Diatom Frustules Decorated with Co Nanoparticles for the Advanced Anode of Li-Ion Batteries.

Silica is regarded as a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity. However, large volume variation and poor electrical conductivity are limiting factors for the development of SiO2 anode materials. To solve this problem, combining SiO2 with a conductive phase and designing hollow porous structures are effective ways. In this work, The Co(II)-EDTA chelate on the surface of diatom biosilica (DBS) frustules and obtained DBS@C-Co composites decorated with Co nanoparticles by calcination without a reducing atmosphere is first precipitated. The unique three-dimensional structure of diatom frustules provides enough space for the volume change of silica during lithiation/delithiation. Co nanoparticles effectively improve the electrical conductivity and electrochemical activity of silica. Through the synergistic effect of the hollow porous structure, carbon layer and Co nanoparticles, the DBS@C-Co-60 composite delivers a high reversible capacity of >620 mAh g-1 at 100 mA g-1 after 270 cycles. This study provides a new method for the synthesis of metal/silica composites and an opportunity for the development of natural resources as advanced active materials for LIBs.

Enhancement Mechanism of Stibnite Dissolution Mediated by Acidithiobacillus ferrooxidans under Extremely Acidic Condition.

Oxidative dissolution of stibnite (Sb2S3), one of the most prevalent geochemical processes for antimony (Sb) release, can be promoted by Sb-oxidizing microbes, which were studied under alkaline and neutral conditions but rarely under acidic conditions. This work is dedicated to unraveling the enhancement mechanism of stibnite dissolution by typical acidophile Acidithiobacillus ferrooxidans under extremely acidic conditions. The results of solution behavior showed that the dissolution of Sb2S3 was significantly enhanced by A. ferrooxidans, with lower pH and higher redox potential values and higher [Sb(III)] and [Sb(V)] than the sterile control. The surface morphology results showed that the cells adsorbed onto the mineral surface and formed biofilms. Much more filamentous secondary minerals were formed for the case with A. ferrooxidans. Further mineral phase compositions and Sb/S speciation transformation analyses showed that more secondary products Sb2O3/SbO2-, Sb2O5/SbO3-, SO42-, as well as intermediates, such as S0, S2O32- were formed for the biotic case, indicating that the dissolution of Sb2S3 and the Sb/S speciation transformation was promoted by A. ferrooxidans. These results were further clarified by the comparative transcriptome analysis. This work demonstrated that through the interaction with Sb2S3, A. ferrooxidans promotes S/Sb oxidation, so as to enhance S/Sb transformation and thus the dissolution of Sb2S3.

The differential inhibitive effects and fates of As(III) and As(V) mediated by Sulfobacillus thermosulfidooxidans grown on S0, Fe2+ and FeS2.

Arsenic often coexists with metal sulfide minerals and occurs in different speciation and different toxicity in responding to Fe/S biooxidation. The differential inhibitive effects and fates of As(III) and As(V) during biooxidations of elemental sulfur (S0), ferrous ions (Fe2+) and pyrite (FeS2) by Sulfobacillus thermosulfidooxidans were studied. The results revealed that the arsenic species hardly changed for the biooxidation of S0, but dramatically changed for the biooxidation of Fe2+ and FeS2. Different transformation degree between As(III) and As(V) occurred for biooxidation of FeS2 in the presence of arsenic, where about 72% of As(III) was transformed to As(V) for the group with As(III) added, and 16% of As(V) was transformed to As(III) for that with As(V) added. Both formation and dissolution of amorphous ferric arsenate occurred during biooxidation of FeS2 with the addition of As(III) or As(V) and for the group grown on Fe2+ with added As(V), which were controlled by the changes of Fe/As molar ratio and pH value in the solution. Jarosite was detected for the group grown on Fe2+ and could adsorb As(III) and As(V). The inhibitive effects of As(V) were higher than As(III) when the strain grew on FeS2, which was contrary to those when the strain grew on S0 and Fe2+. The above results signify that the fates and inhibitive effects of arsenic are much related to each other, and such a relationship is significantly affected by the utilization of Fe/S energy substrates by the sulfur- and ferrous-oxidizing microorganisms.

Global analysis of transcriptome sequences highlights accelerated evolution of immune genes in Danio choprae and Danio albolineatus.

