Biofilm formation and extracellular polymeric substances of acidophilic metal/sulfur-oxidizing archaea

In this study, biofilm formation and extracellular polymeric substances (EPS) of acidophilic archaea were investigated. Three representative archaeal species extremely acidophilic archaeon Ferroplasma acidiphilum, thermoacidophilic archaea Acidianus sp. DSM 29099 and Sulfolobus metallicus were chosen as test organisms. Several cultivation and advanced microscopical techniques e.g. CLSM, AFM & EFM and SEM were used to visualize and characterize biofilm development and EPS of acidophilic archaea. In addition, FLBA, ATR-FTIR and conventional spectroscopic methods were applied for qualification and quantification of EPS components. F. acidiphilum biofilms were heterogeneously distributed on polycarbonate filters over time, and varied within the different growth conditions such as supplementation with glucose. Cells formed a monolayer biofilm and were preferably attached to the defect sites of pyrite surfaces. Biofilm and planktonic cells exhibited significant morphological differences as revealed by AFM. Low coverage of pyrite surface by cells seems to correlate with their low leaching ability. Screening of a lectin library resulted in the detection of 21 lectins able to bind archaeal biofilms on pyrite and to Acidianus sp. DSM 29099 biofilms on elemental sulfur (S0). These lectins can be used in studies for assessment of interactions between various members of microbial bioleaching communities, especially in order to elucidate the role of archaea in detail. The major binding patterns, e.g. tightly bound EPS and loosely bound EPS, were detected on both substrates pyrite and S¬0. The three archaeal species produced various EPS glycoconjugates containing sugar moieties like glucose, galactose, mannose, GlcNAc, GalNAc, sialic acid, and fucose. Additionally, the substratum induced different EPS glycoconjugates and biofilm structures for cells of Acidianus sp. DSM 29099. EPS analysis of S. metallicusT on S0 showed that capsular EPS from planktonic cells were mainly composed of carbohydrates and proteins. In contrast, colloidal EPS from planktonic cells were dominated by carbohydrates. Proteins were found to be major components in EPS from biofilms on S0. In addition, extracellular proteins and nucleic acids were present in the EPS matrix. The existence of these compounds suggest their potential roles in biofilm formation and stabilization. S. metallicusT cells were shown to be embedded in a gel-like and flexible EPS matrix, where cells were often found to be motile (back and forth) either self-propelled by cellular appendages or by ‘Brownian motion’

Arsenate and Arsenite Sorption Using Biogenic Iron Compounds: Treatment of Real Polluted Waters in Batch and Continuous Systems

Arsenic pollution in waters is due to natural and anthropogenic sources. Human exposure to arsenic is associated with acute health problems in areas with high concentrations of this element. Nanometric iron compounds with large specific surface areas and higher binding energy produced by some anaerobic microorganisms are thus expected to be more efficient adsorbents for the removal of harmful metals and metalloids than chemically produced iron oxides. In this study, a natural consortium from an abandoned mine site containing mainly Clostridium species was used to biosynthesize solid Fe(II) compounds, siderite (FeCO3) and iron oxides. Biogenic precipitates were used as adsorbents in contact with solutions containing arsenate and arsenite. The adsorption of As(V) fitted to the Langmuir model (qmax = 0.64 mmol/g, KL = 0.019 mmol/L) at the optimal pH value (pH 2), while the As(III) adsorption mechanism was better represented by the Freundlich model (KF = 0.476 L/g, n = 2.13) at pH 10. Water samples from the Caracarani River (Chile) with high contents of arsenic and zinc were treated with a biogenic precipitate encapsulated in alginate beads in continuous systems. The optimal operation conditions were low feed flow rate and the up-flow system, which significantly improved the contaminant uptake. This study demonstrates the feasibility of the application of biogenic iron compounds in the treatment of polluted waters.Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasTRUEMinisterio de Economía y Competitividadpu

Experimental investigation on thermal performance of underground refuge chamber under natural convection and ventilation

© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the Creative Commons Attribution-NonCommercial-NoDerivatives CC BY-NC-ND licence, https://creativecommons.org/licenses/by-nc-nd/4.0/Thermal performance of densely populated underground buildings is normally influenced by various factors, including the surrounding rock (SR), ventilation, and indoor heat sources. It is recognized that little experimental studies on thermal control for the above building was reported. In this article, a full-size 50-person mine refuge chamber (MRC) was newly constructed to test the thermal performance under natural convection and ventilation. The heat ducts were used to simulate the heat released from human body. Experimental results indicated that: (1) the intensity of the heat transfer between rock and air increases with the rise in heat source rate and ventilation temperature (VT), while it decreases as the initial surrounding rock temperature (ISRT) increases; (2) when considering the joint temperature control of pre-cooled SR, it is recommended to reduce the VT linearly during the evacuation period in order to ensure the thermal safety of personnel. During the non-refuge period, the cold amount should be stored as far as possible into the shallow SR body to make full use of it; (3) to ensure the thermal safety of an MRC with a capacity of 30 people for 96 h, cooling measures are required when the ISRT exceeds 21.3 °C. In addition, when the ISRT reaches 27.6 °C, the per capita ventilation is 0.19 m3/min, and the temperature is 26 °C, which can also meet the requirements. This study provides experimental verification as a basis for future research on underground space temperature control considering the influence of SR.Peer reviewe

