Read by QxMD icon Read


Derek R Lovley
Two recent studies (Mand et al. T. D., G. Kulkarni, and W. W. Metcalf. 2018. J. Bacteriol.:(in press) and Kulkarni, G., T. D. Mand, and W. W. Metcalf. 2018. mBio 9:e01256-18.) analyzed an impressive array of hydrogenase-deficient mutant strains of Methanosarcina barkeri not only to describe H2 -based growth, but also to demonstrate conservation of energy with intracellular hydrogen cycling, a novel strategy for creating a proton-motive force to support ATP synthesis.
August 6, 2018: Journal of Bacteriology
Ming Ma, Hongxia Du, Tao Sun, Siwei An, Guang Yang, Dingyong Wang
Several strains of archaea have the ability to methylate or resist mercury (Hg), and the paddy field is regarded to be conducive to Hg methylation. However, our knowledge of Hg-methylating or Hg-resistant archaea in paddy soils is very limited so far. Therefore, the distribution of archaea and bacteria in the rhizosphere (RS) and bulk soil (BS) of the rice growing in Xiushan Hg-mining area of southwest China was investigated. Bacterial and archaeal 16S rRNA gene amplicon sequencing of the rice rhizosphere along the Hg gradient was conducted...
July 24, 2018: Science of the Total Environment
Manisha S Berde, Domenec Jolis
  A study was conducted to analyze the effect of solubilization due to thermal hydrolysis pretreatment on the microbial population responsible for anaerobic digestion at mesophilic temperature. Metagenomic and microbial population analysis was done on digesters receiving sludge with and without thermal hydrolysis pretreatment. The digester receiving thermal hydrolysis pretreatment was stable at lower detention times and showed a shift in microbial population with predominance of methane-producing population in comparison to conventional digesters receiving no thermal hydrolysis pretreatment...
August 1, 2018: Water Environment Research: a Research Publication of the Water Environment Federation
Thomas D Mand, Gargi Kulkarni, William W Metcalf
The methanogenic archaeon Methanosarcina barkeri encodes three distinct types of hydrogenase, whose functions vary depending on the growth substrate. These include the F420-dependent (Frh), methanophenazine-dependent (Vht), and ferredoxin-dependent (Ech) hydrogenases. To investigate their physiological roles, we characterized a series of mutants lacking each hydrogenase in various combinations. Mutants lacking Frh, Vht, or Ech in any combination failed to grow on H2 /CO2 , whereas only Vht and Ech were essential for growth on acetate...
July 16, 2018: Journal of Bacteriology
Chun-Yu Lai, Qiu-Yi Dong, Bruce E Rittmann, He-Ping Zhao
Employing a special anaerobic membrane biofilm batch reactor (MBBR), we demonstrated antimonate (Sb(V)) reduction using methane (CH4 ) as the sole electron donor. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman and photoluminescence (PL) spectra identified that Sb2 O3 microcrystals were the main reduced products. The Sb(V) reduction rate increased continually over the 111-day experiment, which supports the enrichment of the microorganisms responsible for Sb(V) reduction to Sb(III)...
July 24, 2018: Environmental Science & Technology
Gargi Kulkarni, Thomas D Mand, William W Metcalf
Energy conservation via hydrogen cycling, which generates proton motive force by intracellular H2 production coupled to extracellular consumption, has been controversial since it was first proposed in 1981. It was hypothesized that the methanogenic archaeon Methanosarcina barkeri is capable of energy conservation via H2 cycling, based on genetic data that suggest that H2 is a preferred, but nonessential, intermediate in the electron transport chain of this organism. Here, we characterize a series of hydrogenase mutants to provide direct evidence of H2 cycling...
July 3, 2018: MBio
Norbert K Tavares, Carmen L Zayas, Jorge C Escalante-Semerena
Cobamides (Cbas) are synthesized by many archaea, but some aspects of Cba biosynthesis in these microorganisms remain unclear. Here, we demonstrate that open reading frame MM2060 in the archaeum Methanosarcina mazei strain Gö1 encodes a bifunctional enzyme with l-threonine- O-3-phosphate (l-Thr-P) decarboxylase (EC and l-Thr kinase activities (EC In Salmonella enterica, where Cba biosynthesis has been extensively studied, the activities mentioned above are encoded by separate genes, namely, cobD and pduX, respectively...
July 13, 2018: Biochemistry
Ann A Karim, Daniel R Gestaut, Maeva Fincker, John C Ruth, Eric C Holmes, Wayne Sheu, Alfred M Spormann
Methanogenic archaea can be integrated into a sustainable, carbon-neutral cycle for producing organic chemicals from C1 compounds if the rate, yield, and titer of product synthesis can be improved using metabolic engineering. However, metabolic engineering techniques are limited in methanogens by insufficient methods for controlling cellular protein levels. We conducted a systematic approach to tune protein levels in Methanosarcina acetivorans C2A, a model methanogen, by regulating transcription and translation initiation...
