Fraunhofer Chile Research Foundation

Abstract. Natural gas is widely used for household cooking, with methane (CH4), its main component, being a potent short-lived greenhouse gas (GHG). While often seen as a cleaner alternative, natural gas combustion and leaks contribute to GHG emissions and indoor air pollution. Yet, fugitive methane emissions from residential appliances, especially cookstoves, are poorly quantified in low- and middle-income countries. In this study, we measured CH4, carbon dioxide (CO2), carbon monoxide (CO), and nitrogen oxides (NOx) emissions from cookstoves in 35 homes in Santiago, Chile, and 23 in Bogotá, Colombia, two countries experiencing rapid growth in natural gas use. We assessed continuous methane leaks, ignition-related emissions, and combustion emissions, using a mass balance approach that accounts for air exchange rates and gas concentrations. Our real-world measurements provide rare data on household cookstove emissions and inform emission factors used in GHG inventories. We found that methane emissions from residential stoves in Bogotá and Santiago are over six times higher than the Tier 1 IPCC emission factors currently used in national inventories. Notably, continuous leaks and ignition-related emissions, which are excluded from official estimates, contribute significantly to total methane emissions. These findings suggest that national inventories in Chile and Colombia underestimate methane emissions from household gas use, highlighting the need for more real-world measurements and research across Latin America. Our results have important implications for improving the accuracy of GHG inventories, understanding the role of household energy use in climate change, and guiding effective mitigation strategies.

In recent years, the cultivated area of hazelnuts in Chile has increased significantly. Along with this rapid expansion, biotic constraints that affect the optimal development of the crop have been identified. Among these, bacterial blight disease caused by Xanthomonas arboricola pv. corylina has been particularly relevant. This pathogen has a global distribution and is present in all hazelnut-producing countries. In the spring of 2023, hazelnut orchards were sampled from the Maule to Biobío Regions of Chile. The Chilean isolates recovered from hazelnut tissues showing symptoms of bacterial blight were characterized by their ability to grow on different semi-selective media, their carbohydrate utilization profiles, hypersensitivity response in tobacco plants, and biochemical tests. Additionally, the isolates were identified based on the 16S rRNA gene and multilocus sequence analysis (MLSA) on the rpoD, gyrB, and atpD genes. The results showed that the X. arboricola pv. corylina Chilean isolates differed from previously reported isolates in other geographic areas as they are capable of metabolizing sorbitol and mannitol. Using MLSA and average nucleotide identity (ANI) comparison, these isolates were grouped into four and five phylogenetic clades, respectively, representing a significant difference from what has been reported in similar international studies.

This study investigates the technical and economic impacts of self-dispatch strategies on Concentrated Solar Power (CSP) plants in Chile’s spot electricity market. The PySAM simulation tool was used to model three dispatch scenarios—Marginal Cost-Responsive Dispatch, Daytime Mandated Dispatch, and Continuous Base Load Dispatch—to assess their effects on energy production, load factors, and financial outcomes at the Crucero and Cardones substations. The findings indicate that the Marginal Cost-Responsive Dispatch strategy optimizes revenue by aligning energy generation with periods of higher market prices. This strategy mitigates the adverse financial impacts of zero-marginal-cost periods, which undermine the viability of more rigid approaches like Daytime Mandated Dispatch. Economic analysis shows that only the Marginal Cost-Responsive Dispatch consistently covers annualized capital expenditures (CAPEX), particularly at lower CAPEX levels. In contrast, the alternative scenarios fail to achieve financial sustainability due to forced generation during low-value periods. Consequently, these results underscore the crucial role of dispatch flexibility in enhancing the economic performance of CSP plants. The study suggests that market regulations should be revised to encourage strategies that enable CSP plants to dynamically respond to market conditions, supporting the broader integration of CSP technology into Chile’s energy market. Such adjustments are crucial for advancing the country’s decarbonization goals. Future research should focus on further developing advanced self-dispatch algorithms and hybrid CSP systems to optimize economic outcomes in increasingly dynamic market environments.

Although numerous studies have demonstrated a positive relationship between biodiversity and ecosystem stability, that is low temporal variability in ecosystem functions, the role of interspecific interactions in driving this relationship remains elusive. Here we develop a partitioning framework to disentangle the effects of interspecific interactions on ecosystem variability from those of interaction-independent processes. Applying this framework to competition models and biodiversity experiments in European and North American grasslands, we find that species-specific dynamics observable in monocultures (for example, environmental responses or demographic stochasticity), rather than interspecific interactions observable only in mixtures, explain much of the stabilizing effects of biodiversity on ecosystems. The weak net effect of interspecific interactions results from two counter-balancing effects: an interaction-driven increase in average species variability and an interaction-driven decrease in average species synchrony. We also find that interspecific interactions contributing to higher ecosystem functioning tend to reduce ecosystem variability. Our study provides a systematic empirical assessment of the role of interspecific interactions in shaping grassland ecosystem stability, challenging traditional assumptions about their importance and highlighting species-specific dynamics as the primary mechanism underlying the pervasive biodiversity-stability relationship.

Background Xylan, the second most abundant polysaccharide in plant biomass, requires endoxylanases for its hydrolysis into xylooligosaccharides (XOS). Xylanases have been widely used in industries such as animal feed, bakery, juice production, and paper pulp. Recently, XOS have gained attention for their health benefits, including improved digestion, reduced cholesterol, and antioxidant effects. The cold-adapted GH10 xylanase of Antarctic origin Xyl-L was previously expressed in Escherichia coli, showing promising low-temperature activity. However, Pichia pastoris is currently a preferred host for industrial xylanase production due to its ability to express complex proteins and secrete them into the culture medium. This study explored the expression of Xyl-L in P. pastoris and evaluated its potential for XOS production using common flours as substrates, aiming for applications in the food and nutraceutical industry. Results Comparison between AOX1 (PAOX1) and GAP (PGAP) promoters for recombinant Xyl-L production in P. pastoris showed that the PAOX1 promoter resulted in higher activity per wet-cell weight. Co-transforming PAOX1-Xyl strains with plasmids encoding genes aiding in protein folding (HAC1 or PDI1) did not enhance Xyl-L catalytic activity compared to the parental PAOX1 strain. Thus, PAOX1-Xyl was cultivated in 3 L bioreactors in fed-batch cultures; it is presumed that the enzyme is produced with glycosylations within its structure, given its migration within the SDS-PAGE gels. The produced Xyl-L was purified from the culture supernatant, resulting in peak xylanase activity after 90 h, with specific activity of 5.10 ± 0.21 U/mg, at pH 7.5 and 25∘C, using beechwood xylan. It also showed a Km of 3.5 mg/mL and a kcat of 9.16 s-1. Xyl-L maintained over 80% of relative activity between pH 5.6-8.6 and 37-44∘ C, and was activated by CaCl2 and MgCl2, but inhibited by MnCl2. Xyl-L was tested using several flours (whole wheat, rye, oatmeal and all-purpose) as substrates, where XOS with a polymerization degree (DP) of 2 were obtained from each substrate, whole wheat flour generated XOS with DP 3, and XOS with DP 2, 3 and 4 were produced when beechwood xylan was used as substrate.Conclusions The xylanase Xyl-L was successfully expressed in P. pastoris and proved to be able to degrade various flour substrates, producing XOS with DP ranging from 2 to 4, indicating its potential applications in the nutraceutical and food industries. Further studies must be performed to optimize its production in bioreactors.