Danio fishes, a small type animal with short sexual cycles, are model vertebrate species. To investigate the genic evolution of this genus, the transcriptomes from Danio choprae and Danio albolineatus were sequenced by Illumina HiSeq 4000 platform. A total of 128,427,304 sequence reads from two Danio fishes were generated by Next Generation Sequencing. The resulting in two assemblies contained 88,682 and 88,029 unigenes in the Danio choprae and Danio albolineatus. Analysis of the orthologs from the Danio choprae and Danio albolineatus provided consistent evidence for the accelerated genic evolution in the Danio fishes. Several genes referring to immune functions under positive selection were identified by branch site model analysis, such as REL, GTF2E1, STAT6, MPG in Danio choprae and CYP17A1, ADORA2A, MYCN in Danio albolineatus. Our data provide novel insights into the adaptation in Danio fishes and is useful for understanding the genetic basis of adaptation in zebrafish.

Evidence of cell surface iron speciation of acidophilic iron-oxidizing microorganisms in indirect bioleaching process.

While indirect model has been widely accepted in bioleaching, but the evidence of cell surface iron speciation has not been reported. In the present work the iron speciation on the cell surfaces of four typically acidophilic iron-oxidizing microorganism (mesophilic Acidithiobacillus ferrooxidans ATCC 23270, moderately thermophilic Leptospirillum ferriphilum YSK and Sulfobacillus thermosulfidooxidans St, and extremely thermophilic Acidianus manzaensis YN25) grown on different energy substrates (chalcopyrite, pyrite, ferrous sulfate and elemental sulfur (S(0))) were studied in situ firstly by using synchrotron-based micro- X-ray fluorescence analysis and X-ray absorption near-edge structure spectroscopy. Results showed that the cells grown on iron-containing substrates had apparently higher surface iron content than the cells grown on S(0). Both ferrous iron and ferric iron were detected on the cell surface of all tested AIOMs, and the Fe(II)/Fe(III) ratios of the same microorganism were affected by different energy substrates. The iron distribution and bonding state of single cell of A. manzaensis were then studied in situ by scanning transmission soft X-ray microscopy based on dual-energy contrast analysis and stack analysis. Results showed that the iron species distributed evenly on the cell surface and bonded with amino, carboxyl and hydroxyl groups.

Saccharification of orange peel wastes with crude enzymes from new isolated Aspergillus japonicus PJ01.

This study investigated the saccharification of orange peel wastes with crude enzymes from Aspergillus japonicus PJ01. Pretreated orange peel powder was hydrolyzed by submerged fermentation (SmF) and solid-state fermentation (SSF) crude enzymes, the results showed that 4 % (w/v) of solid loading, undiluted crude enzymes, and 45 °C were suitable saccharification conditions. The hydrolysis kinetics showed that the apparent Michaelis-Menten constant [Formula: see text] and maximal reaction rate [Formula: see text] were 73.32 g/L and 0.118 g/(L min) for SmF enzyme, and 41.45 g/L and 0.116 g/(L min) for SSF enzyme, respectively. After 48 h of hydrolysis, the saccharification yields were 58.5 and 78.7 %, the reducing sugar concentrations were 14.9 and 20.1 mg/mL by SmF and SSF enzymes. Material balance showed that the SmF enzymatic hydrolysate was enriched galacturonic acid > arabinose > galactose > xylose, and the SSF enzymatic hydrolysate was enriched galacturonic acid > xylose > galactose > arabinose.

Differential expression of extracellular thiol groups of moderately thermophilic Sulfobacillus thermosulfidooxidans and extremely thermophilic Acidianus manzaensis grown on S(0) and Fe (2.).

Bio-oxidation of elemental sulfur (S(0)) is very important in bioleaching and sulfur cycle. S(0) was proposed to be first activated by reacting with reactive thiol groups (-SH) of outer membrane proteins, forming -S n H (n ≥ 2) complexes. The differential expression of -SH of moderately thermophilic Sulfobacillus thermosulfidooxidans and extremely thermophilic Acidianus manzaensis grown on Fe(2+) and S(0) was investigated by synchrotron radiation-based scanning transmission X-ray microscopy (STXM) imaging and micro-beam X-ray fluorescence (µ-XRF) mapping. The STXM imaging and µ-XRF mapping of extracellular -SH were based on the analysis of Ca(2+) bound on the cell. By comparing Ca(2+) of the cells with and without labeling by Ca(2+), the distribution and content of thiol groups were obtained. The results showed that, for both S. thermosulfidooxidans and A. manzaensis, the expression of extracellular -SH of S(0)-grown cells was higher than that of Fe(2+)-grown cells. Statistical analysis indicated that the expression of extracellular -SH for S. thermosulfidooxidans and A. manzaensis grown on S(0) was 2.37 times and 2.14 times, respectively, to that on Fe(2+). These results evidently demonstrate that the extracellular thiol groups are most probably involved in elemental sulfur activation and oxidation of the acidophilic sulfur-oxidizing microorganisms.

