Changes in amino acid content of an algal feed species (Navicula sp.) and their effect on growth and survival of juvenile abalone (Haliotis rubra)

The growth and survival of juvenile Haliotis rubra, when fed with the diatom Navicula sp. cultured in f/2 medium containing combined nitrogen at 24.71 mg NO₃-N L^–1 (high), 12.35 mg NO₃-N L^–1 (standard) or 2.47 mg NO₃-N L^–1 (low), were compared in a 33-day trial. The alga in the low nitrogen medium contained 37% less total amino acid than that in the high and standard nitrogen media. There was a slightly greater reduction in essential amino acids (40%) compared to non-essential amino acids (35%). Juvenile abalone feeding on Navicula grown in medium with low nitrate and lower total amino acid content grew more slowly than when fed on the same species grown in standard or higher nitrogen medium with a higher amino acid content. The growth rate of juveniles was highest (43 m d^–1) in the high nitrate treatment followed (40 m d^–1) by the standard nitrate treatment and lowest (31 m d^–1) in the low nitrate treatment. The survival of the juveniles was also effected by the diet. Survival was better in the high and standard nitrogen media (88%) than the low nitrogen medium (75%). The results suggest that in order to achieve uniformity in nutritional quality of diatoms and good growth of abalone juveniles in commercial abalone nurseries, the nitrogen concentration in tanks should be monitored and additional nitrate added to provide an optimum concentration of between 2 and 12 mg NO₃-N L^–1.     

Removal of inorganic nitrogen sources from water by the algal biofilm of the aerial microalga Trentepohlia aurea

Removal of inorganic nitrogen sources by cells of the aerial microalga Trentepohlia aurea grown on the surface of substrate, such as filter paper, has been investigated in a batch system. When the alga grew on the paper dampened with medium, it actively ingested inorganic nitrogenous compounds in the medium. Immobilized cells on the filter papers were called algal biofilm in this study. When the algal biofilms were soaked in modified Bold's Basal medium (using 1 g NH₄Cl l^–1 as a N source), the removal rate was 4.25 mg ammonium-N l^–1 day^–1 in 40 days. In modified medium with added 26 mg nitrite-N, the removal rate of the total inorganic N ion by the biofilms reached 5.11 mg N l^–1 day^–1. This removal rate of total N ion was higher than that in the medium by addition of 26 mg nitrate-N. In addition, we tried to examine simultaneous removal of ammonium, nitrate, and nitrite ions and growth inhibition of cyanobacteria in the medium by using the algal biofilms. Consequently, it was demonstrated that the algal biofilms of T. aurea could be utilized as a biofunctional material for the purification of wastewater.     

Simultaneous nitrification and denitrification in a mixed methanotrophic culture

Simultaneous nitrification and denitrification using a mixed methanotrophic culture was investigated. When both NO₃ ^–-N (108 mg l^–1) and NH₃-N (59 mg l^–1) were added into batch reactors, nitrate removal was complete within 10 h at the rate of 47 mg NO₃ ^–-N g VSS^–1 day^–1 when dissolved oxygen (DO) concentration was maintained at 2 mg DO l^–1. Ammonia removal started simultaneously with nitrate removal at a slower rate of 14 NH₃-N g VSS^–1 day^–1. No significant accumulation of nitrite or nitrate during ammonia utilization suggested the occurrence of simultaneous nitrification and denitrification.     

Partial nitrification in an upflow biological aerated filter by O2 limitation

A laboratory scale upflow biological aerated filter (BAF) packed with a porous expanded polyurethane medium was developed to nitrify ammonium to nitrite selectively. Greater than 95% removal of ammonium was achieved up to 2 kg NH₄ ⁺-N m^–3 d. NO₂ ^–-N was accumulated up to 60% of the total (NO₂ ^– + NO₃ ^–)-N when oxygen was limited.     

