Potencial de mineralización de nitrógeno en suelos con aplicación de cáscara de semilla de girasol / Potential nitrogen mineralization in soils with sunflower seed husk application

Resumen El objetivo de este estudio fue evaluar el potencial de mineralización de nitrógeno (N) de suelos contrastantes luego del aporte de diferentes dosis de cascaras de semillas de girasol (CG) (Helianthus annuus L.), residuo abundante del sudoeste bonaerense (SOB). Se realizaron incubaciones aeróbicas de largo plazo (37 semanas), utilizando tres suelos diferentes (0-20 cm) y distintas dosis de CG calculadas con base en su contenido de N orgánico: 100 (D1), 200 (D2) y 400 (D3) kg N ha-1. Los suelos contrastaron en el contenido de fracciones granulométricas (S1: arena 509 g kg-1; limo 320 g kg-1 y arcilla 171 g kg-1; S2: arena 351 g kg-1; limo 448 g kg-1 y arcilla 201 g kg-1; S3: arena 827 g kg-1, limo 107 g kg-1 y arcilla 66 g kg-1). Las características químicas de CG: conductividad eléctrica= 1,6 dS m-1; pH= 5,6; materia orgánica (MO) = 958 g kg-1; N total= 7,8 g kg-1, relación C:N= 79. Los suelos demostraron diferencias significativas en el N potencialmente mineralizable (N0) con valores que fueron S1>S2>S3, al igual que en la tasa de mineralización (k) (S1 y S3= 0,0036 semana-1, S2=0,0056 semana-1). Se halló una interacción significativa en los aportes de CG y suelos, por lo que se analizó la incorporación en cada suelo. Cuando se aplicó CG, se observó una respuesta positiva sobre S3 con D1 y D2. Para S1 y S2, la aplicación de CG no aumentó el N0, aunque tampoco produjo un detrimento. La dinámica de la mineralización de N acumulada demostró efectos diferentes al aporte de CG con respecto al tipo de suelo. El aporte de CG al suelo incrementó el potencial de mineralización de N en el suelo arenoso-franco, sin disminuir el potencial en los suelos restantes, por lo que podría ser utilizada como enmienda orgánica bajo estas condiciones.

Abstract The objective of this study was to evaluate the potential nitrogen (N) mineralization of contrasting soils after the addition of different sunflower seed hulls (CG) (Helianthus annuus L.) doses, an abundant residue of the southwest of Buenos Aires Province (SOB). Long-term aerobic incubations (37 weeks) were performed, using three different soils (0-20 cm) and various CG levels based on their organic N content: 100 (D1), 200 (D2) and 400 (D3) kg N ha-1. Soils differs in granulometric fractions (S1: sand 509 g kg-1; silt 320 g kg-1 and clay 171 g kg-1; S2: sand 351 g kg-1; silt 448 g kg-1 and clay 201 g kg-1; S3: sand 827 g kg-1, silt 107 g kg-1 and clay 66 g kg-1). The CG chemical characteristics: electrical conductivity= 1.6 dS m-1; pH= 5.6; organic matter (MO) = 958 g kg-1; total N= 7.8 g kg-1, C:N ratio = 79. Significant differences were found in potentially mineralizable N (N0) for three soils, whose values were S1>S2>S3; as well as in the mineralization rate (k) (S1 and S3= 0.0036 week-1, S2=0.0056 week-1). Significant interaction was found with the CG contribution and soils, so the contribution was analyzed for each soil. When GC was applied, a positive response was observed on S3 with D1 and D2. For S1 and S2, the application of GC did not increase the potential for N mineralization, however, it had not a detrimental effect on the potential. Dynamics of accumulated N mineralization showed different effects of CG addition with respect to soil type. The CG addition to soil increased the potential N mineralization in the sandy-loam soil, without reducing the potential in the remaining soils, which is why it could be used as an organic amendment under these conditions.

