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This study aims to elucidate the role of sulfide and its precursors in anaerobic digestion (i.e., cysteine, representing sulfur-containing amino acids, and sulfate) on microbial oleate conversion to methane. Serine, with a similar structure to cysteine but with a hydroxyl group instead of a thiol, was included as a control to assess potential effects on methane formation that were not related to sulfur functionalities. The results showed that copresence of sulfide and oleate in anaerobic batch assays accelerated the methane formation compared to assays with only oleate and mitigated negative effect on methane formation caused by increased sulfide level. Nuclear magnetic resonance spectroscopy of sulfide exposed oleate suggested that sulfide reaction with oleate double bonds likely contributed to negation of the negative effect on the methanogenic activity. Methane formation from oleate was also accelerated in the presence of cysteine or serine, while sulfate decreased the cumulative methane formation from oleate. Neither cysteine nor serine was converted to methane, and their accelerating effects was associated to different mechanisms due to establishment of microbial communities with different structures, as evidenced by high-throughput sequencing of 16S rRNA gene. These outcomes contribute with new knowledge to develop strategies for optimum use of sulfur-and lipid-rich wastes in anaerobic digestion processes. Funding Agencies|Swedish Research Council Formas [2016-01054]; Swedish Energy Agency through the Biogas Research Center (BRC) in Linkoping [35624-2]; MIRAI program for joint Japan-Sweden collabora-tive projects (mirai.nu); Japan Society for the Promotion of Science; Swedish University of Agricultural Sciences; Swedish NMR center at Umea University; [18F18061]

Life science alliance 5(12), e202201491 - (2022). doi:10.26508/lsa.202201491, Aquaporins are protein channels embedded in the lipid bilayer in cells from all organisms on earth that are crucial for water homeostasis. In fish, aquaporins are believed to be important for osmoregulation; however, the molecular mechanism behind this is poorly understood. Here, we present the first structural and functional characterization of a fish aquaporin; cpAQP1aa from the fresh water fish climbing perch (Anabas testudineus), a species that is of high osmoregulatory interest because of its ability to spend time in seawater and on land. These studies show that cpAQP1aa is a water-specific aquaporin with a unique fold on the extracellular side that results in a constriction region. Functional analysis combined with molecular dynamic simulations suggests that phosphorylation at two sites causes structural perturbations in this region that may have implications for channel gating from the extracellular side., Published by EMBO Press, Heidelberg

There is an urgent demand for analytic approaches that enable precise and representative quantification of the transport of biologically active compounds across cellular membranes. In this study, we established a new means to monitor membrane permeation kinetics, using total internal reflection fluorescence microscopy confined to a ≈500 nm thick mesoporous silica substrate, positioned underneath a planar supported cell membrane mimic. This way, we demonstrate spatiotemporally resolved membrane permeation kinetics of a small‐molecule model drug, felodipine, while simultaneously controlling the integrity of, and monitoring the drug binding to, the cell membrane mimic. By contrasting the permeation behaviour of pure felodipine with felodipine coupled to the permeability enhancer caprylate (C8), we provide evidence for C8‐facilitated transport across lipid membranes, thus validating the potential for this approach to successfully quantify carrier system‐induced changes to cellular membrane permeation., A unique angle: A new approach for monitoring the real‐time permeation of drug molecules, from the bulk phase, across a lipid membrane was established by supporting a lipid bilayer on mesoporous silica thin films. Through the use of TIRF microscopy, the angle of incidence of illumination light could be controlled to ensure the resulting evanescence was restricted within the thin film, and thus, only drug permeating the bilayer was resolved.

Acetate production from food waste or sewage sludge was evaluated in four semi-continuous anaerobic digestion processes. To examine the importance of inoculum and substrate for acid production, two different inoculum sources (a wastewater treatment plant (WWTP) and a co-digestion plant treating food and industry waste) and two common substrates (sewage sludge and food waste) were used in process operations. The processes were evaluated with regard to the efficiency of hydrolysis, acidogenesis, acetogenesis, and methanogenesis and the microbial community structure was determined. Feeding sewage sludge led to mixed acid fermentation and low total acid yield, whereas feeding food waste resulted in the production of high acetate and lactate yields. Inoculum from WWTP with sewage sludge substrate resulted in maintained methane production, despite a low hydraulic retention time. For food waste, the process using inoculum from WWTP produced high levels of lactate (30 g/L) and acetate (10 g/L), while the process initiated with inoculum from the co-digestion plant had higher acetate (25 g/L) and lower lactate (15 g/L) levels. The microbial communities developed during acid production consisted of the major genera Lactobacillus (92&ndash, 100%) with food waste substrate, and Roseburia (44&ndash, 45%) and Fastidiosipila (16&ndash, 36%) with sewage sludge substrate. Use of the outgoing material (hydrolysates) in a biogas production system resulted in a non-significant increase in bio-methane production (+5&ndash, 20%) compared with direct biogas production from food waste and sewage sludge.

This study examined the influence of altered operating temperature on microbial community composition and how this affects the ability of anaerobic degradation (AD) processes to cope with increasing loading rate. Four digesters fed household and slaughterhouse waste, mimicking two large-scale processes, were operated in sets of two at 37°C or 52°C, followed by a gradual increase or decrease in temperature in one digester in each set. All digesters were then subjected to step-wise increases in organic loading rate (OLR) from 3 to 7g VS/L/day, concurrently with decreased hydraulic retention time (HRT). Temporal microbial changes were monitored by Illumina MiSeq analysis of bacterial and archaeal 16S rRNA gene sequences. The digester transformed from thermophilic to mesophilic conditions failed at 6g VS/L/day, whereas the reference digesters and the mesophilic-to-thermophilic digester remained stable at all OLR investigated. The bacterial community was characterised by relatively diversified structure dominated by Bacteriodetes and Firmicutes in mesophilic conditions. Increasing temperature caused loss of complexity at phyla level and enhanced the relative abundance of Firmicutes and Thermotogae. Temperature adaptation in the thermophilic-to-mesophilic digester resulted in a bacterial community structure reflecting the communities observed in digesters with initial temperature of 37°C. However, certain populations found in the mesophilic digesters did not appear at detectable levels during operation at 37°C in the thermophilic-to-mesophilic digester. Overall, the results showed that anaerobic process stability was highly dependent on the innate resilience of the microbial community. The mesophilic microbiota formed from a thermophilic community had a slightly different structure than its mesophilic counterpart and was considerably less resistant to increased OLR in digesters examined within this study.

Mesoporous silica nanoparticles are an important class of materials with a wide range of applications. This paper presents a simple protocol for synthesis of particles as small as 40. nm and with a pore size that can be as large as 9. nm. Reaction conditions including type of surfactant, type of catalyst and presence of organic polymer were investigated in order to optimize the synthesis. An important aim of the work was to understand the mechanism behind the formation of these unusual structures and an explanation based on silica condensation in the small aqueous microemulsion droplets that are present inside the drops of an oil-in-water emulsion is put forward.