Type Of Nitrogen Source Research Articles

Production of Palmitoleic and Linoleic Acid in Oleaginous and Nonoleaginous Yeast Biomass

We investigated the possibility of utilizing both oleaginous yeast species accumulating large amounts of lipids (Yarrowia lipolytica, Rhodotorula glutinis, Trichosporon cutaneum, and Candida sp.) and traditional biotechnological nonoleaginous ones (Kluyveromyces polysporus, Torulaspora delbrueckii, and Saccharomyces cerevisiae) as potential producers of dietetically important major fatty acids. The main objective was to examine the cultivation conditions that would induce a high ratio of dietary fatty acids and biomass. Though genus-dependent, the type of nitrogen source had a higher influence on biomass yield than the C/N ratio. The nitrogen source leading to the highest lipid accumulation was potassium nitrate, followed by ammonium sulfate, which is an ideal nitrogen source supporting, in both oleaginous and nonoleaginous species, sufficient biomass growth with concomitantly increased lipid accumulation. All yeast strains displayed high (70–90%) content of unsaturated fatty acids in total cell lipids. The content of dietary fatty acids of interest, namely, palmitoleic acid and linoleic acid, reached in Kluyveromyces and Trichosporon strains over 50% of total fatty acids and the highest yield, over 280 mg per g of dry cell weight of these fatty acids, was observed in Trichosporon with ammonium sulfate as nitrogen source at C/N ratio 70.

Selection of effective macroalgal species and tracing nitrogen sources on the different part of Yantai coast, China indicated by macroalgal δ15N values

To determine the dominant nitrogen sources and select effective macroalgal species for monitoring eutrophication along the Yantai coast, the total carbon (TOC), total nitrogen (TN) and nitrogen stable isotope ratio (δ15N) in macroalgal tissue were analyzed in conjunction with environmental variables in seawater along the Yantai coastline. The ranges of macroalgal tissue δ15N values together with dissolved inorganic nitrogen (DIN) composition indicated that except for the atmospheric deposition, there were three dominant types of nitrogen sources along the Yantai coast, with the agricultural fertilizer usage and factorial wastewater input at the S1 (Zhifu Island coast), the sewage discharge at S2 (the Moon Bay coast), the sewage discharge together with aquaculture impacts at S3 (Fisherman Wharf coast) and S4 (the Horse Island coast). Macroalgal growth were not limited by DIN but limited by P at S2, S3 and S4. Macroalgal species suitable or not for DIN source tracing along the Yantai coast were discussed. For sites with low DIN concentration, many species of three phyla could be used for DIN sources tracing with Laurencia okamurai, Gloiopeltis furcata and Ulva pertusa being ideal species. For site with high DIN concentration, however, species of Rhodophyta were not suitable and only Scytosiphon lomentaria and Monostroma nitidium were chosen.

Nutritional stress effects under different nitrogen sources on the genes in microalga Isochrysis zhangjiangensis and the assistance of Alteromonas macleodii in releasing the stress of amino acid deficiency

