Growth of the fungus Paecilomyces lilacinus with n-hexadecane in submerged and solid-state cultures and recovery of hydrophobin proteins

The filamentous fungus Paecilomyces lilacinus was grown on n-hexadecane in submerged (SmC) and solid-state (SSC) cultures. The maximum CO₂ production rate in SmC (V_max = 11.7 mg CO₂ L_g⁻¹ day⁻¹) was three times lower than in SSC (V_max = 40.4 mg CO₂ L_g⁻¹ day⁻¹). The P. lilacinus hydrophobin (PLHYD) yield from the SSC was 1.3 mg PLHYD g protein⁻¹, but in SmC, this protein was not detected. The PLHYD showed a critical micelle concentration of 0.45 mg mL⁻¹. In addition, the PLHYD modified the hydrophobicity of Teflon from 130.1 ± 2° to 47 ± 2°, forming porous structures with some filaments <1 μm and globular aggregates <0.25 μm diameter. The interfacial studies of this PLHYD could be the basis for the use of the protein to modify surfaces and to stabilize compounds in emulsions.     

Escape protein supplementation of growing steers grazing stargrass

A grazing trial utilizing 35 individually supplemented growing steers (211±42 kg initial body weight (BW)) was conducted to study the effect of supplemental escape protein on the performance of steers grazing on stargrass (Cynodon plectostachyus) during the dry season. N in supplements was 100%, 50%, or 0% natural protein (bloodmeal, coconut meal, and soybean meal), and 0%, 50% or 100% urea. All steers received 2 kg of supplement dry matter (DM) (2.2% N) daily during the 90 days of the experiment. Steers fed the urea supplement had the lowest ADG (0.97 kg day⁻¹). There was a linear (P<0.05) response in ADG to the natural protein level (50 and 100%) in supplements containing bloodmeal (1.11 and 1.21 kg day⁻¹) and coconut meal (1.05 and 1.21 kg day⁻¹), but no response was observed with soybean meal (1.01 and 1.0 kg day⁻¹). Forage intake was not affected by supplementation. As a result of the growth response observed for supplements containing bloodmeal and coconut meal above the urea-based and soybean meal supplements, it was concluded that growing ruminants grazing stargrass in the dry season were deficient in escape protein. ©1997 Elsevier Science B.V.     

Diurnal exchanges of CO2 and CH4 across the water–atmosphere interface in a water chestnut meadow (Trapa natans L.)

CH₄ and CO₂ fluxes across the water–atmosphere interface were measured over a 24 h day–night cycle in a shallow oxbow lake colonized by the water chestnut (Trapa natans L.) (Lanca di Po, Northern Italy). Only exchanges mediated by macrophytes were measured, whilst gas ebullition was not considered in this study. Measurements were performed from 29 to 30 July 2005 with short incubations, when T. natans stands covered the whole basin surface with a mean dry biomass of 504 ± 91 g m⁻². Overall, the oxbow lake resulted net heterotrophic with plant and microbial respiration largely exceeding carbon fixation by photosynthesis. The water chestnut stand was a net sink of CO₂ during the day-light period (−60.5 ± 8.5 mmol m⁻² d⁻¹) but it was a net source at night (207.6 ± 6.1 mmol m⁻² d⁻¹), when the greatest CO₂ efflux rate was measured across the water surface (28.2 ± 2.4 mmol m⁻² h⁻¹). The highest CH₄ effluxes (6.6 ± 1.8 mmol m⁻² h⁻¹) were determined in the T. natans stand during day-time, whilst CH₄ emissions across the plant-free water surface were greatest at night (6.8 ± 2.1 mmol m⁻² h⁻¹). Therefore, we assumed that the water chestnut enhanced methane delivery to the atmosphere. On a daily basis, the oxbow lake was a net source to the atmosphere of both CO₂ (147.1 ± 10.8 mmol m⁻² d⁻¹) and CH₄ (116.3 ± 8.0 mmol m⁻² d⁻¹).     