Consequential study on different levels of C/N ratios used in biofloc-based aquaculture system / Estudo consequente sobre diferentes níveis de proporções C/N utilizadas no sistema de aquicultura à base de biofloc

Biofloc technology is much highlighted these days because of its tremendous effects on aquaculture. Microbes were enriched on cheapest organic carbon source i. e., powdered banana peels and were incorporated in different aquaria rearing grass carp fingerlings under different C/N treatments (10:1, 15:1 and 20:1) and 10% water daily water exchange. The initial growth of fingerlings was recorded. The experiment was settled in triplicates for 60 days and run parallel to control group provided with commercial feed and daily water exchange. Its effect was evaluated by measuring the growth of fingerlings and water parameters of each aquarium. The average % gain in weight and length of fingerlings was obtained significantly highest (28.12 ± 0.30g and 17.29 ± 0.46cm respectively) in aquaria containing pure powdered banana peels with 10% water exchange and C/N ratio was adjusted at 20: 1 (T3) than other treatments and control. Ammonia and other water parameters were also under control in T3 than other experimental and control groups. By all counts, it was concluded that the highest C/N ratio in biofloc system had the potential to increment C. idella growth rate by reducing toxicity and could be used as fish meal substitute.

A tecnologia Biofloc é muito destacada hoje em dia por causa de seus tremendos efeitos na aquicultura. Os micróbios foram enriquecidos com a fonte de carbono orgânico mais barata, i. e., cascas de banana em pó, e foram incorporadas em diferentes aquários de criação de alevinos de carpa-capim sob diferentes tratamentos C/N (10: 1, 15: 1 e 20: 1) e 10% de troca diária de água. O crescimento inicial dos alevinos foi registrado. O experimento foi resolvido em triplicatas por 60 dias e executado paralelamente ao grupo controle fornecido com ração comercial e troca diária de água. Seu efeito foi avaliado medindo o crescimento dos alevinos e os parâmetros da água de cada aquário. O% de ganho médio em peso e comprimento dos alevinos foi obtido significativamente mais alto (28,12 ± 0,30g e 17,29 ± 0,46 cm respectivamente) em aquários contendo cascas de banana em pó puro com 10% de troca de água e a relação C/N foi ajustada em 20: 1 (T3) do que outros tratamentos e controle. A amônia e outros parâmetros da água também estavam sob controle no T3 mais do que nos outros grupos experimentais e de controle. Por todas as contagens, concluiu-se que a maior razão C/N no sistema de bioflocos tem o potencial de incrementar a taxa de crescimento de C. idella reduzindo a toxicidade e pode ser usada como substituto da farinha de peixe.

Consequential study on different levels of C/N ratios used in biofloc-based aquaculture system

Abstract Biofloc technology is much highlighted these days because of its tremendous effects on aquaculture. Microbes were enriched on cheapest organic carbon source i. e., powdered banana peels and were incorporated in different aquaria rearing grass carp fingerlings under different C/N treatments (10:1, 15:1 and 20:1) and 10% water daily water exchange. The initial growth of fingerlings was recorded. The experiment was settled in triplicates for 60 days and run parallel to control group provided with commercial feed and daily water exchange. Its effect was evaluated by measuring the growth of fingerlings and water parameters of each aquarium. The average % gain in weight and length of fingerlings was obtained significantly highest (28.12 ± 0.30g and 17.29 ± 0.46cm respectively) in aquaria containing pure powdered banana peels with 10% water exchange and C/N ratio was adjusted at 20: 1 (T3) than other treatments and control. Ammonia and other water parameters were also under control in T3 than other experimental and control groups. By all counts, it was concluded that the highest C/N ratio in biofloc system had the potential to increment C. idella growth rate by reducing toxicity and could be used as fish meal substitute.

Resumo A tecnologia Biofloc é muito destacada hoje em dia por causa de seus tremendos efeitos na aquicultura. Os micróbios foram enriquecidos com a fonte de carbono orgânico mais barata, i. e., cascas de banana em pó, e foram incorporadas em diferentes aquários de criação de alevinos de carpa-capim sob diferentes tratamentos C/N (10: 1, 15: 1 e 20: 1) e 10% de troca diária de água. O crescimento inicial dos alevinos foi registrado. O experimento foi resolvido em triplicatas por 60 dias e executado paralelamente ao grupo controle fornecido com ração comercial e troca diária de água. Seu efeito foi avaliado medindo o crescimento dos alevinos e os parâmetros da água de cada aquário. O% de ganho médio em peso e comprimento dos alevinos foi obtido significativamente mais alto (28,12 ± 0,30g e 17,29 ± 0,46 cm respectivamente) em aquários contendo cascas de banana em pó puro com 10% de troca de água e a relação C/N foi ajustada em 20: 1 (T3) do que outros tratamentos e controle. A amônia e outros parâmetros da água também estavam sob controle no T3 mais do que nos outros grupos experimentais e de controle. Por todas as contagens, concluiu-se que a maior razão C/N no sistema de bioflocos tem o potencial de incrementar a taxa de crescimento de C. idella reduzindo a toxicidade e pode ser usada como substituto da farinha de peixe.

