Coculture with hemicellulose-fermenting microbes reverses inhibition of corn fiber solubilization by Clostridium thermocellum at elevated solids loadings

Background: The cellulolytic thermophile Clostridium thermocellum is an important biocatalyst due to its ability to solubilize lignocellulosic feedstocks without the need for pretreatment or exogenous enzyme addition. At low concentrations of substrate, C. thermocellum can solubilize corn fiber \u3e 95% in 5 days, but solubilization declines markedly at substrate concentrations higher than 20 g/L. This differs for model cellulose like Avicel, on which the maximum solubilization rate increases in proportion to substrate concentration. The goal of this study was to examine fermentation at increasing corn fiber concentrations and investigate possible reasons for declining performance. Results: The rate of growth of C. thermocellum on corn fiber, inferred from CipA scaffoldin levels measured by LC–MS/MS, showed very little increase with increasing solids loading. To test for inhibition, we evaluated the effects of spent broth on growth and cellulase activity. The liquids remaining after corn fiber fermentation were found to be strongly inhibitory to growth on cellobiose, a substrate that does not require cellulose hydrolysis. Additionally, the hydrolytic activity of C. thermocellum cellulase was also reduced to less-than half by adding spent broth. Noting that \u3e 15 g/L hemicellulose oligosaccharides accumulated in the spent broth of a 40 g/L corn fiber fermentation, we tested the effect of various model carbohydrates on growth on cellobiose and Avicel. Some compounds like xylooligosaccharides caused a decline in cellulolytic activity and a reduction in the maximum solubilization rate on Avicel. However, there were no relevant model compounds that could replicate the strong inhibition by spent broth on C. thermocellum growth on cellobiose. Cocultures of C. thermocellum with hemicellulose-consuming partners—Herbinix spp. strain LL1355 and Thermoanaerobacterium thermosaccharolyticum—exhibited lower levels of unfermented hemicellulose hydrolysis products, a doubling of the maximum solubilization rate, and final solubilization increased from 67 to 93%. Conclusions: This study documents inhibition of C. thermocellum with increasing corn fiber concentration and demonstrates inhibition of cellulase activity by xylooligosaccharides, but further work is needed to understand why growth on cellobiose was inhibited by corn fiber fermentation broth. Our results support the importance of hemicellulose-utilizing coculture partners to augment C. thermocellum in the fermentation of lignocellulosic feedstocks at high solids loading

A collaborative evaluation of LC-MS/MS based methods for BMAA analysis: soluble bound BMAA found to be an important fraction.

Exposure to β-Ν-methylamino-l-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compared. A CYANOCOST initiated workshop was organized aimed at training scientists in BMAA analysis, creating mutual understanding and paving the way towards interlaboratory comparison exercises. During this workshop, we tested different methods (extraction followed by derivatization and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis, or directly followed by LC-MS/MS analysis) for trueness and intermediate precision. We adapted three workup methods for the underivatized analysis of animal, brain and cyanobacterial samples. Based on recovery of the internal standard D3BMAA, the underivatized methods were accurate (mean recovery 80%) and precise (mean relative standard deviation 10%), except for the cyanobacterium Leptolyngbya. However, total BMAA concentrations in the positive controls (cycad seeds) showed higher variation (relative standard deviation 21%-32%), implying that D3BMAA was not a good indicator for the release of BMAA from bound forms. Significant losses occurred during workup for the derivatized method, resulting in low recovery ( < 10%). Most BMAA was found in a trichloroacetic acid soluble, bound form and we recommend including this fraction during analysis

Characterization of Pseudomonas aeruginosa isolates: Occurrence rates, antimicrobial susceptibility patterns, and molecular typing in the global SENTRY Antimicrobial Surveillance Program, 1997-1999

During 1997–1999, a total of 70,067 isolates (6631 Pseudomonas aeruginosa isolates) were analyzed in the SENTRY program by geographic region and body site of infection. The respiratory tract was the most common source of P. aeruginosa. P. aeruginosa isolation rates increased during the study interval. Europe was the only region to show a significant decline in β-lactam and aminoglycoside susceptibility rates. There was a reduction in the rates of susceptibility of Canadian isolates to imipenem and of Latin American isolates to meropenem. A total of 218 multidrug-resistant P. aeruginosa isolates (MDR-PSA; resistant to piperacillin, ceftazidime, imipenem, and gentamicin) were observed; MDR-PSA occurrence rates (percentages of all isolates) ranged from 8.2% (Latin America) to 0.9% (Canada). No antimicrobial inhibited >50% of MDR-PSA strains. Molecular characterization of selected, generally resistant strains was performed. Isolates showing unique ribogroups were found in Europe, Latin America, and the United States, but clonal spread was documented in several medical centers.A. C. Gales, R. N. Jones, J. Turnidge, R. Rennie, and R. Rampha

