Franchi, O., Alvarez, M. I., Pavissich, J. P., Belmonte, M., Pedrouso, A., del Rio, A. V., et al. (2024). Operational variables and microbial community dynamics affect granulation stability in continuous flow aerobic granular sludge reactors. J. Water Process Eng., 59, 104951.
Abstract: Retrofitting wastewater treatment plants with continuous aerobic granular sludge reactors is a promising alternative to enhance treatment capacities and reduce footprint. This study investigates the main variables influencing granulation and microbial dynamics in two reactor configurations (25 L): stirred tanks in series (R1) and a plug-flow-like system (R2). Granule formation was achieved by increasing the organic loading rate (OLR) from 0.7 to 4.1 kg COD/(m3 & sdot;d) and the up-flow velocity in the biomass selector from 1.4 to 6.9 m/h. However, irreversible granule destabilization occurred at day 68 for R1 and day 108 for R2. Principal component analysis and examination of food-to-microorganisms (F/M) ratio medians identified the F/M ratio as the primary variable associated with instability. Microbial analysis revealed that a high F/M ratio induced significant increases in the abundance of specific genera such as Arcobacter, Cloacibacterium, Rikenella, Aquaspirillum and Sphaerotillus, whose overgrowth may negatively impact granule stability. Based on these findings, maximum F/M ratio thresholds were obtained to establish operational conditions allowing the maintenance of stable aerobic granules on continuous flow reactor configurations.
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Ramajo, L., Marba, N., Prado, L., Peron, S., Lardies, M. A., Rodriguez-Navarro, A. B., et al. (2016). Biomineralization changes with food supply confer juvenile scallops (Argopecten purpuratus) resistance to ocean acidification. Glob. Change Biol., 22(6), 2025–2037.
Abstract: Future ocean acidification (OA) will affect physiological traits of marine species, with calcifying species being particularly vulnerable. As OA entails high energy demands, particularly during the rapid juvenile growth phase, food supply may play a key role in the response of marine organisms to OA. We experimentally evaluated the role of food supply in modulating physiological responses and biomineralization processes in juveniles of the Chilean scallop, Argopecten purpuratus, that were exposed to control (pH similar to 8.0) and low pH (pH similar to 7.6) conditions using three food supply treatments (high, intermediate, and low). We found that pH and food levels had additive effects on the physiological response of the juvenile scallops. Metabolic rates, shell growth, net calcification, and ingestion rates increased significantly at low pH conditions, independent of food. These physiological responses increased significantly in organisms exposed to intermediate and high levels of food supply. Hence, food supply seems to play a major role modulating organismal response by providing the energetic means to bolster the physiological response of OA stress. On the contrary, the relative expression of chitin synthase, a functional molecule for biomineralization, increased significantly in scallops exposed to low food supply and low pH, which resulted in a thicker periostracum enriched with chitin polysaccharides. Under reduced food and low pH conditions, the adaptive organismal response was to trade-off growth for the expression of biomineralization molecules and altering of the organic composition of shell periostracum, suggesting that the future performance of these calcifiers will depend on the trajectories of both OA and food supply. Thus, incorporating a suite of traits and multiple stressors in future studies of the adaptive organismal response may provide key insights on OA impacts on marine calcifiers.
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Schmidt-Rivera, X. S., Rodgers, B., Odanye, T., Jalil-Vega, F., & Farmer, J. (2023). The role of aeroponic container farms in sustainable food systems – The environmental credentials. Sci. Total Environ., 860, 160420.
Abstract: Sustainable food production and consumption are key to face the current climate and environmental crisis, hence innovation to produce food with lower impacts are taking more attention. Controlled environment agriculture, also known as vertical farming, is seen as one innovative approach to reduce impacts of producing food while also improv-ing food security. Aeroponic is one of such innovations, which environmental impacts have not been well understood yet. Therefore, this study assesses the environmental impacts of aeroponic farm container system in the UK, including a full set of 19 indicators. The results show that energy requirements drive all the impacts, with climate change estimated at 1.52 kg CO2eq. per 1 kg of microgreens (pea shoots) using 2021 UK grid. Renewable powered systems improve almost all the impacts, with climate change reduced by up to 80 %, making this system competitive with con-ventional agricultural systems. This study proves that aeroponic farm container could offer lower impact food than equivalent imported to the UK, and that also could improve food security in terms of availability, stability, and access to food. Affordability issues need to be assessed in future work.
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Urrejola, S., Nespolo, R., & Lardies, M. A. (2011). Diet-induced developmental plasticity in life histories and energy metabolism in a beetle. Rev. Chil. Hist. Nat., 84(4), 523–533.
Abstract: Adaptive phenotypic plasticity, has been recognized as an important strategy by which organisms maximize fitness in variable environments, which vary through development. A disassociation among stages should represent a null effect of the environment experienced during early ontogeny in the expression of adult traits. Food quality greatly influences survival, development and reproduction in many arthropod herbivores. We examined the effects of diet protein in physiological and life-history traits in the yellow mealworm beetle Tenebrio molitor through ontogeny. We established four experimental treatments: Low Protein (LP), Low Protein Control (LPC), High Protein (HP), and High Protein Control (HPC) with recently eclosioned larvae each. Individuals were maintained on the same diet or transferred to the opposite diet for all pupae period and almost all adult period. Contrary to the expected, the duration of life-cycle, larval growth rate and body mass in T molitor were similar in diet treatments. We found intra-individual trade-offs between environmental diet (rich or poor in protein content) during larval phase and egg number. Larvae fed on a protein-deficient diet exhibited significantly higher respiratory rates than larvae fed on a rich protein diet. Compensatory feeding could act in T molitor larvae indicating differences in metabolism but not in growth rate, body mass and life-cycle characteristics. Our results demonstrate the plasticity of reproductive and metabolic traits and life-cycle characteristics of T molitor and how changes that occur in relation to diet can have profound effects on progeny and female fitness.
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