Effect of carbon/nitrogen ratio on polyhydroxyalkanoates production by Bacillus species under submerged fermentation

Aim: To analyze the effect of carbon/nitrogen (C/N) ratio on polyhydroxyalkanoates (PHAs) production by Bacillus species under submerged fermentation process.Methodology: Preserved polyhydroxyalkanoates producing Bacillus sp. C1 (2013) (KF626477) was revived and growth parameters were optimized by one factor at a time approach. The effect of C/N ratio and the influence of time period on polyhydroxyalkanoates production through submerged fermentation process was evaluated under optimized condition. Primary structural and morphological characterization of extracted polyhydroxyalkanoates was carried out by Fourier Transform Infra-Red Spectroscopy and Field Emission-Scanning Electron Microscopy. Results: Bacillus sp. C1 (2013) produced higher cell biomass in mineral salt medium at pH 9.0, temperature 37oC, dextrose (2%) and ammonium sulphate (1%) as carbon and nitrogen source with 15% inoculum size. Under optimized condition, higher polyhydroxyalkanoates production of 1.09 g l-1 (49.2%) was obtained at 48 hrs with 2: 0.4 C/N ratio. However, in our previous study 0.909 gl-1 of PHAs was produced by the bacteria at 6:1 carbon to nitrogen ratio. Fourier Transform Infra-Red Spectroscopic analysis showed high intense absorption bands at 1720.18 cm−1 resembled to ester carbonyl functional group of PHB, which is the most common homopolymer of PHAs. Surface morphology of poly-beta-hydroxybutyrate film was rough and fairly regular as revealed from Field Emission-Scanning Electron Microscopic imaging. Interpretation: Poly-beta-hydroxybutyrate production by the bacteria increased under higher degrees of nitrogen deficient condition. Thus, optimized C/N ratio can improve the cost affordability of poly-beta-hydroxybutyrate production, however, further research in contrast to different bacteria is highly essential in this regard.

Manejo biológico del tamo de arroz bajo diferentes relaciones C:N empleando consorcios microbianos y promotores de crecimiento vegetal / Bio-based management of rice straw under different C:N ratios using microbial consortia and plant growth promoters

Resumen El tamo de arroz es uno de los residuos agrícolas lignocelulósicos más abundantes en el planeta, luego de los residuos producidos por los cultivos de maíz y trigo, con una producción mundial estimada de 1000 millones de toneladas según estadísticas de la FAO. En el contexto de la agricultura moderna es determinante lograr un manejo ambientalmente sostenible de este recurso mediante su incorporación al suelo, de tal forma que se logre el reciclaje de nutrientes, evitando la incorporación de patógenos al sistema y la inmovilización de elementos como el nitrógeno por la comunidad microbiana. El objetivo de este trabajo consistió en la evaluación de un inoculo microbiano mixto a partir de productos comerciales basados en hongos del género Trichoderma y bacterias aerobias formadoras de endosporas, con potencial degradador del tamo de arroz, así como el empleo de bacterias promotoras de crecimiento vegetal al momento de la siembra, que pudieran aprovechar los nutrientes del proceso de descomposición del tamo de arroz, potenciando su actividad biológica. Los tratamientos fueron evaluados bajo diferentes relaciones C:N del tamo de arroz que favorecieran el proceso de degradación, mediante la adición de nitrógeno inorgánico. Los resultados del trabajo permitieron identificar que la aplicación de una enmienda de nitrógeno a una relación C:N 35 más una dosis adicional de urea al momento de la siembra de las semillas de arroz, fue el tratamiento más adecuado para potenciar el efecto de los microorganismos e incrementar las variables agronómicas obtenidas mediante un esquema de fertilización convencional del cultivo.

