FeAs2 biomineralization on encrusted bacteria in hot springs: an ecological role of symbiotic bacteria

2003 ◽  
Vol 40 (11) ◽  
pp. 1725-1738 ◽  
Author(s):  
Kazue Tazaki ◽  
Islam ABM Rafiqul ◽  
Kaori Nagai ◽  
Takayuki Kurihara
Keyword(s):  
Metal Binding ◽  
Microbial Mats ◽  
Hot Springs ◽  
Hot Spring ◽  
Binding Potential ◽  
Resistant Bacteria ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Ir Analysis

Bacterial FeAs2 mineralization was found in the reddish-brown microbial mats that have grown on the walls of the drainage systems of Masutomi Hot Springs, Yamanashi Prefecture, Japan. The reddish-brown microbial mats, which are mainly composed of bacilliform and coccoid types of bacteria, have been analyzed and observed by microtechniques to interpret the bacterial biomineralization and search for the clues to bioremediation. These bacteria accumulate Fe and As along with other trace elements to form various biominerals. The electron diffraction (ED) pattern of the bacterial capsule identified lollingite (FeAs2) and calcite (CaCO3) on the surface of the cell. Based on Fourier-transform infrared absorbance spectroscopy (FT–IR) analysis, the presence of organic components such as C—H, C=O, CNH, –COOH, and N—H in the reddish-brown microbial mats emphasized the metal-binding potential of the bacteria. X-ray diffraction (XRD) data showed the poorly crystalline character of the precipitates, which consist mainly of hydrous iron oxides (2.7 Å (1 Å = 0.1 nm)). The FeAs2 biominerals form by adsorption onto the bacterial cell wall, as demonstrated by microscopic observations and spectroscopic analysis. These showed that bacteria in the reddish-brown microbial mats have the ability to form biominerals with heavy metals and toxic metalloids like As. Particularly significant in hot spring environments is the role of symbiotic and toxic-resistant bacteria, which have the ability to adapt to high As concentrations. Bacterial FeAs2 mineralization might also be considered a mechanism by which toxic As is removed from the aquatic ecosystem. The results provide evidence for detoxification processes and offer clues to possible methods of bioremediation.

scholarly journals In-Situ Metatranscriptomic Analyses Reveal the Metabolic Flexibility of the Thermophilic Anoxygenic Photosynthetic Bacterium Chloroflexusaggregans in a Hot Spring Cyanobacteria-Dominated Microbial Mat

2021 ◽  
Vol 9 (3) ◽  
pp. 652
Author(s):  
Shigeru Kawai ◽  
Joval N. Martinez ◽  
Mads Lichtenberg ◽  
Erik Trampe ◽  
Michael Kühl ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Environmental Conditions ◽  
Microbial Mats ◽  
Carbon Fixation ◽  
Hot Springs ◽  
Hot Spring ◽  
Photosynthetic Bacterium ◽  
Early Morning ◽  
Metabolic Flexibility

Chloroflexus aggregans is a metabolically versatile, thermophilic, anoxygenic phototrophic member of the phylum Chloroflexota (formerly Chloroflexi), which can grow photoheterotrophically, photoautotrophically, chemoheterotrophically, and chemoautotrophically. In hot spring-associated microbial mats, C. aggregans co-exists with oxygenic cyanobacteria under dynamic micro-environmental conditions. To elucidate the predominant growth modes of C. aggregans, relative transcription levels of energy metabolism- and CO2 fixation-related genes were studied in Nakabusa Hot Springs microbial mats over a diel cycle and correlated with microscale in situ measurements of O2 and light. Metatranscriptomic analyses indicated two periods with different modes of energy metabolism of C. aggregans: (1) phototrophy around midday and (2) chemotrophy in the early morning hours. During midday, C. aggregans mainly employed photoheterotrophy when the microbial mats were hyperoxic (400–800 µmol L−1 O2). In the early morning hours, relative transcription peaks of genes encoding uptake hydrogenase, key enzymes for carbon fixation, respiratory complexes as well as enzymes for TCA cycle and acetate uptake suggest an aerobic chemomixotrophic lifestyle. This is the first in situ study of the versatile energy metabolism of C. aggregans based on gene transcription patterns. The results provide novel insights into the metabolic flexibility of these filamentous anoxygenic phototrophs that thrive under dynamic environmental conditions.