Immobilized glucose oxidase on different supports for biotransformation removal of glucose from oligosaccharide mixtures

Four immobilized forms of glucose oxidase (GOD) were used for biotransformation removal of glucose from its mixture with dextran oligosaccharides. GOD was biospecifically bound to Concanavalin A-bead cellulose (GOD-ConA-TBC) and covalently to triazine-bead cellulose (GOD-TBC). Eupergit C and Eupergit CM were used for preparation of other two forms of immobilized GOD: GOD-EupC and GOD-EupCM. GOD-ConA-TBC and GOD-EupC exhibited the best operational and storage stabilities. pH and temperature optima of these two immobilized enzyme forms were broadened and shifted to higher values (pH 7 and 35 °C) in comparison with those of free GOD. The decrease of V_max values after immobilization was observed, from 256.8 ± 7.0 μmol min⁻¹ mg_GOD⁻¹ for free enzyme to 63.8 ± 4.2 μmol min⁻¹ mg_GOD⁻¹ for GOD-ConA-TBC and 45 ± 2.7 μmol min⁻¹ mg_GOD⁻¹ for GOD-EupC, respectively. Depending on the immobilization mode, the immobilized GODs were able to decrease the glucose content in solution to 3.8–15.6% of its initial amount The best glucose conversion, was achieved by an action of GOD-EupCM on a mixture of 100 g dextran with 9 g of glucose (i.e. 98.7% removal of glucose).     

Leaf production and shoot dynamics of Thalassia testudinum by a direct census method

The annual leaf growth and shoot dynamics of Thalassia testudinum were examined in a meadow located near Havana City, Cuba, using direct censuses between January 1995 and January 1996. The net rate of shoot population change, specific shoot recruitment and mortality rates were calculated as the difference between the densities of shoots (tagged or untagged) in consecutive sampling events. The leaf biomass, the daily production, the turnover rate and the rate of leaf biomass loss were also estimated. The estimated mean dry leaf biomass (124.9 ± 9.5 g m⁻²), daily dry leaf production (3.3 ± 0.2 g m⁻² day⁻¹) and turnover rate (2.7 ± 0.1% day⁻¹) were comparable to values previously reported for this species in Cuba and elsewhere. The production of leaves and shoots were higher in spring, declined towards mid summer, and showed the minimum values in January. Shoot recruitment prevailed over shoot mortality from January to March and from July to August, whereas most of the annual shoot mortality occurred between May and July and between August and October. The meadow examined was in close demographic balance along the study period. The results demonstrate that direct census provides reliable estimates of rapid shoot dynamics in T. testudinum.     

Effects of intraspecific competition on growth and photosynthesis of Atriplex prostrata

We investigated the effect of intraspecific competition on growth parameters and photosynthesis of the salt marsh species Atriplex prostrata Boucher in order to distinguish the effects of density-dependent growth inhibition from salt stress. High plant density caused a reduction of 30% in height, 82% in stem dry mass, 80% in leaf dry mass, and 95% in root dry mass. High density also induced a pronounced 72% reduction in leaf area, 29% decrease in length of mature internodes and 50% decline in net photosynthetic rate. The alteration of net photosynthesis paralleled growth inhibition, decreasing from 7.6 ± 0.9 μmol CO₂ m⁻² s⁻¹ at low density to 3.5 ± 0.4 μmol CO₂ m⁻² s⁻¹ at high density, indicating growth inhibition caused by intraspecific competition is mainly due to a decline in net photosynthesis rate. Plants grown at high density also exhibited a reduction in stomatal conductance from 0.7 ± 0.1 mol H₂O m⁻² s⁻¹ at low density to 0.3 ± 0.1 mol H₂O m⁻² s⁻¹ at high density and a reduction in transpiration rate from 6.0 ± 0.3 mmol H₂O m⁻² s⁻¹ at low density to 4.3 ± 0.3 mmol H₂O m⁻² s⁻¹ at high density. Biomass production was inhibited by an increase in plant density, which reduced the rate of photosynthesis, stomatal conductance and leaf area of plants.     

Effect of supplementation with pelleted citrus pulp on digestibility and intake in beef cattle fed a tropical grass-based diet (Cynodon nlemfuensis)