The expressions of nine nitrogen assimilation-associated genes, NRT2, NAR1, NIA2, NIR, GLN2, GLSF, GSN1, GDH, and AAT2, in the microalga Isochrysis zhangjiangensis were investigated to unveil the effects of limitations of various nitrogen sources (NaNO3 , NH4 Cl, NaNO2 , and an amino acid mixture) on the microalgae. The results demonstrated that the NRT2, NAR1, GLN2, GSN1, and AAT2 genes were highly expressed in lipid-rich microalgae under inorganic nitrogen-deficient conditions and they decreased after nitrogen resupply. Significant increases in the expressions of NAR1, GLN2, and GLSF were found in nitrate-depleted microalgae, whereas significant increases in the expressions of NRT2, NAR1, GLN2, and GSN1 were found in nitrite-depleted microalgae. Significant increases in the expressions of only NRT2 and GSN1 were found in ammonium-depleted microalgae (P<0.05). Except for the NRT2, other genes were expressed at lower levels under amino acid-deficient conditions compared with amino acid-sufficient controls. The expression of the NIA2 gene decreased in nitrogen-depleted microalgae regardless of the initial nitrogen source. However, the results of fatty acid analyses showed that the features of fatty acid profiles followed a similar mode, in which the percentage compositions of C16:0 and C18:1Δ(9) increased in nitrogen-depleted cells and that of C16:1Δ(9) , C18:3Δ(9,12,15) , C18:4Δ(6,9,12,15) , and C18:5Δ(3,6,9,12,15) decreased, regardless of the type of nitrogen source applied. It was also found that the epiphytic bacterium Alteromonas macleodii played a particularly important role in releasing microalgae from the stress of amino acid deficiency. These findings also provide a foundation for regulating microalgal lipid production through manipulation of the nitrogen assimilation-associated genes.

Influence of nutrients and LED light intensities on biomass production of microalgae Chlorella vulgaris

Microalgae are viable sources of biological compounds for biodiesel production. In this study, effects of various types of nitrogen sources and nutrients concentrations in the growth medium and different LED light wavelengths and intensities on biomass production of green algae Chlorella vulgaris were investigated. Warm white light with 80 µmol/m2/sec light intensity was determined as the optimal light for biomass production. The results indicated that microalgae growth with urea as nitrogen source was higher than that of other nitrogen sources such as sodium nitrate, ammonium carbonate and ammonium chloride. Maximum biomass concentration (1.37 g/L) was obtained under the following media compositions: urea 0.25 g/L, K2HPO4 0.04 g/L, MgSO4· 7H2O 0.06 g/L, and ammonium ferric citrate 0.01 g/L. Microalgae growth data under the different light wavelengths and intensities were fitted with a mathematical model.

Study on the Correlation of N, P Nutrients and Chlorella Growth

In this paper, the Chlorella vulgaris in Yellow River Diversion reservoir was selected as experimental subjects to cultivate in laboratory. The the relationship between algae biomass and N,P was studied from the following aspects：the type of nitrogen source, the concentration of N and P，and the ratio of N and P. It was found that KNO3 was one of the best nitrogen source for growth of Chlorella vulgaris. Chlorella vulgaris can live at the lower N concentration, while it was very difficult to survive in the absence of P. So P is the limiting factor for its growth. In addition, the optimum ratio of nitrogen to phosphorus was 16:1, for Chlorella vulgaris’s growth. It was similar to the algae outbreak in the water eutrophication, glycine as the Chlorella nutrition, the algae grew slow at early and later rapid.

Key parameters governing biological hydrogen production from benzoate by Rhodopseudomonas capsulata

Combination of toxic contaminant degradation with hydrogen production has been regarded as a promising but challenging approach in wastewater treatment. In this work, the effects of benzoate concentration, pH and type of nitrogen source on photo-hydrogen production from benzoate by Rhodopseudomonas capsulata were explored. The experimental results show that both benzoate concentration and pH significantly affected the photo-hydrogen production. Taking into account the specific hydrogen production rate and hydrogen yield simultaneously, a benzoate concentration of 5mM and pH of 7.0 were favorable for hydrogen production by R. capsulata with 0.2gL−1 glutamate as the nitrogen source. To further improve the economic viability of this process, NH4Cl could be used to replace the expensive glutamate as nitrogen source, and its desired concentration for hydrogen production was in a range of 0.2–0.4gL−1.

