Modeling and simulation of cephalosporin C production in a fed-batch tower-type bioreactor

Immobilized cell utilization in tower-type bioreactor is one of the main alternatives being studied to improve the industrial bioprocess. Other alternatives for the production of beta -lactam antibiotics, such as a cephalosporin C fed-batch p recess in an aerated stirred-tank bioreactor with free cells of Cepha-losporium acremonium or a tower-type bioreactor with immobilized cells of this fungus, have proven to be more efficient than the batch profess. In the fed-batch process, it is possible to minimize the catabolite repression exerted by the rapidly utilization of carbon sources (such as glucose) in the synthesis of antibiotics by utilizing a suitable flow rate of supplementary medium. In this study, several runs for cephalosporin C production, each lasting 200 h, were conducted in a fed-batch tower-type bioreactor using different hydrolyzed sucrose concentrations, For this study's model, modifications were introduced to take into account the influence of supplementary medium flow rate. The balance equations considered the effect of oxygen limitation inside the bioparticles. In the Monod-type rate equations, eel concentrations, substrate concentrations, and dissolved oxygen were included as reactants affecting the bioreaction rate. The set of differential equations was solved by the numerical method, and the values of the parameters were estimated by the classic nonlinear regression method following Marquardt's procedure with a 95% confidence interval. The simulation results showed that the proposed model fit well with the experimental data,and based on the experimental data and the mathematical model an optimal mass flow rate to maximize the bioprocess productivity could be proposed.

EFFECT OF ASCORBIC-ACID DEFICIENCY ON THE GROWTH, GILL FILAMENT LESIONS AND BEHAVIOR OF PACU FRY (PIARACTUS-MESOPOTAMICUS HOLMBERG, 1887)

The effect of ascorbic acid deficiency was determined in Piaractus mesopotamicus Holmberg, 1887, fish (pacu) under laboratory conditions. A total of 120 fish with an average body weight of 8.64 +/- 1.62 g and measuring 6.15 +/- 0.33 cm in length at the beginning of the experiment were fed diets containing 0, 50, 100 or 200 mg palmitate-coated ascorbic acid/kg dry ration for a period of 24 weeks with measurements every 4 weeks. The experiment was conducted in 20 fiber-cement aquaria of 81-liter capacity. Each aquarium was supplied with dechlorinated water at a flow rate of 1 l/min. Water temperature was measured daily and pH, dissolved oxygen, alkalinity and water conductivity were determined weekly. A fully randomized experimental design was utilized, with 5 replicates of each treatment and 6 fish per aquarium. Ascorbic acid-supplemented fish presented significantly increased growth when compared to unsupplemented fish. Furthermore, unsupplemented fish presented a higher incidence of hyperplasia, hypertrophy and dysplasia of the bone cartilage of gill filaments. The gill lamellae of unsupplemented fish had twisted cartilage and an inflammatory infiltrate at the ends. Anorexia and increased handling stress were also observed in fish fed the unsupplemented diet. The present study suggests that 50 mg ascorbic acid/kg dry ration is sufficient to improve development of pacu fingerlings but the optimum level under aquarium conditions, determined by regression analysis, is 139 mg ascorbic acid/kg dry ration.

Kinetics and mechanism of the induced redox reaction of [Ni(cyclam)](2+) promoted by SO5 center dot-

Oxidation of [Ni(cyclam)](2+), cyclam = 1,4,8,11-tetraazacyclotetradecane, accelerated by sulfur dioxide, was studied spectrophotometrically by following the formation of [Ni(cyclam)](3+) under the conditions: [Ni(cyclam)](2+) = 6.0 x 10(-3) M; initial [Ni(cyclam)](3+) = 8.0 x 10(-6) M; [cyclam] = 6.0 x 10(-3) M; [SO2] = (1.0-5.0) x 10(-4) M and 1.0 M perchloric acid in oxygen saturated solutions at 25.0 degrees C and ionic strength = 1.0 M. The oxidation reaction exhibits autocatalytic behavior in which the induction period depends on the initial Ni(III) concentration. A kinetic study of the reduction of Ni(III) by SO2 under anaerobic conditions, and the oxidation of Ni(II), showed that the rate-determining step involves reduction of Ni(III) by SO2 to produce the SO3.- radical, which rapidly reacts with dissolved oxygen to produce SO5.- and rapidly oxidizes Ni(II). The results clearly show a redox cycling process which depends on the balance of SO2 and oxygen concentrations in solution.

