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Item type:Publication, Access status: with files , Biodegradation of polyhydroxyalkanoates: current state and future prospects(Frontiers Media S.A., 2025); ; ; Polyhydroxyalkanoates (PHAs) are biobased and biodegradable polymers that offer a sustainable alternative to conventional plastics, addressing the escalating concerns over plastic pollution. While their environmental advantages are well-documented, the efficient degradation of PHAs in natural and engineered environments remains a critical component of their lifecycle. This review provides a comprehensive overview of PHA-degrading bacteria isolated from diverse ecosystems and highlights the pivotal role of PHA depolymerases in achieving PHA circularity. Microbial adaptation to diverse environmental conditions, such as extreme temperatures, salinity, and pH, significantly influences enzymes properties, including the stability, activity, and substrate specificity of PHA-degrading enzymes. These adaptations often enhance enzyme, performance, enabling functionality under challenging conditions. Consequently, extremophilic microorganisms are invaluable resources for discovering and engineering robust PHA depolymerases for industrial and environmental applications. This review underscores the urgent need for further research to improve the ecological and economic sustainability of PHA waste management.Publicationtype: Review Article6 13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Exploring the Effects of bolA in Biofilm Formation and Current Generation by Shewanella oneidensis MR-1(2020-05-08); ; ; Microbial electrochemical technologies (METs) have emerged in recent years as a promising alternative green source of energy, with microbes consuming organic matter to produce energy or valuable byproducts. It is the ability of performing extracellular electron transfer that allows these microbes to exchange electrons with an electrode in these systems. The low levels of current achieved have been the limiting factor for the large-scale application of METs. Shewanella oneidensis MR-1 is one of the most studied electroactive organisms regarding extracellular electron transfer, and it has been shown that biofilm formation is a key factor for current generation. The transcription factor bolA has been identified as a central player in biofilm formation in other organisms, with its overexpression leading to increased biofilm. In this work we explore the effect of this gene in biofilm formation and current production by S. oneidensis MR-1. Our results demonstrate that an increased biofilm formation and consequent current generation was achieved by the overexpression of this gene. This information is crucial to optimize electroactive organisms toward their practical application in METs.Publicationtype: Journal ArticleScopus© Citations 17 51 140 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Addition of riboflavin-coupled magnetic beads increases current production in bioelectrochemical systems via the increased formation of anode-biofilms(2019-02-05); ; ; ; Shewanella oneidensis is one of the best-understood model organisms for extracellular electron transfer. Endogenously produced and exported flavin molecules seem to play an important role in this process and mediate the connection between respiratory enzymes on the cell surface and the insoluble substrate by acting as electron shuttle and cytochrome-bound cofactor. Consequently, the addition of riboflavin to a bioelectrochemical system (BES) containing S. oneidensis cells as biocatalyst leads to a strong current increase. Still, an external application of riboflavin to increase current production in continuously operating BESs does not seem to be applicable due to the constant washout of the soluble flavin compound. In this study, we developed a recyclable electron shuttle to overcome the limitation of mediator addition to BES. Riboflavin was coupled to magnetic beads that can easily be recycled from the medium. The effect on current production and cell distribution in a BES as well as the recovery rate and the stability of the beads was investigated. The addition of synthesized beads leads to a more than twofold higher current production, which was likely caused by increased biofilm production. Moreover, 90% of the flavin-coupled beads could be recovered from the BESs using a magnetic separator.Publicationtype: Journal ArticleScopus© Citations 15 91 149 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Development of neutralizing and non-neutralizing antibodies targeting known and novel epitopes of TcdB of clostridioides difficile(2018-12-06)3 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Influence of the potential carbon sources for field denitrification beds on their microbial diversity and the fate of carbon and nitrateNitrogen based eutrophication of ecosystems is a global problem that gains momentum through a growing global population. The water quality of nitrate or ammonium contaminated rivers and streams cannot always be amended in centralized waste water treatment plants. Field denitrification plants