Antibiotic Resistance Genes in the Bacteriophage DNA Fraction of Environmental Samples

Antibiotic resistance is an increasing global problem resulting from the pressure of antibiotic usage, greater mobility of the population, and industrialization. Many antibiotic resistance genes are believed to have originated in microorganisms in the environment, and to have been transferred to other bacteria through mobile genetic elements. Among others, β-lactam antibiotics show clinical efficacy and low toxicity, and they are thus widely used as antimicrobials. Resistance to β-lactam antibiotics is conferred by β-lactamase genes and penicillin-binding proteins, which are chromosomal- or plasmid-encoded, although there is little information available on the contribution of other mobile genetic elements, such as phages. This study is focused on three genes that confer resistance to β-lactam antibiotics, namely two β-lactamase genes (blaTEM and blaCTX-M9) and one encoding a penicillin-binding protein (mecA) in bacteriophage DNA isolated from environmental water samples. The three genes were quantified in the DNA isolated from bacteriophages collected from 30 urban sewage and river water samples, using quantitative PCR amplification. All three genes were detected in the DNA of phages from all the samples tested, in some cases reaching 104 gene copies (GC) of blaTEM or 102 GC of blaCTX-M and mecA. These values are consistent with the amount of fecal pollution in the sample, except for mecA, which showed a higher number of copies in river water samples than in urban sewage. The bla genes from phage DNA were transferred by electroporation to sensitive host bacteria, which became resistant to ampicillin. blaTEM and blaCTX were detected in the DNA of the resistant clones after transfection. This study indicates that phages are reservoirs of resistance genes in the environment

Clinical correlates of grey matter pathology in multiple sclerosis

Traditionally, multiple sclerosis has been viewed as a disease predominantly affecting white matter. However, this view has lately been subject to numerous changes, as new evidence of anatomical and histological changes as well as of molecular targets within the grey matter has arisen. This advance was driven mainly by novel imaging techniques, however, these have not yet been implemented in routine clinical practice. The changes in the grey matter are related to physical and cognitive disability seen in individuals with multiple sclerosis. Furthermore, damage to several grey matter structures can be associated with impairment of specific functions. Therefore, we conclude that grey matter damage - global and regional - has the potential to become a marker of disease activity, complementary to the currently used magnetic resonance markers (global brain atrophy and T2 hyperintense lesions). Furthermore, it may improve the prediction of the future disease course and response to therapy in individual patients and may also become a reliable additional surrogate marker of treatment effect

Rozdział warstw kartonów po napojach

The aim of this work was to find a way for easy separation of layers of beverage cartons. The characterizations of separated products were performed by infrared spectroscopy. Three types of solvents were utilized for separation of polyethylene (pentane-1-ol, hexane-1-ol and octane-1-ol). It was found that separated polyethylene from beverage cartons is not pure substance, but contains some amounts of dyes independently of the used solvent. The best solvent for polyethylene dissolution is octane-1-ol, which removed 99.5% of polyethylene contained in carton. The infrared spectra proved that the trace amounts of polyethylene left on the paper as well as on the aluminium surface. Other possible way of separation all layers was suggested.Celem artykułu jest znalezienie sposobu na łatwy rozdział warstw kartonów po napojach. Charakterystyka rozdzielonych produktów została opracowana na podstawie badań spektroskopii w podczerwieni. Do rozdziału zastosowano trzy rozpuszczalniki polietylenu (pentan-1-ol, heksan-1-ol oraz oktan-1-ol). Stwierdzono, że rozdzielony polietylen z kartonów po napojach nie jest czystą substancją, ale zawiera pewne ilości barwników, niezależnie od stosowanych rozpuszczalników. Najlepszym rozpuszczalnikiem dla oddzielenia polietylenu jest oktan-1-ol, który usunął 99,5% polietylenu zawartego w kartonie. Spektrografia w podczerwieni wykazała, że śladowe ilości polietylenu pozostały na papierze, jak również na powierzchni aluminiowej. Inny możliwy sposób rozdziału wszystkich warstw został zasugerowany w artykule

