Institut für Nutztierwissenschaften

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/20

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Bacillus anthracis in South Africa, 1975–2013: are some lineages vanishing?
(2024) Lekota, Kgaugelo Edward; Hassim, Ayesha; Ledwaba, Maphuti Betty; Glover, Barbara A.; Dekker, Edgar. H.; van Schalkwyk, Louis Ockert; Rossouw, Jennifer; Beyer, Wolfgang; Vergnaud, Gilles; van Heerden, Henriette
The anthrax-causing bacterium Bacillus anthracis comprises the genetic clades A, B, and C. In the northernmost part (Pafuri) of Kruger National Park (KNP), South Africa, both the common A and rare B strains clades occur. The B clade strains were reported to be dominant in Pafuri before 1991, while A clade strains occurred towards the central parts of KNP. The prevalence of B clade strains is currently much lower as only A clade strains have been isolated from 1992 onwards in KNP. In this study 319 B. anthracis strains were characterized with 31-loci multiple-locus variable-number tandem repeat analysis (MLVA-31). B clade strains from soil ( n = 9) and a Tragelaphus strepsiceros carcass ( n = 1) were further characterised by whole genome sequencing and compared to publicly available genomes. The KNP strains clustered in the B clade before 1991 into two dominant genotypes. South African strains cluster into a dominant genotype A.Br.005/006 consisting of KNP as well as the other anthrax endemic region, Northern Cape Province (NCP), South Africa. A few A.Br.001/002 strains from both endemic areas were also identified. Subclade A.Br.101 belonging to the A.Br.Aust94 lineage was reported in the NCP. The B-clade strains seems to be vanishing, while outbreaks in South Africa are caused mainly by the A.Br.005/006 genotypes as well as a few minor clades such as A.Br.001/002 and A.Br.101 present in NCP. This work confirmed the existence of the rare and vanishing B-clade strains that group in B.Br.001 branch with KrugerB and A0991 KNP strains.
Central carbon metabolism, sodium-motive electron ransfer, and ammonium formation by the vaginal pathogen Prevotella bivia
(2021) Schleicher, Lena; Herdan, Sebastian; Fritz, Günter; Trautmann, Andrej; Seifert, Jana; Steuber, Julia
Replacement of the Lactobacillus dominated vaginal microbiome by a mixed bacterial population including Prevotella bivia is associated with bacterial vaginosis (BV). To understand the impact of P. bivia on this microbiome, its growth requirements and mode of energy production were studied. Anoxic growth with glucose depended on CO2 and resulted in succinate formation, indicating phosphoenolpyruvate carboxylation and fumarate reduction as critical steps. The reductive branch of fermentation relied on two highly active, membrane-bound enzymes, namely the quinol:fumarate reductase (QFR) and Na+-translocating NADH:quinone oxidoreductase (NQR). Both enzymes were characterized by activity measurements, in-gel fluorography, and VIS difference spectroscopy, and the Na+-dependent build-up of a transmembrane voltage was demonstrated. NQR is a potential drug target for BV treatment since it is neither found in humans nor in Lactobacillus. In P. bivia, the highly active enzymes L-asparaginase and aspartate ammonia lyase catalyze the conversion of asparagine to the electron acceptor fumarate. However, the by-product ammonium is highly toxic. It has been proposed that P. bivia depends on ammonium-utilizing Gardnerella vaginalis, another typical pathogen associated with BV, and provides key nutrients to it. The product pattern of P. bivia growing on glucose in the presence of mixed amino acids substantiates this notion.
Cognitive alterations in old mice are associated with intestinal barrier dysfunction and induced toll-like receptor 2 and 4 signaling in different brain regions
(2023) Brandt, Annette; Kromm, Franziska; Hernández-Arriaga, Angélica; Martínez Sánchez, Inés; Bozkir, Haktan Övül; Staltner, Raphaela; Baumann, Anja; Camarinha-Silva, Amélia; Heijtz, Rochellys Diaz; Bergheim, Ina
Emerging evidence implicate the ‘microbiota–gut–brain axis’ in cognitive aging and neuroinflammation; however, underlying mechanisms still remain to be elucidated. Here, we assessed if potential alterations in intestinal barrier function and microbiota composition as well as levels of two key pattern-recognition receptors namely Toll-like receptor (TLR) 2 and TLR4, in blood and different brain regions, and depending signaling cascades are paralleling aging associated alterations of cognition in healthy aging mice. Cognitive function was assessed in the Y-maze and intestinal and brain tissue and blood were collected in young (4 months old) and old (24 months old) male C57BL/6 mice to determine intestinal microbiota composition by Illumina amplicon sequencing, the concentration of TLR2 and TLR4 ligands in plasma and brain tissue as well as to determine markers of intestinal barrier function, senescence and TLR2 and TLR4 signaling. Cognitive function was significantly impaired in old mice. Also, in old mice, intestinal microbiota composition was significantly altered, while the relative abundance of Gram-negative or Gram-positive bacteria in the small and large intestines at different ages was not altered. Moreover, intestinal barrier function was impaired in small intestine of old mice, and the levels of TLR2 and TLR4 ligands were also significantly higher in both portal and peripheral blood. Furthermore, levels of TLR2 and TLR4 ligands, and downstream markers of TLR signaling were higher in the hippocampal and prefrontal cortex of old mice compared to young animals. Taken together, our results suggest that even in ‘healthy’ aging, cognitive function is impaired in mice going along with an increased intestinal translocation of TLR ligands and alterations of TLR signaling in several brain regions.
Determination of optimal phage load and administration time for antibacterial treatment
(2024) Plunder, Steffen; Burkard, Markus; Helling, Thomas; Lauer, Ulrich M.; Hoelzle, Ludwig E.; Marongiu, Luigi