scholarly journals Effect of Intercalation Structure of Organo-Modified Montmorillonite/Polylactic Acid on Wheat Straw Fiber/Polylactic Acid Composites

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 896 ◽  
Author(s):  
Qiqi Fan ◽  
Guangping Han ◽  
Wanli Cheng ◽  
Huafeng Tian ◽  
Dong Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermogravimetric Analysis ◽  
Wheat Straw ◽  
Polylactic Acid ◽  
Low Cost ◽  
Interlayer Spacing ◽  
Positive Influence ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Ir Analysis

In this work, an easy way to prepare the polylactic acid (PLA)/wheat straw fiber (WSF) composite was proposed. The method involved uses either the dopamine-treated WSF or the two-step montmorillonite (MMT)-modified WSF as the filler material. In order to achieve the dispersibility and exfoliation of MMT, it was modified by 12-aminododecanoic acid using a two-step route. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to characterize the modified MMT and the coated WSF. As for the properties of PLA/WSF composites, some thermal (using Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis) and mechanical properties (flexural, tensile, and impact) were analyzed. The results showed that the dopamine was successfully coated onto the WSF. Furthermore, Na-MMT was successfully transformed to organo-montmorillonite (OMMT) and formed an exfoliated structure. In addition, a better dispersion of MMT was obtained using the two-step treatment. The interlayer spacing of modified MMT was 4.06 nm, which was 123% higher than that of the unmodified MMT. Additionally, FT-IR analysis suggested that OMMT diffused into the PLA matrix. The thermogravimetric analysis (TGA) showed that a higher thermal stability of PLA/WSF composites was obtained for the modified MMT and dopamine. The results also showed that both the dopamine treated WSF and the two-step-treated MMT exhibited a positive influence on the mechanical properties of PLA/WSF composites, especially on the tensile strength, which increased by 367% compared to the unmodified precursors. This route offers researchers a potential scheme to improve the thermal and mechanical properties of PLA/WSF composites in a low-cost way.

scholarly journals Changes in Quinone Profiles of Hot Spring Microbial Mats with a Thermal Gradient

1999 ◽  
Vol 65 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Akira Hiraishi ◽  
Taichi Umezawa ◽  
Hiroyuki Yamamoto ◽  
Kenji Kato ◽  
Yonosuke Maki
Keyword(s):  
Thermal Gradient ◽  
Microbial Mats ◽  
Hot Springs ◽  
Hot Spring ◽  
Thermal Gradients ◽  
Cyanobacterial Mats ◽  
Dissimilarity Index ◽  
Quinone Profile ◽  
Bacterial Mats ◽  
Different Temperatures

ABSTRACT The respiratory and photosynthetic quinones of microbial mats which occurred in Japanese sulfide-containing neutral-pH hot springs at different temperatures were analyzed by spectrochromatography and mass spectrometry. All of the microbial mats that developed at high temperatures (temperatures above 68°C) were so-called sulfur-turf bacterial mats and produced methionaquinones (MTKs) as the major quinones. A 78°C hot spring sediment had a similar quinone profile.Chloroflexus-mixed mats occurred at temperatures of 61 to 65°C and contained menaquinone 10 (MK-10) as the major component together with significant amounts of either MTKs or plastoquinone 9 (PQ-9). The sunlight-exposed biomats growing at temperatures of 45 to 56°C were all cyanobacterial mats, in which the photosynthetic quinones (PQ-9 and phylloquinone) predominated and MK-10 was the next most abundant component in most cases. Ubiquinones (UQs) were not found or were detected in only small amounts in the biomats growing at temperatures of 50°C and above, whereas the majority of the quinones of a purple photosynthetic mat growing at 34°C were UQs. A numerical analysis of the quinone profiles was performed by using the following three parameters: dissimilarity index (D), microbial divergence index (MDq ), and bioenergetic divergence index (BDq ). A D matrix tree analysis showed that the hot spring mats consisting of the sulfur-turf bacteria, Chloroflexus spp., cyanobacteria, and purple phototrophic bacteria formed distinct clusters. Analyses ofMDq and BDq values indicated that the microbial diversity of hot spring mats decreased as the temperature of the environment increased. The changes in quinone profiles and physiological types of microbial mats in hot springs with thermal gradients are discussed from evolutionary viewpoints.