Alkylphenol ethoxylates and alkylphenols – update information on occurrence, fate and toxicity in aquatic environment

Alkylphenols and their precursors, alkylphenol etoxylates, are a group of manmade chemicals used mainly as surfactants in domestic and industrial applications worldwide. It has been well established that they have endocrine disruption activity, hepatotoxic, genotoxic and other negative effects on animal and human health. In spite of the effort to reduce their use, they persist in the environment not only in industrial but also in remote regions, and were detected in the variety of natural matrices including air, water, soil as well as food products, and human blood and urine worldwide. This article summarizes their occurrence, fate in natural conditions, and toxicity including mode of action. A subject of our concern was the aquatic environment as the most important reservoir and target of their deleterious impact

Aktywacja alkaliczna żużla wielkopiecowego w celu poprawy właściwości sorpcyjnych metali ciężkich

New direction of research uses the alkali-activated slags as sorbents for removing metals cations from the solution. Slag materials modified by alkali-activation were prepared by interaction of blast furnace slag (BFS Basic) with water glass. The prepared alkali-activated slags were dried under different conditions to form new structure in slag. The slag dried at room temperature for 7 days (AA BFS) and in a dryer at 105°C for 8 hours (AA BFS 105) were prepared and characterized with the aim to study their sorption properties. Characterization of the prepared slags by means of infrared spectrometry (with diffuse reflectance method) demonstrates that the alkaline activation forms a new structure. The new structures are products of hydration processes and structural changes after contact with water glass. Changes are significant in the comparison with original blast furnace slag. The influence of this new structure on the sorption properties was studied for the copper Cu(II) and lead Pb(II) cations. The sorption experiments were performed by batch method in the aqueous solutions without pH treatment for the concentration range 2–140 mmol/L. The maximum removal amounts of Cu(II) on the alkali-activated slags were almost three times higher and the maximum removal amounts of Pb(II) were at least twice higher in comparison to the BFS Basic. Removal efficiency achieved almost 100% to initial concentration 20 mmol/L for Cu(II) and Pb(II). The removal efficiency for both cations decreases with increasing concentration of metals cations. The removal efficiency is higher for both alkali-activated blast furnace slags in the comparison with BFS Basic. A mechanism of the metal cations removing is influenced by self-alkalization and the removing is mainly due to precipitation and complexation of copper and lead cations on the surface of slags. The alkaline activated slags can be possibly used for remediation of wastewater containing metals ions.Nowy kierunek badań obejmuje wykorzystanie aktywowanych alkalicznie żużli jako sorbentów do usuwania kationów metali z roztworów. Żużle modyfikowane alkalicznie przygotowano w reakcji żużla wielkopiecowego (BFS Basic) ze szkłem wodnym. Przygotowane żużle aktywowane alkalicznie wysuszono w różnych warunkach, tworząc nową strukturę w żużlu. Żużel wysuszono w temperaturze pokojowej przez 7 dni (AA BFS) i suszarce w temperaturze 105°C przez 8 godzin (AA BFS 105), w celu zbadania ich właściwości sorpcyjnych. Charakterystyka przygotowanych żużli za pomocą spektrometrii w podczerwieni (metodą rozproszonego odbicia) wykazuje, że aktywacja alkaliczna tworzy nową strukturę. Nowe struktury są produktami procesów hydratacji i zmianami strukturalnymi po kontakcie ze szkłem wodnym. Zmiany są znaczące w porównaniu z żużlem wielkopiecowym. Wpływ nowej struktury na właściwości sorpcyjne zbadano dla kationów miedzi Cu (II) i ołowiu Pb (II). Eksperymenty sorpcyjne przeprowadzono metodą wsadową w wodnych roztworach bez obróbki pH w zakresie stężenia 2–140 mmol/l. Maksymalna redukcja Cu (II) w żużlach aktywowanych alkaliami była prawie trzy razy wyższa, a maksymalny stopień redukcji Pb (II) był co najmniej dwa razy wyższy w porównaniu do BFS Basic. Wydajność redukcji osiągnęła prawie 100% w stosunku do początkowego stężenia 20 mmol/l dla Cu (II) i Pb (II). Skuteczność redukcji kationów maleje wraz ze wzrostem stężenia kationów. Skuteczność redukcji jest większa w przypadku żużli wielkopiecowych w porównaniu z BFS Basic. Mechanizm usuwania kationów metali wpływa na samoalkalizację, a redukcja jest głównie spowodowana wytrącaniem się kationów miedzi i ołowiu na powierzchni żużla. Żużle alkaliczne mogą być używane do oczyszczania ścieków zawierających jony metali

