Tobermolite effects on methane removal activity and microbial community of a lab-scale soil biocover

Three identical lab-scale biocovers were packed with an engineered soil (BC 1), tobermolite only (BC 2), and a mixture of the soil and tobermolite (BC 3), and were operated at an inlet load of 338–400 g-CH₄ m^?2 d^?1 and a space velocity of 0.12 h^?1. The methane removal capacity was 293 ± 47 g-CH₄ m^?2 d^?1 in steady state in the BC 3, which was significantly higher than those in the BC 1 and BC 2 (106 ± 24 and 114 ± 48 g-CH₄ m^?2 d^?1, respectively). Quantitative PCR indicated that bacterial and methanotrophic densities (6.62–6.78 × 10⁷ 16S rDNA gene copy number g-dry sample^?1 and 1.37–2.23 × 10⁷ pmoA gene copy number g-dry sample^?1 in the BC 1 and BC 3, respectively) were significantly higher than those in the BC 2. Ribosomal tag pyrosequencing showed that methanotrophs comprised approximately 60 % of the bacterial community in the BC 2 and BC 3, while they only comprised 43 % in the BC 1. The engineered soil favored the growth of total bacteria including methanotrophs, while the presence of tobermolite enhanced the relative abundance of methanotrophs, resulting in an improved habitat for methanotrophs as well as greater methane mitigation performance in the mixture. Moreover, a batch experiment indicated that the soil and tobermolite mixture could display a stable methane oxidation level over wide temperature (20–40 °C, at least 38 μmol g-dry sample^?1 h^?1) and pH (5–8, at least 61 μmol g-dry sample^?1 h^?1) ranges. In conclusion, the soil and tobermolite mixture is promising for methane mitigation.     

Productivity and biochemical composition of <Emphasis Type="Italic">Tetradesmus obliquus</Emphasis> and <Emphasis Type="Italic">Phaeodactylum tricornutum</Emphasis>: effects of different cultivation approaches

The present work evaluated biomass productivity, carbon dioxide fixation rate, and biochemical composition of two microalgal species, Phaeodactylum tricornutum (Bacillariophyta) and Tetradesmus obliquus (Chlorophyta), cultivated indoors in high-technology photobioreactors (HT-PBR) and outdoors both in pilot ponds and low-technology photobioreactors in a greenhouse in southern Italy. Microalgae were grown in standard media, under nitrogen starvation, and in two liquid digestates obtained from anaerobic digestion of agro-zootechnical and vegetable biomass. P. tricornutum, cultivated in semi-continuous mode in indoor HT-PBRs with standard medium, showed a biomass productivity of 21.0?±?2.3 g m^?2 d^?1. Applying nitrogen starvation, the lipid productivity increased from 2.3 up to 4.5?±?0.5 g m^?2 d^?1, with a 24 % decrease of biomass productivity. For T. obliquus, a biomass productivity of 9.1?±?0.9 g m^?2 d^?1 in indoor HT-PBR was obtained using standard medium. Applying liquid digestates as fertilizers in open ponds, T. obliquus gave a biomass productivity (10.8?±?2.0 g m^?2 d^?1) not statistically different from complete medium such as P. tricornutum (6.5?±?2.2 g m^?2 d^?1). The biochemical data showed that the fatty acid composition of the microalgal biomass was affected by the different cultivation conditions for both microalgae. In conclusion, it was found that the microalgal productivity in standard medium was about doubled in HT-PBR compared to open ponds for P. tricornutum and was about 20 % higher for T. obliquus.     

Biomass and terpenoids produced by mutant strains of <Emphasis Type="Italic">Arthrospira</Emphasis> under low temperature and light conditions