scholarly journals Short-Term Stable Isotope Probing of Proteins Reveals Taxa Incorporating Inorganic Carbon in a Hot Spring Microbial Mat

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Laurey Steinke ◽  
Gordon W. Slysz ◽  
Mary S. Lipton ◽  
Christian Klatt ◽  
James J. Moran ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Inorganic Carbon ◽  
Microbial Mats ◽  
Carbon Fixation ◽  
Hot Springs ◽  
Hot Spring ◽  
Stable Isotope Probing ◽  
Short Term ◽  
Low Light ◽  
Assembly Sequences

ABSTRACT The upper green layer of the chlorophototrophic microbial mats associated with the alkaline siliceous hot springs of Yellowstone National Park consists of oxygenic cyanobacteria (Synechococcus spp.), anoxygenic Roseiflexus spp., and several other anoxygenic chlorophototrophs. Synechococcus spp. are believed to be the main fixers of inorganic carbon (Ci), but some evidence suggests that Roseiflexus spp. also contribute to inorganic carbon fixation during low-light, anoxic morning periods. Contributions of other phototrophic taxa have not been investigated. In order to follow the pathway of Ci incorporation into different taxa, mat samples were incubated with [13C]bicarbonate for 3 h during the early-morning, low-light anoxic period. Extracted proteins were treated with trypsin and analyzed by mass spectrometry, leading to peptide identifications and peptide isotopic profile signatures containing evidence of 13C label incorporation. A total of 25,483 peptides, corresponding to 7,221 proteins, were identified from spectral features and associated with mat taxa by comparison to metagenomic assembly sequences. A total of 1,417 peptides, derived from 720 proteins, were detectably labeled with 13C. Most 13C-labeled peptides were derived from proteins of Synechococcus spp. and Roseiflexus spp. Chaperones and proteins of carbohydrate metabolism were most abundantly labeled. Proteins involved in photosynthesis, Ci fixation, and N2 fixation were also labeled in Synechococcus spp. Importantly, most proteins of the 3-hydroxypropionate bi-cycle for Ci fixation in Roseiflexus spp. were labeled, establishing that members of this taxocene contribute to Ci fixation. Other taxa showed much lower [13C]bicarbonate incorporation. IMPORTANCE Yellowstone hot spring mats have been studied as natural models for understanding microbial community ecology and as modern analogs of stromatolites, the earliest community fossils on Earth. Stable-isotope probing of proteins (Pro-SIP) permitted short-term interrogation of the taxa that are involved in the important process of light-driven Ci fixation in this highly active community and will be useful in linking other metabolic processes to mat taxa. Here, evidence is presented that Roseiflexus spp., which use the 3-hydroxypropionate bi-cycle, are active in Ci fixation. Because this pathway imparts a lower degree of selection of isotopically heavy Ci than does the Calvin-Benson-Bassham cycle, the results suggest a mechanism to explain why the natural abundance of 13C in mat biomass is greater than expected if only the latter pathway were involved. Understanding how mat community members influence the 13C/12C ratios of mat biomass will help geochemists interpret the 13C/12C ratios of organic carbon in the fossil record.

RECENT BIOMEDICAL APPLICATIONS OF THE OXFORD SCANNING PROTON MICROPROBE

1999 ◽  
Vol 09 (03n04) ◽  
pp. 199-216 ◽  
Author(s):  
GEOFFREY W. GRIME ◽  
EVA PÅLSGÅRD ◽  
ELSPETH F. GARMAN ◽  
MARTA UGARTE ◽  
DAVID POTTAGE ◽  
...  
Keyword(s):  
Trace Element ◽  
Metal Binding ◽  
Active Sites ◽  
Trace Element Analysis ◽  
X Ray Diffraction ◽  
Element Analysis ◽  
Proton Microprobe ◽  
Scanning Proton Microprobe ◽  
Leaf Cutting