Citrus pulp is an important by-product for sub-tropical and tropical ruminant animal production. In this study, three steers (average body weight = 324 ± 16 kg) were randomly assigned to three levels of pelleted citrus pulp (PCP) supplementation (0, 1.25, and 2.5 kg animal⁻¹ d⁻¹; as-fed) in a 3 × 3 Latin square design to evaluate its effects on forage intake, digestion, and ruminal pH. The basal diet was stargrass (Cynodon nlemfuensis) harvested and chopped every day and fed fresh. Supplementation with increasing amounts of PCP tended (P≤0.10) to result in a linear increase in digestibility of total diet dry matter (DM) and organic matter (OM), but no effects were noticed for digestibility of forage DM or total diet neutral detergent fiber. Forage DM intake decreased linearly (P=0.03) with increasing PCP supplementation, although the decrease tended (quadratic; P=0.08) to be of greater magnitude at the highest level of supplementation. Both a linear increase (P<0.01) and a quadratic trend (greatest increase with first level of supplementation; P=0.09) were also observed for intake of total digestible OM. Average ruminal pH was between 6.6 and 7.2 and was not affected (P=0.29) by supplementation treatment. Although supplementation with PCP depressed forage consumption somewhat, little effect on forage digestion was observed. The provision of digestible OM in the form of supplement was greater than that lost via depressed forage consumption, resulting in an overall increase in energy supply. Our results suggest that high levels of citrus pulp to beef cattle can lower forage intake, but increase total energy intake. High levels of citrus pulp supplementation could be beneficial in combination with forages high in rumen dagradable protein. Systems using grasses with higher ruminally degradable protein content than we used, may benefit from this extra supply of energy which should be tested in a further experiment.     

Seasonal changes of the introduced Caulerpa racemosa var. cylindracea (Caulerpales,Chlorophyta) at the northwest limit of its Mediterranean range

A study of the meadows of the invasive Caulerpa racemosa var. cylindracea (Sonder) Verlaque, Huisman et Boudouresque was carried out over one year at Marseilles (Provence, France) where the alga is thriving, probably since 1994, in the cold waters of the north western Mediterranean Sea. At an early phase of colonisation, the C. racemosa meadow is characterized by a patchy distribution pattern. Several years are necessary to obtain a dense and continuous meadow. In one area colonized for more than 4 years, C. racemosa has developed a continuous meadow with wide seasonal variations. Maximum development was reached in autumn (biomass: 82 ± 3 g DW m⁻²; length of stolons: 1162 ± 86 m m⁻²; number of apices: 8360 ± 405 m⁻²; number of erect axes: 20955 ± 1499 m⁻²) and the minimum from winter to early spring (respectively, 0.3 ± 0.1 g DW m⁻²; 3 ± 1 m m⁻²; 220 ± 55 apices m⁻²; 35 ± 15 erect axes m⁻²). Seasonal variations in the growth rate were highly significant. The season of high growth lasted from June to October. The apical growth rate of a stolon reached a maximum of 7.5 ± 0.3 mm day⁻¹ in early October, then began to decrease significantly from the end of October to December, before becoming nearly nil from January to early May. Annual net production rate expressed in terms of stolon length and biomass was estimated as 5801 m m⁻² a⁻¹ and 612 g DW m⁻² a⁻¹, respectively. During the growth period, the turnover rate of the C. racemosa stolons was estimated at from 25 to 46 days. The growth rate was closely correlated to the seawater temperature (R² = 0.83), whereas no significant correlation was found between growth and irradiance. During the growth period, a decrease in temperature rapidly affects the growth rate, which soon recovers its earlier level when the temperature rises again. In winter, the growth rate decreased rapidly with the seasonal drop in the seawater temperature. Grazing by fish (Sarpa salpa and Boops boops) can also affect the growth rate from September to December by consumption of the erect axes and stolon apices, enhancing the ramification of stolons. Seasonal changes at Marseilles are much sharper than those reported for warmer Mediterranean localities (French Riviera, Italy, Croatia): in winter and early spring C. racemosa meadows decreased and locally disappeared, leaving a barren substrate. C. racemosa survives the lower winter seawater temperatures of the north-western Mediterranean Sea probably in the form of zygotes and/or small fragments (rhizoids, stolons, propagules).     

