Formation of lactic acid by the extracts from the healthy rabbit muscles was studied as affected by the sera of embryos, newborn rabbits and pregnant female rabbits. The blood sera and beta-globulin isolated from them are established to activate anaerobic glycolysis and inhibit the Pasteur reaction. It is shown that protein typical of normal growth, belonging to beta-globulins and circulating in blood of the embryos, newborn rabbits from the first to the fifteenth day of development is "responsible" for this phenomena. Correlation is found between the precipitation test for detecting this protein and its biological effect on glycolysis and the Pasteur reaction.
The methane potential and biodegradability of different ratios of acetate and lignin-rich effluents from a neutral sulfite semi-chemical (NSSC) pulp mill were investigated. Results showed ultimate methane yields up to 333±5mLCH4/gCOD when only acetate-rich substrate was added and subsequently lower methane potentials of 192±4mLCH4/gCOD when the lignin fraction was increased. The presence of lignin showed a linear decay in methane production, resulting in a 41% decrease in methane when the lignin-rich feed had a 30% increase. A negative linear correlation between lignin content and biodegradability was also observed. Furthermore, the effect of hydrotalcite (HT) addition was evaluated and showed increase in methane potential of up to 8%, a faster production rate and higher soluble lignin removal (7-12% higher). Chemical oxygen demand (COD) removal efficiencies between 64 and 83% were obtained for all samples.
Since the 1980s, the pulp and paper industry in Finland has resulted in the accumulation of fibres in lake sediments. One such site in Lake Näsijärvi contains approximately 1.5 million m3 sedimented fibres. In this study, the methane production potential of the sedimented fibres (on average 13% total solids (TS)) was determined in batch assays. Furthermore, the methane production from solid (on average 20% TS) and liquid fractions of sedimented fibres after solid-liquid separation was studied. The sedimented fibres resulted in fast methane production and high methane yields of 250?±?80?L CH4/kg volatile solids (VS). The main part (ca. 90%) of the methane potential was obtained from the solid fraction of the sedimented fibres. In addition, the VS removal from the total and solid sedimented fibres was high, 61-65% and 63-78%, respectively. The liquid fraction also contained a large amount of organics (on average 8.8?g COD/L), treatment of which also has to be considered. The estimations of the methane production potentials in the case area showed potential up to 40 million m3 of methane from sedimented fibres.
Thawing submarine permafrost is a source of methane to the subsurface biosphere. Methane oxidation in submarine permafrost sediments has been proposed, but the responsible microorganisms remain uncharacterized. We analyzed archaeal communities and identified distinct anaerobic methanotrophic assemblages of marine and terrestrial origin (ANME-2a/b, ANME-2d) both in frozen and completely thawed submarine permafrost sediments. Besides archaea potentially involved in anaerobic oxidation of methane (AOM) we found a large diversity of archaea mainly belonging to Bathyarchaeota, Thaumarchaeota, and Euryarchaeota. Methane concentrations and d13C-methane signatures distinguish horizons of potential AOM coupled either to sulfate reduction in a sulfate-methane transition zone (SMTZ) or to the reduction of other electron acceptors, such as iron, manganese or nitrate. Analysis of functional marker genes (mcrA) and fluorescence in situ hybridization (FISH) corroborate potential activity of AOM communities in submarine permafrost sediments at low temperatures. Modeled potential AOM consumes 72-100% of submarine permafrost methane and up to 1.2?Tg of carbon per year for the total expected area of submarine permafrost. This is comparable with AOM habitats such as cold seeps. We thus propose that AOM is active where submarine permafrost thaws, which should be included in global methane budgets.