The Oxford Scanning Proton Microprobe continues to be used in the field of trace element measurement in biological systems, exploiting the unique advantages of sensitive, quantitative trace element analysis using PIXE, high spatial resolution and the long penetrating power of MeV protons. This paper outlines a number of recent applications which highlight these advantages. These include: (a) Analysing the distribution of metals in the pupae of leaf-cutting ants to determine the storage sites and transport mechanism of metals used to harden the edges of the mandibles. (b) A study of the distribution of zinc in the retina of rats to determine the role of zinc in light and dark adaptation of the eye. (c) The analysis of crystals of proteins and other large organic molecules prepared for structure determination using x-ray diffraction. These often contain metal atoms, and the identity and concentration of the metal is an important diagnostic for determining the nature of the protein and the quality of the crystallisation. The crystals are normally small (~100μm) and so microPIXE is being used to characterise them. This technique has wide ranging applications, including qualitative and quantitative identification of metals in reaction centres, in active sites and in metal binding proteins, and of DNA or RNA bound to proteins.

scholarly journals The Genome Sequence of the Crenarchaeon Acidilobus saccharovorans Supports a New Order, Acidilobales, and Suggests an Important Ecological Role in Terrestrial Acidic Hot Springs

2010 ◽  
Vol 76 (16) ◽  
pp. 5652-5657 ◽  
Author(s):  
Andrey V. Mardanov ◽  
Vitali A. Svetlitchnyi ◽  
Alexey V. Beletsky ◽  
Maria I. Prokofeva ◽  
Elizaveta A. Bonch-Osmolovskaya ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Hot Springs ◽  
Hot Spring ◽  
Tricarboxylic Acid Cycle ◽  
Proton Translocation ◽  
New Order ◽  
Organic Substrates ◽  
Transfer Chain ◽  
Terrestrial Hot Spring

ABSTRACT Acidilobus saccharovorans is an anaerobic, organotrophic, thermoacidophilic crenarchaeon isolated from a terrestrial hot spring. We report the complete genome sequence of A. saccharovorans, which has permitted the prediction of genes for Embden-Meyerhof and Entner-Doudoroff pathways and genes associated with the oxidative tricarboxylic acid cycle. The electron transfer chain is branched with two sites of proton translocation and is linked to the reduction of elemental sulfur and thiosulfate. The genomic data suggest an important role of the order Acidilobales in thermoacidophilic ecosystems whereby its members can perform a complete oxidation of organic substrates, closing the anaerobic carbon cycle.

SYNTHESIS AND CHARACTERIZATION OF HEXAMETHYLENE TETRAMINE (HMTA) CAPPED CdS NANOPARTICLES BY HYDROTHERMAL METHOD

2011 ◽  
Vol 10 (03) ◽  
pp. 441-445 ◽  
Author(s):  
M. KARL CHINNU ◽  
L. SARAVANAN ◽  
R. JAYAVEL ◽  
C. M. RAGHAVAN ◽  
K. VIJAI ANAND ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Cadmium Acetate ◽  
Cds Nanoparticles ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Hexamethylene Tetramine ◽  
Ft Ir ◽  
Ir Analysis ◽  
Uv Visible

Cadmium sulfide nanoparticles have been synthesized by hydrothermal method using cadmium acetate, thiosemicarbazide, and sodium hydroxide as precursors with hexamethylene tetramine as the surfactant. From the X-ray diffraction analysis, it is observed that synthesized CdS nanoparticles show cubic phase. The presence of HMTA in CdS was confirmed by FT-IR analysis. The bandgap value of CdS nanostructure has been estimated by DRS–UV-Visible spectral analysis. The formation of flower-like nanoclusters was observed using scanning electron microscopy (SEM). The application of CdS nanoparticles in photocatalytic degradation was also studied.

scholarly journals Synthesis of ZnO Nanostructures by Microwave Irradiation Using Albumen as a Template

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
T. Prakash ◽  
R. Jayaprakash ◽  
G. Neri ◽  
Sanjay Kumar
Keyword(s):  
Electron Microscopy ◽  
Microwave Irradiation ◽  
Fast Method ◽  
Zno Nanostructures ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Ft Ir ◽  
Size And Morphology ◽  
Microwave Assisted Method