Abstract Rice straw is one of the most abundant lignocellulosic agricultural residues on the world, after residues produced by maize and wheat crops, with an estimated global production of 1000 million tones according to FAO statistics. In the context of modern agriculture, it is essential to achieve an environmentally sustainable management of this resource, through the incorporation of rice straw into the soil, in order to achieve nutrient recycling avoiding the incorporation of pathogens into the system and the losses of nitrogen due to soil microbial biomass immobilization. In this context, the objective of this work consisted in the evaluation of a mixed microbial inoculum with degrading potential of rice straw from commercial products based on the fungus Trichoderma spp. and aerobic endospore forming bacteria. It was also used a plant growth promoting bacteria at the time of planting, in order to take advantage of nutrients released from RS decomposition and improve its biological activity. These microbial treatments, were evaluated at different concentrations of inorganic nitrogen amendments that allowed different levels of rice straw´s C:N ratio, favoring the degradation process. Overall results allowed to identify that the application of a nitrogen amendment to rice straw up to C:N 35, plus an additional dose of urea at the time of rice seeds planting, was the most adequate treatment to potentiate the effect of the microorganisms and to increase or maintain the agronomic variables obtained through a conventional fertilization management of the crop.

Kinetic study and modeling of biosurfactant production using Bacillus sp

Background: Surfactants are one of the most important raw materials used in various industrial fields as emulsifiers, corrosion inhibitors, foaming agents, detergent products, and so on. However, commercial surfactant production is costly, and its demand is steadily increasing. This study aimed to evaluate the performance of typical strains of Bacillus sp. to produce biosurfactants through fermentation. It also included the investigation of the effect of initial glucose concentration and the carbon to nitrogen ratio. Results: The biosurfactant yield was in the range of 1­2.46 g/L at initial glucose concentrations of 10­70 g/L. The optimum fermentation condition was achieved at a carbon to nitrogen ratio of 12.4, with a decrease in surface tension of up to 27 mN/m. Conclusions: For further development and industrial applications, the modified Gompertz equation is proposed to predict the cell mass and biosurfactant production as a goodness of fit was obtained with this model. The modified Gompertz equation was also extended to enable the excellent prediction of the surface tension.

Assessment of litter degradation in medicinal plants subjected to ultraviolet-B radiation.

Litter decomposition is an important component of global carbon budget. Elevated influx of ultraviolet-B radiation (UV-B) as a consequence of depletion of stratospheric ozone (O3) layer may affect litter decomposition directly or/ modifying the plant tissue quality. Chemical composition of plant can affect litter decomposition. In the present study, three important medicinal plant species i.e. Acorus calamus, Ocimum sanctum and Cymbopogon citratus were exposed to two levels of supplemental UV-B (sUV1 and sUV2) during the growth period and examined the changes in leaf quality and degradation of leaf litters. The sUV2 treatment (+3.6 kJ m-2 d-1) increased the rate of decomposition by 45% and 31% respectively; in leaf litters from O. sanctum and C. citratus, while no significant effect was noticed in A. calamus leaf litter. Higher accumulation of sclerenchymatous tissue around vascular bundles and increased concentrations of total phenols by 39 mg g-1 probably lowered the decomposition rate; finding k value: 0.0049 g g-1 d-1 in leaf litters of A. calamus. The C/ N ratio was increased by 14% at sUV2 in C. citratus, whereas in O. sanctum it decreased by 13.6% after treatment. Results of the present experiment illustrates that firstly UV-B can modify the decomposition rate of leaf litter of test plant species, secondly it can alter the tissue chemistry particularly leaf phenolics, N and P concentrations strongly and thus affecting the decay rate and thirdly UV-B effects on decay rate and leaf chemistry is species specific.

Influence of long term application of fertilizers on soil organic matter content.

