, 30, 60, 90, 120, and 150% PSC to produce a rate response curve for WSP in a second soil incubation. The EDTA, HEEDTA, and citric acid significantly (P < 0.05) reduced P sorption in the loam and sand when measured by WSP. In soils without P fertilizer added, EDTA and HEEDTA resulted in a significant increase in WSP concentrations, as well as increased concentrations of Mehlich-1 P and Mehlich-3 P. With increasing chelation rates of EDTA and HEEDTA, there was a linear increase in WSP for both soils, indicating higher rates were most effective at decreasing P sorption. The application of chelating agents, with and without P fertilizer, could potentially increase plant availability of P, therefore reducing P fertilizer.