Hydrocarbon production from secondarily treated piggery wastewater by the green alga Botryococcus braunii

A laboratory study was conducted on the removal of nitrogen and phosphorus from piggery wastewater during growth of Botryococcus braunii UTEX 572, together with measurements of hydrocarbon formation by the alga. The influence was tested of the initial nitrogen and phosphorus concentration on the optimum concentration range for a culture in secondarily treated piggery wastewater. A high cell density (> 7 g L^–1 d. wt) was obtained with 510 mg L^–1 NO₃-N. Growth increased with nitrogen concentration at the basal phosphorus concentration (14 mg P L^–1). The growth rate was nearly independent ( = 0.027 0.030 h^–1) of the initial phosphate concentration, except under conditions of phosphate deficiency ( = 0.019 h^–1). B. braunii grew well in piggery wastewater pretreated by a membrane bioreactor (MBR) with acidogenic fermentation. A dry cell weight of 8.5 mgL^–1 and hydrocarbon level of 0.95 gL^–1 were obtained, and nitrate was removed at a rate of 620 mg NL^–1. These results indicate that pretreated piggery wastewater provides a good culture medium for the growth and hydrocarbon production by B. braunii.     

Nitrate removal from the effluent of a fertilizer industry using a bioreactor packed with immobilized cells of <Emphasis Type="Italic">Pseudomonas stutzeri</Emphasis>and<Emphasis Type="Italic">Comamonas testosteroni</Emphasis>

A bioreactor for the removal of nitrate nitrogen (NO₃-N) from industrial effluent is described which is comprised of a glass column (60 cm × 6 cm) packed with alginate beads containing denitrifying organisms Pseudomonas stutzeri and Comamonas testosteroni. The effluent containing high concentrations of nitrate (600–950 mg l^–1) from the fertilizer industry and fusel oil (methanol as a major component) as organic carbon were used in the process. The reactor is operated in the continuous mode by injecting the pretreated nitrate-containing effluent at the top of the column. The Hydraulic retention time (HRT) was adjusted by changing the flow rates. When nitrate-containing wastewater was treated with immobilized cells, the nitrate removal rate reached a maximum 1.66 ± 0.07 Kg NO₃-N m^–3d^–1 at an influent NO₃-N concentration of 850 mg NO_3M-N l^–1within 12 h. The denitrification activity of the immobilized cells was compared with that of the free cells.     

Nitrite and nitrate synthesis from pyruvic-oxime by anAlcaligenes sp.

AnAlcaligenes sp. isolated from soil was characterized as to its ability to oxidize and grow on pyruvic-oxime. Abundant nitrification of pyruvic-oxime was demonstrated with maximal nitrite and nitrate production of 1867 mg NO₂ ^–-N per liter and 42 mg NO₃ ^–-N per liter. TheAlcaligenes sp. oxidized hydroxylamine and this metabolism was stimulated when either acetate or pyruvate was present. This organism was also capable of limited pyruvic-oxime oxidation when cultured in an acidic medium. The metabolism of pyruvic-oxime and nitrification by theAlcaligenes sp. in the environment are discussed.     

The influence of nitrogen concentration and ammonium/nitrate ratio on N-uptake,mineral composition and yield of citrus