The filamentous Cyanobacterium Arthrospira is commercially produced and is a functional, high-value, health food. We identified 5 low temperature and low light intensity tolerant strains of Arthrospira sp. (GMPA1, GMPA7, GMPB1, GMPC1, and GMPC3) using ethyl methanesulfonate mutagenesis and low temperature screening. The 5 Arthrospira strains grew rapidly below 14?°C, 43.75 μmol photons m^?2 s^?1 and performed breed conservation at 2.5?°C, 8.75 μmol photons m^?2 s^?1. We used morphological identification and molecular genetic analysis to identify GMPA1, GMPA7, GMPB1 and GMPC1 as Arthrospira platensis, while GMPC3 was identified as Arthrospira maxima. Growth at different culture temperatures was determined at regular intervals using dry biomass. At 16?°C and 43.75 μmol photons m^?2 s^?1, the maximum dry biomass production and the mean dry biomass productivity of GMPA1, GMPB1, and GMPC1 were 2057?±?80 mg l^?1, 68.7?±?2.5 mg l^?1 day^?1, 1839?±?44 mg l^?1, 60.6?±?1.8 mg l^?1 day^?1, and 2113?±?64 mg l^?1, 77.7?±?2.5 mg l^?1 day^?1 respectively. GMPB1 was chosen for additional low temperature tolerance studies and growth temperature preference. In winter, GMPB1 grew well at mean temperatures <10?°C, achieving 3258 mg dry biomass from a starting 68 mg. In summer, GMPB1 grew rapidly at mean temperatures more than 28?°C, achieving 1140 mg l^?1 dry biomass from a starting 240 mg. Phytonutrient analysis of GMPB1 showed high levels of C-phycocyanin and carotenoids. Arthrospira metabolism relates to terpenoids, and the methyl-d-erythritol 4-phosphate pathway is the only terpenoid biosynthetic pathway in Cyanobacteria. The 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) gene from GMPB1 was cloned and phylogenetic analysis showed that GMPB1 is closest to the Cyanobacterium Oscillatoria nigro-viridis PCC711. Low temperature tolerant Arthrospira strains could broaden the areas suitable for cultivation, extend the seasonal cultivation time, and lower production costs.     

The membraneless bioelectrochemical reactor stimulates hydrogen fermentation by inhibiting methanogenic archaea

The membraneless bioelectrochemical reactor (Ml-BER) is useful for dark hydrogen fermentation. The effect of the electrochemical reaction on microorganisms in the Ml-BER was investigated using glucose as the substrate and compared with organisms in a membraneless non-bioelectrochemical reactor (Ml-NBER) and bioelectrochemical reactor (BER) with a proton exchange membrane. The potentials on the working electrode of the Ml-BER and BER with membrane were regulated to ?0.9 V (versus Ag/AgCl) to avoid water electrolysis with a carbon electrode. The Ml-BER showed suppressed methane production (19.8?±?9.1 mg-C·L^?1·day^?1) and increased hydrogen production (12.6?±?3.1 mg-H·L^?1·day^?1) at pH_out 6.2?±?0.1, and the major intermediate was butyrate (24.9?±?2.4 mM), suggesting efficient hydrogen fermentation. In contrast, the Ml-NBER showed high methane production (239.3?±?17.9 mg-C·L^?1·day^?1) and low hydrogen production (0.2?±?0.0 mg-H·L^?1·day^?1) at pH_out 6.3?±?0.1. In the cathodic chamber of the BER with membrane, methane production was high (276.3?±?20.4 mg-C·L^?1·day^?1) (pH_out, 7.2?±?0.1). In the anodic chamber of the BER with membrane (anode-BER), gas production was low because of high lactate production (43.6?±?1.7 mM) at pH_out 5.0?±?0.1. Methanogenic archaea were not detected in the Ml-BER and anode-BER. However, Methanosarcina sp. and Methanobacterium sp. were found in Ml-NBER. Prokaryotic copy numbers in the Ml-BER and Ml-NBER were similar, as were the bacterial community structures. Thus, the electrochemical reaction in the Ml-BER affected hydrogenotrophic and acetoclastic methanogens, but not the bacterial community.     

