Josefa Rodríguez

Solubilisation and mineralisation of [14C]lignocellulose from wheat straw by Streptomyces cyaneus CECT 3335 during growth in solid-state fermentation

Abstract Nine Streptomyces strains were screened for their ability to solubilise and mineralise 14C-labelled lignin during growth in solid-state fermentation. Streptomyces viridosporus was confirmed as an active lignin-degrading organism along with a new isolate, Streptomyces sp. UAH 15, further classified as Streptomyces cyaneus CECT 3335. This organism was able to solubilise and mineralise the [14C]lignin fraction of lignocellulose (44.96 ± 1.77% and 3.41 ± 0.48% respectively) after 21 days of incubation. Cell-free filtrates from Streptomyces sp. grown in solid-state fermentation were capable of solubilising up to 20% of the [14C]lignin after 2 days incubation, with most of the product detected in the acid-soluble rather than in the water-soluble fraction. Identification of the extracellular enzymes produced during growth of S. cyaneus CECT 3335 revealed that extracellular peroxidase and phenol oxidase activities were present, with the activity of phenol oxidase being 100 times greater than peroxidase activity. The activity of these two enzymes was found to correlate with both solubilisation and mineralisation rates. This is the first report of phenol oxidase activity produced by a Streptomyces strain during growth in solid-state fermentation. A role for the enzyme in the solubilisation and mineralisation of lignocellulose by S. cyaneus is suggested.

Application of the affinity binding of xylanases to oat-spelt xylan in the purification of endoxylanase CM-2 from Streptomyces chattanoogensis CECT 3336

bstract The use of the insoluble polysaccharides Avicel and oat-spelt xylan for the binding and subsequent purification of active xylanases from Streptomyces chattanoogensis was investigated. Maximum recovery of xylanases was achieved with oat-spelt xylan, using NaCl (2 M) to remove active protein. The application of this technique to the purification of xylanases resulted in the purification of an endoxylanase (CM-2) with high specific activity (729.5 U mg−1). The properties of the purified enzyme, exhibiting activity and stability between 40 °C and 60 °C and between pH 5 and 8, suggest a potential role for both the enzyme and the rapid purification protocol in the removal of hemicelluloses from kraft pulp prior to bleaching.

Production and characterization of ferulic acid esterase activity in crude extracts by Streptomyces avermitilis CECT 3339

Streptomyces avermitilis CECT 3339 produces extracellular ferulic acid esterase (FAE) activity during growth on a range of lignocellulose substrates. Maximal levels of FAE activity were detected in culture filtrates from S. avermitilis CECT 3339 grown in media containing wheat bran and yeast extract as carbon and nitrogen sources respectively. Biochemical characterization of this enzyme activity revealed that it was 100-fold higher when wheat bran was pretreated with Celluclast (a mix of hydrolytic enzymes). FAE was found to be end-product-inhibited. Characterization of the properties of the enzyme showed that FAE exhibited an activity optimum pH at 6 with pH stability between pH 6 and 8. The optimum temperature was 50 °C while the temperature stability was between 30 °C and 40 °C, with rapid inactivation at 60 °C and above. The characteristics and stability of FAE from S. avermitilis CECT 3339 suggest a potential role for this enzyme in combination with endoxylanases for the upgrading of plant-residue silage and for biopulping.

Screening of mannanases in actinomycetes and their potential application in the biobleaching of pine kraft pulps

Abstract Fifty actinomycete strains were screened for the production of mannanase activity during growth in both liquid and solid media. Streptomyces scabies CECT 3340 and Streptomyces ipomoea CECT 3341 were selected for their ability to produce high levels of mannanase (294.3 U/l and 242.9 U/l, respectively) during growth in liquid culture. β-Mannosidase (15.3 U/l) and α-galactosidase (7.7 U/l) activities were also detected in culture filtrate from S. scabies CECT 3340. Highest levels of mannanase activity for S. scabies CECT 3340 were achieved in media containing locust bean gum and asparagine (4.8 U mg−1 protein) whilst in S. ipomoea CECT 3341 greatest activity was detected in media containing locust bean gum and yeast extract (13.2 U mg−1 protein). No carboxymethylcellulase activity was detected. In biobleaching experiments, enzyme treatment, carried out with mannanase activity produced by S. ipomoea CECT 3341, followed by alkaline extraction of pine kraft pulp resulted in the release of colour (A465, 0.69) and chromophoric material from the pulp (A237, 12.9; A254, 6.9 and A280, 6.7). The ability of this enzyme complex to improve the bleaching of pine kraft pulps was also shown by a pulp brightness increase (2.4 units ISO) and a reduction in kappa number (from 21.4 units to 20.1 units) with the absence of variations on the viscosity values.

