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This chapter critically reviews the potential of biogas, whose main constituent is methane (second most significant greenhouse gas), as a suitable carbon feedstock for the generation of polyhydroxyalkanoates (PHA). The capacity of synthesizing PHA (up to about 60% of their cell dry mass) from this source under nutrient-limiting conditions corresponds to type II methane-oxidizing bacteria, which belong to the α-proteobacteria phylum and assimilate C1 compounds via the serine pathway. The metabolism of methane oxidation and PHA accumulation is systematically described, along with the mechanisms of PHA used as an energy and carbon source by bacteria. In addition, the main operational limitations of this technology, namely, innovative bioreactors for biogas bioconversion and product recovery, are discussed. Finally, the techno-economic analysis of this approach reveals that the production costs of biogas-based PHA are competitive compared with conventional feedstocks used in industrial PHA production. In brief, the use of biogas constitutes an attractive and viable alternative for bioplastics production that might improve the economic sustainability of the anaerobic digestion, with widespread applicability in agro-industrial, livestock, and urban solid waste treatment facilities.

Producción Científica, Methane, with a global warming potential twenty five times higher than that of CO2 is the second most important greenhouse gas emitted nowadays. Its bioconversion into microbial molecules with a high retail value in the industry offers a potential cost-efficient and environmentally friendly solution for mitigating anthropogenic diluted CH4-laden streams. Methane bio-refinery for the production of different compounds such as ectoine, feed proteins, biofuels, bioplastics and polysaccharides, apart from new bioproducts characteristic of methanotrophic bacteria, has been recently tested in discontinuous and continuous bioreactors with promising results. This review constitutes a critical discussion about the state-of-the-art of the potential and research niches of biotechnologies applied in a CH4 biorefinery approach., 2019-12-12, Ministerio de Economía, Industria y Competitividad (Proyect CTM2015-70442-R), Junta de Castilla y León (UIC71)

Methane, a near-term climate forcer exhibiting a global warming capacity 90-fold higher compared to carbon dioxide on a 10-year horizon, is the second most prevalent greenhouse gas (GHG) within the global GHG inventory. Both physical/chemical and biological technologies are available for the treatment of CH4 emissions, the later also allowing for the production of high-added value products such as polyhydroxyalkanoates (PHAs) at significantly lower raw material costs. Among CH4 biotechnologies, turbulent contactors such as stirred tank reactors or bubble column bioreactors have been the most employed for the methanotrophic production of PHAs under nutrient-limited conditions. However, the moderate biomass productivities achieved at the expense of high energy consumption in these systems has headed the most recent research towards the development of new bioreactor configurations and the implementation of strategies to enhance CH4 mass transfer, such as the internal gas recycling or the use of non-aqueous phases. Also, the specificity of type II methanotrophs to accumulate these bioproducts, mainly as poly-3-hydroxybutyrate (PHB), has stimulated the development of novel enrichment procedures based on modifications in the nitrogen source and concentration, the oxygen content, the pH and the composition of micronutrients (e.g. Cu2+) to effectively select this type of methanotrophs. Finally, current research is focused on the use of co-substrates during methanotrophic cultivation to increase PHA yields and modify the composition of the biocomposite, thus enhancing the thermal and mechanical properties of the product and boosting its widespread production at industrial-scale.

Producción Científica, The valorization of biogas as a feedstock for the generation of added-value bioproducts will play a key role on the sustainability of anaerobic digestion. The present work assessed the influence of key environmental parameters (O2:CH4 ratio, temperature and nitrogen source) on the growth and polyhydroxybutyrate (PHB) synthesis under nitrogen limiting conditions of the type II methanotroph Methylocystis hirsuta CSC1 using biogas as a feedstock. The O2:CH4 ratios tested (1:1, 1.5:1 and 2:1) did not affect significantly M. hirsuta CSC1 growth yields (~5 g TSS mol−1 CH4), although lower CH4 removal rates were reached under O2-limiting conditions (ratio 1:1). The highest PHB content (45 wt%) was achieved at a ratio 2:1 and was threefold higher than those obtained at lower ratios (~15 wt%). The increase in temperature from 15 to 25 °C resulted in increases in the growth yield (from 5 to 6 g TSS mol−1 CH4) and PHB content (from 32 to 40 wt%). Conversely, the lowest PHB content (30 wt%) was reached at 37 °C, together with a negligible growth under nutrient sufficient conditions. The nitrogen source also played a key role on both M. hirsuta CSC1 growth and PHB synthesis. Thus, ammonium resulted in the highest growth yield (7 g TSS mol−1 CH4), although the maximum PHB content was achieved when biomass was previously grown in nitrate as the nitrogen source (41 wt%). Nitrite exerted an inhibitory effect on M. hirsuta CSC1 growth., Ministerio de Economía y Competitividad (BES-2016-077160) y (proyecto CTM2015-70442-R), Junta de Castilla y León y EU-FEDER (CLU 2017-09), (VA281P18) y (UIC 071)

