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- ItemAirborne bacterial emission fluxes from manure-fertilized agricultural soil(Oxford : Wiley-Blackwell, 2020) Thiel, Nadine; Münch, Steffen; Behrens, Wiebke; Junker, Vera; Faust, Matthias; Biniasch, Oliver; Kabelitz, Tina; Siller, Paul; Boedeker, Christian; Schumann, Peter; Roesler, Uwe; Amon, Thomas; Schepanski, Kerstin; Funk, Roger; Nübel, UlrichThis is the first study to quantify the dependence on wind velocity of airborne bacterial emission fluxes from soil. It demonstrates that manure bacteria get aerosolized from fertilized soil more easily than soil bacteria, and it applies bacterial genomic sequencing for the first time to trace environmental faecal contamination back to its source in the chicken barn. We report quantitative, airborne emission fluxes of bacteria during and following the fertilization of agricultural soil with manure from broiler chickens. During the fertilization process, the concentration of airborne bacteria culturable on blood agar medium increased more than 600 000-fold, and 1 m3 of air carried 2.9 × 105 viable enterococci, i.e. indicators of faecal contamination which had been undetectable in background air samples. Trajectory modelling suggested that atmospheric residence times and dispersion pathways were dependent on the time of day at which fertilization was performed. Measurements in a wind tunnel indicated that airborne bacterial emission fluxes from freshly fertilized soil under local climatic conditions on average were 100-fold higher than a previous estimate of average emissions from land. Faecal bacteria collected from soil and dust up to seven weeks after fertilization could be traced to their origins in the poultry barn by genomic sequencing. Comparative analyses of 16S rRNA gene sequences from manure, soil and dust showed that manure bacteria got aerosolized preferably, likely due to their attachment to low-density manure particles. Our data show that fertilization with manure may cause substantial increases of bacterial emissions from agricultural land. After mechanical incorporation of manure into soil, however, the associated risk of airborne infection is low.
- ItemBioactive secondary metabolites with multiple activities from a fungal endophyte(Oxford : Wiley-Blackwell, 2016) Bogner, Catherine W.; Kamdem, Ramsay S.T.; Sichtermann, Gisela; Matthäus, Christian; Hölscher, Dirk; Popp, Jürgen; Proksch, Peter; Grundler, Florian M.W.; Schouten, AlexanderIn order to replace particularly biohazardous nematocides, there is a strong drive to finding natural product-based alternatives with the aim of containing nematode pests in agriculture. The metabolites produced by the fungal endophyte Fusarium oxysporum 162 when cultivated on rice media were isolated and their structures elucidated. Eleven compounds were obtained, of which six were isolated from a Fusarium spp. for the first time. The three most potent nematode-antagonistic compounds, 4-hydroxybenzoic acid, indole-3-acetic acid (IAA) and gibepyrone D had LC50 values of 104, 117 and 134 μg ml−1, respectively, after 72 h. IAA is a well-known phytohormone that plays a role in triggering plant resistance, thus suggesting a dual activity, either directly, by killing or compromising nematodes, or indirectly, by inducing defence mechanisms against pathogens (nematodes) in plants. Such compounds may serve as important leads in the development of novel, environmental friendly, nematocides.
- ItemNovel genetic modules encoding high-level antibiotic-free protein expression in probiotic lactobacilli(Oxford : Wiley-Blackwell, 2023) Dey, Sourik; Blanch‐Asensio, Marc; Balaji Kuttae, Sanjana; Sankaran, ShrikrishnanLactobacilli are ubiquitous in nature, often beneficially associated with animals as commensals and probiotics, and are extensively used in food fermentation. Due to this close-knit association, there is considerable interest to engineer them for healthcare applications in both humans and animals, for which high-performance and versatile genetic parts are greatly desired. For the first time, we describe two genetic modules in Lactiplantibacillus plantarum that achieve high-level gene expression using plasmids that can be retained without antibiotics, bacteriocins or genomic manipulations. These include (i) a promoter, PtlpA, from a phylogenetically distant bacterium, Salmonella typhimurium, which drives up to 5-fold higher level of gene expression compared to previously reported promoters and (ii) multiple toxin-antitoxin systems as a self-contained and easy-to-implement plasmid retention strategy that facilitates the engineering of tuneable transient genetically modified organisms. These modules and the fundamental factors underlying their functionality that are described in this work will greatly contribute to expanding the genetic programmability of lactobacilli for healthcare applications.