ZnO nanostructures have been successfully prepared by a microwave irradiation method. The role of albumen as a template in addressing the size and morphology of ZnO has been investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG-DTA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. A heterogeneous mixture of Zn(OH)2 and ZnO was obtained in absence of albumen. Pure ZnO nanostructures, consisting of rod- and whisker-like nanoparticles embedded in a sheet matrix, were obtained in the presence of albumen. Optical and photoluminescence (PL) properties of the synthesized samples were also compared. Results obtained indicate that the microwave-assisted method is a promising low temperature, cheap, and fast method for the production of ZnO nanostructures.

scholarly journals Linear Dextrin as Potential Insulin Delivery System: Effect of Degree of Polymerization on the Physicochemical Properties of Linear Dextrin–Insulin Inclusion Complexes

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4187
Author(s):  
Huifang Xie ◽  
Xin Ma ◽  
Wenbin Lin ◽  
Shiting Dong ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Inclusion Complexes ◽  
Aqueous Ethanol ◽  
Potato Starch ◽  
Degree Of Polymerization ◽  
X Ray Diffraction ◽  
System Effect ◽  
X Ray ◽  
Ft Ir ◽  
Ir Analysis ◽  
Differential Solubility

In the current study, linear dextrin (LD) was prepared using waxy potato starch debranched with pullulanase, which has attracted immense interest in the food, pharmaceutical, and cosmetic industries as a versatile ingredient. Various LDs were separated on the basis of their differential solubility in aqueous/ethanol solutions of different volumetric ratios. Three LD products—LD Fabrications with 40% ethanol (F-40); LD Fabrications with 50% ethanol (F-50); and LD Fabrications with 60%, 70%, and 80% ethanol (F-M)—were obtained with an average degree of polymerization (DP) values of 31.44, 21.84, and 16.10, respectively. The results of Fourier transform infrared spectroscopy (FT-IR) analysis revealed that the reaction mainly involved hydrogen bonding and a hydrophobic interaction between LD and insulin in the process of inclusion complex formation. X-ray diffraction (XRD) results indicated that insulin was encapsulated in LD. The results of circular dichroism (CD) showed that the changes in the secondary structure of insulin were negligible during the release from the inclusion complexes. The order of encapsulation capacity is as follows: the complex composed of F-M and insulin (F-M-INS) > the complex composed of LD and insulin (LD-INS) > the complex composed of F-50 and insulin (F-50-INS) > and the complex composed of F-40 and insulin (F-40-INS). F-M-INS inclusion complexes showed a better effect on reducing the release of insulin in gastric juice and promoting the release of insulin in intestinal juice and blood plasma than LD-INS.

scholarly journals Synthesis of Biomaterial-Based Hydrogels Reinforced with Cellulose Nanocrystals for Biomedical Applications

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Pavan Kumar Dara ◽  
Mahadevan Raghavankutty ◽  
Karthik Deekonda ◽  
Anil Kumar Vemu ◽  
Visnuvinayagam Sivam ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Cellulose Nanocrystals ◽  
Chemical Interaction ◽  
Fibroblast Cell ◽  
X Ray Diffraction ◽  
L929 Fibroblast ◽  
Formic Acid Hydrolysis ◽  
Ft Ir ◽  
Good Biocompatibility ◽  
Ir Analysis

Cellulose nanocrystals (CNC) were prepared by formic acid hydrolysis and TEMPO- (2,2,6,6-tetramethyl-piperidine-1-oxyl-) mediated oxidation. The prepared CNCs were reinforced into biopolymers chitosan (CHI), alginate (ALG), and gelatin (GEL) to obtain “CNC-ALG-GEL” and “CNC-CHI-GEL” hydrogels. The synthesized hydrogels were characterized for physicochemical, thermal, and structural characterization using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal gravity analysis (TGA), and X-ray diffraction (XRD) analyses. Notably, the reinforcement of CNC has not altered the molecular structure of a biopolymer as revealed by FT-IR analysis. The hydrogels reinforced with CNC have shown better thermal stability and miscibility as revealed by thermal gravity analysis. The physicochemical, thermal, and structural characterization revealed the chemical interaction and electrostatic attraction between the CNC and biopolymers. The biocompatibility was investigated by evaluating the viability of the L929 fibroblast cell, which represents good biocompatibility and nontoxic nature. These hydrogels could be implemented in therapeutic biomedical research and regenerative medicinal applications.

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