Cites: Environ Microbiol. 2016 Sep;18(9):3073-91 PMID 26971539
Cites: Front Microbiol. 2015 Dec 18;6:1423 PMID 26733968
Cites: Nat Commun. 2015 Jun 30;6:7477 PMID 26123199
Cites: Science. 2016 Feb 12;351(6274):703-7 PMID 26912857
Coastal marine sediments contain varying concentrations of iron, oxygen, nitrate and organic carbon. It is unknown how organic carbon content influences the activity of nitrate-reducing and phototrophic Fe(II)-oxidizers and microbial Fe-redox cycling in such sediments. Therefore, microcosms were prepared with two coastal marine sediments (Kalø Vig and Norsminde Fjord at Aarhus Bay, Denmark) varying in TOC from 0.4 to 3.0 wt%. The microcosms were incubated under light/dark conditions with/without addition of nitrate and/or Fe(II). Although most probable number (MPN) counts of phototrophic Fe(II)-oxidizers were five times lower in the low-TOC sediment, phototrophic Fe(II) oxidation rates were higher compared with the high-TOC sediment. Fe(III)-amended microcosms showed that this lower net Fe(II) oxidation in the high-TOC sediment is caused by concurrent bacterial Fe(III) reduction. In contrast, MPN counts of nitrate-reducing Fe(II)-oxidizers and net rates of nitrate-reducing Fe(II) oxidation were comparable in low- and high-TOC sediments. However, the ratio of nitratereduced :iron(II)oxidized was higher in the high-TOC sediment, suggesting that a part of the nitrate was reduced by mixotrophic nitrate-reducing Fe(II)-oxidizers and chemoorganoheterotrophic nitrate-reducers. Our results demonstrate that dynamic microbial Fe cycling occurs in these sediments and that the extent of Fe cycling is dependent on organic carbon content.
Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, 306 Tanana Loop, 99775 Fairbanks, AK, USA; Biotechnology and Bioengineering Department, Cinvestav, 2508 IPN Av, 07360, Mexico City, Mexico. Electronic address: email@example.com.
Anaerobic oxidation of methane (AOM) is a biological process that plays an important role in reducing the CH4 emissions from a wide range of ecosystems. Arctic and sub-Arctic lakes are recognized as significant contributors to global methane (CH4) emission, since CH4 production is increasing as permafrost thaws and provides fuels for methanogenesis. Methanotrophy, including AOM, is critical to reducing CH4 emissions. The identity, activity, and metabolic processes of anaerobic methane oxidizers are poorly understood, yet this information is critical to understanding CH4 cycling and ultimately to predicting future CH4 emissions. This study sought to identify the microorganisms involved in AOM in sub-Arctic lake sediments using DNA- and phospholipid-fatty acid (PLFA)- based stable isotope probing. Results indicated that aerobic methanotrophs belonging to the genus Methylobacter assimilate carbon from CH4, either directly or indirectly. Other organisms that were found, in minor proportions, to assimilate CH4-derived carbon were methylotrophs and iron reducers, which might indicate the flow of CH4-derived carbon from anaerobic methanotrophs into the broader microbial community. While various other taxa have been reported in the literature to anaerobically oxidize methane in various environments (e.g. ANME-type archaea and Methylomirabilis Oxyfera), this report directly suggest that Methylobacter can perform this function, expanding our understanding of CH4 oxidation in anaerobic lake sediments.
Sediments of the Kymijoki River are highly contaminated with polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). These persistent PCDD/Fs resist biotic degradation and therefore the potential for microbial reductive dechlorination was assessed to determine how microbes impact the fate of these compounds. Anaerobic sediment microcosms of five different sites in the river were spiked with 1,2,3,4-tetrachlorodibenzofuran (1,2,3,4-TeCDF) as a model compound to determine the dechlorination potential in the sediments. Dechlorinating bacteria were active in all the study sites of the river. The extent of dechlorination over 10 and 29 months corresponded to the levels of aged PCDD/Fs, with sediments of the most contaminated site at Kuusankoski being the most active for reductive dechlorination. The dechlorination activity and levels of aged PCDD/Fs were correlated within the sediment cores at the all sites. The pathway of 1,2,3,4-TeCDF dechlorination was mainly via 1,3,4-trichlorodibenzofuran (TrCDF) to 1,3-dichlorodibenzofuran (DiCDF). Dechlorination via 1,2,4-TrCDF to further dechlorination products was also detected. Lateral reductive dechlorination would decrease the toxicity of 2,3,7,8-substituted PCDD/Fs. Our data suggest that sediments of the Kymijoki River contain indigenous microorganisms that are responsible for dechlorination of PCDD/Fs, especially at the most contaminated site.
