Biology subjects

Rau, J.

Publications and source records attributed to Rau, J..

4 recordsLinked to original sources

bioRxiv2025

Native and regenerated cellulose show similar environmental biodegradation behavior across global terrestrial and aquatic ecosystems

Cellulose is the most abundant natural polymer and serves as the structural scaffolding molecule of plants, and materials from cellulose fibers are considered important to the global shift toward renewable materials. Yet, uncertainty remains about their persistence in natural environments. Here we show that native and regenerated cellulose, ranging from cotton and linen to viscose, modal, and lyocell, despite minor structural differences, are biodegraded at comparable rates, indicating that there is no scientifically justified distinction regarding environmental behavior. We assessed the biodegradation of diverse cellulosic materials, including powders, loose fibers, fabrics, and nonwovens, under technical and natural conditions across soil, home compost, freshwater, and marine coastal and deep-sea environments. Our study combined a total of 152 scenarios with laboratory tests, mesocosm and field experiments, spanning from polar to tropical regions and temperatures from -1.8 {degrees}C in the high Arctic Ocean to 38.4 {degrees}C in a marine beach in the Mediterranean Sea, and between -6.1 to 54.1 {degrees}C in agricultural soil. All neat cellulosic fibers showed inherent biodegradability, with biodegradation half-lives typically ranging from weeks to months. Biodegradation rates were primarily driven by water availability, temperature, and nutrient levels, while the role of oxygen was indifferent. Standardized lab tests aligned well with field observations, confirming their validity for assessing inherent biodegradability with environmental relevance. However, biodegradation of biodegradable polymers in real-world scenarios is influenced by product-level modifications such as dyeing and finishing. By distinguishing the effects of fiber chemistry separately from those of finishing treatments, this study clarifies the role of cellulose in a sustainable materials economy and supports evidence-based regulation of fiber biodegradability claims and product labeling.

microbiology↗

bioRxiv2025

Up-to-date MALDI-TOF MS based identification of the complete Corynebacterium diphtheriae species complex for improved diagnostics

The Corynebacterium (C.) diphtheriae species complex (CdSC) comprises the closely related pathogenic species C. diphtheriae, C. belfantii, C. rouxii, C. ulcerans, C. silvaticum, C. ramonii and C. pseudotuberculosis according to the taxonomic revisions after 2018. Due to their close relationship, reliable species identification within the CdSC is also challenging using MALDI-TOF mass spectrometry (MS) for fast and reliable identification of bacteria. However, the most commonly used commercial databases for MALDI-TOF MS do not reflect the current CdSC taxonomy. Therefore, the objective of the present study is to expand the Bruker MALDI-Biotyper database version K (MBTK) in order to achieve reliable identification for all currently known Corynebacterium species within the CdSC. Furthermore, the database extensions were verified with a systematic formal validation procedure in accordance with the German guideline for species identification by MALDI- TOF MS. For this, 321 strains including all seven valid species of the CdSC were identified with a set of 328 spectra using the commercial MBTK database and a customer-supplemented modified MBTK. This custom database version included 33 reference spectra of the CdSC and representatives of all four recently described species. The results of the formal validations for both, the commercial and the extended database, combined partly with a single signal analysis, provide a substantiated basis for the identification of bacteria of the CdSC. A key element for a fast up-to-date identification has been the exchange of user-generated sets of MSPs on the open access MALDI-UP catalogue that includes reference spectra for all members of the CdSC. HighlightsO_LIUsing MALDI-TOF MS, all current species of the C. diphtheriae species complex are accurately identified according to the current taxonomy C_LIO_LIValidation was performed using spectra from different institutions and an approved gold standard protocol C_LIO_LIThe extension and exchange of user created reference spectra via the MALDI User Platform proved to be a key tool for precise identification of bacteria C_LI Importance StatementBacteria belonging to the Corynebacterium (C.) diphtheriae complex are important pathogens for humans and animals. Identification of the species of this complex described since 2018, i.e. C. belfantii, C. rouxii, C. ramonii, and C. silvaticum, using the widely approved MALDI-TOF mass spectrometry is possible. This has been achieved by improved identification using supplemented MALDI reference databases. Comprehensive validation meets the requirements for accurate pathogen identification in accordance with recognised guidelines. This approach of identification is certainly a model for other bacterial species of interest to react on current taxonomic revisions in a short time frame.

microbiology↗

bioRxiv2025

Establishment and Thorough External Validation of a FTIR Spectroscopy Classifier for Salmonella Serogroup Differentiation

As one of the most relevant food-borne pathogens, the reliable detection, confirmation and fine-typing of Salmonella strains is very important. Salmonella serotype determination by rabbit antisera posts the worldwide-accepted standard but is labor intensive, costly and needs extensive experience. As an alternative, successful discrimination between strains of different serogroups by FTIR spectroscopy has been developed before for various bacterial groups. In the current study, firstly a FTIR Classifier operating on an IR Biotyper(R) spectrometer (Bruker, Germany) was designed to distinguish between n=36 different Salmonella serogroups. A FTIR classifier is an AI-based tool used in FTIR spectroscopy to analyze and classify different materials based on their infrared spectra. Secondly, the differentiation performance of this classifier was determined by a thorough external single-lab validation carried out in line with the Guidelines for Validating Species Identifications Using MALDI-ToF-MS issued by the German Federal Office of Consumer Protection for a targeted identification: The most common Salmonella serogroups in Europe, serogroups O:4 (B), O:6,7 (C1), O:8 (C2-C3) and O:9 (D1) were chosen as target parameters and validated using a total of n=1039 infrared absorbance spectra from a total of n=167 strains pertaining to n=39 serogroups. In summary, serogroups O:4, O:6,7 and O:9 perfectly met the adapted guideline requirements and resulted in a >99% inclusivity each. Serogroup O:8 arrived at a 96.1% true-positive rate due to one deviating strain. This validated classification method can thus be used in routine analysis for quick and easy differentiation of the most common Salmonella serogroups in food surveillance. In addition, using the cluster analysis tools of the IR BT(R), a preselection of isolates before subjecting them to thorough serotyping decreases the workload in current routine analyses.

microbiology↗

bioRxiv2020

Toxigenic and zoonotic Corynebacterium ulcerans emerges from widespread hedgehog disease

Toxin-producing Corynebacterium ulcerans, causing diphtheria in humans, were isolated from 53 diseased hedgehogs during spring 2020 in Belgium. Isolates showed low levels of acquired antimicrobial resistance. Pronounced strain diversity suggests emergence from an endemic situation. These findings stress the need for raising public awareness and improved wildlife disease surveillance.

microbiology↗