Feasibility study of biogas upgrading coupled with nutrient removal from anaerobic effluents using microalgae-based processes

Producción CientíficaThe present research was conducted to simultaneously optimize biogas upgrading and carbon and nutrient removal from centrates in a 180-L high-rate algal pond interconnected to an external CO2 absorption unit. Different biogas and centrate supply strategies were assessed to increase biomass lipid content. Results showed 99 % CO2 removal efficiencies from simulated biogas at liquid recirculation rates in the absorption column of 9.9 m3 m−2 h−1, concomitant with nitrogen and phosphorus removal efficiencies of 100 and 82 %, respectively, using a 1:70 diluted centrate at a hydraulic retention time of 7 days. The lipid content of the harvested algal–bacterial biomass remained low (2.9–11.2 %) regardless of the operational conditions, with no particular trend over time. The good settling characteristics of the algal–bacterial flocs resulted in harvesting efficiencies over 95 %, which represents a cost-effective alternative for algal biomass reutilization compared to conventional physical–chemical techniques. Finally, high microalgae biodiversity was found regardless of the operational conditions.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. (Project GR76, VA024U14, and RTA2013-00056-C03-02

High level of antibiotic production in a double polyphosphate kinase and phosphate-binding protein mutant of streptomyces lividans

Phosphate metabolism regulates most of the life processes of microorganisms. In the present work we obtained and studied a Streptomyces lividans ppk/pstS double mutant, which lacks polyphosphate kinase (PPK) and the high-affinity phosphate-binding protein (PstS), impairing at the same time the intracellular storage of polyphosphate and the intake of new inorganic phosphate from a phosphate-limited medium, respectively. In some of the aspects analyzed, the ppk/pstS double mutant was more similar to the wt strain than was the single pstS mutant. The double mutant was thus able to grow in phosphate-limited media, whereas the pstS mutant required the addition of 1 mM phosphate under the assay conditions used. The double mutant was able to incorporate more than one fourth of the inorganic phosphate incorporated by the wt strain, whereas phosphate incorporation was almost completely impaired in the pstS mutant. Noteworthy, under phosphate limitation conditions, the double ppk/pstS mutant showed a higher production of the endogenous antibiotic actinorhodin and the heterologous antitumor 8-demethyl-tetracenomycin (up to 10-fold with respect to the wt strain), opening new possibilities for the use of this strain in the heterologous expression of antibiotic pathways. © 2013 Federation of European Microbiological Societies.This work has been supported by grants BFU2006-13668 and EUI2008-03631 to R. I. Santamaría from the Ministerio de Educación y Ciencia. The IBFG acknowledges the institutional support of the Ramón Areces Foundation during 2011–2012.Peer Reviewe

Galacto-oligosaccharides derived from lactulose protects against colorectal cancer development in a animal model

Resumen del trabajo presentado al IX Workshop on Probiotics, Prebiotics of the Spanish Society of Probiotics and Prebiotics (Sociedad Española de Probióticos y Prebióticos, SEPyP), celebrado en Zaragoza (España) del 15 al 16 de febrero de 2018.[Introduction] Colorectal cancer has become one of the leading causes of cancer-related mortality worldwide; consequently, much attention has been focused on preventive and therapeutic strategies. In this sense, prebiotics have been reported as potential anti-inflammatory and anti-carcinogenic agents within the gastrointestinal tract. In this work, we have investigated the protective effect of novel galacto-oligosacharides derived from lactulose (GOS-Lu). These prebiotics have shown strong bifidogenic properties in vivo (Clemente et al., 2011; Hernández-Hernández et al., 2012).[Objectives] GOS-Lu has been tested here as potential antitumor preventive prebiotic, in a rat model developed with azoxymethane (AOM) as chemical inducer of colorectal cancer.[Methods] Male Fisher 344 rats were randomly assigned to two groups (n=10 per group, including 2 rats lacking colorectal cancer AOM induction): one cohort (negative control) with drinking water, and experimental cohort with 10% GOS-Lu (w/v) added to drinking water. Eight animals in each cohort received two doses of AOM (10 mg/kg) plus two treatments with DSS (3% and 2%). After 17 weeks, animals were sacrificed and colon tissues analyzed for number of tumors and tumor mucosa affected area.[Results] Anatomical studies showed that caecum weight was enlarged a 35.2% on average (p<0.05) in experimental animals fed GOS-Lu. The number of colon tumors was decreased 57.5% on average (p<0.05) in prebiotic-fed animals. In addition, the tumor affected area in colon mucosa was reduced a 50.5% on average (p<0.05) in animals drinking GOS-Lu in water.[Conclusions] These findings suggest that inclusion of the prebiotic preparation GOS-Lu might contribute to the prevention of this important neoplasia.Peer reviewe

Optimization of texture measurements method: optimal grid parameter

Colorectal cancer (CRC) is one of the most common neoplasias worldwide, and its incidence is increasing. Consumption of prebiotics is a useful strategy in order to prevent this important disease. These nutraceutical compounds might exert protective biological functions as antitumors. In order to test the chemopreventive effect of GOS-Lu (galacto-oligosaccharides derived from lactulose) prebiotic preparation against this cancer, an animal model (Rattus norvegicus F344) was used. In this model, two doses of azoxymethane (10 mg/kg) and two treatments with dextran sodium sulfate (DSS) were administered to the animals. Animals were fed for 20 weeks, and either control drinking water or drinking water containing 10% (w/w) GOS-Lu prebiotic preparation was provided to them. Animals were sacrificed after those 20 weeks, and their digestive tract tissues were analyzed. The results revealed a statistically significant reduction in the number of colon tumors in the GOS-Lu cohort with respect to control animals. Metagenomics sequencing was used for studying colon microbiota populations, revealing significant reductions in populations of pro-inflammatory bacteria families and species, and significant increases in interesting beneficial populations, such as Bifidobacterium. Therefore, oral administration of the prebiotic GOS-Lu preparation may be an effective strategy for preventing CRC.This work was funded by the research project grants RTC-2014-1525 from MINECO (Spanish Ministry of Economy, Industry and Competitiveness), AGL2017-84614-C2-1-R from MINECO, and AGR2011-7626 from Junta de Andalucía (Spain).Peer Reviewe