Improved ethanol production from the slurry of pretreated brewers' spent grain through different co-fermentation strategies.

The aim of this work was to bioconvert all sugars in BSG into ethanol using a process scheme that includes the enzymatic hydrolysis of the whole slurry resulting from the pretreatment of BSG with phosphoric and sulfuric acid using previously optimised conditions, followed by the co-fermentation of the mixed sugars. More than 90% of the sugars in raw BSG were recovered in the pretreatment and the subsequent enzymatic hydrolysis of the whole slurry. The co-fermentation of the enzymatic hydrolysates with Escherichia coli was then compared with that the co-culture of Scheffersomyces stipitis and Saccharomyces cerevisiae, which resulted in lower ethanol production. The co-fermentation strategy with a single microorganism (E. coli) when BSG was pretreated with phosphoric acid resulted into the highest ethanol concentration, 39 g/L, which means that 222 L of ethanol can be obtained from a ton of BSG without detoxification requirements.

Biorefinery based on olive biomass. State of the art and future trends.

With currently more than nine million hectares, olive tree cultivation has spread worldwide, table olives and olive oil as the main products. Moreover, a number of by-products and residues derived from both tree cultivation and the process of industrial olive oil production, most having no practical applications, are obtained yearly. This paper reviews the research regarding these by-products, namely biomass from olive tree pruning, olive stones, olive pomace and wastewaters obtained from the process of olive oil production. Furthermore, a wide range of compounds has been identified and can be produced using a broad definition of the term biorefinery based on olive tree biomass. As an example, this paper reviews ethanol production as one of the main proposed applications, as well as research on other value-added products. Finally, this paper also assesses recent technological advances, future perspectives and challenges in each stage of the process.

Development of a process for the production of L-amino-acids concentrates from microalgae by enzymatic hydrolysis.

A process for the production of l-amino-acids concentrates from microalgae biomass by enzymatic hydrolysis has been developed. The process includes pre-treatment for cell-disruption, enzymatic hydrolysis and final separation by centrifugation. Thermal and mechanical cell-disruption methods have been tested, selecting mechanical disruption using bead milling for 30 min. The enzymatic hydrolysis was done using the commercial enzymes Alcalase and Flavourzyme. Maximum hydrolysis was obtained for biomass concentrations under 270 g/l and previous additional treatment with Viscozyme, reaching a 42% hydrolysis. Repeated reaction steps increased the hydrolysis from 42% (4h) with a single step to 59% (8h) after two successive steps. Further increase of the number of steps had a meagre impact on the global yield. The process widens the portfolio of products that can be obtained from microalgae biomass and is a new possibility to enhance the economic viability of microalgae-based biofuels production processes.

Biocatalytic synthesis of polypyrrole powder, colloids, and films using horseradish peroxidase.

Polypyrrole was synthesized in high yield by a biocatalytic method in mild aqueous media using hydrogen peroxide as oxidizer. A redox mediator, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) diammonium salt, was used to oxidize the pyrrole. ABTS is a very effective peroxidase substrate, which was enzymatically oxidized to generate a radical cation that in turn was able to chemically oxidize pyrrole. This indirect biocatalytic method was implemented because pyrrole is not a substrate of horseradish peroxidase, however, the polymerization process was successfully optimized and later adapted to prepare also polypyrrole thin films and water dispersible polypyrrole colloids. The polypyrrole powder and colloids were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, electrical conductivity, and thermogravimetric analysis. In addition, the deposition of the polypyrrole thin film was monitored using a quartz-crystal microbalance and its morphology studied by optical and scanning electron microscopy. The biocatalytic polymerization of pyrrole results in a polymer spectroscopically very similar to chemically synthesized polypyrrole.

Determination of phenol using an enhanced chemiluminescent assay.

Enhanced chemiluminescence (ECL) describes the phenomenon of increased light output in the luminol oxidation reaction catalysed by horseradish peroxidase (HRP) in the presence of certain compounds, such as para-iodophenol. In this work, the effects of phenol on the para-iodophenol-enhanced HRP-catalysed chemiluninescent reaction intensity in an aqueous buffer (Tris-HCl buffer, pH 8.5) and in a surfactant-water-octane mixture were compared. Preincubation of HRP at low phenol concentrations stimulated the chemiluminescent intensity in the assay performed in an aqueous buffer, but did not have significant effect in the sodium bis(2-ethylhexyl)sulphosuccinate) (Aerosol OT, AOT) applied system. It was also observed that HRP preincubation with phenol concentration higher than 0.003 mg/mL produced an inhibitory effect on the enzyme activity for both assay systems. Only an inhibitory effect of phenol on the chemiluminescent intensity in the surfactant system in octane (as organic solvent) was observed. Three assays were developed to determine phenol concentration in water and in an organic solvent mixture. The detection limits were 0.006, 0.003 and 0.0005 mg/mL, respectively, for the buffer-containing system, the AOT-applied system with phenol standard solutions in water and for the AOT-applied system with phenol standard solutions in octane.

[Acute respiratory failure secondary to Pneumocystis carinii pneumonia in children]. / Fracaso respiratorio agudo secundario a neumonía por Pneumocystis carinii en la infancia.

OBJECTIVE: The objective of this study was to ascertain the clinical and epidemiological characteristics of Pneumocystis carinii pneumonia (PCP) cases admitted to the Pediatric Intensive Care Unit (PICU). PATIENTS AND METHODS: A retrospective study was carried out on the 8 PCP cases admitted to the PICU from July 1991 to September 1994. The variables studied were: age, sex, geographic origin, associated pathology, immunological status, clinical manifestations, biochemical data, radiology, findings in bronchoalveolar lavage fluid (BAL), response to therapy and clinical follow-up. RESULTS: Age of the patients varied between 3 months and 9 years and there were 5 males and 3 females. Associated pathologies included AIDS (4 cases), severe combined immunodeficiency (SCID), Job's syndrome, and immunodeficiencies secondary to non-Hodgkin's lymphoma (NHL) and acute lymphoid leukemia (ALL), one case of each. Four cases appeared in a 22 day period. All cases but one suffered acute respiratory failure and needed mechanical ventilation. Diagnosis was established by means of BAL in every case. All cases showed a bilateral diffuse alveolo-interstitial pattern on chest films. Treatment was trimethoprim-sulfamethoxazole. In the acute illnesses, 2 patients died (cases of terminal SCID and NHL). CONCLUSIONS: To date, epidemic presentation of PCP has not been reported in our community. Four of our cases, with no demonstrable previous relation, appeared over a short period of time. We have not found a relationship between LDH levels and severity, as expressed by mechanical ventilation time. Every AIDS case survived the acute episode and CD4 counts were normal in most cases.