Diet and nutrition of range goats on a sarcocaulescent shrubland from Baja California Sur,Mexico

Botanical composition of diets of range goats was studied to determine seasonal preference indices of forage species and nutritional quality of selected diets on a sarcocaulescent shrubland from the Sonoran desert in Baja California Sur, Mexico. Extrusas from five esophageal cannulated adult female goats (40 kg of BW) were collected at the beginning and at the end of each season from April of 2001 to March of 2002. At the end of spring, goats selected higher amounts of browse legumes and cacti species, but during late summer, autumn and winter goats mainly preferred browse non-legumes followed by forb species. Goats selected a constant diet in truly digestible crude protein (annual mean = 11 ± 0.4% DM) and metabolizable energy (2.4 ± 0.1 Mcal kg⁻¹) throughout the year. However, during late spring and early summer, goats selected diets higher in non-structural carbohydrates (NSC), truly IVDOM and truly digestible NSC. Dietary Ca, Mg, K, Mn, Fe were in substantial amounts to meet requirements of a range goat weighing 40.0 kg BW consuming 76.3 g DM kg^0.75 d⁻¹ in all seasons. It is concluded that range goats may require supplementary protein and energy to overcome pregnancy and lactation requirements throughout the year. Copper content appeared marginally deficient almost the entire year and Zn during late summer and autumn.     

Volatile fatty acids accumulation and rhamnolipid generation in situ from waste activated sludge fermentation stimulated by external rhamnolipid addition

The solubilization and acidification of waste activated sludge (WAS) were apparently enhanced by external rhamnolipid (RL) addition. The maximum solute carbohydrate concentrations increased linearly from 48 ± 5 mg COD L⁻¹ in the un-pretreated WAS (blank) to 566 ± 19 mg COD L⁻¹, and protein increased from 1050 ± 8 to 3493 ± 16 mg COD L⁻¹ at RL dosage of 0.10 g g⁻¹ TSS. The highest VFAs concentration peaked at 3840 mg COD L⁻¹ at RL dosage of 0.04 g g⁻¹ TSS, which was 4.24-fold higher than the blank test. RL was generated in situ during WAS fermentation when external RL was added. It was detected that RL concentration was increased from initial 880 ± 92 mg L⁻¹ to 1312 ± 7 mg L⁻¹ at the end of 96 h with RL dosage of 0.04 g g⁻¹ TSS, which was increased to 1.49-fold. Meanwhile, methane production was notably reduced to a quite low level of 2.0 mL CH₄ g⁻¹ VSS, showing effective inhibition of methanogens by RL (58.8 mL CH₄ g⁻¹ VSS in the blank). In addition, the activity of hydrolytic enzymes (protease and α-glucosidase) was enhanced accordingly. VFAs accumulation and RL generation in situ demonstrated that the additional RL substantially performed enhanced biological effects for waste activated sludge fermentation.     

Optimal PAR intensity for spring bloom in the Northwest Pacific marginal seas

Using ten years (2003–2012) of satellite Chlorophyll-a data, we report that annual phytoplankton bloom climax in the Northwest Pacific marginal seas (17°–58°N) delays northward at a rate of 22.98 ± 2.86 km day⁻¹. The spring bloom is a dominant feature of the phytoplankton seasonal cycle in this region, except for the northern South China Sea, which features a winter bloom. The sea surface hourly Photosynthetically Available Radiation (PAR) intensity averaged over the bloom peak duration is nearly uniform (1.04 ± 0.10 W m⁻² h⁻¹) among the four sub-regions (i.e. the northern South China Sea, the Kuroshio waters, the Sea of Japan and the Sea of Okhotsk), although different algal species in these four distinct ecological provinces could adapt to a much larger change in other environmental parameters (including total daily PAR, day length, sea surface temperature, net surface heat flux, mixed layer depth, wind speed and euphotic depth). The differences of the hourly PAR intensity between the four provinces during their bloom periods are smaller than those during non-bloom seasons. In contrast, an increasing total daily PAR (W m⁻² day⁻¹), due to the longer day length at higher latitudes, may balance decreasing sea surface temperature and induce algal flowering. Our results point to an optimal hourly light intensity for the annual phytoplankton bloom peak timing in this entire region, which could potentially become an indicator for the requirement of these annual bloom peaks.     