Candida zeylanoides as a new yeast model for lipid metabolism studies: effect of nitrogen sources on fatty acid accumulation

Lipid homeostasis is well-known in oleaginous yeasts, but there are few non-oleaginous yeast models apart from Saccharomyces cerevisiae. We are proposing the non-oleaginous yeast Candida zeylanoides QU 33 as model. The aim of this study was to investigate the influence of the carbon/nitrogen ratio and the type of nitrogen source upon oil accumulation by this yeast grown on shake flask cultures. The maximum biomass was obtained in yeast extract (2.39 ± 0.19 g/l), followed by peptone (2.24 ± 0.05 g/l), while the highest content of microbial oil (0.35 ± 0.01 g/l) and the maximum lipid yield (15.63%) were achieved with peptone. Oleic acid was the predominant cellular fatty acid in all culture media (>32.23%), followed by linoleic (>15.79%) and palmitic acids (>13.47%). The highest lipid yield using glucose and peptone was obtained at the C/N ratio of 200:1.

종속영양 질산화- 호기적탈질 세균 Stenotrophomonas sp. CW-4Y의 분리와 질소제거 특성

CW-4Y was identified as Stenotrophomonas sp. by morphological and physiological characteristics, and phylogenetic analysis of its 16S rDNA gene sequence. Nitrogen removal by CW-4Y was analyzed in relation to the ammonium concentration, presence of organic carbon, carbon source, and carbon-to-nitrogen ratio (C/N). Stenotrophomonas CW-4Y has heterotrophic nitrification and aerobic denitrification abilities. Stenotrophomonas CW-4Y utilized only glucose as carbon sources, and heterotrophic nitrification and aerobic denitrification were observed regardless of the type of nitrogen source. The maximum ammonium removal rate of CW-4Y was 80 <TEX>$mg-N{\cdot}L^{-1}{</TEX><TEX>\cdot}d^{-1}$</TEX> and its denitrification rate of 192 <TEX>$mg-N{\cdot}L^{-1}{\cdot}d^{-1}$</TEX> at <TEX>$NO_3{^-}-N$</TEX> (about 280 ppm) in shake culture experiments at a C/N ratio of about 15 was about 30 times higher than those of other bacteria with the same ability.

English

Production of phytase by Aspergillus japonicus URM 5633 was investigated by solid state fermentation (SSF) using cassava bast as substrate. The effects of temperature, pH and initial moisture on phytase production were studied using a full factorial design 23. The maximum phytase activity was 174 U/g dry substrate. The optimum conditions for phytase production were pH 6.5 and 40% initial moisture at 26&deg;C with 96 h of fermentation. A factorial design 22 was created to optimise phytase production, where the initial moisture and temperature were the variables studied. The parameters for phytase production were fixed at 30% initial moisture, 30&deg;C and pH 5.5, and the maximum activity obtained was 183.1 U/g dry substrate. The effects of glucose concentration, nitrogen source type and nitrogen source concentration in phytase production was studied using the 23 factorial design. Nitrogen source concentration was significant for phytase activity and had a negative effect, indicating that smaller values increased enzyme activity. The optimum activity for phytase occurred at pH 3.6 and at an apparent optimum temperature of 60&deg;C. Phytase was stable in the pH range of 2.4-3.0 at 30-70&deg;C. The enzymatic activity increased significantly in the presence of FeSO4. &nbsp; Key words: Filamentous fungus, residue, enzyme, production, characterization.

A Novel Approach for Environmentally Friendly Production of Single Cell Protein From Petrochemical Wastewater Using a Halophilic Microorganism in Different Conditions

In this study, biodegradation of petrochemical wastewater and production of single cell protein from it as carbon source was investigated using several process parameters. The process parameters such as carbon source, type of phosphorus source, phosphorus source concentration, type of nitrogen source, nitrogen source concentration, and temperature were considered. In order to investigate the influence of process parameters, a factorial design using Taguchi method was applied with six factors at four levels. The optimum medium composition for single cell protein production was found to contain petrochemical wastewater 8%, peptone 0.2%, and K2HPO4 0.008% at temperature 37°C. The percentage ratio of single cell protein to cell dry weight in optimal conditions was 76.4%. In conclusion, Haloarcula sp. IRU1 can degrade petrochemical wastewater and use it as carbon source for single cell protein production in different conditions.

