Search results for "OMAS"
showing 10 items of 1725 documents
Cultivation and biochemical characterization of isolated Sicilian microalgal species in salt and temperature stress conditions
2021
Abstract In the last years, the possibility to exploit autochthone microalgae in regional applications has been explored. The regional-based microalgal industry may bring several benefits, as autochthone microalgae are already adapted to the biotic and abiotic stresses of their environment. In this work, this concept was applied to Sicily, in which three microalgal strains were collected from the coastline. Monoalgal strains were then isolated and molecular characterization was performed for the species determination. Three of them, two strains of Chlorella and one of Dunaliella, were cultivated in lab-scale in four different conditions: Low Temperature-Low Salt (LT-LS), High-Temperature-Lo…
The effect of iron on the biodegradation of natural dissolved organic matter
2016
Iron (Fe) may alter the biodegradation of dissolved organic matter (DOM), by interacting with (DOM), phosphorus (P) and microbes. We isolated DOM and a bacterial community from boreal lake water and examined bacterial growth on DOM in laboratory experiments. Fe was introduced either together with DOM (DOM-Fe) or into bacterial suspension, which led to the formation of insoluble Fe-precipitates on bacterial surfaces (Fe coating). In the latter case, the density of planktonic bacteria was an order of magnitude lower than that in the corresponding treatment without introduced Fe. The association of Fe with DOM decreased bacterial growth, respiration, and growth efficiency compared with DOM alo…
Soil microbial and microfaunal communities and organic matter quality in reindeer winter and summer ranges in Finnish subarctic mountain birch forests
2008
Abstract Reindeer husbandry has significant influences on the aboveground plant communities and the structure of the mountain birch forests in the Fennoscandian subarctic. We investigated how the reindeer-mediated aboveground changes affect soil microbial and microfaunal communities and enzymatic activities. We hypothesized that in areas with intensive summer browsing by reindeer, the carbon flow to belowground is reduced, but the carbon substances are more readily degradable. This is likely to influence both the abundance and the trophic structure of microbial and microfaunal communities. However, despite large differences in the vegetation, the reindeer ranges did not differ in the amount…
Responses of microbial-feeding nematodes to organic matter distribution and predation in experimental soil habitat
2001
Abstract Soils are spatially heterogeneous environments, a condition which is likely to affect the structure and function of soil food webs. To study the influence of soil organic matter distribution on decomposer food webs, we established microcosms that contained either: (1) large patches of initially sterile humus-litter mixture placed within sterile sand matrix (creating a large-patch habitat; LPH); or (2) blend of sand and humus-litter mixture (creating a small-patch habitat; SPH). Ten species of bacteria and ten species of fungi, and two bacterial-feeding ( Acrobeloides tricornis , Caenorhabditis elegans ) and two fungal-feeding ( Aphelenchus avenae , Aphelenchoides sp.) nematodes wer…
Widespread contribution of methane-cycle bacteria to the diets of lake profundal chironomid larvae.
2008
Reports of unexpectedly 13C-depleted chironomid larvae in lakes have led to an hypothesis that significant transfer of detrital organic matter to chironomid larvae may occur via methane-cycle bacteria. However, to date little is known of how such transfer might vary across species and lakes. We gathered data from 87 lakes to determine how widespread this phenomenon might be and to define boundaries for its likely magnitude. Carbon stable isotope values of chironomid larvae varied greatly between taxa. Very marked 13C-depletion was evident only in certain taxa, especially Chironomus plumosus, C. anthracinus, and C. tenuistylus, all characteristic of eutrophic or dystrophic lakes and known to…
Effects of compost input and tillage intensity on soil microbial biomass and activity under Mediterranean conditions
2010
Organic amendment and tillage reduction are two common practices to contrast soil organic matter decline, thus promoting sustainable cropping and carbon sequestration. In a horticultural land use system under Mediterranean climate, we evaluated the 9-year effects of two compost inputs (15 and 30 t ha−1 y−1, low and high input, respectively) and two tillage intensities (intensive and reduced) on soil macronutrients concentration, microbial biomass and activity. Total organic C, total N and POlsen were smaller in plots amended at low input, whilst intensive tillage decreased them at both compost inputs. These decreases in intensively tilled plots was ascribed to the disruption of soil aggrega…
Hydrothermal liquefaction of waste biomass in stirred reactors: One step forward to the integral valorization of municipal sludge
2020
Abstract Hydrothermal liquefaction (HTL) of municipal sludge (MS) was performed at 350 °C for 30 min (subcritical water) and at 400 °C for 0 min (supercritical water) at fixed kinetic severity (LogR0 = 8.9) in static and stirred batch reactors to study the effect of the flow regime on the energy recovery (ER) of the process and on the quality of the products. With adopted experimental procedures it was possible to reduce to less than 10% the yield of lost organic compounds, termed volatiles (VT), and to collect and quantify a liquid hydrocarbon fraction (HC) separated from the biocrude (BC). The highest value of the HC yield, 25% w/w, was obtained in supercritical conditions. The C content …
Levan production byZymomonas mobilis cells. Attached to plaited spheres
1997
In this work, an immobilization method for polymer-levan production by a non-flocculating Z mobilis culture was developed. The extent of cell attachment to the stainless steel wire surface, culture growth and product synthesis were described. It was established that during short-term passive immobilization of non-flocculating Z mobilis cells on a stainless steel wire surface, sufficient amounts of biomass for proper levan and ethanol fermentation could not be obtained. Adherence of cells was improved by pressing the paste-like biomass within stainless steel spheres knitted from wire with subsequent dehydration. Biomass fixed in metal spheres was used for repeated batch fermentation of levan…
Effect of iron and aeration on superoxide dismutase and catalase activity of PHB-producing Azotobacter chroococcum
2009
Abstract The effect of aeration level and iron concentration on Azotobacter chroococcum 23 growth, PHB accumulation and antioxidative enzyme activities was investigated in shake flask experiments. Biomass yield and carbon source conversation coefficients increased in the presence of iron in the growth medium and under decreased aeration. The highest biomass production was observed for the culture grown in a medium with 36 μM of initial iron concentration and moderate aeration level. The highest PHB accumulation level (70–72% from cell dry weight) under our experimental conditions was observed at decreased aeration in the growth medium with 180 μM of initial iron concentration. Results obtai…
Fecal pellets from a dense aggregation of suspension-feeders in a stream: An example of ecosystem engineering
1998
Blackfly larvae (Diptera: Simuliidae) are "allogenic ecosystem engineers" that capture fine particulate and dissolved matter from suspension and egest much larger fecal pellets. We investigated the effects of blackfly larvae on organic matter transport at 25 sites along a small stream that flowed 500 m from a lake to the sea. Blackfly density was high upstream (>6 x 10(5) ind. m(-2)) and the numbers of fecal pellets in suspension rose markedly downstream from the blackfly aggregation. A total of 1.6 x 10(9) fecal pellets (biomass 3.2 kg C d(-1)) were discharged to the sea each day and 8.0 x 10(8) pellets (biomass 1.6 kg C d(-1)) were lost from suspension. Sedimenting pellets were available …