Właściwości sorpcyjne żużla

The aim of this work was to find if slags could be multifunction sorbents. Investigated slags were blast-furnace slag and steel making slag. The contribution is aimed at characterization of slags and their sorption properties. The characterization of slags were performed by X-ray fluorescence spectroscopy and infrared spectroscopy. It was found by infrared analysis that blast furnace slag contains mainly silicates and a small amount of carbonates. Steel making slag has lower content of silicate minerals and a higher amount of carbonates. The characterized samples of the blast furnace and steel making slags were tested as possible sorbents. The sorption experiments were carried out by batch method in aqueous medium. The selected metal cations (Cu(II) and Zn(II)) and anions (CrO4-2) were used as adsorbates. The sorption experiments were performed with standards of slags to find the best ratio for sorption of metals cations and chromates. The best ratio for sorption metals cations was 1:200 (solid:liquid) for both slags. The best ratio for sorption of chromates was 1:100 for steel making slag and 1:200 for blast-furnace slag. It was found that metal cations removing is influenced by alkalization property of slags. Maximum adsorbent amount of cooper is 0.23 mmol/g on the blast-furnace slag and 0.38 mmol/g on the steel making slag. Maximum adsorbent amount of zinc is 0.17 mmol/g on the blast-furnace slag and 0.35 mmol/g on the steel making slag. The maximum adsorbed amount of chromates for the blast-furnace slag is 15 µmol/g and for steel making slag is 89 µmol/g. The mechanism of the metal cations removing is supposed to be an adsorption combined with precipitation indicated by a high pH after sorption experiments. Slags can be possibly used for remediation of wastewater containing metal ions.Celem pracy było sprawdzenie czy żużle mogą być wielofunkcyjnymi sorbentami. Badaniu poddano żużel wielkopiecowy oraz żużel stalowniczy. W pracy skupiono się na przygotowaniu charakterystyki żużli i ich właściwości sorpcyjnych. Przeprowadzono badania spektroskopem fluorescencji rentgenowskiej oraz spektroskopem w podczerwieni. Dzięki analizie w podczerwieni odkryto, że żużel wielkopiecowy zawiera głównie krzemiany i niewielkie ilości węglanów. Żużel stalowniczy zawiera niższą wartość krzemianów i wyższą węglanów. Opisane próbki żużli wielkopiecowych i stalowniczych zostały sprawdzone jako potencjalne sorbenty. Testy sorpcji zostały przeprowadzone metodą partii w środowisku wodnym. Wybrane kationy metali (Cu(II) oraz Zn(II) oraz aniony (CrO4-2) zostały użyte w charakterze adsorbatów. Badania sorpcji zostały przeprowadzone z zachowaniem standardów, aby znaleźć najlepszą proporcję kationów metali do chromianów dla przeprowadzenia sorpcji. Najlepszy stosunek dla sorpcji kationów metalu wyniósł 1:200 (faza stała: ciecz ) w obydwu rodzajach żużla. Najlepszy współczynnik dla sorpcji chromianów wyniósł 1:100 dla żużla stalowniczego oraz 1:200 dla żużla wielkopiecowego. Odkryto, że na eliminację kationów metalu mają wpływ właściwości alkalizujące żużli. Najwyższa wartość adsorpcji miedzi wynosi 0,23 mmola/g w przypadku żużla wielkopiecowego i 0,38 mmola/g w żużlu stalowniczym. Najwyższa wartość adsorpcji cynku wynosi 0,17 mmola/g przy żużlu wielkopiecowym i 0,35 mmola/g przy żużlu stalowniczym. Maksymalna wartość adsorpcji chromianów dla żużla wielkopiecowego wyniosła 15 µmola/g, a przy stalowniczym 89 µmola/g. Mechanizm usuwania kationów metalu powinien być połączeniem adsorpcji ze strącaniem przy wysokim pH. Wykazano, że można stosować żużle do oczyszczania wód ściekowych zawierających jony metali