English

Many phosphate solubilizing fungi (PSF) are found in soil and their introduction in the rhizosphere of crops not only increases the availability of phosphorus from insoluble sources of phosphate but also increases the efficiency of phosphate fertilizers such as superphosphate and rock phosphate. Studies on 2 strains belonging to Aspergillus niger, and 1 strain each of Aspergillus flavus, Penicillium aurantiogriseum and Penicillium claviformis with special reference to phosphate solubilization were performed in this communication. All the fungal strains showed halo zone around them on Pikovskaya plates. Quantitative estimation of 3 indigenous strains along with the other 2 non-indigenous strains taken as reference strains was done in two nutrient broths namely: Czapek’s Dox and Pikovskaya containing dicalcium phosphate (DCP) as insoluble source of phosphorus. Out of the two media selected for the study, Pikovskaya broth supported better solubilization. The insoluble phosphates DCP, TCP (tricalcium phosphate) and hypt (hydroxyapatite) were tested, DCP was least solubilized by all strains but there was no significant difference in solubilization of TCP and hydroxyapatite. There was significant negative correlation between pH and phosphate solubilized in all forms of insoluble phosphates. Types of nitrogen sources and metal ions were also screened during the study. (Na4)2SO4 supported more solubilization than NaNO3, whereas phosphate solubilizing activity decreased (except in A. niger ATCC 282) in presence of Mn+2 and Fe+3 but presence of Al+3 did not have statistically significant effect on solubilization. Though various species of Penicillium have been reported for phosphate solubilization in literature but to the best of our knowledge this is first report of phosphate solubilization by P. claviformis. Key words: Aspergillus, Penicillium, phosphate solubilisation, dicalcium phosphate, tricalcium phosphate, hydroxyapatite.

Feasibility of Hydrothermal Nitrogen Doping Process for Enhancing Visible Light Photocatalytic Activity of Metatitanic Acid Powder

Wide band-gap photocatalyst is active only under UV light irradiation. Nitrogen doping into photocatalyst is able to extend the light absorption to the visible light region, allowing more solar energy to be utilized in photocatalytic applications. The hydrothermal process is widely applied for the preparation of nitrogen-doped TiO2. The hydrothermal method is attractive for its simplicity and environment friendly conditions. Metatitanic acid (MTA) is an industrially available intermediate product in sulfate process for TiO2production, which is mesoporous material with large specific surface area and pore volume. In this work, MTA powder was hydrothermally treated with three types of nitrogen sources (urea, hexamethylenetetramine, and ammonium hydroxide) and subsequently heat-treated in N2flow. The results of UV-Vis diffuse reflection spectra and XPS show that it is possible to dope the nitrogen dopant into MTA by the hydrothermal process and the post-heat treatment. Higher photocatalytic activity in photodegrading rhodamine B dye under visible light was obtained when processed in ammonium hydroxide (MTA-A), but weaker in the samples of urea (MTA-U) and hexamethylenetetramine (MTA-H).

Saccharomyces cerevisiae can secrete Sapp1p proteinase of Candida parapsilosis but cannot use it for efficient nitrogen acquisition