Comparative study of multi-enzyme production from typical agro-industrial residues and ultrasound-assisted extraction of crude enzyme in fermentation with Aspergillus japonicus PJ01.

Submerged fermentation (SmF) and solid-state fermentation (SSF) of Aspergillus japonicus PJ01 for multi-enzyme complexes (MEC) production were comparatively studied. The results showed that orange peel and wheat bran were the best substrates for MEC production in SmF and SSF, respectively. After 72 h of cultivation under SmF, the maximal pectinase, CMCase, and xylanase activities reached 2610, 85, and 335 U/gds (units/gram dry substrate), respectively; while after 72 h of cultivation under SSF, these three enzymes' activities reached 966, 58, and 1004 U/gds, respectively. Effects of ultrasound on extraction of crude enzymes from SSF medium were determined, the maximal activities of pectinase, CMCase, and xylanase increased to 1.20, 1.48, and 1.30-fold, respectively. Apparent different mycelia growths of SSF and SmF were observed by scanning electron microscopy; and different isoforms of the crude enzyme extracts from SSF and SmF were presented by zymogram analysis.

The effect of energy substrates on PHB accumulation of Acidiphilium cryptum DX1-1.

The effect of glucose and elemental sulfur on the growth and PHB accumulation of Acidiphilium cryptum DX1-1 was investigated. Meanwhile, the differential expressions of 19 genes related with PHB accumulation, sulfur metabolism and carbon fixed in heterotrophy, phytotrophy and mixotrophy were studied by RT-qPCR. The results showed that strain DX1-1 could accumulate PHB with sulfur as the energy substance and atmospheric CO2 as carbon resource. Glucose could improve the growth of strain DX1-1 cultured in medium with sulfur as the energy substance, and almost all the key enzyme-encoding genes related with PHB, sulfur metabolism and carbon fixed were basically up-regulated. PHB polymerase (Arcy_3030), ribulose-bisphosphate carboxylase (Acry_0825), ribulose-phosphate-epimerase (Acry_0022), and cysteine synthase A (Acry_2560) played important role in PHB accumulation, the modified expression of which could influence the PHB yield. With CO2 as carbon resource, the main initial substance of PHB accumulation for strain DX1-1 was acetyl-CoA, instead of acetate with the glucose as the carbon resource. Because of accumulating PHB by fixed atmospheric CO2 while independent of light, A. cryptum DX1-1 may have specifically potential in production of PHB.

Biosynthesis and Detection of Domoic Acid from Diatom Pseudo-nitzschia: A Review.

The domoic acid (DA) produced by certain species of the marine pennate diatom genus Pseudo-nitzschia is highly neurotoxic and can induce nerve excitability and neurotoxicity by binding with ionotropic glutamate receptors, causing amnesic shellfish poisoning in humans who consume seafood contaminated with DA. In recent years, poisoning of humans caused by DA has occurred around the world, which has attracted increasing attention, and studies on DA production by Pseudo-nitzschia have become the hotpot. This article reviews the progress in the biosynthesis of DA by the typical diatom Pseudo-nitzschia, in which the metabolic pathway of the biosynthesis of DA and its precursors, i.e., geranyl pyrophosphate and L-glutamate, and the various environmental factors affecting DA production including temperature, light intensity, nutrients, trace metals, and alien bacteria are discussed. The detection methods of DA (including bioassays, enzyme linked immunosorbent assays, high performance liquid chromatography, capillary electrophoresis and biosensors), as well as the morphology and toxigenicity of Pseudo-nitzschia are also presented.

Physiological evaluation of a new Chlorella sorokiniana isolate for its biomass production and lipid accumulation in photoautotrophic and heterotrophic cultures.