Insight Into Interactions of Thermoacidophilic Archaea With Elemental Sulfur: Biofilm Dynamics and EPS Analysis

Biooxidation of reduced inorganic sulfur compounds (RISCs) by thermoacidophiles is of particular interest for the biomining industry and for environmental issues, e.g., formation of acid mine drainage (AMD). Up to now, interfacial interactions of acidophiles with elemental sulfur as well as the mechanisms of sulfur oxidation by acidophiles, especially thermoacidophiles, are not yet fully clear. This work focused on how a crenarchaeal isolate Acidianus sp. DSM 29099 interacts with elemental sulfur. Analysis by Confocal laser scanning microscopy (CLSM) and Atomic force microscopy (AFM) in combination with Epifluorescence microscopy (EFM) shows that biofilms on elemental sulfur are characterized by single colonies and a monolayer in first stage and later on 3-D structures with a diameter of up to 100 μm. The analysis of extracellular polymeric substances (EPS) by a non-destructive lectin approach (fluorescence lectin-barcoding analysis) using several fluorochromes shows that intial attachment was featured by footprints rich in biofilm cells that were embedded in an EPS matrix consisting of various glycoconjugates. Wet chemistry data indicate that carbohydrates, proteins, lipids and uronic acids are the main components. Attenuated reflectance (ATR)-Fourier transformation infrared spectroscopy (FTIR) and high-performance anion exchange chromatography with pulsed amperometric detection (HPAE-PAD) indicate glucose and mannose as the main monosaccharides in EPS polysaccharides. EPS composition as well as sugar types in EPS vary according to substrate (sulfur or tetrathionate) and lifestyle (biofilms and planktonic cells). This study provides information on the building blocks/make up as well as dynamics of biofilms of thermoacidophilic archaea in extremely acidic environments

Mediation of Extracellular Polymeric Substances in Microbial Reduction of Hematite by Shewanella oneidensis MR-1

Extracellular electron transfer (EET) plays a fundamental role in microbial reduction/oxidation of minerals. Extracellular polymeric substances (EPS) surrounding the cells constitute a matrix that separates the cell’s outer membrane from insoluble minerals and environmental fluid. This study investigated the effects of EPS on EET processes during microbial reduction of hematite by the iron-reducing strain Shewanella oneidensis MR-1 (MR-1). Electrochemical characterization techniques were employed to determine the influence of EPS components on the redox ability of MR-1. Cells with removed EPS exhibited approximately 30% higher hematite reduction than regular MR-1 cells, and produced a current density of 56 μA cm-2, corresponding to 3–4 fold that of regular MR-1. The superior EET of EPS-deprived cells could be attributed to direct contact between outer membrane proteins and hematite surface, as indicated by more redox peaks being detected by cyclic voltammetry and differential pulse voltammetry. The significantly reduced current density of MR-1 cells treated with proteinase K and deoxyribonuclease suggests that the electron transfer capacity across the EPS layer depends mainly on the spatial distribution of specific proteins and electron shuttles. Exopolysaccharides in EPS tend to inhibit electron transfer, however they also favor the attachment of cells onto hematite surfaces. Consistently, the charge transfer resistance of cells lacking EPS was only 116.3 Ω, approximately 44 times lower than that of regular cells (5,139.1 Ω). These findings point to a negative influence of EPS on EET processes for microbial reduction/oxidation of minerals

bifA Regulates Biofilm Development of Pseudomonas putida MnB1 as a Primary Response to H2O2 and Mn2+

