Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Mixed cellulose ester filter as a separator for air-diffusion cathode microbial fuel cells
No full textSeparator is important to prevent bio-contamination of the catalyst layer of air-diffusion cathode microbial fuel cells (MFCs). Mixed cellulose ester filter (MCEF) was examined as a separator for an air-cathode MFC in the present study. The MCEF-MFC produced a maximum power density of 780.7 +/- 18.7 mW/m(2), which was comparable to 770.9 +/- 35.9 mW/m(2) of MFC with Nafion membrane (NFM) as a separator. Long-term examination demonstrated a more stable performance of the MCEF-MFC than NFM-MFC. After 25 cycles, the maximum voltage of the MCEF-MFC decreased by only 1.3% from 425.1 +/- 4.3 mV (initial 5 cycles) to 419.5 +/- 2.3 mV (last 5 cycles). However, it was decreased by 9.1% from 424.8 +/- 5.7 to 386 +/- 2.5 mV for the NFM-MFC. The coulombic efficiency (CE) of the MCEF-MFC did not change (from 3.11 +/- 0.09% to 3.13 +/- 0.02%), while it decreased by 9.12% from 3.18 +/- 0.04% to 2.89 +/- 0.02% for the NFM-MFC. The MCEF separator was with less biofouling than the NFM separator over 60 days' operation, which might be the reason for the more table long-term performance of the MCEF-MFC. The results demonstrated that MCEF was feasible as a separator to set up good-performing and cost-effective air-diffusion cathode MFC
Accelerated ciprofloxacin biodegradation in the presence of magnetite nanoparticles
No full textCiprofloxacin (CIP) biodegradation was investigated using enrichments obtained in the presence of magnetite nanoparticles, CIP and human fecal sewage. CIP addition inhibited methanogenic activity and altered the bacterial community composition. The magnetite-supplemented enrichments significantly promoted CIP biodegradation, especially in the presence of 2-bromoethanesulfonate (BES). When BES was added, CIP biodegradation in the magnetite-supplemented enrichments was 67% higher than in the magnetite-unamended enrichments. Fe (II) concentrations were also significantly increased in the BES and magnetite-supplemented enrichments. This indicated that there might be a positive relationship of CIP biodegradation with microbial reduction of Fe (III) to Fe (II). As for the magnetite-supplemented enrichments, DNA-sequencing analysis revealed that Stenotrophomonas was the dominant genus, while Desulfovibrio became the dominant genus in the presence of BES. These two genera might be related to Fe (III) reduction in the magnetite. The findings provide a strategy for improving CIP biodegradation during waste treatment. (C) 2017 Elsevier Ltd. All rights reserved
Natural and engineered polyhydroxyalkanoate (PHA) synthase: key enzyme in biopolyester production
No full textWith the finite supply of petroleum and increasing concern with environmental issues associated with their harvest and processing, the development of more eco-friendly, sustainable alternative biopolymers that can effectively fill the role of petro-polymers has become a major focus. Polyhydroxyalkanoate (PHA) can be naturally produced by many species of bacteria and the PHA synthase is believed to be key enzyme in this natural pathway. Natural PHA synthases are diverse and can affect the properties of the produced PHAs, such as monomer composition, molecular weights, and material properties. Moreover, recent studies have led to major advances in the searching of PHA synthases that display specific properties, as well as engineering efforts that offer more efficient PHA synthases, increased PHA compound production, or even novel biopolyesters which cannot be naturally produced. In this article, we review the updated information of natural PHA synthases and their engineering strategies for improved performance in polyester production. We also speculate future trends on the development of robust PHA synthases and their application in biopolyester production
Effects of organic loading rate on biogas production from macroalgae: Performance and microbial community structure
No full textMacroalgae biomass has been considered as a promising feedstock for biogas production. In order to improve the efficiency of anaerobic digestion (AD) of macroalgae, semi-continuous fermentation was conducted to examine the effects of organic loading rate (OLR) on biogas production from Macrocystis pyrifer. Results showed that, under OLRs of 1.37, 2.74, 4.12 and 6.85 kg VSsubstrate/(m(3).d), the average unit biogas yields were 438.9, 477.3, 480.1 and 188.7 mL/(g VSsubstrate d), respectively. It indicated that biogas production was promoted by the increased OLR in an appropriate range while inhibited by the OLR beyond the appropriate range. The investigation on physical-chemical parameters revealed that unfavorable VFAs concentration, pH and salinity might be the main causes for system failure due to the overrange OLR, while the total phenols failed to reach the inhibitory concentration. Microbial community analysis demonstrated that several bacterial and archaeal phyla altered with increase in OLR apparently. (C) 2017 Elsevier Ltd. All rights reserved