July 13, 2018: ACS Synthetic Biology
Justus Hardegen, Adriel Latorre-Pérez, Cristina Vilanova, Thomas Günther, Manuel Porcar, Olaf Luschnig, Claudia Simeonov, Christian Abendroth
In this work, liquid and solid fractions of grass biomass were used as co-substrates for anaerobic co-digestion of sewage sludge. The input of grass biomass was increased gradually, and the underlying methanogenic microbiome was assessed by means of microscopy-based cell counting and full-length 16S rRNA gene high-throughput sequencing, proving for the first time the suitability of nanopore-based portable sequencers as a monitoring tool for anaerobic digestion systems. In both cases co-fermentation resulted in an increased number of bacteria and methanogenic archaea...
October 2018: Bioresource Technology
Zhongzhong Wang, Qidong Yin, Mengqi Gu, Kai He, Guangxue Wu
Effect of dosing ferroferric oxide (Fe3 O4 ) on the anaerobic treatment of azo dye Reactive Red 2 (RR2) was investigated in two anaerobic sequencing batch reactors (ASBRs). System performance, dye degradation pathways, and microbial activities and structure were examined. The addition of Fe3 O4 significantly improved treatment efficiency, with the removal efficiency of RR2 increased by 116%, the maximum methane (CH4 ) yield potential and the peak CH4 production rate improved by 7.7% and 22.3%, and the lag phase shortened by 39...
September 5, 2018: Journal of Hazardous Materials
Tai-Ho Hu, Liang-Ming Whang, Chi-Yu Huang
This study evaluated the methanogens responsible for methanogenic degradation of tetramethylammonium hydroxide (TMAH) in a continuous flow bioreactor. The enriched methanogens attained an estimated maximum specific TMAH degradation rate and half-saturation constant of 39.5 mg TMAH/gVSS/h and 820 mg/L, following the Monod-type kinetic expression for methanogenic TMAH degradation. Presence of sulfide more than 20 mg/L significantly extended lag period and slowed down specific TMAH degradation rates. The results of terminal restriction fragment length polymorphism (T-RFLP), cloning/sequencing, and quantitative real-time PCR analyses targeting on the methyl coenzyme M reductase alpha subunit (mcrA) genes retrieved from the bioreactor and batch experiments indicated that Methanomethylovorans species were the dominant methanogens responsible for methanogenic degradation of TMAH...
September 5, 2018: Journal of Hazardous Materials
Tatiana A Vishnivetskaya, Joy Buongiorno, Jordan Bird, Kirill Krivushin, Elena V Spirina, Victoria Oshurkova, Victoria A Shcherbakova, Gary Wilson, Karen G Lloyd, Elizaveta M Rivkina
Polar permafrost is at the forefront of climate change, yet only a few studies have enriched the native methane-producing microbes that might provide positive feedbacks to climate change. Samples Ant1 and Ant2, collected in Antarctic Miers Valley from permafrost sediments, with and without biogenic methane, respectively, were evaluated for methanogenic activity and presence of methanogens. After a one-year incubation of both samples under anaerobic conditions, methane production was observed only at room temperature in microcosm Ant1 with CO2/H2 (20/80) as carbon and energy sources and was monitored during the subsequent 10 years...
August 1, 2018: FEMS Microbiology Ecology
Danielle V Miller, Benjamin J Rauch, Kim Harich, Huimin Xu, John J Perona, Robert H White
The methionine salvage pathway (MSP) is critical for regeneration of S-adenosyl-l-methionine (SAM), a widely used cofactor involved in many essential metabolic reactions. The MSP has been completely elucidated in aerobic organisms, and found to rely on molecular oxygen. Since anaerobic organisms do not use O2, an alternative pathway(s) must be operating. We sought to evaluate whether the functions of two annotated MSP enzymes from Methanocaldococcus jannaschii, a methylthioinosine phosphorylase (MTIP) and a methylthioribose 1-phosphate isomerase (MTRI), are consistent with functioning in a modified anaerobic MSP (AnMSP)...
July 2018: Microbiology
Souichiro Kato, Kensuke Igarashi
Recent studies have shown that interspecies electron transfer between chemoheterotrophic bacteria and methanogenic archaea can be mediated by electric currents flowing through conductive iron oxides, a process termed electric syntrophy. In this study, we conducted enrichment experiments with methanogenic microbial communities from rice paddy soil in the presence of ferrihydrite and/or sulfate to determine whether electric syntrophy could be enabled by biogenic iron sulfides. Although supplementation with either ferrihydrite or sulfate alone suppressed methanogenesis, supplementation with both ferrihydrite and sulfate enhanced methanogenesis...
