Studies on the purification of wastewater from the nitrogen fertilizer industry by intensive algal cultures. I. Growth of Chlorella vulgaris in wastes.

The possibility of growth of intensive cultures of Chlorella vulgaris on industrial wastewater from nitrogen fertizer plant containing ammonia, urea and nitrate was investigated. Good growth of algae was obtained when the waste was enriched with phosphorus and inoculum contained a high number of cells. The optimal pH for the culture was 7.0--8.0. The main factor limiting growth of algae on wastes on the concentration of ammonia nitrogen. Chlorella vulgaris grows quite well in wastes containing 600 mg NH4-N/l but is inhibited at concentration about 100 mg NH4-N/l.     

半连续及连续培养小球藻减排沼液及CO2

采用半连续或连续模式培养小球藻,考察小球藻减排沼液和CO2的能力。结果表明:在半连续培养模式中,当更新率为30%时,沼液中的N、P质量浓度可分别稳定在16～18和0.4～0.6 mg/L,达到污水二级排放标准;提高更新率到40%以上,3 d后微藻生物量及其对沼液中N、P的吸收达到动态平衡,但N、P去除率未达到污水直接排放标准;在连续培养模式中,分别选用20%及30%的日更新率,7 L规模12 d后沼液中的总氮(TN)仍高达55.64 mg/L。说明大规模培养条件下的光限制是微藻法减排沼液的主要制约因素。     

Determining the level of total nitrogen in wastes from the microbiological industry]

Optimization of the Kjeldahl method for determination of total nitrogen in the objects of microbial synthesis was performed in regard to biomass of the benzylpenicillin-producing culture, activated sludge and certain organic compounds. Mathematical processing of the data was carried out, which showed that the difference in the mean values for the five tested conditions of mineralization was insignificant. The method is useful in assaying the final and intermediate products as well as the waste in biotechnological production.     

Nitrate accumulation and growth of Aster tripolium L. with a continuous and intermittent nitrogen supply*

Abstract The ‘tidal salt marsh’ ecotype of the halophyte Aster tripolium L. was grown in a nutrient solution with either a continuous or an intermittent NO₃^? supply with either Cl^? or SO₄^2? as the alternative anion. With increasing periods of NO₃^? supply per week the rate of the dry weight increment increased. When NO₃^? was supplied for longer than 48 h per week, the dry weight and the organic-N content in the shoots hardly increased, whereas the NO₃^? content in shoots and roots increased further. With alternated supply of a nutrient solution containing NO₃^? with one containing Cl^?, the internal NO₃^? content in the shoot was lower than in shoots grown in solutions in which NO₃^? alternated with SO₄^2?. It is concluded, that NO₃^? does not have a specific function in osmoregulation.     

Intermolecular nitrogen transfer in the enzymic conversion of glutamate to delta-aminolevulinic acid by extracts of Chlorella vulgaris.

delta-Aminolevulinic acid (ALA), the universal biosynthetic precursor of tetrapyrrole pigments, is synthesized from glutamate in plants, algae, and many bacteria via a three-step process that begins with activation by ligation of glutamate to tRNA(Glu), followed by reduction to glutamate-1-semialdehyde (GSA) and conversion of GSA to ALA. The GSA aminotransferase step requires no substrate other than GSA. A previous study examined whether the aminotransferase reaction proceeds via intramolecular or intermolecular N transfer and concluded that the reaction catalyzed by Chlamydomonas extracts occurs via intermolecular N transfer (Y.-H.L. Mau and W.-Y. Wang [1988] Plant Physiol 86: 793-797). However, in that study the possibility was not excluded that the result was a consequence of N exchange among product ALA molecules during the incubation, rather than intermolecular N transfer during the conversion of GSA to ALA. Therefore, this question was reexamined in another species and with additional controls. A gel-filtered extract of Chlorella vulgaris cells was incubated with ATP, Mg2+, NADPH, tRNA, and a mixture of L-glutamate molecules, one-half of which were labeled with 15N and the other half with 13C at C-1. The ALA product was purified, derivatized, and analyzed by gas chromatography-mass spectrometry. A significant fraction of the ALA molecules was heavy by two mass units, indicating incorporation of both 15N and 13C. These results show that the N and C atoms of each ALA molecule were derived from different glutamate molecules. Control experiments indicated that the results could not be attributed to exchange of N atoms between glutamate or ALA molecules during the incubation. These results confirm the earlier conclusion that GSA is converted to ALA via intermolecular N transfer and extend the results to another species. The labeling results, combined with the results of kinetic and inhibitor studies, support a model for the GSA aminotransferase reaction in which a single molecule of GSA is converted to ALA via an enzyme-bound 4,5-diaminovaleric acid intermediate.     

Optimization of CO2 concentration and light intensity for biodiesel production by Chlorella vulgaris FACHB-1072 under nitrogen deficiency with phosphorus luxury uptake

Microalgal biodiesel is an alternative bioenergy for the future. Nitrogen deprivation is usually used to increase lipid content in microalgae, however, it also lowers biomass production, resulting in not much increase of lipid productivity. Our previous study found that phosphorus played an important role in enhancing biodiesel productivity of C. vulgaris FACHB-1072 under nitrogen deficient condition. The aim of this study was to optimize two significant parameters of CO₂ concentration (0.03, 4, 6, 12 %) and light intensity (40, 120, 200 μmol photons m^-2 s^-1) with respect to biodiesel productivity and P uptake rate of C. vulgaris FACHB-1072. It was found that the optimized conditions were 4 % CO₂ concentration and 200 μmol photons m^-2 s^-1 light intensity. The maximum biodiesel productivity was 34.56 mg L^-1 day^-1; 2.7 times higher than the control (nutrient sufficient condition). Phosphorus was accumulated as polyphosphate and its maximum uptake rate was 2.08 mg L^-1 day^-1; twice that of the control. After optimization, the performances under nitrogen deficiency were significantly better compared with those under nitrogen sufficiency, which were rarely reported in literature. Our findings suggest a great potential to combine phosphorus removal from wastewater with biodiesel production via microalgae.     

