• Coprinuslactone protects the edible mushroom Coprinus comatus against biofilm infections by blocking both quorum-sensing and MurA.

      de Carvalho, Maira P; Gulotta, Giuseppe; do Amaral, Matheus W; Lünsdorf, Heinrich; Sasse, Florenz; Abraham, Wolf-Rainer; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-10-03)
      Pathogens embedded in biofilms are involved in many infections and are very difficult to treat with antibiotics because of higher resistance compared to planktonic cells. Therefore, new approaches for their control are urgently needed. One way to search for biofilm dispersing compounds is to look at defense strategies of organisms exposed to wet environments, which makes them prone to biofilm infections. It is reasonable to assume that mushrooms have developed mechanisms to control biofilms on their sporocarps (fruiting bodies). A preliminary screening for biofilms on sporocarps revealed several species with few or no bacteria on their sporocarps. From the edible mushroom Coprinus comatus where no bacteria on the sporocarp could be detected (3R,4S)-2-methylene-3,4-dihydroxypentanoic acid 1,4-lactone, named coprinuslactone, was isolated. Coprinuslactone interfered with quorum-sensing and dispersed biofilms of Pseudomonas aeruginosa, where it also reduced the formation of the pathogenicity factors pyocyanin and rhamnolipid B. Coprinuslactone also damaged Staphylococcus aureus cells in biofilms at subtoxic concentrations. Furthermore, it inhibited UDP-N-acetylglucosamine enolpyruvyl transferase (MurA), essential for bacterial cell wall synthesis. These two modes of action ensure the inhibition of a broad spectrum of pathogens on the fruiting body but may also be useful for future clinical applications. This article is protected by copyright. All rights reserved.
    • Proposal of Henriciella barbarensis sp. nov. and Henriciella algicola sp. nov., stalked species of the genus and emendation of the genus Henriciella.

      Abraham, Wolf-Rainer; de Carvalho, Maira Peres; da Costa Neves, Thais Souto Paula; Memoria, Marina Torquato; Tartuci, Iago Toledo; Vancanneyt, Marc; Smit, John; Rohde, M; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7,38124 Braunschweig, Germany. (2017-08)
      Two Gram-negative, heterotrophic, aerobic, prosthecated, marine bacteria, designated strains MCS23T and MCS27T, were isolated from seawater samples. NaCl was required for growth. The major polar lipid detected in strain MCS27T was phosphatidylglycerol, whereas those detected in MCS23T were phosphatidylglycerol, sulfoquinovosyl diacylglycerol and 1,2-diacyl-3-α-d-glucuronopyranosyl-sn-glycerol taurineamide. The most abundant cellular fatty acids were C18 : 1ω7 and C16 : 0, hydroxyl-fatty acids were 3-OH C12 : 0 in both strains and 3-OH C11 : 0 in MCS23T. Strains MCS23T and MCS27T had DNA G+C contents of 57.0 and 55.0 mol%, respectively. The two strains shared 99.3 % 16S rRNA gene sequence similarity; levels of similarity with the type strains of species of the genus Henriciella were 99.4-97.8 % but DNA-DNA hybridizations were 53 % or lower. Besides their 16S rRNA gene sequences, the novel strains can be differentiated from other species of the genus Henriciella by cell morphology, lipid and fatty acid patterns and enzyme activities. The data obtained led to the identification of two novel species, for which the names Henriciella barbarensis sp. nov. (type strain MCS23T=LMG 28705T=CCUG 66934T) and Henriciella algicola sp. nov. (type strain MCS27T=LMG 29152T=CCUG 67844T) are proposed. As these two novel species are the first prosthecate species in the genus Henriciella, an emended genus description is also provided.
    • Unsaturated Fatty Acids Control Biofilm Formation of and Other Gram-Positive Bacteria.

      Yuyama, Kamila Tomoko; Rohde, Manfred; Molinari, Gabriella; Stadler, Marc; Abraham, Wolf-Rainer; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI, 2020-11-08)
      Infections involving biofilms are difficult to treat due to increased resistances against antibiotics and the immune system. Hence, there is an urgent demand for novel drugs against biofilm infections. During our search for novel biofilm inhibitors from fungi, we isolated linoleic acid from the ascomycete Hypoxylon fragiforme which showed biofilm inhibition of several bacteria at sub-MIC concentrations. Many fatty acids possess antimicrobial activities, but their minimum inhibitory concentrations (MIC) are high and reports on biofilm interferences are scarce. We demonstrated that not only linoleic acid but several unsaturated long-chain fatty acids inhibited biofilms at sub-MIC concentrations. The antibiofilm activity exerted by long-chain fatty acids was mainly against Gram-positive bacteria, especially against Staphylococcus aureus. Micrographs of treated S. aureus biofilms revealed a reduction in the extracellular polymeric substances, pointing to a possible mode of action of fatty acids on S. aureus biofilms. The fatty acids had a strong species specificity. Poly-unsaturated fatty acids had higher activities than saturated ones, but no obvious rule could be found for the optimal length and desaturation for maximal activity. As free fatty acids are non-toxic and ubiquitous in food, they may offer a novel tool, especially in combination with antibiotics, for the control of biofilm infections.