Faecal samples were taken from three diet-managed phenylketonuric children to determine effects of beta-2-thienylalanine (beta-2-t) on indigenous bacteria. From sample swabs, 127 anaerobes were identified and tested for beta-2-t inhibition on a phenylalanine (Phe)-free medium, Anaerobe Inhibition Test (AIT) agar. Of the isolates, 77.9% grew sufficiently to assay reactions on at least 25% of AIT plates. Using Phe-containing Columbia agar, 86.5% of the strains could be assayed. None of 28 Bacteroides cultures was inhibited by beta-2-t on AIT. Of the genera, Bifidobacterium, Eubacterium, Lactobacillus, Peptostreptococcus, and Propionibacterium, no isolates which would grow on AIT were inhibited. At least one isolate of each of the genera Peptococcus, Fusobacterium, and Clostridium was inhibited. Of 127 total isolates, only nine were inhibited by beta-2-t on AIT, and inhibition was abolished on Columbia agar. Thirty-nine "aerobes" were isolated from the same patients. Strains of the genera tested reacted similarly to previously tested strains from non-PKU sources. Also, anaerobically isolated Excherichia coli were inhibited, while Streptococcus faecalis cultures were not, confirming results on aerobically-isolated non-PKU cultures of the same species. These studies, the first dealing with beta-2-t and anaerobic bacteria, suggest that little change in intestinal bacterial populations might be expected during in vivo beta-2-t treatment.
Arctic permafrost environments store large amounts of organic carbon. As a result of global warming, intensified permafrost degradation and release of significant quantities of the currently conserved organic matter is predicted for high latitudes. To improve our understanding of the present and future carbon dynamics in climate sensitive permafrost ecosystems, the present study investigates structure and carbon turnover of the bacterial community in a permafrost-affected soil of the Lena Delta (72 degrees 22'N, 126 degrees 28'E) in northeastern Siberia. 16S rRNA gene clone libraries revealed the presence of all major soil bacterial groups and of the canditate divisions OD1 and OP11. A shift within the bacterial community was observed along the soil profile indicated by the absence of Alphaproteobacteria and Betaproteobacteria and a simultaneous increase in abundance and diversity of fermenting bacteria like Firmicutes and Actinobacteria near the permafrost table. BIOLOG EcoPlates were used to describe the spectrum of utilized carbon sources of the bacterial community in different horizons under in situ temperature conditions in the presence and absence of oxygen. The results revealed distinct qualitative differences in the substrates used and the turnover rates under oxic and anoxic conditions. It can be concluded that constantly negative redox potentials as characteristic for the near permafrost table horizons of the investigated soil did effectively shape the structure of the indigenous bacterial community limiting its phylum-level diversity and carbon turnover capacity.
Future ocean acidification (OA) and warming following climate change elicit pervasive stressors to the inhabitants of the sea. Previous experimental exposure to OA for 16 weeks at pH levels predicted for 2100 has shown to result in serious immune suppression of the Norway lobster, Nephrops norvegicus. The lobsters are currently affected by stressors such as periodical hypoxia inducing high levels of bioavailable manganese (Mn). Here, we aimed to investigate possible effects of interactions between OA and these stressors on total hemocyte counts (THCs) and on recovery of inoculated bacteria in the lobsters, measured as a proxy for bacteriostatic response. The effects were judged by following numbers of culturable Vibrio parahaemolyticus in hepatopancreas, 4 and 24h post inoculation in lobsters kept in replicate tanks with six different treatments: either ambient (pCO2~500 µatm/pH~8.1 U) or CO2-manipulated seawater (OA; pCO2~1550 µatm/pH~7.6 U) for 8 weeks. During the last 2 weeks, additional stress of either hypoxia (~23% oxygen saturation) or Mn (~9 mg L(-1)) was added except in control treatments. Our results showed clear effect on bacteriostatic response in Norway lobsters exposed to these stressors. In lobsters kept in ambient seawater without additional stressors, the number of culturable bacteria in hepatopancreas was reduced by ~34%. In combined treatment of ambient seawater and hypoxia, the reduction was ~23%, while in the Mn-exposed animals, there was no reduction at all. This was also the case in all OA treatments where mean numbers of culturable V. parahaemolyticus tended to increase. In lobsters from ambient seawater with or without hypoxia, the THC was not significantly different as was also the case in OA without additional stressors. However, in OA treatments combined with either hypoxia or Mn, THC was reduced by ~35%. While the reduction of culturable V. parahaemolyticus in lobsters was clearly affected by these stressors, we found no notable effects on growth, survival or hemolytic properties of the bacteria itself. Thus, we conclude that this predicted stress scenario is beneficial for the pathogen in its interaction with the host. As OA proceeds, it may force the health of the ecologically and economically important N. norvegicus to a tipping point if exposed to more short-term stressors such as the periodical events of hypoxia and Mn. This could impact lobster condition and biomass and may as well increase the risk for bacterial transmission to consumers.