Approximately 1 million tons of waste cooking oils (WCO) are generated in European Union per year. Oftentimes, these oily wastes are discharged through public sewerage systems, increasing the water treatment costs in wastewater treatment plants. The oleaginous yeast Yarrowia lipolytica W29 is used to simultaneously degrade WCO and to produce lipase (market demand is increasing due to its application in the field of bioenergy). A statistical experimental design based on Taguchi method is employed to assess the effect of initial medium pH, WCO, and arabic gum concentration on lipase production. Initial medium pH is found to be the most significant parameter and the interaction between WCO and arabic gum concentration had the highest influence for lipase production. Additionally, the effect of oxygen mass transfer is studied in batch cultures in a stirred tank bioreactor and the maximum lipase activity (12 000 U · L−1) is obtained at kLa of 16 h−1. Simultaneously with lipase production, also lipid‐rich biomass (48% of lipids mass per dry cellular mass), enriched in unsaturated fatty acids (oleic and linoleic acids) is obtained. Practical Applications: In this work it was demonstrated the possibility of replacing an expensive edible oil (olive oil) by a non‐edible oil waste (WCO) for lipase production. Moreover, no more wastes are produced, since whole cells of Yarrowia lipolytica W29 (lipid‐rich biomass), are a potential source for food supplements. Thus, the bioprocess described fulfill the requisites of circular economy: a low cost substrate is used as raw material, added‐value products (lipase and lipid‐rich biomass) are obtained and no further wastes are generated (take‐make‐dispose concept). Waste cooking oils (WCO) are generated from vegetable oils used at high temperatures in food frying. The biological degradation of WCO by the oleaginous yeast Yarrowia lipolytica W29, with concomitant production of added‐value compounds (lipase and lipid‐rich biomass), allows the reduction of pollutant burden of these oily wastes.

Summary Leaf litter decomposition is an important process in many streams. The flow of carbon and nutrients to higher trophic levels generally depends on litter characteristics and environmental conditions, and is driven by the activities of microbes and invertebrate shredders. However, little is known about what drives litter decomposition in oceanic islands, where invertebrate communities are species‐poor. In this study, we assessed the relative importance of litter quality and environmental conditions on the biological colonisation and decomposition of litter exposed to and protected from macroinvertebrates, in the Azores archipelago, North Atlantic Ocean. Three leaf litter species with distinct physical and chemical characteristics (Acacia melanoxylon, Clethra arborea and Pittosporum undulatum) were incubated in six streams with distinct water characteristics. Coarse and fine mesh bags were used to isolate the relative role of macroinvertebrates on litter decomposition. Incubation of litter took place in late spring – early summer and lasted for up to 56 days. No significant differences in litter decomposition rates were found between coarse and fine mesh bags suggesting that microbes, especially aquatic hyphomycetes, are the key players in litter decomposition in these island streams. Litter decomposition rates were inversely proportional to initial lignin concentration: A. melanoxylon 0.0080 day−1, C. arborea 0.0121 day−1, P. undulatum 0.0292 day−1, on average across streams. Litter decomposition rates and associated decomposers differed among streams, suggesting that environmental conditions (e.g. nutrient concentration) may be important moderators of biological activities in these streams, as found for continental streams. Species richness, fungal biomass and reproductive activity of aquatic hyphomycetes on decomposing litter were recorded in Atlantic islands for the first time and were at levels similar to those found for continental streams. High microbial activities in Atlantic island streams ensure litter decomposition when shredder abundance is low.

The invasion of native riparian forests by exotic tree species can lead to profound changes in the ecological integrity of freshwater ecosystems. We assessed litter decomposition of native (Alnus glutinosa and Quercus robur) and invasive (Acacia melanoxylon and Acacia dealbata) tree species, and associated microbial activity and community structure, after being immersed for conditioning in 3 reference and 3 "invaded" streams in Serra da Lousã (central Portugal) and used in microcosms simulating stream conditions. Litter decomposition differed among species, in the order: Al. glutinosa > Q. robur > (Ac. melanoxylon ~Ac. dealbata). Alnus glutinosa litter decomposed faster probably because it was soft and had high nitrogen concentration for decomposers. Quercus robur litter decomposed slower most likely because it was tough and had high polyphenol and low nitrogen concentrations. Acacia melanoxylon litter was the toughest and had a thick cuticle that likely acted as a physical barrier for microbial colonization. In Ac. dealbata, the small-sized leaflets and high lignin concentration may have limited microbial litter decomposition. Litter decomposition was faster in "invaded" streams, probably because they were N-limited and increases in nitrogen concentration in water, promoted by Acacia species invasion, stimulated microbial activity on litter. The aquatic hyphomycete community structure differed among litter species and between stream types, further suggesting that microbes were sensitive to litter characteristics and water nutrient concentrations. Overall, the invasion of native riparian forests by Acacia species may affect microbial decomposer activity, thus altering important stream ecosystem processes, such as litter decomposition and nutrient cycles.

Non-native nitrogen-fixing Acacia species have been invading riparian ecosystems worldwide, potentially threatening stream communities that strongly depend on allochthonous litter. We examined the effects of the invasion of native deciduous temperate forests by Acacia species on litter decomposition and associated fungal decomposers in streams. Litter of native (Alnus glutinosa and Quercus robur) and invasive (Acacia melanoxylon) species were enclosed in fine-mesh bags and immersed in three native and three invaded streams, for 14-98 days. Litter decomposition rates, fungal biomass, and aquatic hyphomycete sporulation rates were higher in invaded than in native streams, likely due to the higher water nitrogen concentration found in invaded streams. Alnus glutinosa litter had higher aquatic hyphomycete sporulation rates and species richness, and higher decomposition rates, probably because they were soft and nitrogen rich. Quercus robur litter also had high aquatic hyphomycete sporulation rates but lower decomposition rates than Al. glutinosa, probably due to high polyphenol concentration and carbon:nitrogen ratio. Acacia melanoxylon litter had lower aquatic hyphomycete sporulation rates and species richness, and lower decomposition rates, most likely because it was very tough. Thus, litter decomposition rates varied in the order: Al. glutinosa > Q. robur > Ac. melanoxylon. The aquatic hyphomycete community structure strongly differed between native and invaded streams, and among litter species, suggesting that microbes were sensitive to water nitrogen concentration and litter characteristics. Overall, increases in water nitrogen concentration and alterations in litter characteristics promoted by the invasion of native riparian forests by Acacia species may affect the activity and community structure of microbial decomposers, and instream litter decomposition, thus altering the functioning of stream ecosystems.

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The clinical results of the studies point to the positive effects of radiofrequency on the reduction in adipose tissue; however, the low methodological make this topic still debatable, requiring more controlled studies.

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