Peel of araticum fruit (Annona crassiflora Mart.) as a source of antioxidant compounds with α-amylase, α-glucosidase and glycation inhibitory activities

Annona crassiflora Mart., whose fruit is popularly known as araticum, is a member of the Annonaceae family found in the Brazilian Cerrado. Although this plant has several medicinal uses, its bioactive molecules are not fully understood. A bioguided assay was performed to identify the main bioactive compounds of A. crassiflora fruit peel from the ethanol extract fractions with antioxidant capacity and α-amylase, α-glucosidase and glycation inhibitory activities. Ethyl acetate and n-butanol fractions showed, respectively, higher antioxidant capacity (DPPH IC₅₀ 1.5 ± 0.1 and 0.8 ± 0.1 μg mL⁻¹, ORAC 3355 ± 164 and 2714 ± 79 μmol trolox eq/g, and FRAP 888 ± 16 and 921 ± 9 μmol trolox eq/g) and inhibitory activities against α-amylase (IC₅₀ 4.5 ± 0.8 and 1.7 ± 0.3 μg mL⁻¹), α-glucosidase (IC₅₀ 554.5 ± 158.6 and 787.8 ± 140.6 μg mL⁻¹) and glycation (IC₅₀ 14.3 ± 3.3 and 16.0 ± 4.2 μg mL⁻¹), and lower cytotoxicity, compared to the other fractions and crude ethanol extract. The HPLC-ESI-MS/MS analysis identified various biomolecules known as potent antioxidants, such as chlorogenic acid, (epi)catechin, procyanidins, caffeoyl-hexosides, quercetin-glucosides and kaempferol. The fruit peel of A. crassiflora, a specie from Cerrado, the Brazilian Savanna, provided a source of antioxidant compounds with properties to block carbohydrate digestive enzymes and formation of glycation products. Thus, there is potential to use the by-products of araticum in order to identify and isolate phytochemicals for application in nutraceutical supplements, food additives and pharmaceuticals products.     

Growth and loss of distal tissue in blades of Lessonia nigrescens and Lessonia trabeculata (Laminariales)

Meristematic growth and loss of distal tissue from blades of two ecologically important species in the south-east Pacific, Lessonia nigrescens and Lessonia trabeculata, was evaluated during 1 year. Comparative growth was determined by a hole-punch method, loss of distal tissue from the blades was determined by subtracting final blade length (with loss) from expected blade lengths (without loss); growth and tissue loss were transformed to fresh biomass units for calculation of inter-algae differences. The results showed that blade elongation rate increased at the beginning of spring, and declined towards the end of summer, with mean values between 0.40 and 0.08 cm day⁻¹ for L. nigrescens, and 0.65–0.17 cm day⁻¹ for L. trabeculata. Loss of distal tissue varied seasonally when examined as length units for both species; with mean values between 0.24 and 0.10 cm day⁻¹ for L. nigrescens, and 0.51–0.25 cm day⁻¹ for L. trabeculata. Variations in fresh biomass units were only observed in Lessonia trabeculata, increasing in spring, with mean values to 0.13 g (fresh weight) day⁻¹. Annual growth and loss of distal tissue were higher in L. trabeculata (0.41 and 0.39 cm day⁻¹, respectively) than in L nigrescens (0.19 and 0.15 cm day⁻¹). When growth and tissue loss were considered as fresh biomass, monthly gains significantly outweighed loss of distal tissue in both species, but parallel results based on length data followed a different trend. L. trabeculata released about 50% of its growth biomass as particulate organic matter, while the comparative value for L. nigrescens was about 20%.     

A ‘conovenomic’ analysis of the milked venom from the mollusk-hunting cone snail Conus textile—The pharmacological importance of post-translational modifications

Cone snail venoms provide a largely untapped source of novel peptide drug leads. To enhance the discovery phase, a detailed comparative proteomic analysis was undertaken on milked venom from the mollusk-hunting cone snail, Conus textile, from three different geographic locations (Hawai’i, American Samoa and Australia's Great Barrier Reef). A novel milked venom conopeptide rich in post-translational modifications was discovered, characterized and named α-conotoxin TxIC. We assign this conopeptide to the 4/7 α-conotoxin family based on the peptide's sequence homology and cDNA pre-propeptide alignment. Pharmacologically, α-conotoxin TxIC demonstrates minimal activity on human acetylcholine receptor models (100 μM, <5% inhibition), compared to its high paralytic potency in invertebrates, PD₅₀ = 34.2 nMol kg⁻¹. The non-post-translationally modified form, [Pro]^2,8[Glu]¹⁶α-conotoxin TxIC, demonstrates differential selectivity for the α3β2 isoform of the nicotinic acetylcholine receptor with maximal inhibition of 96% and an observed IC₅₀ of 5.4 ± 0.5 μM. Interestingly its comparative PD₅₀ (3.6 μMol kg⁻¹) in invertebrates was ∼100 fold more than that of the native peptide. Differentiating α-conotoxin TxIC from other α-conotoxins is the high degree of post-translational modification (44% of residues). This includes the incorporation of γ-carboxyglutamic acid, two moieties of 4-trans hydroxyproline, two disulfide bond linkages, and C-terminal amidation. These findings expand upon the known chemical diversity of α-conotoxins and illustrate a potential driver of toxin phyla-selectivity within Conus.     