June 6, 2018: MicrobiologyOpen
Adarshi P Welegedara, Luke A Adams, Thomas Huber, Bim Graham, Gottfried Otting
Selenocysteine (Sec) is a naturally occurring amino acid that is also referred to as the 21st amino acid. Site-specific incorporation of Sec into proteins is attractive, because the reactivity of a selenol group exceeds that of a thiol group and thus allows site-specific protein modifications. It is incorporated into proteins by an unusual enzymatic mechanism which, in E. coli and other organisms, involves the recognition of a selenocysteine insertion sequence (SECIS) in the mRNA of the target protein. Reengineering of the natural machinery for Sec incorporation at arbitrary sites independent of SECIS elements, however, is challenging...
July 18, 2018: Bioconjugate Chemistry
Sheng-Chia Chen, Te-Ming Yen, Ting-Hao Chang, Shwu-Huey Liaw
Archaeal/fungal Rib7 and eubacterial RibG possess a reductase domain for ribosyl reduction in the second and third steps, respectively, of riboflavin biosynthesis. These enzymes are specific for an amino and a carbonyl group of the pyrimidine ring, respectively. Here, several crystal structures of Methanosarcina mazei Rib7 are reported at 2.27-1.95 Å resolution, which are the first archaeal dimeric Rib7 structures. Mutational analysis displayed that no detectable activity was observed for the Bacillus subtilis RibG K151A, K151D, and K151E mutants, and the M...
June 8, 2018: Biochemical and Biophysical Research Communications
Patrik Fladischer, Alexandra Weingartner, Johannes Blamauer, Barbara Darnhofer, Ruth Birner-Gruenberger, Tsvetan Kardashliev, Anna Joelle Ruff, Ulrich Schwaneberg, Birgit Wiltschi
The site-specific incorporation of non-canonical amino acids (ncAAs) at amber codons requires an aminoacyl-tRNA synthetase and a cognate amber suppressor tRNA (tRNACUA ). The archaeal tyrosyl-tRNA synthetase from Methanocaldococcus jannaschii and the pyrrolysyl-tRNA synthetase (PylRS) from Methanosarcina mazei have been extensively engineered to accept a versatile set of ncAAs. The PylRS/tRNACUA pair from the bacterium Desulfitobacterium hafniense is functional in Escherichia coli, however, variants of this PylRS have not been reported yet...
June 3, 2018: Biotechnology Journal
Julian C W Willis, Jason W Chin
Genetically encoding distinct non-canonical amino acids (ncAAs) into proteins synthesized in cells requires mutually orthogonal aminoacyl-tRNA synthetase (aaRS)/tRNA pairs. The pyrrolysyl-tRNA synthetase/Pyl tRNA pair from Methanosarcina mazei (Mm) has been engineered to incorporate diverse ncAAs and is commonly considered an ideal pair for genetic code expansion. However, finding new aaRS/tRNA pairs that share the advantages of the MmPylRS/MmPyl tRNA pair and are orthogonal to both endogenous aaRS/tRNA pairs and the MmPylRS/MmPyl tRNA pair has proved challenging...
August 2018: Nature Chemistry
Zhaobo Chen, Xue Li, Dongxue Hu, Yubo Cui, Fuguang Gu, Fuquan Jia, Tingting Xiao, Haiyan Su, Jiao Xu, Haixu Wang, Pan Wu, Ying Zhang, Na Jiang
In this study, a pilot scale anaerobic membrane bioreactor (AnMBR) was operated for 80 days to treat pharmaceutical wastewater containing m-cresol (MC) and iso-propyl alcohol (IPA). The aim of the study is to investigate the performance and methane fermentation characteristics of AnMBR at different hydraulic retention time (HRT) (48, 36, 24, 18 and 12 h). The average total removal efficiencies of MC and IPA were 95%, 96% during the 80 days, which demonstrated that the AnMBR system performed well in the MC and IPA removal...
September 2018: Chemosphere
Hai-Hsuan Cheng, Liang-Ming Whang, Tse-Fu Yi, Cheng-Pin Liu, Tsair-Fuh Lin, Mao-Song Yeh
A pilot-scale single-stage anaerobic fluidized membrane bioreactor (AFMBR) was firstly used in this study to treat cold-rolling emulsion wastewater from steel industry. It was continuously operated for 302 days with influent COD concentration of 860-1120 mg/L. Under a hydraulic retention time of 1.5 d, the average effluent COD concentration of 72 mg/L achieved corresponding 90% of COD removal. The permeate flux was varied between 1.7 and 2.9 L/m2 /h during operation which decreased with increased biomass concentration inside AFMBR...
September 2018: Bioresource Technology
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"