A novel green unicellular microalgal isolate from the freshwater of the Inner Mongolia Province of China and named as CCTCC M209220, grows between pH 6 and 11 and temperatures of 20-35°C with optimal conditions at pH 9 and 30°C. Morphological features and the phylogenetic analysis for the 18S rRNA gene reveal that the isolate is a Chlorella sorokiniana strain. A nitrogen source test reveals that this strain can grow well with nitrate and urea, but not ammonium. The strain can grow heterotrophically with glucose as the carbon source and accumulates lipid content as high as 56% (w/w) dry weight after 7 days in high glucose concentrations compared to 19% lipids achieved in 30 days of photoautotrophic culture. The relative neutral lipid content as a fraction of the total lipid is also much higher in heterotrophic culture as compared to photoautotrophic culture.

Highly-efficient and sequential recovery of rare earth elements, alumina and silica from coal fly ash via a novel recyclable ZnO sinter method.

A novel sinter method using ZnO as the activator instead of the conventional Na2CO3/CaCO3, (NH4)2SO4, and K2S2O7 was developed to achieve efficient sequential extraction of rare earth elements (REEs), alumina (Al), and silica (Si) from coal fly ash (CFA). Up to 93.3% Si, 87.1% REEs (70.7% Ce, 82.5% La, 83.2% Gd, 87.1% Nd, 62.3% Dy, and 81.7% Y), and 92.9% Al were extracted from CFA, respectively. Moreover, 93.1% of the ZnO activator was efficiently recycled, and the yield of red mud was only 14.9%. X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) results showed that the speciation transformation of Al/Si during CFA/ZnO roasting was as follows: mullite, quartz, amorphous Al2O3, and SiO2 → Zn0.75Al1.5Si1.5O6, kyanite and willemite → gahnite and quartz/cristobalite solid solutions. The change in the REEs occurrence mode hinted at the migration of most REEs in aluminosilicates forms with Si during roasting, and disassociation with Si into the acid-soluble form after alkali leaching. These results indicate that the coupling of Al-Si-REE in CF was broken by this ZnO sinter method, promoting the sequential and efficient extraction of REEs, Al, and Si from CFA. This study provides a green and efficient strategy for element recovery from CFA, substantially reducing residues and favoring REEs concentration.

Efficient dealkalization of red mud and recovery of valuable metals by a sulfur-oxidizing bacterium.

Red mud (RM) is a highly alkaline polymetallic waste generated via the Bayer process during alumina production. It contains metals that are critical for a sustainable development of modern society. Due to a shortage of global resources of many metals, efficient large-scale processing of RM has been receiving increasing attention from both researchers and industry. This study investigated the solubilization of metals from RM, together with RM dealkalization, via sulfur (S0) oxidation catalyzed by the moderately thermophilic bacterium Sulfobacillus thermosulfidooxidans. Optimization of the bioleaching process was conducted in shake flasks and 5-L bioreactors, with varying S0:RM mass ratios and aeration rates. The ICP analysis was used to monitor the concentrations of dissolved elements from RM, and solid residues were analyzed for surface morphology, phase composition, and Na distribution using the SEM, XRD, and STXM techniques, respectively. The results show that highest metal recoveries (89% of Al, 84% of Ce, and 91% of Y) were achieved with the S0:RM mass ratio of 2:1 and aeration rate of 1 L/min. Additionally, effective dealkalization of RM was achieved under the above conditions, based on the high rates (>95%) of Na, K, and Ca dissolution. This study proves the feasibility of using bacterially catalyzed S0 oxidation to simultaneously dealkalize RM and efficiently extract valuable metals from the amassing industrial waste.

Effects of copper exposure on expression of glutathione-related genes in Acidithiobacillus ferrooxidans.

The response of Acidithiobacillus ferrooxidans to variations in extracellular Cu exposure was investigated in terms of glutathione-related genes expression profiling based on reverse-transcription quantitative PCR analysis. The results show that the higher concentration of Cu would induce the expression of glutathione-related enzymes and cells elicited specific transcriptional responses when challenged with environmental Cu (0.08 mol l(-1)) conditions over a 60-min period. In comparison to the control, glutathione S-transferases (GST) and glutathione reductase (GR) were highly expressed when the cells were grown in the medium with copper, and the increase of glutathione and glutathione-related enzymes makes the cells acclimate to oxidative stress induced by Cu and protects the cells from toxicity caused by Cu exposure. It suggests that in order for Acidithiobacillus ferrooxidans to counteract the conditions of external Cu exposure, it modulated its expression level of GST, GR, glutathione hydrolase, and glutathione synthetase, which may protect organisms from oxidative damage. These parameters may be used to assess the biological impact of Cu in mining activities.

