New applications and performance of bioelectrochemical systems

Bioelectrochemical systems (BESs) are emerging technologies which use microorganisms to catalyze the reactions at the anode and/or cathode. BES research is advancing rapidly, and a whole range of applications using different electron donors and acceptors has already been developed. In this mini review, we focus on technological aspects of the expanding application of BESs. We will analyze the anode and cathode half-reactions in terms of their standard and actual potential and report the overpotentials of these half-reactions by comparing the reported potentials with their theoretical potentials. When combining anodes with cathodes in a BES, new bottlenecks and opportunities arise. For application of BESs, it is crucial to lower the internal energy losses and increase productivity at the same time. Membranes are a crucial element to obtain high efficiencies and pure products but increase the internal resistance of BESs. The comparison between production of fuels and chemicals in BESs and in present production processes should gain more attention in future BES research. By making this comparison, it will become clear if the scope of BESs can and should be further developed into the field of biorefineries

Electron storage in electroactive biofilms

Microbial electrochemical technologies (METs) are promising for sustainable applications. Recently, electron storage during intermittent operation of electroactive biofilms (EABs) has been shown to play an important role in power output and electron efficiencies. Insights into electron storage mechanisms, and the conditions under which these occur, are essential to improve microbial electrochemical conversions and to optimize biotechnological processes. Here, we discuss the two main mechanisms for electron storage in EABs: storage in the form of reduced redox active components in the electron transport chain and in the form of polymers. We review electron storage in EABs and in other microorganisms and will discuss how the mechanisms of electron storage can be influenced.This work is part of the research program Vidi (with project number 17516), which is (partly) financed by the Dutch Research Council (NWO). The research was performed in cooperation with Wetsus, the European Centre of Excellence for Sustainable Water Technology. Wetsus is cofunded by the Dutch Ministry of Economic Affairs and Ministry of Infrastructure and Environment, the European Union Regional Development Fund, the Province of Fryslân, and the Northern Netherlands Provinces. The authors would like to thank the participants of the research theme ‘Resource Recovery’ for the fruitful discussions and their financial support. The authors also acknowledge the financial support given by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 – Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Individual and Population Level Effects of Partner Notification for Chlamydia trachomatis

10.1371/journal.pone.0051438PLoS ONE712

Turns in transmembrane helices – determination of the minimal length of a “helical hairpin” and derivation of a fine-grained turn propensity scale

We have recently reported a first experimental turn propensity scale for transmembrane helices. This scale was derived from measurements of how efficiently a given residue placed in the middle of a 40 residue poly(Leu) stretch induces the formation of a "helical hairpin" with two rather than one transmembrane segment. We have now extended these studies, and have determined the minimum length of a poly(Leu) stretch compatible with the formation of a helical hairpin. We have also derived a more fine-grained turn propensity scale by (i) introducing each of the 20 amino acid residues into the middle of the shortest poly(Leu) stretch compatible with helical hairpin formation, and (ii) introducing pairs of residues in the middle of the 40 residue poly(Leu) stretch. The new turn propensities are consistent with the amino acid frequencies found in short hairpin loops in membrane proteins of known 3D structure

Ala-insertion scanning mutagenesis of the glycophorin A transmembrane helix

Alanine insertions into the glycophorinA transmembrane helix are found to disrupthelix-helix dimerization in a way thatis fully consistentwith earlier saturation mutagenesis datas,uggesting that Ala-insertion scanning can be used to rapidly map the approximate locatiofn structurally and/or functionally importantsegments in trans-membrane helice

Frequency and determinants of consistent STI/HIV testing among men who have sex with men testing at STI outpatient clinics in the Netherlands: a longitudinal study.

Men who have sex with men (MSM) are at highest risk for STIs and HIV infections in the Netherlands. However, official guidelines on STI testing among MSM are lacking. They are advised to test for STIs at least every six months, but their testing behaviour is not well known. This study aimed to get insight into the proportion and determinants of consistent 6-monthly STI testing among MSM testing at STI outpatient clinics in the Netherlands

The Role of Reinfection and Partner Notification in the Efficacy of Chlamydia Screening Programs

Repeated Chlamydia trachomatis infections after treatment are common. One reason is reinfection from untreated partners in ongoing sexual partnerships. Mathematical models that are used to predict the impact of screening on reducing chlamydia prevalence often do not incorporate reinfection and might overestimate the expected impact. We describe a pair compartmental model that explicitly incorporates sexual partnership duration and reinfection. The pair model predicts a weaker impact of screening when compared directly with a model that does not accommodate partnerships. Effective management of sex partners to prevent reinfection might need to be strengthened in chlamydia control program

Membrane topology of the 60 kDa Oxa1p-homologue from Escherichia coli

We have characterized the membrane topology of a 60-kDa inner membrane protein from Escherichia coli that is homologous to the recently identified Oxa1p protein in Saccharomyces cerevisiae mitochondria implicated in the assembly of mitochondrial inner membrane proteins. Hydrophobicity and alkaline phosphatase fusion analyses suggest a membrane topology with six transmembrane segments, including an N-terminal signal-anchor sequence not present in mitochondrial Oxa1p. In contrast to partial N-terminal fusion protein constructs, the full-length protein folds into a protease-resistant conformation, suggesting that important folding determinants are present in the C-terminal part of the molecule

Microbial acclimation to concentrated human urine in Bio-electrochemical system

The aim of this study is to promote the gradual acclimation of bioelectroactive microorganisms in BES to concentrated human urine, and to assess different anode potentials and carbon materials in Microbial Electrolysis Cells (MEC). Human urine is highly concentrated in nutrients, representing more than 80% of the total N load and around 45% of the total P load in municipal wastewater. Separation of urine from other wastewater streams is an interesting option to keep these valuable nutrients concentrated, in order to develop a suitable nutrient recovery concept. This work is integrated in the Value from Urine (VFU) concept, where phosphate is recovered from source segregated human urine through struvite precipitation and ammonia is recovered in a Bio-electrochemical System (BES). Enrichment of an anaerobic sludge community in urine-degrading-electroactive microorganisms was promoted in an Microbial Fuel Cell (MFC) operated with increasing concentrations of real human urine (after phosphorous removal, as struvite). This acclimated electroactive biofilm was used to inoculate the anode of MECs, aiming at H2 and ammonia production in the cathode compartment. Different carbon modified anodes and defined anode potentials were assessed in terms of performance and microbial diversity of the developed electroactive biofilms