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Selected AbstractsA cost-effective cane molasses medium for enhanced cell-bound phytase production by Pichia anomalaJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2004A. Vohra Abstract Aim:, Formulation of an inexpensive cane molasses medium for improved cell-bound phytase production by Pichia anomala. Methods and Results:, Cell-bound phytase production by Pichia anomala was compared in synthetic glucose,beef extract and cane molasses media. The yeast was cultivated in 250 ml flasks containing 50 ml of the medium, inoculated with a 12 h-old inoculum (3 × 106 CFU ml,1) and incubated at 25°C for 24 h at 250 rev min,1. Different cultural parameters were optimized in cane molasses medium in batch fermentation. The cell-bound phytase content increased significantly in cane molasses medium (176 U g,1 dry biomass) when compared with the synthetic medium (100 U g,1 dry biomass). In fed-batch fermentation, a marked increase in biomass (20 g l,1) and the phytase yield (3000 U l,1) were recorded in cane molasses medium. The cost of production in cane molasses medium was £0·006 per 1000 U, which is much lower when compared with that in synthetic medium (£0·25 per 1000 U). Conclusions:, An overall 86·6% enhancement in phytase yield was attained in optimized cane molasses medium using fed-batch fermentation when compared with that in synthetic medium. Furthermore, the production in cane molasses medium is cost-effective. Significance and Impact of the Study:, Phytase yield was improved in cane molasses when compared with the synthetic medium, and the cost of production was also significantly reduced. This enzyme can find application in the animal feed industry for improving the nutritional status of feed and combating environmental pollution. [source] Beta-glucan production by Botryosphaeria rhodina in different bench-top bioreactorsJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2004L. Selbmann Abstract Aims:, Evaluation of the technical feasibility of transferring , -glucan production by Botryosphaeria rhodina DABAC-P82 from shaken flasks to bench-top bioreactors. Methods and Results:, Three different bioreactors were used: 3 l stirred tank reactor (STR-1) equipped with two different six-blade turbines; STR as above but equipped with a three-blade marine propeller plus draft-tube (STR-2); 2 l air-lift column reactor (ALR) equipped with an external loop. STR-1, tested at three different stirrer speeds (300, 500 and 700 rev min,1) appeared to be less suitable for , -glucan production by the fungus, being maximum production (19·4 g l,1), productivity (0·42 g l,1 h,1) and yield (0·48 g g,1 of glucose consumed) markedly lower than those obtained in shaken culture (29·7 g l,1, 1·23 g l,1 h,1 and 0·61 g g,1, respectively). Better performances were obtained with both STR-2 and ALR. With the latter, in particular, the increase of production was accompanied by reduced fermentation time (25·7 g l,1 after only 22 h); productivity and yield were highest (1·17 g l,1 h,1 and 0·62 g g,1 of glucose consumed, respectively). Conclusion:, Using an air-lift reactor with external loop, the scaling up from shaken flasks to bench-top bioreactor of the , -glucan production by B. rhodina DABAC-P82 is technically feasible. Significance and Impact of the Study:, Although culture conditions are still to be optimized, the results obtained using the ARL are highly promising. [source] Removal of cupric ions from acidic sulfate solution using reticulated vitreous carbon rotating cylinder electrodesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2004Gavin W Reade Abstract The potentiostatic deposition of copper from acid sulfate solutions (0.50 mol dm,3 Na2SO4 at pH 2 and 298 K) was studied at four porosity grades (10, 30, 60 and 100 pores per linear inch, ppi) of reticulated vitreous carbon (RVC) rotating cylinder electrode (RCE). The rate of removal of cupric ions from a 200 cm3 volume of electrolyte was examined as a function of the grade of RVC foam, the electrode potential and the initial cupric ion concentration. For the 100 ppi material, the product of the mass transport coefficient and the electroactive area per unit volume of electrode (kmAe) was equal to 0.28 s,1 at a potential of ,500 mV vs SCE for an initial cupric ion concentration of 0.85 mmol dm,3 and a constant rotation speed of 1500 rev min,1. Under the experimental conditions, an initial dissolved copper concentration of 63.5 ppm could be reduced to <0.1 ppm in approximately 60 min using a 100 ppi RVC RCE. SEM studies showed some non-uniform deposition of metal due to heterogeneous nucleation of copper together with the development of rough deposits. Copyright © 2004 Society of Chemical Industry [source] Development of a robust once-a-day glipizide matrix systemJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2007Shahla Jamzad The robustness of a new hydroxypropylmethylcellulose (HPMC) based modified release glipizide (10 mg) formulation was studied. The tablet formulations were prepared by dry blending the ingredients and direct compression, incorporating a range of