Effect of co-substrate feeding on methane yield of anaerobic digestion of <Emphasis Type="Italic">Chlorella vulgaris</Emphasis>

Microalgal production has many advantages over the use of terrestrial plants; therefore, increases in the use of microalgae for energy production can be expected. Algal biomass can be processed anaerobically to methane; however, the unfavorable C/N ratio of the substrate may have an inhibitory effect. The impact of the application of used cooking oil, maize silage, and mill residue on anaerobic co-digestion of the microalgal Chlorella vulgaris was studied in semi-continuous, laboratory-scale digestion. During the full period of the trial involving anaerobic digestion of algae in the case of mono-digestion and co-digestion with used cooking oil, maize silage, and mill residue, the volumetric methane yields were 0.38?±?0.07, 1.56?±?0.26, 1.19?±?0.18, and 1.16?±?0.13 L L^?1, respectively. Trials were carried out to determine the long-term effect of the total solid (TS) content of substrates (co-digestion of C. vulgaris and used cooking oil at 3.8 and 7.2 % of TS, respectively). Both designs could be increased to 5.5 g VS L^?1 d^?1, but a higher TS% resulted in increased methane production and a longer period of decline in the methane yield due to washout. The sharp decrease in methane content at the end of 90 days was accompanied by a reorganization of the methanogenic archaeal community.     

Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials

Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (~20 % (v/v)) and low (~100 ppmv) methane mixing ratios. Methylocystis parvus in autoclaved aerated concrete (AAC) exhibited the highest methane removal rate at high (28.5?±?3.8 μg CH₄ g^?1 building material h^?1) and low (1.7?±?0.4 μg CH₄ g^?1 building material h^?1) methane mixing ratio. Due to the higher volume of pores with diameter >5 μm compared to other materials tested, AAC was able to adsorb more bacteria which might explain for the higher methane removal observed. The total methane and carbon dioxide-carbon in the headspace was decreased for 65.2?±?10.9 % when M. parvus in Ytong was incubated for 100 h. This study showed that immobilized MOB on building materials could be used to remove methane from the air and also act as carbon sink.     

Improvement of Biomethane Production from Sewage Sludge in Co-digestion with Glycerol and Waste Frying Oil,Using a Design of Experiments

A central composite design circumscribed method was used to define the experimental conditions that improve the methane production rate (k_CH4, liters of methane per kilogram of VS of waste added and per day) and the cumulative methane production (cMP, liters of methane per kilogram of VS of waste added) of the co-digestion of sewage sludge (SS) with crude glycerol (cGly) and waste frying oil (WFO). Three factors were selected, i.e., SS concentration, global co-substrate concentration, and mass fraction of cGly (x_cGly) in a mixture of cGly and WFO (in chemical oxygen demand, COD). SS digestion without co-substrate reached a cMP of (294?±?6) L·kg^?1 and a k_CH4 of (64?±?1) L·kg^?1·d^?1, at standard temperature and pressure conditions and expressed relatively to the initial volatile solids. After statistical analysis, SS and co-substrate concentrations of 4.6 g·L^?1 and 8.8 g·L^?1 (in COD), respectively, with x_cGly of 0.8, were defined to simultaneously boost cMP (91 % more) and k_CH4 (3-fold increase). Application of these conditions would yield 214 MWh more in electricity per 1000 m³ of SS digested.     

Tree Species Composition, Structure, and Aboveground Wood Biomass of a Riparian Forest of the Lower Miranda River, Southern Pantanal, Brazil

The aboveground wood biomass (AWB) of tropical forests plays an important role in the global carbon cycle, and local AWB estimates provide essential data that enable the extrapolation of biomass stocks to ecosystem or biome-wide carbon cycle modelling. Few AWB estimates exist in Neotropical freshwater floodplains, where tree species distribution and forest structure depend on the height and duration of periodic inundations. We investigated tree species composition, forest structure, wood specific gravity, and AWB of trees ≥10 cm dbh in 16 plots totalling an area of 1 ha in a seasonally inundated riparian forest of the lower Miranda River, southern Pantanal, Brazil. The 443 tree individuals belonged to 46 species. Four species (Inga vera, Ocotea suaveolens, Tabebuia heptaphylla and Cecropia pachystachya) comprised more than 50% of the Total Importance Values (TIV), and floristic similarities between the plots averaged 38%. Although we detected an overall increase in species diversity correlated with decreasing flood levels, the most important tree species had almost identical distribution patterns along the flooding gradient. The stand basal area per plot (±?s.d.) amounted to 3.0?±?1.1 m² (47.8?±?18.1 m²/ha), and the tree heights averaged 10.9?±?1.4 m. Multiplying the individual basal areas by individual tree heights and a form factor of 0.6, we estimated the aboveground wood volume (AWV) for each individual, and for each plot (24.4?±?11.7 m³, 391.1?±?188 m³/ha). Wood specific gravity (SG) varied between 0.39 g/cm³ (Cecropia pachystachya) and 0.87 g/cm³ (Tabebuia heptaphylla), with a stand level average of 0.63?±?0.12 g/cm³. Multiplying the individual AWV with species SG, we estimated the plot AWB to be 16.2?±?6.4 Mg (259.4?±?102 Mg/ha). This value is comparable to that reported for late-successional forest stands of Amazonian floodplain forests, and it is close to the worldwide tropical average AWB. Because tree heights in the present forest were comparatively low when compared to other Neotropical forests, we found that resprouting of stems accounted for comparatively high basal areas. We argue that stem resprouting is an adaptation of tree species originating in non-flooded Cerrado to the seasonal inundations of riparian forests.     