The soil samples were collected from the soils of Long Term Fertilizer Experiments that have been fertilized for the last 25 years from a) control plot (receiving no fertilizer/FYM); b) plot receiving 100% NPK fertilizer application and c) Plot receiving 100% N in the form of FYM, to study the changes in nature and amount of organic matter and these were compared with a similar adjacent soil under natural vegetation. The soil samples were collected from 0-15 cm (surface) and 15-30 cm (sub surface) layers. The humic substances were fractionated by Tyurins method. The total N and available N content was determined and C/N ratio was calculated. The humic acid was isolated, purified and analyzed for oxygen containing functional groups and spectral properties. It was observed that the soil under natural vegetation had a higher total N while the soil under continuous cultivation had higher available N. The C/N ratio of soil under natural vegetation was high compared to the soil under continuous cultivation. These values were high in surface layers compare to sub surface layers. The oxygen containing functional groups in Humic acid (HA) were high in soil under natural vegetation compared to the soil under continuous cultivation. The total acidity and COOH content of surface layers was high compared to sub surface layers in soils under both situations. Phenolic OH groups of subsurface layer was high in soil under natural vegetation and continuous cultivation indicating that this group in sub surface layers and high potential for interaction with clays and metal ions. The higher contents of total acidity and –COOH groups in soil under natural vegetation could be attributed to the difference in chemical composition and molecular weight of humic substances. The E4/E6 ratios of HA’S were less than 5.0 indicating high degree of condensation of aromatic humic acid. The potentiometric titrations of humic acids with standard 0.1 N NaOH indicated a gradual increase in pH with the addition of base thus indicating a high buffering capacity of humic acid. The potentiometric titration curves were sigmoid in nature indicating an apparent mono basic character and had a single break suggesting weak acidic character of humic acids. The conduct metric titrations of humic acids showed a slow increase in the initial stage followed by a steep increase at later stages. The apparent pKa values calculated from potentiometric titration data using Henderson-Hassebalch equation varied from 5.24 to 5.68.

Effect of reproductive growth on source-sink relationship of Alisma plantago-aquatica / 中草药

Objective: The effects of the reproductive growth on the source-sink relationship and source-sink characteristic indexes of Alisma plantago-aquatica were studied in order to provide a potential reference for the cultural techniques of high yield and quality and breeding. Methods: The dry weight in each part and the content of non-structure carbohydrates and nitrogen compounds in the leaves and tubers from the wiping off bolting and bolting plant were tested; The accumulative process of physiological indexes was compared. Results: Reproductive growth could benefit the accumulation of reproductive sink, go against the increase of source of leaves and vegetative sink, and obviously increase the plant total storage capacity and the total biomass. Wiping off the reproductive growth could increase the C/N ratio in the leaves at the later stages of plant growth and the tubers during the yield formative period, and promote the production of the leaves and tubers. Conclusion: During the process of cultivation, it is supposed to promptly adjust the plant C/N ratio by artificial measures for increasing the tuber production. The strains with suitable amounts and high C/N ratio in the leaves and high nitrogen content in the tubers at the later stages of the plant growth should be chosen for breeding.

Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation

Baffled shake flask cultivation of Aurantiochytrium sp. B-072 was carried out at in a glucose-monosodium glutamate mineral medium at different C/N-ratios (30-165) with glucose fixed at 90 g/L. With increasing C/N-ratio, a modest increase in lipid content (60 to 73 % w/w) was observed whereas fat-free biomass decreased but overall biomass showed little variation. FA-profiles were not affected to a large extent by C/N-ratio and absolute docosahexaenoic (DHA)-levels fell in narrow range (5-6 g/L). However at C/N > 64 a rapid decrease in lipid synthetic rate and/or incomplete glucose utilization occurred. Glucose and FA-fluxes based on fat-free biomass peaked at a C/N ratio of 56. This condition was chosen for calculation of the redox balance (NAD(P)H) and energy (ATP) requirement and to estimate the in vivo P/O ratio during the main period of fatty acid biosynthesis. Several models with different routes for NADPH, acetyl-CoA formation and re-oxidation of OAA formed via ATP-citrate lyase were considered as these influence the redox- and energy balance. As an example, using a commonly shown scheme whereby NADPH is supplied by a cytosolic "transhydrogenase cycle" (pyruvate-OAA-malate-pyruvate) and OAA formed by ATP-citrate lyase is recycled via import into the mitochondria as malate, the calculated NADPH-requirement amounted to 5.5 with an ATP-demand of 10.5 mmol/(g fat-free biomass x h) and an in vivo P/O-ratio (not including non-growth associated maintenance) of 1.6. The lowest ATP requirement is found when acetyl-CoA would be transported directly from the mitochondria to the cytosol by carnitine acetyltransferase. Assay of some enzymes critical for NADPH supply indicates that activity of glucose-6-phosphate dehydrogenase, the first enzyme in the HMP pathway, is far insufficient for the required NADPH-flux and malic enzyme must be a major source. Activity of the latter (ca. 300 mU/mg protein) far exceeds that in oleaginous fungi and yeast.