In short-term water culture experiments with different ¹⁵N labeled ammonium or nitrate concentrations, citrus seedlings absorbed NH₄ ⁺ at a higher rate than NO₃ ^–. Maximum NO₃ ^– uptake by the whole plant occurred at 120 mg L^–1 NO₃ ^–-N, whereas NH₄ ⁺ absorption was saturated at 240 mg L^–1 NH₄ ⁺-N. ¹⁵NH₄ ⁺ accumulated in roots and to a lesser degree in both leaves and stems. However, ¹⁵NO₃ ^– was mostly partitioned between leaves and roots.Adding increasing amounts of unlabeled NH₄ ⁺ (15–60 mg L^–1 N) to nutrient solutions containing 120 mg L^–1 N as ¹⁵N labeled nitrate reduced ¹⁵NO₃ ^– uptake. Maximum inhibition of ¹⁵NO₃ ^– uptake was about 55% at 2.14 mM NH₄ ⁺ (30 mg L^–1 NH₄ ⁺-N) and it did not increase any further at higher NH₄ ⁺ proportions.In a long-term experiment, the effects of concentration and source of added N (NO₃ ^– or NH₄ ⁺) on nutrient concentrations in leaves from plants grown in sand were evaluated. Leaf concentration of N, P, Mg, Fe and Cu were increased by NH₄ ⁺ versus NO₃ ^– nutrition, whereas the reverse was true for Ca, K, Zn and Mn.The effects of different NO₃ ^–-N:NH₄ ⁺-N ratios (100:0, 75:25, 50:50, 25:75 and 0:100) at 120 mg L^–1 total N on leaf nutrient concentrations, fruit yield and fruit characteristics were investigated in another long-term experiment with plants grown in sand cultures. Nitrogen concentrations in leaves were highest when plants were provided with either NO₃ ^– or NH₄ ⁺ as a sole source of N. Lowest N concentration in leaves was found with a 75:25 NO₃ ^–-N/NH₄ ⁺-N ratio. With increasing proportions of NH₄ ⁺ in the N supply, leaf nutrients such as P, Mg, Fe and Cu increased, whereas Ca, K, Mn and Zn decreased. Yield in number of fruits per tree was increased significantly by supplying all N as NH₄ ⁺, although fruit weight was reduced. The number of fruits per tree was lowest with the 75:25 NO₃ ^–-N:NH₄ ⁺-N ratio, but in this treatment fruits reached their highest weight. Rind thickness, juice acidity, and colour index of fruits decreased with increasing NH₄ ⁺ in the N supply, whereas the % pulp and maturity index increased. Percent of juice in fruits and total soluble solids were only slightly affected by NO₃ ^–:NH₄ ⁺ ratio.     

Simultaneous Removal of Mn(II) and Nitrate by the Manganese-Oxidizing Bacterium Acinetobacter sp. SZ28 in Anaerobic Conditions

A novel bacterium, strain SZ28, identified as Acinetobacter sp., showed anaerobic denitrification ability using Mn(II) as the electron donor. Nitrate-nitrogen concentration decreased from nearly 16.52–mg L^?1 to 4.4–mg L^?1, without accumulation of nitrite as an intermediate, with a maximum of 0.063–mg NO₃^?-N L^?1 h^?1, reaching a peak of 0.085–mg NO₃^?-N L^?1 h^?1 in sodium acetate. The nitrate removal rate reached 0.067–mg NO₃^?-N L^?1 h^?1, 0.059–mg NO₃^?-N L^?1 h^?1, and 0.078 mg NO₃^?-N L^?1 h^?1 using Mn(II), S(II), and Fe(II) as electron donors, respectively. The optimum pH was 6.0, with a removal rate of 0.063–mg NO₃^?-N L^?1 h^?1     

Enhanced nitrite build-up in proportion to increasing alklinity/NH4+ ratio of influent in biofilm reactor

When the alkalinity/NH₄ ⁺ratio increased from 4.1 to 9.4, the ammonium removal rate increased from 45 to 90 mg NO_x-N l^–1 h^–1. An increase in alkalinity/NH₄ ⁺ratio was a major reason for higher pH and free ammonia (FA) concentration in the reactor. The high concentration of FA showed a selective inhibition for Nitrobacter, which caused enhanced nitrite build-up in a biofilm reactor.     