Biodiesel synthesis from Chlorella vulgaris under effect of nitrogen limitation,intensity and quality light: estimation on the based fatty acids profiles

Cultures under nitrogen limitation for Chlorella vulgaris were kept under different light quality (white, blue, yellow and violet) at 70 and 140 µE m^?2 s^?1; to evaluate the effect on fatty acids profiles and biodiesel quality. The results showed a maximum biomass and cell density at 140 µE m^?2 s^?1 of: white light (0.69 g L^?1 and 6.5?×?10⁶ cells mL^?1, respectively) and blue light (0.65 g L^?1 and 8.0?×?10⁶ cells mL^?1, respectively); compared to violet and yellow light. The chlorophyll concentration (µg mg^?1 biomass dry weight) at 70 µE m^?2 s^?1 were in the order of light: white (25.61)?>?violet (17.10)?>?yellow (11.68)?>?blue (11.40) and, at 140 µE m^?2 s^?1 were: violet (23.64)?>?white (10.20)?>?yellow (9.66)?>?blue (7.99), suggesting the violet light stimulates the increase of chlorophyll a at higher intensity. The maximum lipid content (% w/w) were present under blue light (43.11), yellow (70.92) and violet (83.87) at 140 µE m^?2 s^?1. The different wavelengths did not have a negative effect on the quality of the biodiesel, however; violet light presented greater productivity and the indicators such as CFPP were related to the oxidative stability value and low PUFA content, leading biodiesel to good oxidative stability.

     

Investigation and modeling of the effects of light spectrum and incident angle on the growth of Chlorella vulgaris in photobioreactors

An in‐depth investigation of how various illumination conditions influence microalgal growth in photobioreactors (PBR) has been presented. Effects of both the light emission spectrum (white and red) and the light incident angle (0° and 60°) on the PBR surface were investigated. The experiments were conducted in two fully controlled lab‐scale PBRs, a torus PBR and a thin flat‐panel PBR for high cell density culture. The results obtained in the torus PBR were used to build the kinetic growth model of Chlorella vulgaris taken as a model species. The PBR model was then applied to the thin flat‐panel PBR, which was run with various illumination conditions. Its detailed representation of local rate of photon absorption under various conditions (spectral calculation of light attenuation, incident angle influence) enabled the model to take into account all the tested conditions with no further adjustment. This allowed a detailed investigation of the coupling between radiation field and photosynthetic growth. Effects of all the radiation conditions together with pigment acclimation, which was found to be relevant, were investigated in depth. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:247–261, 2016     

On the extent of the electrical potential across the thylakoid membrane induced by continuous light in Chlorella cells

The extent of the electrical potential Δ?_ss across the thylakoid membrane of Chlorella cells was estimated under steady state conditions. This has been achieved by comparing the absorption change which occurs after continuous light is switched off with a calibrated field indicating absorption change induced by flash light. Under saturating light conditions Δ?_ss is in the order of 100 mV.     

Effect of L-glutamic acid on the growth and ammonium removal from ammonium solution and natural wastewater by Chlorella vulgaris NTM06

The main objective of this laboratory scale experiment was to study the effect of l-glutamic acid on the growth in media and removal of ammonium from ammonium solution and natural wastewater by Chlorella vulgaris NTM06. It was observed that higher levels (1.0% and 1.5%) of l-glutamic acid compared to control (0% l-glutamic acid) negatively affected growth of C. vulgaris NTM06 and enhanced removal of ammonium from ammonium solution as well as natural wastewater. After 24h of incubation, 99% of 169.3mg NH(4)(+)-N/l was removed from ammonium solution by 1.5% l-glutamic acid treated C. vulgairs NTM06 cultures; removal in case of control was 70%. In case of natural wastewaters with initial ammonium concentrations of 1550, 775, 310 and 155 mg NH(4)(+)-N/l, removal after 48 h of incubation were 60%, 88%, 61% and 55% respectively. Ammonium removals from ammonium solutions of pH 4.0-8.0 were similar, whereas adsorption of ammonium ions on to the surface of dead C. vulgaris NTM06 cells was around 11%. Compared to dark, cultures incubated under the light showed higher initial removal of ammonium, however, after 24h, differences were not significant. Further research on the role of l-glutamic acid in micro-algal treatment of wastewater and its combination with other approaches such as co-immobilization of micro-algae with other organisms, starvation of micro-algal cells and the use of polymers is recommended.     

Biophysical basis of growth promotion in primary leaves ofPhaseolus vulgaris L. by hormones versus light

Rapid cell enlargement in primary leaves of bean is induced by bright white light (WL), gibberellic acid (GA3) or the cytokinin N6-benzyladenine (BA). In previous studies it has been show that all three agents cause an increase in wall extensibility, although by different mechanisms. Here we examine the effects of the three growth promoters on the osmotic potential difference (delta Psi), the accumulation of solutes (delta TSC), the wall yield threshold (Y) and the growth potential (delta Psi -Y). With GA3 and BA, but not WL, there was a rapid decline in delta Psi as measured by the osmotic concentration of expressed sap. Unlike WL, neither GA3 nor BA promoted the accumulation of osmotic solutes. The decline in delta Psi, however, was apparently counteracted by a decline in Y since the growth potential, as measured by the external-osmoticum method, remained unchanged. It is concluded that WL, GA3 and BA all promote cell enlargement of bean leaves by increasing one cellular growth parameter, wall extensibility. Only WL, however, promotes osmotic adjustment during growth.