Red mud regulates arsenic fate at acidic pH via regulating arsenopyrite bio-oxidation and S, Fe, Al, Si speciation transformation.

Red mud (RM) as waste of industrial aluminum production is piling up in huge ponds. RM could be a cost-effective adsorbent for heavy metals, but adsorption is vulnerable to pH changes, metal ions speciation and the occurrence of iron bearing minerals. In this study, the precipitation and elemental speciation transformation relevant to arsenic fate in responding to the addition of RM during arsenopyrite bio-oxidation by Sulfobacillus thermosulfidooxidans was investigated. The results show that the addition of RM significantly changed the arsenic precipitation and the solution chemistry and thus affected the arsenopyrite bio-oxidation and arsenic fate. An addition of a small amount (≤ 4 g/L) of RM substantially promoted arsenopyrite bio-oxidation with formation of SiO2 @ (As, Fe, Al, Si) spherical nanoparticles that can enhance the stability of the immobilized arsenic. The SiO2-based spherical nanoparticles precipitate was mainly composed of jarosites, amorphous ferric arsenate and crystalline scorodite, and its formation were controlled by Fe3+ concentration and solution pH. An addition of increased amount of RM (≥ 6 g/L) resulted in a significant increase of the solution pH and a decrease in the Fe2+ bio-oxidation activity, and spherical nanoparticles were not formed. Consequently, the dissolution of arsenopyrite was inhibited and the release of arsenic was blocked. This study suggests the applicability of RM in mitigation of arsenic pollution from bio-oxidation of As-bearing sulfide minerals.

Correlation Between Fe/S/As Speciation Transformation and Depth Distribution of Acidithiobacillus ferrooxidans and Acidiphilium acidophilum in Simulated Acidic Water Column.

It is well known that speciation transformations of As(III) vs. As(V) in acid mine drainage (AMD) are mainly driven by microbially mediated redox reactions of Fe and S. However, these processes are rarely investigated. In this study, columns containing mine water were inoculated with two typical acidophilic Fe/S-oxidizing/reducing bacteria [the chemoautotrophic Acidithiobacillus (At.) ferrooxidans and the heterotrophic Acidiphilium (Aph.) acidophilum], and three typical energy substrates (Fe2+, S0, and glucose) and two concentrations of As(III) (2.0 and 4.5 mM) were added. The correlation between Fe/S/As speciation transformation and bacterial depth distribution at three different depths, i.e., 15, 55, and 105 cm from the top of the columns, was comparatively investigated. The results show that the cell growth at the top and in the middle of the columns was much more significantly inhibited by the additions of As(III) than at the bottom, where the cell growth was promoted even on days 24-44. At. ferrooxidans dominated over Aph. acidophilum in most samples collected from the three depths, but the elevated proportions of Aph. acidophilum were observed in the top and bottom column samples when 4.5 mM As(III) was added. Fe2+ bio-oxidation and Fe3+ reduction coupled to As(III) oxidation occurred for all three column depths. At the column top surfaces, jarosites were formed, and the addition of As(III) could lead to the formation of the amorphous FeAsO4⋅2H2O. Furthermore, the higher As(III) concentration could inhibit Fe2+ bio-oxidation and the formation of FeAsO4⋅2H2O and jarosites. S oxidation coupled to Fe3+ reduction occurred at the bottom of the columns, with the formations of FeAsO4⋅2H2O precipitate and S intermediates. The formed FeAsO4⋅2H2O and jarosites at the top and bottom of the columns could adsorb to and coprecipitate with As(III) and As(V), resulting in the transfer of As from solution to solid phases, thus further affecting As speciation transformation. The distribution difference of Fe/S energy substrates could apparently affect Fe/S/As speciation transformation and bacterial depth distribution between the top and bottom of the water columns. These findings are valuable for elucidating As fate and toxicity mediated by microbially driven Fe/S redox in AMD environments.

Real-time PCR analysis of metabolic pathway of PHB in Acidiphilium cryptum DX1-1.