Methane oxidation in boreal peat soils treated with various nitrogen compounds

The potential methane consumption activity was examined in various plant communities of a boreal Sphagnum-dominated Bakchar bog of West Siberia. In aerobic laboratory incubations, the peat consumed methane with the maximal rates varied from 17 to 153 nmol CH₄ h^–1g^{– 1}.The highest oxidation took place in the peat from the cotton grass and dwarf shrub-cotton grass communities. The addition of different N-compounds inhibited CH₄-uptake and was not a simple influence of shift in ionic balance (`salt effect'). The introduction of sodium chloride resulted in significantly weaker inhibition effect than the same amount of nitrite and nitrate salts. The inhibition occurred at NH₄ ⁺-N concentrations exceeding 100 mg kg^–1, which was more than 200 times higher native N-content in peat. Communities with high CH₄-uptake activity were more sensitive to ammonium. The inhibition by ammonium was non-competitive. The inhibition by ammonium was mainly due to the toxic action of nitrite and/or nitrate produced by nitrifiers. A strong positive correlation was found between the potential nitrifying activity and inhibition of CH₄-uptake in ammonium-treated peat (R ²= 0.87). The oxidized N-compounds were more strong inhibitors than ammonium and their toxicity increased in the following range: NH₄ ⁺< NO₂ ^–< NO₃ ^–.     

Factors influencing artemisinin production from shoot cultures of Artemisia annua L.

Artemisinin, an anti-malarial drug isolated from the annual wormwood Artemisia annua L., has a marked activity against chloroquine-resistant and chloroquine-sensitive strains of Plasmodium falciparum, and is useful in treatment of cerebral malaria. Shoot cultures of Artemisia annua L. were established on Murashige and Skoog basal medium which contained (per litre) 30 g sucrose, 0.5 mg 6-benzyladenine and 0.05 mg naphthaleneacetic acid. Using an optimized combination of sucrose (30 g/l), nitrate (45 mM), inorganic phosphate (200 mg/l), gibberellic acid (7 mg/l) and the ratio of NH₄ ⁺-N to NO₃ ^–-N of 1:3, artemisinin production reached 26.7 mg/l after 30 days. This procedure provides a potential alternative for production of artemisinin from in vitro tissue cultures.     

Denitrification kinetics of simulated fish processing wastewater at different ratios of nitrate to biomass

Denitrification was studied in anoxic batch cultures of a simulated fish processing wastewater at 37 r C and pH 7.5, using a denitrifying enrichment culture from fishery wastewater. Different initial nitrate to biomass ratios (So/Xo) were used: nitrate and biomass varied from 7.5 to 94.7 mg NO₃-N l^–1, and from 20 to 4300 mg volatile suspended solids l^–1, respectively. The specific maximum denitrification rate (r _m) and the cell yield (Y _{X / S}) depended on the So/Xo ratio under anoxic conditions: r _m increased from 1.2 to 1584 mg NO₃-N g^–1 VSS h^–1 and Y _{X / S} decreased from 42 to 0.03 mg VSS mg^–1 NO₃-N when So/Xo varied from 5.5 10^{– 3} to 9.3 mg NO₃-N/mg VSS. Nomenclature C_{NO3 – N} nitrate concentration, mg NO₃-N l^–1 K _S saturation constant, mg NO₃-N l^–1 r _m specific maximum denitrification rate, mg NO₃-N g^–1 VSS h^–1 So initial substrate concentration, mg l^–1 t time, h TOC total organic carbon VSS volatile suspended solids x biomass concentration, g VSS l^–1 Xo initial biomass concentration, g VSS l^–1 Y _X/S substrate to biomass cell yield, mg VSS/mg N Greek symbols: _m maximum specific growth rate of the anoxic microbial population, 1 h^–1     

Enhancing biological nitrogen removal from tannery effluent by using the efficient Brachymonas denitrificans in pilot plant operations