Grafting of nano-Ag particles on –SO3 -coated nanopolymers for promoting methane hydrate formation
No full textAcceptor-rich bulk heterojunction polymer solar cells with balanced charge mobilities
No full textIn this work, we reported efficient polymer solar cells with balanced hole/electron mobilities tuned by the acceptor content in bulk heterojunction blend films. The photovoltaic cells were fabricated with two new wide band-gap D-A polymers PBDDIDT and PBDDIDTT as the donor material. The molecular conformations of new polymers are carefully evaluated by theoretical calculations. The results of photovoltaic studies show that two devices reach their optimal conditions with rich PC71BM content up to 80% in blend films, which is uncommon with most of reported PSCs. The as-cast devices based on PBDDIDT and PBDDIDTT reveal good photovoltaic performance with PCE of 7.04% and 6.40%, respectively. The influence of PC71BM content on photovoltaic properties is further detailed studied by photoluminescence emission spectra, charge mobilities and heterojunction morphology. The results exhibit that more efficient charge transport between donor and acceptor occurs in rich PC71BM blend films. Meanwhile, the hole and electron mobilities are simultaneously enhanced and afford a good balance in rich PC71BM blend films (D/A, 1: 4) which is critical for the improvement of current density and fill factors. (C) 2017 Elsevier B.V. All rights reserved
Modulation of the Acetone/Butanol Ratio during Fermentation of Corn Stover-derived Hydrolysate by Clostridium beijerinckii NCIMB 8052
No full textProducing biobutanol from lignocellulosic biomass has shown promise
to ultimately reduce greenhouse gases and alleviate the global energy crisis. However, because of the recalcitrance of a lignocellulosic biomass, a pretreatment of the
substrate is needed which in many cases releases soluble lignin compounds (SLCs),
which inhibit growth of butanol-producing clostridia. In this study, we found that
SLCs changed the acetone/butanol ratio (A/B ratio) during butanol fermentation. The
typical A/B molar ratio during Clostridium beijerinckii NCIMB 8052 batch fermentation
with glucose as the carbon source is about 0.5. In the present study, the A/B molar
ratio during batch fermentation with a lignocellulosic hydrolysate as the carbon
source was 0.95 at the end of fermentation. Structural and redox potential changes of
the SLCs were characterized before and after fermentation by using gas chromatography/mass spectrometry and electrochemical analyses, which indicated that some exogenous SLCs were involved in distributing electron flow to C. beijerinckii, leading to modulation of the redox balance. This was further demonstrated by the NADH/NAD ratio
and trxB gene expression profile assays at the onset of solventogenic growth. As a result, the A/B ratio of end products changed significantly during C. beijerinckii fermentation using corn stover-derived hydrolysate as the carbon source compared to glucose as
the carbon source. These results revealed that SLCs not only inhibited cell growth but
also modulated the A/B ratio during C. beijerinckii butanol fermentation
Emerging trends for microbiome analysis: from single-cell functional imaging to microbiome big data
No full textMethod development has always been and will continue to be a core driving force of microbiome science. In this perspective, we argue that in the next decade, method development in microbiome analysis will be driven by three key changes in both ways of thinking and technological platforms: ① a shift from dissecting microbiota structure by sequencing to tracking microbiota state, function, and intercellular interaction via imaging; ② a shift from interrogating a consortium or population of cells to probing individual cells; and ③ a shift from microbiome data analysis to microbiome data science. Some of the recent method-development efforts by Chinese microbiome scientists and their international collaborators that underlie these technological trends are highlighted here. It is our belief that the China Microbiome Initiative has the opportunity to deliver outstanding “Made-in-China” tools to the international research community, by building an ambitious, competitive, and collaborative program at the forefront of method development for microbiome science