Yeasts and others parameters of pollution of the Ribeirao Claro stream in Rio Claro, São Paulo

The main water source of the Rio Claro municipal district (DAAE) was analysed for determining the level of organic contamination. Temperature, pH, light penetration, conductivity, dissolved oxygen, total dissolved phosphate, ortophosphate, ammonia, heterotrofic bacteria, total coliforms, fecal coliforms, total yeasts and fermentative yeasts were analysed during one year with samples being collected on a monthly basis. Bathing quality of the water from sites 1, 2 and 3 were classified, respectively, as Satisfactory, Very Good and Improper based on fecal coliform counts. Total yeast counts were appropriate as a complement for the appraisal of fresh water contamination by coliform counts. Seventeen yeast species belonging to genera Candida, Cryptococcus, Kloeckera, Pichia and Rhodotorula were found but none of them could be correlated with a level of contamination. Candida famata, C. robusta-like and C. colliculosa were isolated at all of the sites and between the five species found only at the more polluted site, Rhodotorula mucilaginosa was prevalent.

A comparative study of the electrogeneration of hydrogen peroxide using Vulcan and Printex carbon supports

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Anthropogenic influences on annual flux of cations and anions at meio stream basin, São Paulo State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Using Efinol (R) L during transportation of marbled hatchetfish, Carnegiella strigata (Gunther)

The objective of this experiment was to test the efficacy of a probiotic (Efinol (R) L) during transportation of marbled hatchetfish, Carnegiella strigata. Wild specimens were captured from a small stream and transported for 24 h in plastic fish boxes with a probiotic (10 mg L-1) and probiotic-free water. The boxes were sampled at 3. 12 and 24 h of transport. At the end of the experiment, the survival rate was close to.100%) in both treatments. Dissolved oxygen diminished with time in both treatments, but the probiotic group had significantly higher levels. Conductivity. pH and ammonia increased significantly during the transport. demonstrating higher levels in the probiotic-free group. Fish from both treatments presented very high net Na+ and K+ effluxes after 3 h of transport. At 24 h, net K+ effluxes in fish of the probiotic treatment reached values close to zero and a significantly lower Na+ efflux was observed. Cortisol levels in both treatments at 3 and 12 h were significantly higher than that in control samples. Higher body cortisol levels were observed in the probiotic-frec group than that in the probiotic group at 3 and 12 h. The results demonstrate that addition of a probiotic during fish transport improves water quality and leads to fish presenting a lower stress response intensity.

Genotoxicity and mutagenicity of water samples from the Monjolinho River (Brazil) after receiving untreated effluents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Benefits of using the probiotic Efinol((R))L during transportation of cardinal tetra, Paracheirodon axelrodi (Schultz), in the Amazon

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Variação espaço-temporal na distribuição e abundância de Moenkhausia sanctaefilomenae (Characiformes: Characidae) em lagoas da planície de inundação do rio Cuiabá, Pantanal, Brasil

Identifying the biotic and abiotic factors that determine the variation in the distribution and abundance of populations has become a great challenge for the field of ecology in recent years. Thus, in this study we evaluated the effect of abiotic variables and the abundance of predators on the abundance of Moenkhausia sanctaefilomenae, the variation in the average length of the individuals between lakes and periods, and the effect of the abiotic variables and abundance of predators on the structure in length of that species. Sixteen lakes of the Cuiaba river flood plain were sampled in June (drying period), September (dry period) and December (flooding period) 2005 and March (flood period) 2006. For M. sanctaefilomenae, the distribution is ampler and the abundance is greater at the end of the drying period, beginning of dry season, reducing gradually over the periods of dry, drying and flood season. Additionally, the period affects the structure in size of the populations that are spatially homogeneous. Smaller individuals were captured at the end of the drying period and the larger individuals at the start of flooding. During the end of the drying period and in the beginning of the dry season, the spatial variation in the abundance of the population was positively related with pH, dissolved oxygen and macrophyte cover and area of the lake, but not with the local abundance of predators in the littoral zone of the lakes.

Os efeitos da ação antrópica sobre a distribuição de macroinvertebrados no Rio Guareí, São Paulo

In this study, it was examined, during the period from March to December 2006, the effects of human disturbance on themacroinvertebrates that live near macrophytes in Guare River, São Paulo State - Brazil. It was questioned if the high conductivityrecorded in Guare River affected the distribution of the macroinvertebrates and what were the most important variables thataffect macroinvertebrates in a river with a strong nutrient concentration. The objective of this study was to investigate theeffects of environmental variables on densities and composition of the macroinvertebrates. Three stands of aquatic plantswere sampled with with 0.25 mm mesh net on a 0.07 m2 square metal frame. Air and water temperature, depth, pH, electricalconductivity, suspended solids, dissolved oxygen and macrophyte biomass were measured. A canonical correspondence analysis(CCA) was performed using the density of the macroinvertebrates and environmental variables. Chironomidae, Culicidae,Acanthagrion, Coryphaeschna, Erythrodiplax, Miathyria marcella, Micrathyria, Gastropoda, Ostracoda and Hemiptera werethe only taxa that showed significant correlation with the axes. From the results, we can conclude that the high conductivity recordedin Guare River due to the high amount of organic matter released during its course did not significantly affected thedistribution of the macroinvertebrates during the studied period. However, the ACC recorded that oxygen was the most significantenvironmental factor for the density variance of the macroinvertebrates, especially larval Odonata.