Functional rigidity of a methane biofilter during the temporal microbial succession

Temporal microbial succession was investigated in relation to the performance of a methane biofilter. A laboratory-scale biofilter packed with perlite was operated for 108 days, without a deliberate biomass control. The system performance was stable over the period with a mean elimination capacity of 1,563 g m^?3 day^?1, despite a temporal deterioration (45–56 days). Ribosomal-tag pyrosequencing showed that bacterial communities at days 14–28 were distinct from those of days 68–108. The accumulation of nonviable substances strongly coincided with the community change (R ²?>?0.97). Rhodobacter, Hydrogenophaga, and Methylomonas were dominated in the earlier period, while Methylocaldum and Methylococcus were abundant in the later period. The methanotrophic proportion gradually increased to 41 %, and type I methanotrophs became predominant over time. However, community structure and methanotrophic population density stably retained over time, allowing the system to keep the similar performance. Therefore, the perlite biofilter system was functionally rigid against the temporal microbial succession.     

Above- and belowground dynamics of plant community succession following abandonment of farmland on the Loess Plateau, China

Aboveground and belowground changes during vegetation restoration and vegetation successions need to be characterized in relation to their individual responses to changes in soil resources. We examined above- and belowground vegetation characteristics, soil moisture, and nutrient status at the end of the growing season in 2006 in plots with vegetation succession ages of 2, 4, 6, and 8 years (two replicates each) that had been established on abandoned cropland, where potatoes had been grown for 3 years, using hoe and plow cultivation, immediately prior to vegetation clearance and subsequent natural plant colonization. A plant community comprising pioneer species [e.g., Artemisia capillaries, (subshrub)] was characterized by low levels of species richness (7.5?±?1.4 species m^?2), plant density (35.7?±?4.2 stems m^?2), fine root length density (940.1?±?90.1 m m^?2), and root area density (2.3?±?0.3 m² m^?2) that increased rapidly with time. Aboveground and belowground characteristics of both A. capillaries and the later successional species, Stipa bungeana (C3 perennial grass), increased in the first 6 years, but in the following 2 years A. capillaries declined while S. bungeana thrived. Thus, the fine root length density of A. capillaries, 812.4 m m^?2 after 2 years, changed by a factor of 1.7, 2.0, and 0.4 in the 4th, 6th, and 8th years, whereas that of S. bungeana changed from 278.4 m m^?2, after 4 years, and by 1.7 and 23.3 times in the 6th and 8th years, respectively. Secondary vegetation succession resulted in reduced soil moisture contents. Soil available P and N mainly influenced aboveground characteristics, while soil moisture mainly influenced belowground characteristics. However, soil moisture had no significant affect on S. bungeana belowground characteristics at the population level in this semiarid region.     

Multiple driving factors explain spatial and temporal variability in coral calcification rates on the Bermuda platform