were suggested as a solution for a decentralized reduction of nitrate to dinitrogen. Here, stable and cheap organic carbon sources serve as carbon and electron source for a microbial community. Still, our knowledge on the impact of these organic carbon sources on the development and diversity of these cultures is sparse. Moreover, the stability of these denitrification plants at different nitrate loading rates especially in the higher concentration regime were not tested so far. In this study, we compare the fate of carbon and nitrogen as well as the microbial community of wood pellet (WP) (pressed sawdust), wheat straw, and wood chips (WC) based laboratory denitrification reactors. Our study reveals that the diversity and composition of the community is strongly dependent on the carbon source. The diversity decreased in the order WC, wheat straw, and WPs. The three reactor types were characterized by different nitrate reduction kinetics and were affected differently by high nitrate loading rates. While the nitrate reduction kinetics were negatively influenced by higher nitrate doses in the wheat straw reactors, WPs as carbon source sustained the opposite trend and WC lead to an overall slower but concentration independent nitrate reduction rate. Counterintuitively, the concentration of soluble organic carbon was highest in the WP reactors but methane emission was not detectable. This is corroborated by the microbial diversity data in which methanogenic species were highly underrepresented compared to the other two reactor types. In contrary, the methane emissions in the wheat straw and WC reactors were comparable to each other.Publicationtype: Journal ArticleScopus© Citations 27 102 214 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Improvement of the process stability of arylmalonate decarboxylase by immobilization for biocatalytic profen synthesis(Frontiers Media S.A., 2017-03-16); ; ; ; The enzyme arylmalonate decarboxylase (AMDase) enables the selective synthesis of enantiopure (S)-arylpropinates in a simple single-step decarboxylation of dicarboxylic acid precursors. However, the poor enzyme stability with a half-life time of about 1.2 h under process conditions is a serious limitation of the productivity, which results in a need for high catalyst loads. By immobilization on an amino C2 acrylate carrier the operational stability of the (S)-selective AMDase variant G74C/M159L/C188G/V43I/A125P/V156L was increased to a half-life of about 8.6 days, which represents a 158-fold improvement. Further optimization was achieved by simple immobilization of the cell lysate to eliminate the cost- and time intensive enzyme purification step.Publicationtype: Journal ArticleScopus© Citations 14 306 491 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Highly effective inhibition of biofilm formation by the first metagenome-derived AI-2 quenching enzyme(Frontiers Media S.A., 2016-07-13); ; ; ; Bacterial cell-cell communication (quorum sensing, QS) represents a fundamental process crucial for biofilm formation, pathogenicity, and virulence allowing coordinated, concerted actions of bacteria depending on their cell density. With the widespread appearance of antibiotic-resistance of biofilms, there is an increasing need for novel strategies to control harmful biofilms. One attractive and most likely effective approach is to target bacterial communication systems for novel drug design in biotechnological and medical applications. In this study, metagenomic large-insert libraries were constructed and screened for QS interfering activities (quorum quenching, QQ) using recently established reporter strains. Overall, 142 out of 46,400 metagenomic clones were identified to interfere with acyl-homoserine lactones (AHLs), 13 with autoinducer-2 (AI-2). Five cosmid clones with highest simultaneous interfering activities were further analyzed and the respective open reading frames conferring QQ activities identified. Those showed homologies to bacterial oxidoreductases, proteases, amidases and aminotransferases. Evaluating the ability of the respective purified QQ-proteins to prevent biofilm formation of several model systems demonstrated highest inhibitory effects of QQ-2 using the crystal violet biofilm assay. This was confirmed by heterologous expression of the respective QQ proteins in Klebsiella oxytoca M5a1 and monitoring biofilm formation in a continuous flow cell system. Moreover, QQ-2 chemically immobilized to the glass surface of the flow cell effectively inhibited biofilm formation of K. oxytoca as well as clinical K. pneumoniae isolates derived from patients with urinary tract infections. Indications were obtained by molecular and biochemical characterizations that QQ-2 represents an oxidoreductase most likely reducing the signaling molecules AHL and AI-2 to QS-inactive hydroxy-derivatives. Overall, we propose that the identified novel QQ-2 protein efficiently inhibits AI-2 modulated biofilm formation by modifying the signal molecule; and thus appears particularly attractive for medical and biotechnological applications.Publicationtype: Journal ArticleScopus© Citations 53 329 289