- ItemExpanding the genetic programmability of Lactiplantibacillus plantarum(Oxford : Wiley-Blackwell, 2024) Blanch‐Asensio, Marc; Dey, Sourik; Tadimarri, Varun Sai; Sankaran, ShrikrishnanLactobacilli are ubiquitous in nature and symbiotically provide health benefits for countless organisms including humans, animals and plants. They are vital for the fermented food industry and are being extensively explored for healthcare applications. For all these reasons, there is considerable interest in enhancing and controlling their capabilities through the engineering of genetic modules and circuits. One of the most robust and reliable microbial chassis for these synthetic biology applications is the widely used Lactiplantibacillus plantarum species. However, the genetic toolkit needed to advance its applicability remains poorly equipped. This mini-review highlights the genetic parts that have been discovered to achieve food-grade recombinant protein production and speculates on lessons learned from these studies for L. plantarum engineering. Furthermore, strategies to identify, create and optimize genetic parts for real-time regulation of gene expression and enhancement of biosafety are also suggested.
- ItemAntimicrobial effects of microwave-induced plasma torch (MiniMIP) treatment on Candida albicans biofilms(Oxford : Wiley-Blackwell, 2019) Handorf, Oliver; Schnabel, Uta; Bösel, André; Weihe, Thomas; Bekeschus, Sander; Graf, Alexander Christian; Riedel, Katharina; Ehlbeck, JörgThe susceptibility of Candida albicans biofilms to a non-thermal plasma treatment has been investigated in terms of growth, survival and cell viability by a series of in vitro experiments. For different time periods, the C. albicans strain SC5314 was treated with a microwave-induced plasma torch (MiniMIP). The MiniMIP treatment had a strong effect (reduction factor (RF) = 2.97 after 50 s treatment) at a distance of 3 cm between the nozzle and the superior regions of the biofilms. In addition, a viability reduction of 77% after a 20 s plasma treatment and a metabolism reduction of 90% after a 40 s plasma treatment time were observed for C. albicans. After such a treatment, the biofilms revealed an altered morphology of their cells by atomic force microscopy (AFM). Additionally, fluorescence microscopy and confocal laser scanning microscopy (CLSM) analyses of plasma-treated biofilms showed that an inactivation of cells mainly appeared on the bottom side of the biofilms. Thus, the plasma inactivation of the overgrown surface reveals a new possibility to combat biofilms. © 2019 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.
- ItemCaspase-1 inflammasome activity in patients with Staphylococcus aureus bacteremia(Oxford : Wiley-Blackwell, 2019) Rasmussen, Gunlög; Idosa, Berhane Asfaw; Bäckman, Anders; Monecke, Stefan; Strålin, Kristoffer; Särndahl, Eva; Söderquist, BoThe inflammasome is a multiprotein complex that mediates caspase-1 activation with subsequent maturation of the proinflammatory cytokines IL-1ß and IL-18. The NLRP3 inflammasome is known to be activated by Staphylococcus aureus, one of the leading causes of bacteremia worldwide. Inflammasome activation and regulation in response to bacterial infection have been found to be of importance for a balanced host immune response. However, inflammasome signaling in vivo in humans initiated by S. aureus is currently sparsely studied. This study therefore aimed to investigate NLRP3 inflammasome activity in 20 patients with S. aureus bacteremia (SAB), by repeated measurement during the first week of bacteremia, compared with controls. Caspase-1 activity was measured in monocytes and neutrophils by flow cytometry detecting FLICA (fluorescent-labeled inhibitor of caspase-1), while IL-1ß and IL-18 was measured by Luminex and ELISA, respectively. As a measure of inflammasome priming, messenger RNA (mRNA) expression of NLRP3, CASP1 (procaspase-1), and IL1B (pro-IL-1ß) was analyzed by quantitative PCR. We found induced caspase-1 activity in innate immune cells with subsequent release of IL-18 in patients during the acute phase of bacteremia, indicating activation of the inflammasome. There was substantial interindividual variation in caspase-1 activity between patients with SAB. We also found an altered inflammasome priming with low mRNA levels of NLRP3 accompanied by elevated mRNA levels of IL1B. This increased knowledge of the individual host immune response in SAB could provide support in the effort to optimize management and treatment of each individual patient. © 2019 The Authors. Microbiology and Immunology published by The Societies and John Wiley & Sons Australia, Ltd