Experimental studies have shown that coral calcification rates are dependent on light, nutrients, food availability, temperature, and seawater aragonite saturation (Ω _arag), but the relative importance of each parameter in natural settings remains uncertain. In this study, we applied Calcein fluorescent dyes as time indicators within the skeleton of coral colonies (n = 3) of Porites astreoides and Diploria strigosa at three study sites distributed across the northern Bermuda coral reef platform. We evaluated the correlation between seasonal average growth rates based on coral density and extension rates with average temperature, light, and seawater Ω _arag in an effort to decipher the relative importance of each parameter. The results show significant seasonal differences among coral calcification rates ranging from summer maximums of 243 ± 58 and 274 ± 57 mmol CaCO₃ m^?2 d^?1 to winter minimums of 135 ± 39 and 101 ± 34 mmol CaCO₃ m^?2 d^?1 for P. astreoides and D. strigosa, respectively. We also placed small coral colonies (n = 10) in transparent chambers and measured the instantaneous rate of calcification under light and dark treatments at the same study sites. The results showed that the skeletal growth of D. strigosa and P. astreoides, whether hourly or seasonal, was highly sensitive to Ω _arag. We believe this high sensitivity, however, is misleading, due to covariance between light and Ω _arag, with the former being the strongest driver of calcification variability. For the seasonal data, we assessed the impact that the observed seasonal differences in temperature (4.0 °C), light (5.1 mol photons m^?2 d^?1), and Ω _arag (0.16 units) would have on coral growth rates based on established relationships derived from laboratory studies and found that they could account for approximately 44, 52, and 5 %, respectively, of the observed seasonal change of 81 ± 14 mmol CaCO₃ m^?2 d^?1. Using short-term light and dark incubations, we show how the covariance of light and Ω _arag can lead to the false conclusion that calcification is more sensitive to Ω _arag than it really is.     

Microalgal cultivation in porous substrate bioreactor for extracellular polysaccharide production

Netrium digitus is a representative of the species-rich class Zygnematophyceae (Streptophyta). Its intensive extracellular polysaccharide (EPS) production makes this alga interesting for biotechnological applications with a focus on cosmetics and food additives. Quantitative data on growth and EPS production in suspension and, for the first time, in immobilized culture using lab-scale porous substrate bioreactors, so-called Twin-Layer (TL) systems, is presented. It is shown that the cell as well as the EPS dry weight content is increased at least sixfold in immobilized compared to suspension culture. Due to the high amount of EPS, the biofilms reach a thickness of more than 8 mm after 27 days at 70 μmol photons m^?2 s^?1 and with 1.5% CO₂ supply. Frequent exchange of the growth medium results in a linear cell biomass increase of 2.02?±?0.09 g m^?2 growth area day^?1 compared to 2.99?±?0.09 g m^?2 day^?1, when the medium is not exchanged. Under this mode of cultivation, the EPS production is lower and a final concentration of 12.18?±?1.25 g m^?2 compared to 20.76?±?0.85 g m^?2, when medium was exchanged, is reached. It is clearly demonstrated that the relatively slow growing, but excessively EPS producing, microalgal species N. digitus can be grown in porous substrate bioreactors and that this culturing technique is a promising alternative to suspension culture for the Zygnematophyceae.     

Depositional fluxes and sources of particulate carbon and nitrogen in natural lakes and a young boreal reservoir in Northern Québec

We investigated the depositional trends of total particles, carbon and nitrogen in a newly created, 600-km² hydroelectric reservoir in Northern Québec, and compared the results with those observed in lakes of the surrounding region. We show that particulate fluxes exhibit a large degree of spatial heterogeneity in both the reservoir (68–548 mg POC m^?2 d^?1 and 5–33 mg PN m^?2 d^?1) and the natural lakes (30–150 mg POC m^?2 d^?1 and 3–12 mg PN m^?2 d^?1) and that on average, settling fluxes of the reservoir (211 ± 46 mg POC m^?2 d^?1 and 14 ± 3 mg PN m^?2 d^?1) exceeded lake deposition (79 ± 13 mg POC m^?2 d^?1 and 7 ± 1 mg PN m^?2 d^?1) by approximately two-fold. Our results also show that the nature of the organic matter reaching the sediments was significantly different between lakes and the reservoir, which can have consequences for benthic metabolism and the long-term storage. We found that sinking fluxes in the reservoir were mostly regulated by local morphological and hydrological conditions, with higher fluxes along or in the vicinity of the old riverbed (average 400 ± 73 mg POC m^?2 d^?1 and 24 ± 5 mg PN m^?2 d^?1) and lower fluxes in calmer zones such as side bays (average 106 ± 10 mg POC m^?2 d^?1 and 8 ± 1 mg PN m^?2 d^?1). In lakes, where settling fluxes were not linked to the trophy, or dissolved organic carbon, the actual nature of the sedimenting organic material was influenced by lake morphometry and the relative contribution of algal versus terrestrial sources. We conclude that re-suspension and erosion play a major role in shaping the reservoir sinking fluxes which explain both, the higher reservoir deposition and also some of the qualitative differences between the two systems. Despite all these differences, sinking particulate organic carbon fluxes were small and surprisingly similar relative to the surface carbon dioxide emissions in both the reservoir and lakes, representing approximately 16–17 % of the carbon efflux estimated for these same systems in 2008.     