Efecto de nutrientes sobre la producción de biomasa del hongo medicinal Ganoderma lucidum / Effect of nutrients in the biomass production of the medicinal mushroom Ganoderma lucidum

El hongo Ganoderma lucidum, en los constituyentes de su biomasa, tiene compuestos con propiedades benéficas para la salud; es por esto que el conocimiento de las condiciones nutricionales adecuadas para su crecimiento permitirá su producción industrial y a bajo costo. En este trabajo se evaluó a nivel de matraz el efecto de la relación C/N, y la presencia de diferentes fuentes de carbono, nitrógeno y micronutrientes sobre la producción de biomasa. Empleando glucosa y peptona como fuentes de carbono y nitrógeno, respectivamente, se encontró una relación C/N óptima de 16,7:1 para la cual la máxima producción de biomasa fue de 25 g/L. Manteniendo esta relación C/N, y sustituyendo la glucosa por lactosa o harina de cebada y la peptona por extracto de levadura, la producción de biomasa se incrementó a 35 g/L. En presencia de harina de cebada la adición al medio de cultivo de sales de Mg y K, y de tiamina, no generó un mayor incremento en la producción de biomasa. La producción de biomasa de G. lucidum se ve favorecida por la presencia en el medio de cultivo de relaciones C/N cercanas a las reportadas conforme a la composición típica de los hongos, así como por la presencia de sustratos complejos como la harina de cebada que le aportan además de la fuente de carbono micronutrientes necesarios para su desarrollo.

Ganoderma lucidum fungus has some biomass components with beneficial health properties. The knowledge about its nutritionals requirements for growing will favor its industrial production at lower cost. In this work, the effect of C/N ratio, the presence of different carbon, nitrogen and micronutrients sources, on fungal biomass production, were evaluated. Using glucose and peptone as carbon and nitrogen sources, respectively, an optimal C/N ratio of 16,7:1 was found, for which the maximal biomass production was 25 g/L. Replacing glucose by lactose or barley flour and peptone by yeast extract at the same C/N ratio, the biomass production was enhanced to 35 g/L. With barley flour in the culture medium, the presence of Mg and K salts and thiamine did not turn out into a major increase of biomass. The G. lucidum biomass production is promoted by C/N ratios in the culture medium nearly equivalent to that found in the fungus, as well as the presence of complex substrates as barley flour which, additionally, contributes with important micronutrients along with the carbon source.

Growth of the Ectomycorrhizal Fungus Pisolithus Microcarpus in different nutritional conditions

The most important plant species employed in reforestation programs depend on ectomycorrhizal fungi for their establishment and growth. The exploitation of this symbiosis to improve forest productivity requires fungal inoculants in a large scale level. To develop such a technology it is necessary to define the optimal composition of the culture medium for each fungus. With these objectives in mind, the effect of the composition of the culture medium on biomass production of the ectomycorrhizal fungus Pisolithus microcarpus (isolate UFSC-Pt116) was studied. The original composition of two culture media, already employed for cultivation of ectomycorrhizal fungi, was submitted to several variations with the C/N ratio as the main variable. A variation of the Pridham-Gottlieb medium was the most efficient for the production of biomass. Therefore, it was submitted to a factorial assay where glucose, peptone and yeast extract components were the factors analyzed. Results showed that the glucose concentration may be increased up to 40 percent in order to promote higher biomass production. Peptone had a positive effect on this variable, whereas yeast extract promoted a deleterious effect. These results indicate that it is advisable to eliminate yeast extract from the medium and replace it with peptone prior to use.