Purification and properties of a chitinase from Penicillium oxalicum autolysates

A chitinase (EC. 3.2.1.14) from autolysed culture filtrate of Penicillium oxalicum was purified by precipitation with ammonium sulphate, gel filtration and ion exchange chromatographies. The purified enzyme showed a single protein band in SDS gel electrophoresis. The enzyme is an acidic protein with a pI of 4.5 and has a molecular weight of 54 900 as estimated from SDS gel electrophoresis and 21 500 from gel filtration. The optimum pH and temperature were 5.0 and 35°C, respectively. The enzyme was stable at temperatures up to 45°C and in a pH range between 4.0 and 6.0. The Km was 2.5 mg ml‐1 for colloidal chitin, Hg2+ and Ag+ were effective inhibitors. The viscosimetric study carried out using carboxymethyl chitin as substrate revealed the endotype action of this enzyme.

Short communication: Effect of water activity on cell growth and phenol oxidase production by Streptomyces cyaneus var. viridochromogenes in surface culture

In surface cultures of Streptomyces cyaneus var. viridochromogenes, NaCl depressed water activity (aw) without supporting growth. Reducing aw from 0.987 to 0.951 led to 3- and 4-fold increases in intracellular and extracellular phenol oxidase activities, respectively.

Laser beam welding quality monitoring system based in high-speed (10 kHz) uncooled MWIR imaging sensors

The combination of flexibility, productivity, precision and zero-defect manufacturing in future laser-based equipment are a major challenge that faces this enabling technology. New sensors for online monitoring and real-time control of laserbased processes are necessary for improving products quality and increasing manufacture yields. New approaches to fully automate processes towards zero-defect manufacturing demand smarter heads where lasers, optics, actuators, sensors and electronics will be integrated in a unique compact and affordable device. Many defects arising in laser-based manufacturing processes come from instabilities in the dynamics of the laser process. Temperature and heat dynamics are key parameters to be monitored. Low cost infrared imagers with high-speed of response will constitute the next generation of sensors to be implemented in future monitoring and control systems for laser-based processes, capable to provide simultaneous information about heat dynamics and spatial distribution. This work describes the result of using an innovative low-cost high-speed infrared imager based on the first quantum infrared imager monolithically integrated with Si-CMOS ROIC of the market. The sensor is able to provide low resolution images at frame rates up to 10 KHz in uncooled operation at the same cost as traditional infrared spot detectors. In order to demonstrate the capabilities of the new sensor technology, a low-cost camera was assembled on a standard production laser welding head, allowing to register melting pool images at frame rates of 10 kHz. In addition, a specific software was developed for defect detection and classification. Multiple laser welding processes were recorded with the aim to study the performance of the system and its application to the real-time monitoring of laser welding processes. During the experiments, different types of defects were produced and monitored. The classifier was fed with the experimental images obtained. Self-learning strategies were implemented with very promising results, demonstrating the feasibility of using low-cost high-speed infrared imagers in advancing towards a real-time / in-line zero-defect production systems.

In-hospital capacity-building in research and management for pediatric professionals

We describe an educational strategy aimed at capacity-building of hospital health care professionals in research and management initiated at a pediatric hospital in 2006, and the results obtained eight years after its implementation. Research and Management in Pediatrics (GIP) is an annual 250-hour course combining meetings and off-site assignments delivered through the Hospitals on-line campus. It provides students with practical tools for research (epidemiology, methodology, bibliographic search, evidencebased medicine, biostatistics) and management (strategic planning, management programs, health services research, quality improvement, health economics). Assessment methods included integrative exercises, a final evaluation, and a group research or management project. Results obtained over the 2006-2013 period were highly satisfactory. An intensive training program on research and management is a useful strategy for in-hospital capacity-building of pediatric health care professionals in basic tools for research activities, critical reading of biomedical literature and rational management of pediatric health services.