Extended rhodamine photosensitizers for photodynamic therapy of cancer cells

Extended thio- and selenorhodamines with a linear or angular fused benzo group were prepared. The absorption maxima for these compounds fell between 640 and 700 nm. The extended rhodamines were evaluated for their potential as photosensitizers for photodynamic therapy in Colo-26 cells. These compounds were examined for their photophysical properties (absorption, fluorescence, and ability to generate singlet oxygen), for their dark and phototoxicity toward Colo-26 cells, and for their co-localization with mitochondrial-specific agents in Colo-26 and HUT-78 cells. The angular extended rhodamines were effective photosensitizers toward Colo-26 cells with 1.0 J cm⁻² laser light delivered at λ_max ± 2 nm with values of EC₅₀ of (2.8 ± 0.4) × 10⁻⁷ M for sulfur-containing analogue 6-S and (6.4 ± 0.4) × 10⁻⁸ M for selenium-containing analogue 6-Se. The linear extended rhodamines were effective photosensitizers toward Colo-26 cells with 5 and 10 J cm⁻² of broad-band light (EC₅₀’s ⩽ 2.4 × 10⁻⁷ M).     

Kinetic analysis of photosynthetic growth and photohydrogen production of two strains of Rhodobacter Capsulatus

Two mutants of Rhodobacter Capsulatus (JP91 and IR3), a photosynthetic purple non-sulfur bacterium, were grown in a batch photobioreactor under illumination with 30 mmol l⁻¹ dl-lactate and 5 mmol l⁻¹ l-glutamate as carbon and nitrogen source, respectively. Bacterial growth was measured by monitoring the increase in absorbance at 660 nm. The photosynthetic growth processes under different cultivated temperatures are well fitted by a specific logistic model to analyze the kinetics of photosynthetic growth of two strains, thus the apparent growth rates (k) of these photosynthetic bacteria, the variations of cell dry weight (CDW) as well as their relationship with temperature are obtained. In present work, k is (0.1465 ± 0.0146), (0.2266 ± 0.0207) and (0.3963 ± 0.0257) h⁻¹ for JP91 and (0.1117 ± 0.0122), (0.1218 ± 0.0133) and (0.2223 ± 0.0152) h⁻¹ for IR3 at 26, 30 and 34 °C, respectively. And the difference between CDW_max and CDW₀ is (0.8997 ± 0.0097), (0.8585 ± 0.0093) and (0.9241 ± 0.0099) g l⁻¹ for JP91 and (0.8167 ± 0.0089), (0.7878 ± 0.0086) and (0.8358 ± 0.0091) g l⁻¹ for IR3 at 26, 30 and 34 °C, respectively. Also real-time monitoring of hydrogen production rates is acquired by recording the flow rates of photohydrogen for these two strains under different temperatures. The effects of temperature on the bacteria growth, hydrogen production capability and substrate conversion efficiency are discussed based on these results. The most preferment temperature, 30 °C, showed good substrate conversion efficiency of 52.7 and 68.2% for JP91 and IR3, respectively.     

Horseradish peroxidase production from Spodoptera frugiperda larvae: A simple and inexpensive method

Horseradish peroxidase is used in many biotechnological fields including diagnostics, biocatalysts and biosensors. Horseradish peroxidase isozyme C (HRPC) was extracellularly expressed in Spodoptera frugiperda Sf9 cell culture and in intact larvae. At day 6 post-infection, the concentration of active HRPC in suspension cultures was 3.0 ± 0.1 μg per 1 × 10⁶ cells or 3.0 ± 0.1 mg l⁻¹ with a multiplicity of infection of 1 in the presence of 7.2 μM hemin. Similar yields were obtained in monolayer cultures. In larvae, the HRPC expression level was 137 ± 17 mg HRPC kg⁻¹ larvae at day 6 post-infection with a single larvae thus producing approximately 41 μg HRPC. The whole larval extract was separated by ion exchange chromatography and HRPC was purified in a single step with a yield of 75% and a purification factor of 117. The molecular weight of recombinant HRPC was 44,016 Da, and its glycosylation pattern agreed with that expected for invertebrates. The K_m and V_max were 12.1 ± 1.7 mM and 2673 ± 113 U mg⁻¹, respectively, similar to those of HRP purified from Armoracia rusticana roots. The method described in this study, based on overexpression of HRPC in S. frugiperda larvae, is a simple and inexpensive way to obtain high levels of active enzyme for research and other biotechnological applications.     