The time, yield and related genes expression of PHB accumulation of Acidiphilium cryptum DX1-1 were investigated under four different initial C/N ratios 1.2, 2.4, 7.5, and 24. The results of time and yield of PHB accumulation show that the initial C/N ratio 2.4 was optimum for strain DX1-1 to accumulate PHB, both higher and lower initial C/N ratios did not favor that process. Based on the genome of Acidiphilium cryptum JF-5, 13 PHB accumulation related genes in strain JF-5 were chosen and successfully cloned from strain DX1-1. The differential expression of the 13 functional genes, in different C/N ratios as cited above, was then studied by Real-time PCR. The results show that all the 13 genes were most upregulated when initial C/N ratio was 2.4, and among which the gene Acry_3030 encoding poly-beta-hydroxybutyrate polymerase and Acry_0626 encoding acetyl-CoA synthetase were much more upregulated than the other genes, which prove that they play the most important role for PHB accumulation and acetate is the main initial substance for PHB accumulation for strain DX1-1. Potential regulatory motifs analysis shows that the genes related to PHB accumulation are regulated by different promoters and that the motif had weak similarity to the model promoters, suggesting that PHB- metabolism in Acidiphilium cryptum may be mediated by a different mechanism.

Humic acid promotes arsenopyrite bio-oxidation and arsenic immobilization.

The bio-oxidative dissolution of arsenopyrite, the most severe arsenic contamination source, can be mediated by organic substances, but pertinent studies on this subject are scarce. In this study, the bio-oxidative dissolution of arsenopyrite by Sulfobacillus thermosulfidooxidans and arsenic immobilization were evaluated in the presence of humic acid (HA). The mineral dissolution was monitored through analyses of the parameters in solution, phase and element speciation transformations on the mineral surface, and arsenic immobilization on the surfaces of cells and jarosites-HA. The results show that the presence of HA enhances the dissolution of arsenopyrite, e.g., 7.1% of arsenopyrite was in the residue after 12 d of bio-oxidation compared to 19.3% in the absence of HA. Meanwhile, the presence of HA led to changes of the fates of As and Fe and no accumulation of elemental sulfur (S0) or ferric arsenate on the mineral surface. Moreover, a flocculent porous structure was formed on the surfaces of both microbial cells and jarosites, on which a large amount of arsenic was adsorbed. These results clearly indicate that HA can simultaneously promote the dissolution of arsenopyrite and arsenic immobilization, which may be significant for bioleaching of arsenopyrite-bearing contaminated sites.

Investigation of elemental sulfur speciation transformation mediated by Acidithiobacillus ferrooxidans.

The speciation transformation of elemental sulfur mediated by the leaching bacterium Acidithiobacillus ferrooxidans was investigated using an integrated approach including scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, and X-ray absorption near edge spectroscopy (XANES). Our results showed that when grown on elemental sulfur powder, At. ferrooxidans ATCC23270 cells were first attached to sulfur particles and modified the surface sulfur with some amphiphilic compounds. In addition, part of the elemental sulfur powder might be converted to polysulfides. Furthermore, sulfur globules were accumulated inside the cells. XANES spectra of these cells suggested that these globules consisted of elemental sulfur bound to thiol groups of protein.

In situ characterization of change in superficial organic components of thermoacidophilic archaeon Acidianus manzaensis YN-25.

For the first time, synchrotron radiation (SR) -based carbon K-edge X-ray absorption near edge structure (XANES) spectroscopy in-situ characterization was conducted to evaluate the evolution of superficial (about 10 nm) organic components of extracellular polymeric substances (EPS) of thermoacidophilic archaeon Acidianus manzaensis YN-25 acclimated with different energy substrates (FeS2, CuFeS2, S0, FeSO4). The atomic force microscopy (AFM) morphology scanning showed that the strain acclimated with different energy substrates varied a lot in EPS amount. XANES results showed clear associations between the energy substrates and the changes in organic composition in terms of typical function groups (CO, CO and CN). The chalcopyrite- and pyrite-acclimated cells contained higher proportion of proteins but less proportion of polysaccharides than the S0-acclimated cells. The FeSO4-acclimated cells contained the highest proportion of proteins, while the S0-acclimated cells contained more lipids and polysaccharides. The results of linear-combination and peak fitting of the K-edge XANES for the extracellular superficial organic component C is consistent with the trend in comparison with the results of FTIR and spectrophotometric determination, but there are significant differences in the values. These differences are caused by the inconsistencies of measurement depth between XANES and the latter two characterization methods.