release modifying agents up to ± 20% w/w relative to an optimized formulation. The dissolution was assessed in 900 mL pH 6.8 buffer at 75 rev min,1 paddle speed. Calculated difference and similarity factors (f1 and f2) and results of analysis of variance suggest that the overall release profiles were similar. Compositional changes up to ± 20% w/w and a reduction of drug dose to half did not change the general release pattern of this low dose/pH-dependent drug in a significant way. It is concluded that the drug release from the developed matrix systems is highly dependent on the kinetics of hydration and erosion, and that the proposed compositional changes within ± 20% w/w did not alter this relationship. The particulate systems used were characterized by determining the Carr index, Hausner ratio and the rheological properties using a texture analyser. Results indicate that the release is reproducible and the system has potential for successful scale-up operation, while complying with recommended Food and Drug Administration guidelines "Scale Up and Post Approval Changes". [source] The influence of aggregate microenvironment on the dissolution of oxazepam in ternary surfactant interactive mixturesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2002Peter J. Stewart ABSTRACT The purpose of this research was to test the hypothesis that the dissolution rate of oxazepam in interactive mixtures was dependent on the influence of surfactant within the microenvironment of mixed oxazepam-surfactant aggegrates produced during dissolution. The studies utilised both powder and intrinsic dissolution methodology; spectrophotometric assays were developed and validated and dissolution data were modelled using multi-exponential equations and dissolution rate constants estimated using non-linear least squares algorithms. For a series of water-soluble ternary additives to the oxazepam interactive mixture, sodium lauryl sulfate and cetrimide were shown not only to decrease aggregation through enhanced dispersion, but also to increase the dissolution rate constant. Such an increase in dissolution rate constant was observed in the intrinsic dissolution studies when surfactant concentrations exceeded the critical micelle concentration and the oxazepam solubility increased. Laser diffraction particle sizing during the dissolution process confirmed the presence of dispersed particles and aggregates and demonstrated that the presence of surfactant improved the state of dispersion. The results of studies using different rotational speeds produced unexpected increases in aggregation and decreases in dissolution rate constants at about 150 rev min,1, consistent with the transient formation of loose aggregates containing dissolved surfactant. [source] Crystallization conditions and formation of orthorhombic paracetamol from ethanolic solutionJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2002N. Al-Zoubi Orthorhombic paracetamol exhibits far better tabletability than the monoclinic form and its bulk crystallization from solution attracts much interest. In this study, temperature changes in supersaturated ethanolic solution have been recorded after seeding with orthorhombic crystals under different cooling temperatures (TC) and agitation rates (AR). Average cooling rate (CR), time for maximum temperature deviation (tmax) and area confined between curves of measured and reference temperature plots (AUC) were calculated and correlated with crystal yield (Y). The micromeritic (size and shape) and the compression properties, the density and the orthorhombic content of the crystalline product were evaluated and related to the main crystallization conditions applied (TC and AR). Conditions for optimal crystal yield and orthorhombic content were elucidated. It was found that crystal yield (Y) increased with AR and decreased with TC. The ratio tmax/CR provided good prediction of crystal yield (Y = 58.92 ,1.386 tmax/CR, r2 = 0.964 and P = 0.0001). TC and AR linearly affected crystal size and the size distribution, probably due to alterations in supersaturation, but they did not affect the crystal shape significantly. Density and compression properties (yield pressure and elastic recovery) were determined by the content of the orthorhombic form, which increased linearly with AR (P = 0.009) and with TC (P = 0.039) when agitation was between 300 and 500 rev min,1, while tmax decreased. At 700 rev min,1 orthorhombic content was maximized and became independent to TC. Higher orthorhombic content and crystal yield was expected for lower TC and for lower tmax, which corresponded to higher AR and might have also been affected by alteration of seeding and harvesting procedure. [source] Modification of culture conditions for production of the anti-tubercular hirsutellones by the insect pathogenic fungus Hirsutella nivea BCC 2594LETTERS IN APPLIED MICROBIOLOGY, Issue 2 2008S. Madla Abstract Aims:, This work aimed to improve the production of anti-tubercular hirsutellones by the insect pathogenic fungus Hirsutella nivea BCC 2594. Methods and Results:, The fungus was cultivated under different carbon/nitrogen