Summary Laboratory scale and pilot plant reactors were inoculated with an efficient denitrifier, Brachymonas denitrificans(CCUG 45880), in order to evaluate whether a bio-augmentation approach can be used to enhance biological nitrogen removal from tannery effluents. To determine the effectiveness of the introduced strain, denitrifying activity in the activated sludge was monitored by nitrate uptake rate (NUR) measurement of NO₃-N. Fluorescent in situ hybridization (FISH) technique was used to monitor the growth of the augmented species. The laboratory scale nitrate removal efficiency with the introduced B. denitrificans (3.7±0.6 mg NO₃-N gVSS ⁻¹ h ⁻¹) was higher than that of the activated sludge without the addition of the bacteria (3.5±0.7 mg NO₃-N gVSS ⁻¹ h ⁻¹); the NUR in the pilot plant after and before the introduction of the strain was also of the magnitude of 12.0±1.4 and 10.6±1.4 mg NO₃-N gVSS ⁻¹ day ⁻¹ , respectively. In situ hybridization results revealed that the introduced denitrifying bacteria significantly facilitated the development of a dense denitrifying bacterial population in the activated sludge, which enhanced in situ denitrification activity. FISH data indicated that once introduced, B. denitrificans remained abundant throughout the experimental period. The ability to seed a bioreactor with bacterial strain capable of removing target pollutants from tannery effluents in a mixed microbial community suggests that this approach could have commercial applications.     

Different nitrogen sources and growth responses of Spirulina platensis in microenvironments

Spirulina platensis was cultivated, in comparative studies, using several sources of nitrogen. The standard source used (sodium nitrate) was the same as that used in the synthetic medium Zarrouk, whereas the alternative nitrogen sources consisted of ammonium nitrate, urea, ammonium chloride, ammonium sulphate or acid ammonium phosphate. The initial nitrogen concentrations tested were 0.01, 0.03 and 0.05 M in an aerated photobioreactor at 30 °C, with an illuminance of 1900 lux, and 12 h-light/12 h-dark photoperiod over a period of 672 h. Maximum biomass was produced in medium containing sodium nitrate (0.01–0.03–0.05 M), followed by ammonium nitrate (0.01 M) and urea (0.01 M). The final biomass concentrations were 1.992 g l^–1 (0.03 M sodium nitrate), 1.628 g l^–1 (0.05 M sodium nitrate), 1.559 g l^–1 (0.01 M sodium nitrate), 0.993 g l^–1 (0.01 M ammonium nitrate) and 0.910 g l^–1 (0.01 M urea). This suggested that it is possible to utilize nitrogen sources other than sodium nitrate for growing S. platensis, in order to decrease the production costs of scaled up projects.     

Nitrogen and phosphorus uptake in seedlings of the seagrass Amphibolis antarctica in Western Australia

The uptake of nitrate, ammonium and phosphate was examined in vitro in seedlings of the seagrass Amphibolis antarctica ((Labill.) Sonder ex Aschers.). Uptake of all three nutrients was significantly correlated with external concentration up to 800 µ g l^–1. The uptake of nitrate (0–200 µ g NO₃-N g dry wt^–1 h^–1) was significantly lower than the uptake of ammonium (0–500 µ g NH₄-N g dry wt^–1 h^–1), suggesting that the seedlings have a higher affinity for this form of nitrogen in the water column.Data were in general agreement with uptake rates recorded for other seagrasses, notably Zostera marina. In comparison to the dominant macroalgae for the same region, seedlings had either similar or higher uptake rates in relation to external concentration, lending support to the hypothesis that seedlings, which do not possess roots, behave like macroalgae in terms of nutrient acquisition from the water column.A comparison with literature data on adult seagrass suggests, however, that seagrasses show lower uptake rates than macroalgae suggesting that the macroalgae, which are totally reliant on the water column for nutrients, are more efficient at uptake than seagrasses which may potentially use the sediment for a nutrient source.     