Characteristics of simultaneous organic and nutrient removal in a pilot-scale vertical submerged membrane bioreactor (VSMBR) treating municipal wastewater at various temperatures

A pilot-scale vertical submerged membrane bioreactor (VSMBR) with anoxic and oxic zones in one reactor was operated in an attempt to reduce the problems concerning effective removal of organic matter and nutrients from municipal wastewater. Source water with total chemical oxygen demand (TCOD)/total nitrogen (TN) ratio of 5.5 was treated at various temperatures (13–25 °C) over an interval of about 1 year. As a result, total suspended solid (TSS) and TCOD were removed by 100% and higher than 98%, respectively. Moreover, the average removal efficiencies of TN and total phosphorus (TP) were found to be 74% and 78% at 8 h-hydraulic retention time (HRT) and 60-days sludge retention time (SRT). Under these conditions, the specific removal rates (SRR) of TN and TP were found to be 0.093 kg N m⁻³ day⁻¹ and 0.008 kg P m⁻³ day⁻¹, and the daily production of excess sludge (DPES), 0.058 kg TSS day⁻¹.     

Two ways to achieve an anammox influent from real reject water treatment at lab-scale: Partial SBR nitrification and SHARON process

A comparative study to produce the correct influent for Anammox process from anaerobic sludge reject water (700–800 mg NH₄⁺-N L⁻¹) was considered here. The influent for the Anammox process must be composed of NH₄⁺-N and NO₂⁻-N in a ratio 1:1 and therefore only a partial nitrification of ammonium to nitrite is required. The modifications of parameters (temperature, ammonium concentration, pH and solid retention time) allows to achieve this partial nitrification with a final effluent only composed by NH₄⁺-N and NO₂⁻-N at the right stoichiometric ratio. The equal ratio of HCO₃⁻/NH₄⁺ in reject water results in a natural pH decrease when approximately 50% of NH₄⁺ is oxidised. A Sequencing batch reactor (SBR) and a chemostat type of reactor (single-reactor high activity ammonia removal over nitrite (SHARON) process) were studied to obtain the required Anammox influent. At steady state conditions, both systems had a specific conversion rate around 40 mg NH₄⁺-N g⁻¹ volatile suspended solids (VSS) h⁻¹, but in terms of absolute nitrogen removal the SBR conversion was 1.1 kg N day⁻¹ m⁻³, whereas in the SHARON chemostat was 0.35 kg N day⁻¹ m⁻³ due to the different hydraulic retention time (HRT) used. Both systems are compared from operational (including starvation experiments) and kinetic point of view and their advantages/disadvantages are discussed.     

Investigation of Foscan® interactions with plasma proteins

The present study investigates the interaction of the second generation photosensitizer Foscan® with plasma albumin and lipoproteins. Spectroscopic studies indicated the presence of monomeric and aggregated Foscan® species upon addition to plasma protein solutions. Kinetics of Foscan® disaggregation in albumin-enriched solutions were very sensitive to the protein concentration and incubation temperature. Kinetic analysis demonstrated that two types of Foscan® aggregated species could be involved in disaggregation: dimers with a rate constant of k₁ = (2.30 ± 0.15) × 10⁻³ s⁻¹ and higher aggregates with rate constants varying from (0.55 ± 0.04) × 10⁻³ s⁻¹ for the lowest to the (0.17 ± 0.02) × 10⁻³ s⁻¹ for the highest albumin concentration. Disaggregation considerably increased with the temperature rise from 15 °C to 37 °C. Compared to albumin, Foscan® disaggregation kinetics in the presence of lipoproteins displayed poorer dependency on lipoprotein concentrations and smaller variations in disaggregation rate constants. Gel-filtration chromatography analysis of Foscan® in albumin solutions demonstrated the presence of aggregated fraction of free, non-bound to protein Foscan® and monomeric Foscan®, bound to protein.