Pseudomonas putida (P. putida) MnB1 is a widely used model strain in environment science and technology for determining microbial manganese oxidation. Numerous studies have demonstrated that the growth and metabolism of P. putida MnB1 are influenced by various environmental factors. In this study, we investigated the effects of hydrogen peroxide (H2O2) and manganese (Mn2+) on proliferation, Mn2+ acquisition, anti-oxidative system, and biofilm formation of P. putida MnB1. The related orthologs of 4 genes, mco, mntABC, sod, and bifA, were amplified from P. putida GB1 and their involvement were assayed, respectively. We found that P. putida MnB1 degraded H2O2, and quickly recovered for proliferation, but its intracellular oxidative stress state was maintained, with rapid biofilm formation after H2O2 depletion. The data from mco, mntABC, sod and bifA expression levels by qRT-PCR, elucidated a sensitivity toward bifA-mediated biofilm formation, in contrary to intracellular anti-oxidative system under H2O2 exposure. Meanwhile, Mn2+ ion supply inhibited biofilm formation of P. putida MnB1. The expression pattern of these genes showed that Mn2+ ion supply likely functioned to modulate biofilm formation rather than only acting as nutrient substrate for P. putida MnB1. Furthermore, blockade of BifA activity by GTP increased the formation and development of biofilms during H2O2 exposure, while converse response to Mn2+ ion supply was evident. These distinct cellular responses to H2O2 and Mn2+ provide insights on the common mechanism by which environmental microorganisms may be protected from exogenous factors. We postulate that BifA-mediated biofilm formation but not intracellular anti-oxidative system may be a primary protective strategy adopted by P. putida MnB1. These findings will highlight the understanding of microbial adaptation mechanisms to distinct environmental stresses

Genome-wide analysis of circular RNAs in goat skin fibroblast cells in response to Orf virus infection

Orf, caused by Orf virus (ORFV), is a globally distributed zoonotic disease responsible for serious economic losses in the agricultural sector. However, the mechanism underlying ORFV infection remains largely unknown. Circular RNAs (circRNAs), a novel type of endogenous non-coding RNAs, play important roles in various pathological processes but their involvement in ORFV infection and host response is unclear. In the current study, whole transcriptome sequencing and small RNA sequencing were performed in ORFV-infected goat skin fibroblast cells and uninfected cells. A total of 151 circRNAs, 341 messenger RNAs (mRNAs), and 56 microRNAs (miRNAs) were differently expressed following ORFV infection. Four circRNAs: circRNA1001, circRNA1684, circRNA3127 and circRNA7880 were validated by qRT-PCR and Sanger sequencing. Gene ontology (GO) analysis indicated that host genes of differently expressed circRNAs were significantly enriched in regulation of inflammatory response, epithelial structure maintenance, positive regulation of cell migration, positive regulation of ubiquitin-protein transferase activity, regulation of ion transmembrane transport, etc. The constructed circRNA-miRNA-mRNA network suggested that circRNAs may function as miRNA sponges indirectly regulating gene expression following ORFV infection. Our study presented the first comprehensive profiles of circRNAs in response to ORFV infection, thus providing new clues for the mechanisms of interactions between ORFV and the host

Polarization management for coherent optical receivers

The constant growth of bandwidth requirements in optical communication networks has prompted the evolution from conventional on-off-keying (OOK) transmission techniques to coherent, polarization multiplexed schemes. The higher spectral efficiency afforded by this approach enables per channel data rates of 100–400Gbps over existing fiber infrastructure. Both the transmitters and receivers benefit from monolithic integration, as it reduces costs and offers rugged performance. A block diagram of a coherent polarization multiplex receiver is shown in Fig. 1(a) and basically consists of: i) polarization splitters ii) high performance 90º hybrids and iii) high speed photodiodes. A first monolithically integrated coherent receiver was presented in [1], which, however, required external polarization management. Integration of the polarization managing elements, such as polarization splitters or polarization rotators, is challenging as they exhibit stringing fabrication tolerances. Here, we will review some recent advances in integrated polarization management. Furthermore, we discuss the design of tunable, fabrication tolerant polarization splitters based on Mach-Zehnder structures as shown in Fig. 1(b) [2], carried out in the EU-FP7 Mirthe project. The operation of a monolithically integrated polarization multiplex coherent receiver based on these polarization splitters has been recently demonstrated [3].Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Hysterothylacium sinense Li, An & Zhang, 2007, sp. nov.