Baixa diversidade de zooplâncton na desembocadura de uma represa eutrófica (SP, Brasil): reflexo da poluição?

The Tiete River (in São Paulo state) receives most of the efuents of the metropolitan region of São Paulo; and the Barra Bonita reservoir, 200 km distant downstream, receives and recycle most of that pollution load. This work studied the ecological features of the zooplankton (Rotifera, Cladocera and Copepoda) sampled in a point of Tiete River's mouth. Monthly samples were collected, from April, 2001 to February, 2008. The hypothesis currently tested was that the composition and availability of zooplankton were similar to the others reservoir regions (middle and lacustrine sensu Thornton) and to other reservoirs of the Upper Parana River basin, supporting the idea that these organisms manage to stand the strong pollution. The reservoir shows a typical variation of accumulation, with wide variation of seasonal altimetric grading and large fow in the rainy pe- riod, infuenced by the rainfall regime, with efects upon zooplankton assemblage. As a whole, 24 species were registered: 12 Rotifera, 8 Cladocera and 4 Copepoda. Data showed that the hypothesis formulated must be rejected, due the variation trends of zooplankton environmental attributes not being regular, with relatively high abundance values for a lotic environment in specifc months, and low organism abundance or absence in other months. Those facts can be attributed to pollution efects conducting to low dissolved oxygen concentration (> 4mg.l-1) in some months, which causes the zooplankton community to be very much afected. [K]

Influence of the heat treatment in the electrochemical corrosion of Al-Zn-Mg alloys

The localized corrosion of Al-(5.03%)Zn-(1.67%)Mg-(0.23%)Cu alloys and high purity Al has been studied using electrochemical techniques, optical microscopy, SEM and EDX. The samples were previously submitted to different heat treatments in which coherent and incoherent MgZn 2 precipitates with different distribution and aggregation degree were produced. The influence of NaCl and Na 2SO 4, dissolved oxygen, immersion time and convection were studied. In NaCl solutions, pitting potentials for the alloys were more negative than for aluminium, indicating an increase in their susceptibility to localized corrosion. Moreover, annealed and cold-rolled alloys presented more negative pitting and repassivation potentials than those submitted to age hardening with direct or interrupted quenching. In annealed and cold-rolled samples, pit nucleation and propagation takes place in the zones where MgZn 2 is accumulated. In the case of the age-hardened alloys, a double pitting behaviour is observed, the first one in the magnesium and zinc enriched regions and the second in the matrix. While the cold water quenched alloy is susceptible to stress corrosion craking, the alloy submitted to the interrupted quenching process is less susceptible to intergranular attack. The sulphate ion shifts the pitting potential of aluminium and the alloys by chloride towards more positive values because it impedes local accumulations of the latter. © 1992 Chapman & Hall.

Uso de macroalgas para avaliação da Poluição orgânica no Rio Preto, noroeste do estado de São Paulo.

The Preto River, located in the northwest of São Paulo State, receives a total wastewater load of 15.150 kg DBO day-1, from which 13.685 kg DBO day-1 (90.5%) corresponds to domestic sewage, and the city of São José do Rio Preto contributes with 12.400 kg DBO day-1 (90% of domestic sewage). During the period from August 1990 through January 1991, monthly sampling was carried out to evaluate the use of macroalgae as bioindicator of organic pollution. Five sampling sites were established along the main river and the following variables were analised: temperature, conductance, turbidity, dissolved oxygen, BOD, COD, total and fecal coliforms, and composition and abundance of macroalgal communities. Data were submitted to analysis of variance, correlation coefficient, cluster analysis (four different approaches) and converted to biological indices (species deficit, relative pollution, saprobity, diversity and uniformity indices). A wide range in water quality was found (particularly for conductance, oxygen, BOD and COD) among the sampling sites, which were classified into three groups (polluted, moderately polluted and unpolluted/weakly polluted). As regards the occurrence and abundance of macroalgae the Rhodophyta were found only in unpolluted or weakly polluted sites, whereas Cyanophyta occurred mostly under high pollution load; the Chlorophyta species were observed under a wide range of conditions. Among the biological indices, saprobity was the most sensitive and correlated to all water variables and the other indices. Cluster analyses showed that the composition of macroalgal communities was consistent with the levels of organic pollution in the Preto River.

Physicochemical features of rivers and lakes in pantanal wetland

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)