Heterotrophic nitrification and aerobic denitrification by the bacterium Pseudomonas stutzeri YZN-001

A strain YZN-001 was isolated from swine manure effluent and was identified as Pseudomonas stutzeri. It can utilise not only nitrate and nitrite, but also ammonium. The strain had the capability to fully remove as much as 275.08 mg L⁻¹ NO₃⁻–N and 171.40 mg L⁻¹ NO₂⁻–N under aerobic conditions. Furthermore, At 30 °C, the utilization of ammonium is approximately 95% by 18 h with a similar level removed by 72 h and 2 weeks at 10 and 4 °C, respectively. Triplicate sets of tightly sealed serum bottles were used to test the heterotrophic nitrifying ability of P. stutzeri YZN-001. The results showing that 39% of removed NH₄⁺–N was completely oxidised to nitrogen gas by 18 h. Indicating that the strain has heterotrophic nitrification and aerobic denitrification abilities, with the notable ability to remove ammonium at low temperatures, demonstrating a potential using the strain for future application in waste water treatment.     

Anammox bacteria enrichment in upflow anaerobic sludge blanket (UASB) reactor

We investigated the anaerobic ammonium oxidation (anammox) reaction in a labscale upflow anaerobic sludge blanket (UASB) reactor. Our aim was to detect and enrich the organisms responsible for the anammox reaction using a synthetic medium that contained low concentrations of substrates (ammonium and nitrite). The reactor was inoculated with granular sludge collected from a full-scale anaerobic digestor used for treating brewery wastewater. The experiment was performed during 260 days under conditions of constant ammonium concentration (50 mg NH₄/⁺-N/L) and different nitrite concentrations (50∼150 mg NO₂-N/L). After 200 days, anammox activity was observed in the system. The microorganisms involved in this anammox reaction were identified as CandidatusB. Anammoxidans andK. Stuttgartiensis using fluorescencein situ hybridization (FISH) method.     

Intracellular nitrite accumulation: The cause of growth inhibition of Microcystis aeruginosa exposure to high nitrite level

The aim of the present study is to test the role of intracellular nitrite in external nitrite suppressing algal growth. We examined the growth of Microcystis aeruginosa at different nitrite levels under high nitrate conditions and without nitrate conditions. There were higher intracellular nitrite and lower P_m^chla, R_d ^chla, α^chl, maximum cell density and specific growth rate in high nitrate group than nitrate absence group at 5 mg NO₂^?‐N L^?1. At 10 and 15 mg NO₂^?‐N L^?1, P_m^chla, R_d ^chla, α^chl, maximum cell densities and specific growth rates in the high nitrate group became higher than those of the nitrate absence group, while a lower intracellular nitrite in the high nitrate group than nitrate absence group was observed. In addition, the intracellular nitrite and the growth of M. aeruginosa in the high nitrate group did not change from 5 to 10 mg NO₂^?‐N L^?1. In the nitrite uptake experiment, with nitrite concentration increasing from 5 to 15 mg NO₂^?‐N L^?1, maximum nitrite uptake rate of alga increased, and half‐saturation constant of alga decreased. These results indicate that external nitrite inhibited algal growth through stimulating intracellular nitrite rise, which resulted from overexpression of nitrite transporter.     

Effects of amino acids, nitrate, and ammonium on the growth and taxol production in cell cultures of Taxus yunnanensis

The effects of concentration of amino acids, nitrate, and ammonium on the growth and taxol production in cultures of cell line TY-21 of Taxus yunnanensis were investigated. Addition of 20 different amino acids each at 15–20 mg l^–1 to B5 medium significantly improved callus growth but inhibited taxol formation in the cultures. The optimum nitrate concentration was 20–30 mM for both growth and taxol production. Ammonium greatly suppressed growth but strongly promoted taxol formation in the cells when it was the sole inorganic nitrogen in the medium. Culturing the suspension cells in nitrate-containing medium for 15 days and then in a medium in which ammonium was the sole inorganic nitrogen for 7 days increased taxol yield by 104%, reaching up to 28.1 mg l^–1.