CIGB-247 is a cancer vaccine that is a formulation of a recombinant protein antigen representative of the human vascular endothelial growth factor (VEGF) with a bacterially-derived adjuvant (VSSP). The vaccine has shown an excellent safety profile in mice, rats, rabbits, not-human primates and in recent clinical trials in cancer patients. Response to the vaccine is characterized by specific antibody titers that neutralize VEGF/VEGFR2 binding and a cytotoxic tumor-specific response. To expand our present anti-VEGF active immunotherapy strategies, we have now studied in mice and non-human primates the effects of vaccination with a formulation of our recombinant VEGF antigen and aluminum phosphate adjuvant (hereafter denominated CIGB-247-A). Administered bi-weekly, CIGB-247-A produces high titers of anti-VEGF IgG blocking antibodies in 2 mice strains. Particularly in BALB/c, the treatment impaired subcutaneous F3II mammary tumor growth and reduced the number of spontaneous lung macro metastases, increasing animals' survival. Spleen cells from specifically immunized mice directly killed F3II tumor cells in vitro. CIGB-247-A also showed to be immunogenic in non-human primates, which developed anti-VEGF blocking antibodies and the ability for specific direct cell cytotoxic responses, all without impairing the healing of deep skin wounds or other side effect. Our results support consideration of aluminum phosphate as a suitable adjuvant for the development of new vaccine formulations using VEGF as antigen.

The determination of polyvinylalcohol (PVA) by the formation of the blue iodine–PVA complex method was established for a semi-micro method scale. The direct addition of iodine solution proved to be a better iodine source than iodine generated in situ. The ageing of reagents requires frequent calibrations. Common biopolymers such as starch, albumin and cellulose produced much lower colour intensity with reagents and their impact on the analysis is negligible. The method is not affected by paper filter filtration. The detection of PVA was successfully tested in different wastewater types and the method proved to be a powerful tool for PVA detection. It must be emphasised that quantification of PVA is strongly dependent on the PVA type and the quantification capacity; without information of the PVA structure or type is only tentative.

Some organic contaminants can accumulate in organisms and cause irreversible damages in biological systems through direct or indirect toxic effects. In this study the feasibility of the electrokinetic (EK) process for the remediation of 17β-oestradiol (E2), 17α-ethinyloestradiol (EE2), bisphenol A (BPA), nonylphenol (NP), octylphenol (OP) and triclosan (TCS) in soils was studied in a stationary laboratory cell. The experiments were conducted using a silty loam soil (S2) at 0, 10 and 20 mA and a sandy soil (S3) at 0 and 10 mA. A pH control in the anolyte reservoir (pH > 13) at 10 mA was carried out using S2, too. Photo and electrodegradation experiments were also fulfilled. Results showed that EK is a viable method for the remediation of these contaminants, both through mobilization by electroosmotic flow (EOF) and electrodegradation. As EOF is very sensible to soil pH, the control in the anolyte increased EOF rate, consequently enhancing contaminants mobilization towards the cathode end. The extent of the mobilization towards the electrode end was mainly dependent on compounds solubility and octanol-water partition coefficient. In the last 24 h of experiments, BPA presented the highest mobilization rate (ca. 4 μg min−1) with NP not being detected in the catholyte. At the end of all experiments the percentage of contaminants that remained in the soil ranged between 17 and 50 for S2, and between 27 and 48 for S3, with no statistical differences between treatments. The mass balance performed showed that the amount of contaminant not detected in the cell is similar to the quantity that potentially may suffer photo and electrodegradation.