Characterization of a d-psicose-producing enzyme, d-psicose 3-epimerase, from Clostridium sp.

The gene coding for d-psicose 3-epimerase (DPEase) from Clostridium sp. BNL1100 was cloned and expressed in Escherichia coli. The recombinant enzyme was purified by Ni-affinity chromatography. It was a metal-dependent enzyme and required Co²⁺ as optimum cofactor. It displayed catalytic activity maximally at pH 8.0 and 65 °C (as measured over 5 min). The optimum substrate was d-psicose, and the K _m, turnover number (k _cat), and catalytic efficiency (k _cat/K _m) for d-psicose were 227 mM, 32,185 min^?1, and 141 min^?1 mM^?1, respectively. At pH 8.0 and 55 °C, 120 g d-psicose l^?1 was produced from 500 g d-fructose l^?1 after 5 h.     

Fed-Batch Cultivation of Arthrospira platensis Using Carbon Dioxide from Alcoholic Fermentation and Urea as Carbon and Nitrogen Sources

To reduce CO₂ emissions from alcoholic fermentation, Arthrospira platensis was cultivated in tubular photobioreactor using either urea or nitrate as nitrogen sources at different light intensities (60 μmol m^?2 s^?1?≤?I?≤?240 μmol m^?2 s^?1). The type of carbon source (pure CO₂ or CO₂ from fermentation) did not show any appreciable influence on the main cultivation parameters, whereas substitution of nitrate for urea increased the nitrogen-to-cell conversion factor (Y _X/N ), and the maximum cell concentration (X _m ) and productivity (P _X ) increased with I. As a result, the best performance using gaseous emissions from alcoholic fermentation (X _m ?=?2,960?±?35 g m^?3, P _X ?=?425?±?5.9 g m^?3 day^?1 and Y _X/N ?=?15?±?0.2 g g^?1) was obtained at I?=?120 μmol m^?2 s^?1 using urea as nitrogen source. The results obtained in this work demonstrate that the combined use of effluents rich in urea and carbon dioxide could be exploited in large-scale cyanobacteria cultivations to reduce not only the production costs of these photosynthetic microorganisms but also the environmental impact associated to the release of greenhouse emissions.     

Ulva lactuca and U. flexuosa (Chlorophyta,Ulvophyceae) cultivation in Brazilian tropical waters: recruitment,growth, and ulvan yield

Ulva spp. are used in a wide range of commercial applications, including bioremediation, food, bioenergy, pharmaceuticals, and agriculture. The sulfated polysaccharide ulvan obtained from Ulva spp. is of interest for triggering plant defenses against disease. However, the cultivation of Ulva spp. is still in its infancy. This study verified the feasibility of cultivating Ulva lactuca and Ulva flexuosa at two sites on the tropical Brazilian coast. We investigated the following: (a) methods to induce sporulation, (b) comparison of seeding ropes inoculated in vitro versus seeding at sea over 40 days, (c) production and harvest cycles at 15 and 30 days, (d) growth productivity of U. flexuosa at sea and in outdoor tanks, and (e) comparison of ulvan yields from biomass cultivated in tanks and the sea. High nutrient treatment was the most efficient method to induce sporulation (7,540?±?3,133 spores m^?1). Sea-based cultivation of U. flexuosa was only successful at one site. Seeding of ropes in vitro was more efficient than seeding at sea (0.31?±?0.20 g m^?2 day^?1), and 15-day harvest cycles were most efficient (20.1?±?1.8 % day^?1; 0.46?±?0.11 g m^?2 day^?1). Despite differences in plant growth in tanks (27.9?±?4.4 % day^?1) and at sea (20.1?±?1.8 % day^?1), the dry biomass and ulvan yields (17.7?±?5.0 %) did not differ between these systems. Cultivation of U. flexuosa was feasible at sea using in vitro seeding with a production cycle of 15 days in Brazilian tropical waters and tanks with high irradiance and enriched seawater.     