Secreted aspartic proteinase Sapp1p of Candida parapsilosis represents one of the factors contributing to the pathogenicity of the fungus. The proteinase is synthesized as an inactive pre-pro-enzyme, but only processed Sapp1p is secreted into extracellular space. We constructed a plasmid containing the SAPP1 coding sequence under control of the ScGAL1 promoter and used it for proteinase expression in a Saccharomyces cerevisiae kex2Δ mutant. Because Sapp1p maturation depends on cleavage by Kex2p proteinase, the kex2Δ mutant secreted only the pro-form of Sapp1p. Characterization of this secreted proteinase form revealed that the Sapp1p signal peptide consists of 23 amino acids. Additionally, we prepared a plasmid with the SAPP1 coding sequence under control of its authentic CpSAPP1 promoter, which contains two GATAA motifs. While in C. parapsilosis SAPP1 expression is repressed by good low molecular weight nitrogen sources (e.g., ammonium ions), S. cerevisiae cells harboring this plasmid secreted a low concentration of active proteinase regardless of the type of nitrogen source used. Quantitative real-time PCR analysis of a set of genes related to nitrogen metabolism and uptake (GAT1, GLN3, STP2, GAP1, OPT1, and PTR2) obtained from S. cerevisiae cells transformed with either plasmid encoding SAPP1 under control of its own promoter or empty vector and cultivated in media containing various nitrogen sources also suggested that SAPP1 expression can be connected with the S. cerevisiae regulatory network. However, this regulation occurs in a different manner than in C. parapsilosis.

Optimization of Process Variables Affecting the Production of Extracellular Protease by Kluyveromyces marxianus

The optimized production of extracellular protease by Kluyveromyces marxianus IF0 0288 is investigated in yeast medium containing glucose as the carbon source in fully aerobic batch fermentation (150 rpm). Four parameters - type of nitrogen source, initial culture pH, temperature and length of fermentation- influencing the growth and protease production, were considered using both the “one variable at a time” approach and response surface methodology (RSM). Experimental and statistical evidence is presented for 36-fold increase in protease volumetric activity during 72 hours of fermentation with conventionally optimized nutrition (0.04% w/v bovine serum albumin) and cultivation (pH 5.5, 25oC) conditions. The optimal initial pH-value 5.46 and temperature 25.9oC were identified by the RMS and further improved on application both the volumetric activity (42.5-fold) and specific protease activity (51-fold). The results provide for the first time the evidence that K. marxianus is potentially an efficient producer of extracellular protease. Keywords: Aerobic batch fermentation, factorial design, food industry, incubation time, initial pH, Kluyveromyces marxianus, nitrogen source, optimization, process temperature, protease activity, response surface methodology, serine protease, statistical analysis, submerged fermentation, yeast

Optimization of single-cell protein production from textile effluent at extreme conditions

The textile industry is one of the greatest generators of liquid effluent pollutants, due to the high quantities of water used in the dyeing processes. In this study, single-cell protein (SCP) production from textile effluent by Haloarcula sp. IRU1 was optimized by the Taguchi orthogonal array (OA) design. An OA layout was constructed with six factors: carbon source concentration, type of phosphorus source, phosphorus source concentration, type of nitrogen source, nitrogen source concentration, and temperature at four levels for the proposed experimental design. Qualitek-4 software was used to design and analyze the Taguchi experiments. The optimized conditions for the maximum production of SCP were 8% textile effluent (as the carbon source), 0.4% tryptone (as the nitrogen source), and 0.001% Na3PO4 (as the phosphorus source), at a temperature of 47°C. In conclusion, halophilic microorganism Haloarcula sp. IRU1 could potentially be a suitable microorganism for the biodegradation of textile effluent and production of SCP at extreme conditions.

Some factors affecting tannase production by Aspergillus niger Van Tieghem

One variable at a time procedure was used to evaluate the effect of qualitative variables on the production of tannase from Aspergillus niger Van Tieghem. These variables including: fermentation technique, agitation condition, tannins source, adding carbohydrates incorporation with tannic acid, nitrogen source type and divalent cations. Submerged fermentation under intermittent shaking gave the highest total tannase activity. Maximum extracellular tannase activity (305 units/50 mL) was attained in medium containing tannic acid as tannins source and sodium nitrate as nitrogen source at 30 °C for 96 h. All added carbohydrates showed significant adverse effects on the production of tannase. All tested divalent cations significantly decreased tannase production. Moreover, split plot design was carried out to study the effect of fermentation temperature and fermentation time on tannase production. The results indicated maximum tannase production (312.7 units/50 mL) at 35 °C for 96 h. In other words, increasing fermentation temperature from 30 °C to 35 °C resulted in increasing tannase production.

