Differential photosynthetic plasticity of Amazonian tree species in response to light environments.

To investigate how and to what extent there are differences in the photosynthetic plasticity of trees in response to different light environments, six species from three successional groups (late successional, mid-successional, and pioneers) were exposed to three different light environments [deep shade - DS (5% full sunlight - FS), moderate shade - MS (35% FS) and full sunlight - FS]. Maximum net photosynthesis (Amax), leaf N partitioning, stomatal, mesophile, and biochemical limitations (SL, ML, and BL, respectively), carboxylation velocity (Vcmax), and electron transport (Jmax) rates, and the state of photosynthetic induction (IS) were evaluated. Higher values of Amax, Vcmax, and Jmax in FS were observed for pioneer species, which invested the largest amount of leaf N in Rubisco. The lower IS for pioneer species reveals its reduced ability to take advantage of sunflecks. In general, the main photosynthetic limitations are diffusive, with SL and ML having equal importance under FS, and ML decreasing along with irradiance. The leaf traits, which are more determinant of the photosynthetic process, respond independently in relation to the successional group, especially with low light availability. An effective partitioning of leaf N between photosynthetic and structural components played a crucial role in the acclimation process and determined the increase or decrease of photosynthesis in response to the light conditions.

Production of arachidonic acid by Mortierella alpina using wastes from potato chips industry.

AIMS: This research aimed to determine the potential use of wastes from the potato chips industry as a carbon source to develop an economical culture medium for the production of biomass, lipids and arachidonic acid (ARA) by Mortierella alpina. METHODS AND RESULTS: A synthetic culture medium was optimized using a Plackett-Burman and central composite rotatable design, and used as a base to evaluate and characterize the potential use of wastes from the potato chips industry as carbon sources for the production of biomass, lipids and ARA by M. alpina. The waste was selected among other solid and liquid hydrolysed residues/by-products, and local low-cost alternatives for nitrogen sources were also evaluated. After 6 days of fermentation, the biomass concentration reached 20 g l-1 with 40% of total lipids, and a 35% ARA content in the lipids fraction. Savings in production were calculated using a sensitivity analysis for the alternative culture medium in different scenarios. CONCLUSIONS: This study showed a 7% savings in culture media expenses in the production of ARA-enriched biomass of M. alpina, compared to the conventional synthetic culture medium, when waste from the potato chips industry was used as an alternative source of carbon and macro/microelements, supplemented with a low-cost yeast extract alternative. SIGNIFICANCE AND IMPACT OF THE STUDY: The demonstration of the use of potato chips wastes as a low-cost carbon source for the biomass, lipids and ARA production, suggesting an eco-friendly alternative for the use of agri-food wastes for valuable metabolites production.

Influence of airflow intensity on phytase production by solid-state fermentation.

Phytase production by Aspergillus niger F3 by solid state fermentation (SSF) on citrus peel was evaluated at pilot scale under different aeration conditions. The best airflow intensity was 1 VkgM (Lair kg medium(-1) min(-1)), which allowed to produce 65 units of phytases per gram in dry basis (65 Ug(-1) d.b.) as it removed the metabolic heat generated by the microorganism, Agitation did not improve heat removal. Airflow intensity was considered as scale-up criterion. When the airflow intensity was maintained at 1 VkgM for SSF with 2 and 20 kg of medium, the kinetics parameters for biomass and enzyme concentration at the end of fermentation differed by less than 2. The air flow intensity was required to maintain the temperature and cool the SSF and to provide oxygen for microbial growth. Air flow intensity is a key a factor that must be considered when scale-up of SSF is attempted.

Arthrospira platensis biomass with high protein content cultivated in continuous process using urea as nitrogen source.

AIMS: Arthrospira platensis has been studied for single-cell protein production because of its biomass composition and its ability of growing in alternative media. This work evaluated the effects of different dilution rates (D) and urea concentrations (N(0)) on A. platensis continuous culture, in terms of growth, kinetic parameters, biomass composition and nitrogen removal. METHODS AND RESULTS: Arthrospira platensis was continuously cultivated in a glass-made vertical column photobioreactor agitated with Rushton turbines. There were used different dilution rates (0·04-0·44 day(-1)) and urea concentrations (0·5 and 5 mmol l(-1)). With N(0) = 5 mmol l(-1), the maximum steady-state biomass concentration was 1415 mg l(-1), achieved with D = 0·04 day(-1), but the highest protein content (71·9%) was obtained by applying D = 0·12 day(-1), attaining a protein productivity of 106·41 mg l(-1) day(-1). Nitrogen removal reached 99% on steady-state conditions. CONCLUSIONS: The best results were achieved by applying N(0) = 5 mmol l(-1); however, urea led to inhibitory conditions at D ≥ 0·16 day(-1), inducing the system wash-out. The agitation afforded satisfactory mixture and did not harm the trichomes structure. SIGNIFICANCE AND IMPACT OF THE STUDY: These results can enhance the basis for the continuous removal of nitrogenous wastewater pollutants using cyanobacteria, with an easily assembled photobioreactor.

The behavior of kinetic parameters in production of pectinase and xylanase by solid-state fermentation.

Solid-state fermentation (SSF) is defined as the growth of microbes without a free-flowing aqueous phase. The feasibility of using a citrus peel for producing pectinase and xylanase via the SSF process by Aspergillus niger F3 was evaluated in a 2 kg bioreactor. Different aeration conditions were tested to optimize the pectinase and xylanase production. The best air flow intensity was 1 V kg M (volumetric air flow per kilogram of medium), which allowed a sufficient amount of O2 for the microorganism growth producing 265 U/g and 65 U/g pectinases and xylanases, respectively. A mathematical model was applied to determine the different kinetic parameters related to SSF. The specific growth rate and biomass oxygen yield decreased during fermentation, whereas an increase in the maintenance coefficient for the different employed carbon sources was concurrently observed.

Lymphoma of unknown origin located in paravertebral muscles: an unusual cause of low back pain in children.

The authors report a case of an adolescent with a poorly differentiated lymphoma of unknown origin located at paravertebral muscles, whose presently symptom was low back pain.

Calcified mucinous adenocarcinoma of the stomach.

Two cases of unusual mucinous adenocarcinomas of the stomach with calcification are reported. One of the cases demonstrated hypercalcemia. Endoscopic verification of the calcifications was confirmed. This report represents the 49th and 50th reported cases in the world's literature.