Enrichment culture and identification of endophytic methanotrophs isolated from peatland plants

Aerobic methane-oxidizing bacteria (MOB) are an environmentally significant group of microorganisms due to their role in the global carbon cycle. Research conducted over the past few decades has increased the interest in discovering novel genera of methane-degrading bacteria, which efficiently utilize methane and decrease the global warming effect. Moreover, methanotrophs have more promising applications in environmental bioengineering, biotechnology, and pharmacy. The investigations were undertaken to recognize the variety of endophytic methanotrophic bacteria associated with Carex nigra, Vaccinium oxycoccus, and Eriophorum vaginatum originating from Moszne peatland (East Poland). Methanotrophic bacteria were isolated from plants by adding sterile fragments of different parts of plants (roots and stems) to agar mineral medium (nitrate mineral salts (NMS)) and incubated at different methane values (1–20% CH4). Single colonies were streaked on new NMS agar media and, after incubation, transferred to liquid NMS medium. Bacterial growth dynamics in the culture solution was studied by optical density—OD600 and methane consumption. Changes in the methane concentration during incubation were controlled by the gas chromatography technique. Characterization of methanotrophs was made by fluorescence in situ hybridization (FISH) with Mg705 and Mg84 for type I methanotrophs and Ma450 for type II methanotrophs. Identification of endophytes was performed after 16S ribosomal RNA (rRNA) and mmoX gene amplification. Our study confirmed the presence of both types of methanotrophic bacteria (types I and II) with the predominance of type I methanotrophs. Among cultivable methanotrophs, there were different strains of the genus Methylomonas and Methylosinus. Furthermore, we determined the potential of the examined bacteria for methane oxidation, which ranged from 0.463 ± 0.067 to 5.928 ± 0.169 μmol/L CH4/mL/day.     

Comparing soil carbon sequestration in coastal freshwater wetlands with various geomorphic features and plant communities in Veracruz,Mexico

Background and aims

Wetlands are important carbon sinks across the planet. However, soil carbon sequestration in tropical freshwater wetlands has been studied less than its counterpart in temperate wetlands. We compared carbon stocks and carbon sequestration in freshwater wetlands with various geomorphic features (estuarine, perilacustrine and depressional) and various plant communities (marshes and swamps) on the tropical coastal plain of the Gulf of Mexico in the state of Veracruz, Mexico. These swamps are dominated by Ficus insipida, Pachira aquatic and Annona glabra and the marshes by Typha domingensis, Thalia geniculata, Cyperus giganteus, and Pontederia sagittata.

Methods

The soil carbon concentration and bulk density were measured every 2 cm along 80 cm soil profiles in five swamps and five marshes. Short-term sediment accretion rates were measured during a year using horizontal makers in three of the five swamps and marshes, the carbon sequestration was calculated using the accretion rates, and the bulk density and the percentage of organic carbon in the surficial layer was measured.

Results

The average carbon concentration ranged from 50 to 150 gC kg^?1 in the marshes and 50 to 225 gC kg^?1 in the swamps. When the wetlands were grouped according to their geomorphic features, no significant differences in the carbon stock (P?=?0.095) were found (estuarine (25.50?±?2.26 kgC m^?2), perilacustrine (28.33?±?2.74 kgC m^?2) and depressional wetlands (34.93?±?4.56 kgC m^?2)). However, the carbon stock was significantly higher (P?=?0.030) in the swamps (34.96?±?1.3 kgC m^?2) than in the marshes (25.85?±?1.19 kgC m^?2). The average sediment accretion rates were 1.55?±?0.09 cm yr^?1 in the swamps and 0.84?±?0.02 cm yr^?1 in the marshes with significant differences (P?=?0.040). The rate of carbon sequestration was higher (P?=?0.001) in swamp soils (0.92?±?0.12 kgC m^?2 yr^?1) than marsh soils (0.31?±?0.08 kgC m^?2 yr^?1). Differences in the rates of carbon sequestration associated with geomorphic features were found between the swamp ecosystems (P?<?0.05); i.e., higher values were found in the swamps than in the marshes in perilacustrine and estuarine wetlands (P?<?0.05). However, no significant differences (P?=?0.324) in carbon sequestration rates were found between the marsh and swamp areas of the depressional site.