Growth of the Ectomycorrhizal Fungus Pisolithus Microcarpus in different nutritional conditions

The most important plant species employed in reforestation programs depend on ectomycorrhizal fungi for their establishment and growth. The exploitation of this symbiosis to improve forest productivity requires fungal inoculants in a large scale level. To develop such a technology it is necessary to define the optimal composition of the culture medium for each fungus. With these objectives in mind, the effect of the composition of the culture medium on biomass production of the ectomycorrhizal fungus Pisolithus microcarpus (isolate UFSC-Pt116) was studied. The original composition of two culture media, already employed for cultivation of ectomycorrhizal fungi, was submitted to several variations with the C/N ratio as the main variable. A variation of the Pridham-Gottlieb medium was the most efficient for the production of biomass. Therefore, it was submitted to a factorial assay where glucose, peptone and yeast extract components were the factors analyzed. Results showed that the glucose concentration may be increased up to 40 % in order to promote higher biomass production. Peptone had a positive effect on this variable, whereas yeast extract promoted a deleterious effect. These results indicate that it is advisable to eliminate yeast extract from the medium and replace it with peptone prior to use.

Effect of molasses addition on carbon/nitrogen ratio in the nursery phase of Litopenaeus vannamei shrimp culture - DOI: 10.4025/actascibiolsci.v31i4.4496 / Efeito da adição do melaço na relação carbono/nitrogênio no cultivo de camarão Litopenaeus vannamei na fase berçário - DOI: 10.4025/actascibiolsci.v31i4.4496

The effect of molasses addiction on carbon:nitrogen ratios (C:N) on the performance of Litopenaeus vannamei shrimp during the nursery phase cultured without water exchange was investigated. The C:N ratios were evaluated in 25:1 (25M) and 15:1 (15M) proportion and a control (0M), with no carbon source addition, in a randomized experimental design with four replicates. Post-larvae (PL) with initial weight of 2.5 ± 0.5 mg were stocked in 12 tanks (800 L net volume), at the density of 6.25 PL L-1 during 42 culture days. At the end of culture, the shrimps weights on 25M (532.0 mg) and 15M (540.0 mg) treatments were higher (p 0.05) than the 0M (428.6 mg) treatment. Shrimp survival was high in all treatments (77.9 to 90.0%), but without significant difference (p 0.05). Therefore, the 15 and 25:1 C:N ratios showed an increased growth performance of nursery phase L. vannamei post-larvae cultured without water exchange.

Investigou-se o efeito da adição do melaço nas relações carbono:nitrogênio (C:N) sobre o desempenho zootécnico do camarão Litopenaeus vannamei, na fase berçário, quando cultivado sem renovação de água. As relações do C:N foram avaliadas nas proporções de 25:1 (25M), 15:1 (15M) e o controle (0M), sem aplicação de carbono, em delineamento experimental inteiramente casualizado, com quatro repetições. Pós-larvas (PL) com peso inicial de 2,5 ± 0,5 mg, foram estocadas em 12 tanques (800 L volume útil), em densidades de 6,25 PL L-1, durante 42 dias de cultivo. Ao final do cultivo, os pesos finais dos camarões dos tratamentos 25M (532,0 mg) e 15M (540,0 mg) foram superiores (p 0,05) aos do tratamento 0M (428,6 mg). A sobrevivência dos camarões foi satisfatória em todos os tratamentos (77,9 a 90,0%), mas não houve diferença significativa (p 0,05) entre os mesmos. Desta forma, conclui-se que as relações C:N de 15 e 25:1 são mais eficientes ao propiciarem melhor desempenho no crescimento das pós-larvas de L. vannamei cultivadas na fase berçário sem renovação de água

Optimation of the Fermentation Conditions for Human ApolipoproteinA-I Expression / 微生物学通报

Optimization of the fermentation condition for human apolipoproteinA-I expression in recombinant Escherichia coli was investigated. The recombinant plasmid pBV220-ApoA-I was transformed respectively into different E.coli hosts such as JM109, BL21(DE3),DH5?, BMH7118,and TG1. The best host E.coli was DH5? in which the recombinant ApoA-I expression percentage was 21.2% corresponding to that in BL21(DE3) in flask shaker cultivation,while the ApoA-I expressed percentage in E.coli TG1 was 11%.Fed-batch cultivation was performed in FMG-5L fermentor,the optimum fermentation cultivation conditions were as following :optimum pH value was 7.0 in growth phase and 7.4 in the expression phase. The initial glucose concentration in batch phase was 3 g?L -1.The optimum C/N ratio was 2∶1.The recombinant ApoA-I reached about 40% of the total protein, and concentration of ApoA-I was 2.86 g?L -1.