Using phages as antibacterials is becoming a customary practice in Western countries. Nonetheless, successful treatments must consider the growth rate of the bacterial host and the degradation of the virions. Therefore, successful treatments require administering the right amount of phage (viral load, Vφ) at the right moment (administration time, Tφ). The present protocols implement a machine learning approach to determine the best combination of Vφ and Tφ to obtain the elimination of the target bacterium from a system. Basic Protocol 1: One bacterium, one phage. Alternate Protocol 1: One bacterium, one phage (wrapping function). Alternate Protocol 2: One bacterium, one phage (wrapping function, alternative growing model). Basic Protocol 2: Two bacteria, one phage. Alternate Protocol 3: Two bacteria, one phage (launch from terminal).
Intestinal dysbiosis associated with non-nutritive sweeteners intake: an effect without a cause?
(2025) Marongiu, Luigi; Brzozowska, Ewa; Hetjens, Svetlana; Hoelzle, Ludwig E.; Venturelli, Sascha; Brzozowska, Ewa; Laboratory of Medical Microbiology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland; Hetjens, Svetlana; Department of Medical Statistics, Biomathematics and Information Processing, University Clinic Mannheim, Mannheim, Germany; Hoelzle, Ludwig E.; Department of Food Microbiology and Hygiene, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Venturelli, Sascha; Department of Nutritional Biochemistry, University of Hohenheim, Stuttgart, Germany
Non-nutritive sweeteners (NNS) are present in various commercial articles, from foodstuffs to oral hygiene products. Despite their alleged safety, mounting evidence indicates that NNS intake is associated with an alteration of intestinal bacterial populations (dysbiosis) in animals and humans. Since NNS are commercialized based on the assumption that they are not metabolized by human cells and negligible effect on bacterial, the insurgence of dysbiosis associated with NNS intake remains unexplained. The current review aims to assess the effect of selected NNS (acesulfame potassium, advantame, aspartame, neotame, saccharin, stevia, and sucralose) on the human intestinal microbiota. Findings from this review suggests that NNS intake is linked not only to alterations in human physiology but also to modifications of bacterial biochemistry, including the hindrance of quorum sensing pathways, in a species-specific manner. Moreover, there were suggestions that NNS could also affect the biology of phages, namely by binding to the active sites of proteins involved in the infection process and altering the induction rate of prophages. The studies gathered in the present review provide a framework for understanding how NNS might be connected to dysbiosis, both directly through alterations in bacterial biochemistry and indirectly through impaired phage activity.
New insights into the phylogeny of the A.Br.161 (“A.Br.Heroin”) clade of Bacillus anthracis
(2024) Antwerpen, Markus; Beyer, Wolfgang; Grass, Gregor; Anderson, Deborah
Bacillus anthracis is a rare but highly dangerous zoonotic bacterial pathogen. At the beginning of this century, a new manifestation of the disease, injectional anthrax, emerged as a result of recreational heroin consumption involving contaminated drugs. The organisms associated with this 13-year-lasting outbreak event in European drug consumers were all grouped into the canonical single-nucleotide polymorphism (canSNP) clade A-branch (A.Br.) 161 of B. anthracis . Related clade A.Br.161 strains of B. anthracis not associated with heroin consumption have also been identified from different countries, mostly in Asia. Because of inadvertent spread by anthropogenic activities, other strains of this A.Br.161 lineage were, however, isolated from several countries. Thus, without additional isolates from this clade, its origin of evolution or its autochthonous region remains obscure. Here, we genomically characterized six new A.Br.161 group isolates, some of which were from Iran, with others likely historically introduced into Germany. All the chromosomes of these isolates could be grouped into a distinct sub-clade within the A.Br.161 clade. This sub-clade is separated from the main A.Br.161 lineage by a single SNP. We have developed this SNP into a PCR assay facilitating the future attribution of strains to this group.
Nutrient–response modeling with a single and interpretable artificial neuron
(2025) Rodehutscord, Markus; Ahmadi, Hamed
Precise estimation of nutrient requirements and utilization efficiency is fundamental to nutritional sciences, yet it is mainly performed using classical nonlinear regression models. These models are interpretable but require careful selection of the functional form and initial parameter values. Flexible machine learning (ML) methods are seemingly disliked due to their perceived “black box” nature, which can obscure biological insight. A minimal and interpretable ML framework addresses this gap in nutrient–response modeling. The proposed approach uses a single artificial neuron with a hyperbolic tangent activation. Mathematically, this resembles a four-parameter sigmoidal function but with greater flexibility and distinct parameter definitions, allowing capture of the monotonic, saturating dynamics typical of essential nutrient responses. The method is enhanced with modern ML best practices, including data augmentation, Bayesian regularization, and bootstrap resampling, providing robust, uncertainty-quantified estimates of key nutritional metrics—such as asymptotic response, inflection point, and nutrient requirements—even from small datasets. Evaluations across 12 diverse datasets from poultry and fish studies, including amino acids and phosphorus, demonstrated that the single artificial neuron matches or exceeds the performance of classical models while providing full analytical transparency. The framework is implemented as a no-code graphical application, ‘NutriCurvist’, offering an easy-to-use alternative tool for nutrient-response modeling to support data-driven, precision nutrition.

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