Hysterothylacium sinense sp. nov. (Figs. 1–2) Type host: Astroconger myriaster (Brevoort). Other hosts: Trichiurus haumela (Forsskål), Saurida elongata Temminck and Schlegel, Coryphaena hippurus Linnaeus, Sillago sihama (Forsskål) and Argyrosomus argentatus (Houttuyn). Site of infection: Intestine. Date of collection: 28 September 2006. Type locality: Shidao Island (122 ° 26 ’ 42 ’’ E; 36 ° 52 ’ 57 ’’ N), Yellow Sea, Shandong Province, China. Prevalence and intensity: 12.1 % (4 infected / 33 examined), 2–16 (7.3) specimens in Astroconger myriaster; 4.5 % (1 infected / 22 examined), 5 specimens in Trichiurus haumela; 3.4 % (1 infected / 29 examined), 4 specimens in Saurida elongate; 6.3 % (1 infected / 16 examined), 8 specimens in Coryphaena hippurus; 4.3 % (1 infected / 23 examined), 3 specimens in Sillago sihama; 1.7 % (1 infected / 60 examined), 2 specimens in Argyrosomus argentatus. Type specimens: Holotype male (HBNU-0706), allotype female (HBNU-0707), paratypes: 8 male (HBNU-0708) and 5 female (HBNU-0709). Etymology: The species name refers to its geographic location (China). Description: Medium sized, whitish nematodes, cuticle with fine, transverse striations. Lateral alae present, very broad. Anterior end with 3 lips; dorsal lip slightly smaller than sub-ventrals, with deep postlabial grooves and prominent lateral flanges. Proximal part of each lip with four lobes. Dorsal lip with 2 lateral double papillae; sub-ventral lips each with one amphid, one single papilla and one double papilla. Interlabia well developed, triangular with base wider than length, about 1 / 2 length of lips. Oesophagus long, slightly broader posteriorly than anteriorly. Nerve ring encircling oesophagus between first and second sixths of its length. Ventriculus almost spherical, approximately as wide as oesophagus. Ventricular appendix narrow, usually somewhat shorter than intestinal caecum. Excretory pore slightly posterior to nerve ring. Rectum hyaline, tube-shaped, surrounded by 3 large, unicellular rectal glands. Tail conical, relatively short, tip of male tail without any ornamentation; tip of female tail covered with numerous nodular protuberance. Male (based on 9 mature specimens): Body 23.1–40.1 (32.0) mm long, maximum width 197–345 (283). Dorsal lip 78.6–123 (102) long, 108–116 (110) wide. Sub-ventral lips 101–125 (113) long, 98–115 (111) wide. Interlabia 49–58 (50) long, 68–113 (91) wide. Lateral alae 49–87 (67) wide in the level of oesophagus. Oesophagus 2.04–3.45 (2.74) mm long, 7.2–10.3 (9.0) % of body length (BL), 69–123 (95) wide. Nerve ring 473–682 (593) from anterior extremity; excretory pore 491–742 (640) from anterior extremity. Ventriculus 97–152 (131) long by 87–151 (122) wide. Ventricular appendix 1.07–2.43 (1.67) mm long by 49–114 (87) wide. Intestinal caecum 1.26–2.33 (1.78) mm long, 61–71 (65) % of oesophageal length; 58–113 (90) wide. Ratio of intestinal caecum to ventricular appendix 1: 0.80–1.08 (1: 0.94). Ejaculatory duct 1.21–2.28 (1.66) mm long, 4.1–7.1 (5.2) % of BL. Spicules slender, of equal length, 1.65–2.67 (2.10) mm long, 102–166 (127) % of ejaculatory duct (ED) and 5.1–9.5 (6.7) % of BL. Gubernaculum absent. Tail 78–124 (95) long; tail tip 19–29 (21) long, without ornamentation. Caudal papillae arranged as follows: 22–27 pairs of preanal papillaee, 1 pair of very small paranal papillae and 3 pairs of postanal papillae. Female (based on 6 gravid specimens): Body 29.3–43.9 (38.4) mm long, maximum width 293–362 (324). Dorsal lip 87–154 (123) long, 94–133 (124) wide. Sub-ventral lips 102–145 (136) long, 98–131 (118) wide. Interlabia 49–50 (49) long, 87–113 (92) wide. Lateral alae 49–78 (66) wide. Oesophagus 2.74–3.40 (3.03) mm long, 6.8–9.9 (8.1) % of BL; maximum width 97–134 (121). Nerve ring 531–633 (604) from anterior extremity; excretory pore 580–752 (672) from anterior extremity. Ventriculus 121–153 (144) long by 97– 154 (130) wide. Ventricular appendix 1.51–1.89 (1.69) mm long by 68–97 (80) wide. Intestinal caecum 1.99– 2.28 (2.11) mm long, 65.1 –75.0 (69.7) % of oesophageal length; 97–122 (113) wide. Ratio of intestinal caecum to ventricular appendix 1: 0.68–0.95 (1: 0.81). Tail length 232–321 (262), tail tip 19–20 (19) long, with numerous nodular protuberances. Vulva slit-like, without salient lips, located pre-equatorially, 23.9–31.7 (28.7) % from anterior end. Vagina muscular, directed posteriorly. Uteri opposed. Eggs embryonated, oval, 36.0– 38.1 (37.5) long by 37.3–41.1 (39.1) wide.Published as part of Li, Liang, An, Ruiyong & Zhang, Luping, 2007, A new species of Hysterothylacium (Nematoda: Anisakidae) from marine fishes from Yellow Sea, China, with a key to the species of the genus Hysterothylacium, pp. 43-52 in Zootaxa 1614 on pages 44-45, DOI: 10.5281/zenodo.17903