Conclusions

Swamp soils are more important contributors to the carbon stock and sequestration than are marsh soils, resulting in a reduction in global warming, which suggests that the plant community is an important factor that needs to be considered in global carbon budgets and projects of restoration and conservation of wetlands.     

Carbon Dioxide and Methane Fluxes From Tree Stems,Coarse Woody Debris,and Soils in an Upland Temperate Forest

Forest soils and canopies are major components of ecosystem CO₂ and CH₄ fluxes. In contrast, less is known about coarse woody debris and living tree stems, both of which function as active surfaces for CO₂ and CH₄ fluxes. We measured CO₂ and CH₄ fluxes from soils, coarse woody debris, and tree stems over the growing season in an upland temperate forest. Soils were CO₂ sources (4.58 ± 2.46 µmol m^?2 s^?1, mean ± 1 SD) and net sinks of CH₄ (?2.17 ± 1.60 nmol m^?2 s^?1). Coarse woody debris was a CO₂ source (4.23 ± 3.42 µmol m^?2 s^?1) and net CH₄ sink, but with large uncertainty (?0.27 ± 1.04 nmol m^?2 s^?1) and with substantial differences depending on wood decay status. Stems were CO₂ sources (1.93 ± 1.63 µmol m^?2 s^?1), but also net CH₄ sources (up to 0.98 nmol m^?2 s^?1), with a mean of 0.11 ± 0.21 nmol m^?2 s^?1 and significant differences depending on tree species. Stems of N. sylvatica, F. grandifolia, and L. tulipifera consistently emitted CH₄, whereas stems of A. rubrum, B. lenta, and Q. spp. were intermittent sources. Coarse woody debris and stems accounted for 35% of total measured CO₂ fluxes, whereas CH₄ emissions from living stems offset net soil and CWD CH₄ uptake by 3.5%. Our results demonstrate the importance of CH₄ emissions from living stems in upland forests and the need to consider multiple forest components to understand and interpret ecosystem CO₂ and CH₄ dynamics.     

Nutritional study of Kapparazii powderTM as a food ingredient

Kappaphycus alvarezii is one of the most important commercial sources of carrageenan. Red seaweeds are found in tropical areas, and K. alvarezii is famous for its high growth rate among other tropical red seaweeds. This study was conducted to produce Kapparazii powder^TM, a product comprised of high amount of carrageenan with valuable nutrients from K. alvarezii found in Sabah, Malaysia. Spray drying and an environmentally friendly process without using chemicals were employed to produce Kapparazii powder^TM. Physicochemical properties of Kapparazii powder^TM such as proximate composition (moisture, protein, lipid, ash, and crude fiber), mineral content, heavy metals, vitamins, amino acid, color, viscosity, gel strength, swelling capacity, and water and oil holding capacity were evaluated. Kapparazii powder^TM contained moisture (4.69?±?0.03 %), protein (5.11?±?0.02 %), lipid (1.00?±?0.02 %), ash (14.52?±?0.01 %), and crude fiber (0.93?±?0.02 %). Color analysis of Kapparazii powder^TM showed that lightness (L ^*)?=?89.51?±?0.02, redness (a ^*)?=??1.27?±?0.03, and yellowness (b^*)?=?5.49?±?0.02. The value of viscosity, gel strength, swelling capacity, and water and oil holding capacity of the Kapparazii powder^TM were 0.06?±?0.00 Pa.s, 82.77?±?3.66 gf, 100?±?0.00 mL.g^?1, 4.67?±?0.58 g.g^?1, and 5.11?±?0.36 g.g^?1, respectively. Moreover, Kapparazii powder^TM did not inhibit proliferation of L929 cells after 24 h of exposure at the highest concentration (2 mg.mL^?1). In conclusion, the Kapparazii powder^TM as a source of high nutrient hydrocolloid suggested on the point of healthy ingredient for food industry application.