sources and aerations (shake vs static flasks) to improve the production of the anti-tubercular alkaloids, hirsutellones A,D. Under the basal conditions, static cultivation at 25°C in minimum salt medium, only hirsutellone B and C were detected with maximum concentrations of 139·00 and 18·27 mg l,1. Substitution of fructose for glucose and peptone for yeast extract increased the titres of hirsutellones A, B and C about two- to threefold. However, hirsutellone D was not detected in this medium. Culture agitation induced the production of hirsutellone D. As a result, the significant amounts of hirsutellones A,D were obtained with the concentration of 29·93, 169·63, 22·65 and 15·71 mg l,1 within 15 days. Conclusions:, Improved titres of hirsutellones in H. nivea BCC 2549 were achieved with an agitated (200 rev min,1) fructose,peptone medium at 25°C. Significance and Impact of the Study:, Improved yields of hirsutellones B,D will enable medicinal chemistry modifications leading to a development of a potential candidate for tuberculosis therapy. [source] Role of casein on induction and enhancement of production of a bacterial milk clotting protease from an indigenously isolated Bacillus subtilisLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2008K. Dutt Abstract Aims:, To isolate and enhance the yield of a bacterial milk clotting protease (MCP) through process optimization and scale up. Materials and Results:,Bacillus subtilis was isolated as MCP producer with good milk clotting activity (MCA) per proteolytic activity (PA) index. The enzyme production was inducible with casein and enhanced with fructose and ammonium nitrate resulting in 571·43 U ml,1 of enzyme. Conclusions:, Medium containing 4% fructose, 0·75% casein, 0·3% NH4NO3 and 10 mmol l,1 CaCl2, pH 6·0, inoculated with 4% (v/v) inoculum, incubated at 37°C, 200 rev min,1 for 72 h gave maximum production. A 6·67-fold increase in MCP yield with very high MCA per PA index was observed after final optimization indicating similarity to rennets. Significance and Impact of the Study:, Mostly fungal MCPs have been reported. The MCA and MCA per PA index of this bacterium is comparable to that of many fungal reports and better than quite a few bacterial MCPs. Thus, this enzyme by B. subtilis has good probability of successful use in cheese production. [source] Production of Shiga toxin by Shiga toxin-expressing Escherichia coli (STEC) in broth media: from divergence to definitionLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2007L.B. Rocha Abstract Aims:, To determine the suitability of eight different commercial broth media for Shiga toxin (Stx) production. Methods and Results:, Shiga toxin-producing Escherichia coli (STEC) strains producing Stx1 or Stx2 were grown at 37°C (250 rev min,1) for 24 h in brain heart infusion broth, E. coli broth, Evans medium, Luria-Bertani broth, Penassay broth, buffered-peptone water, syncase broth and trypticase soy broth. Toxin production was measured by enzyme-linked immunosorbent assay (ELISA) in polymyxin-treated cell pellets and/or supernatants of cultures, ELISA optical densities reached 1 when isolates were grown for 2,4 h in E. coli broth in the presence of antibiotic. Besides, a collection of STEC-expressing Stx strains was evaluated and the Stx production was assayed in the supernatants and in polymyxin-treated pellets of bacterial growth after 4 h of cultivation in E. coli broth in the presence of antibiotic. Conclusions:, The most suitable medium for Stx production was E. coli broth when the bacterial isolates were grown for 4 h in the presence of ciprofloxacin and the Stx production is detected in the supernatant. Significance and Impact of the Study:, This study presents the first comprehensive comparison of different broth media with regard to Stx production to establish optimal culture conditions for STEC detection in routine diagnostic laboratories. [source] Effect of agitation intensity on the exo-biopolymer production and mycelial morphology in Cordyceps militarisLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2002J.P. Park Aims:,The influence of agitation intensity on Cordyceps militaris morphology and exo-biopolymer production was investigated in a 5 litre stirred vessel using a six-blade Rushton turbine impeller. Methods and Results:,The mycelial morphology of C. militaris was characterized by means of image analysis, which included mean diameter, circularity, roughness and compactness of the pellets. The morphological parameters of the pellets grown under different stirring conditions were significantly different, which correspondingly altered exo-biopolymer production yields. Conclusions:,The compactness of the pellets was found to be the most critical parameter affecting exo-biopolymer biosynthesis; more compact pellets were formed at 150 rev min,1 with maximum exo-biopolymer production (15 g l,1). Significance and Impact of the Study:,The results of this study suggest that morphological change of pellets is a good indicator for identifying the cell activity for exo-biopolymer production. 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