Screening of Nitrogen Sources in the Medium for &lt;i&gt;Streptococcus thermophilus&lt;/i&gt; Using Plackett–Burman Design

This study demonstrates that the type of nitrogen sources has an important influence on the growth of Streptococcus thermophilus.at the same time ,viable counts was studied by in the medium containing various nitrogen sources (peptone, yeast extract, meat extract, tryptone，soya peptone and casein hydrolysate). The results indicated that soya peptone was the most efficient nitrogen source and and the influence of different concentrations of soya peptone on growth was determined. The results indicated that viable bacteria were stimulated by the high soya peptone concentration (30g/L).

Development of highly active and stable non-precious oxygen reduction catalysts for PEM fuel cells using polypyrrole and a chelating agent

Nitrogen-modified carbon nanofibers to be used as catalysts in the oxygen reduction reaction (ORR) were synthesized by pyrolysis in the presence of cobalt with PPy and a chelating agent, such as ethylenediamine (ED). It has been found that the type of nitrogen source has a remarkable impact on the catalytic activity and stability of ORR catalysts. XPS and elemental analysis indicated that the combination of ED and PPy as nitrogen sources provided a synergistic effect toward increasing the total nitrogen content of the catalysts and the content of useful nitrogen functional groups such as pyridinic-N and graphitic-N that are responsible for high ORR activity and stability in acidic environments.

The influence of different nitrogen and carbon sources on mycotoxin production in Alternaria alternata

The aim of this study was to determine the influence of different carbon and nitrogen sources on the production of the mycotoxins alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) by Alternaria alternata at 28°C using a semi-synthetic medium (modified Czapek-Dox broth) supplemented with nitrogen and carbon sources. Additionally the effect of shaken and static cultivation on mycotoxin production was tested. Initial experiments showed a clear dependency between nitrogen depletion and mycotoxin production. To assess whether nitrogen limitation in general or the type of nitrogen source triggers the production, various nitrogen sources including several ammonium/nitrate salts and amino acids were tested. In static culture the production of AOH/AME can be enhanced greatly with phenylalanine whereas some nitrogen sources seem to inhibit the AOH/AME production completely. TA was not significantly affected by the choice of nitrogen source. In shaken culture the overall production of all mycotoxins was lower compared to static cultivation. Furthermore tests with a wide variety of carbon sources including monosaccharides, disaccharides, complex saccharides such as starch as well as glycerol and acetate were performed. In shaken culture AOH was produced when glucose, fructose, sucrose, acetate or mixtures of glucose/sucrose and glucose/acetate were used as carbon sources. AME production was not detected. The use of sodium acetate resulted in the highest AOH production. In static culture AOH production was also stimulated by acetate and the amount is comparable to shaken conditions. Under static conditions production of AOH was lower except when cultivated with acetate. In static cultivation 9 of 14 tested carbon sources induced mycotoxin production compared to 4 in shaken culture. This is the first study which analyses the influence of carbon and nitrogen sources in a semi-synthetic medium and assesses the effects of culture conditions on mycotoxin production by A. alternata.

The combination of benzamides/NCS as nitrogen/halogen sources for aminohalogenation of β-nitrostyrenes resulting in dichlorinated haloamides

The combination of benzamide and NCS was found to be an efficient nitrogen/halogen source for aminohalogenation of β-nitrostyrenes. The reaction was convenient to carry out by using 4-dimethylaminopyridine as the catalyst, resulting in vicinal dichlorinated haloamino nitroalkanes with opposite regiochemistry to that generated from other electron-deficient olefins observed previously. The reaction proceeded smoothly at room temperature with good yields and excellent regioselectivities. A mechanism involving a chloronium intermediate was proposed to explain the resulting regiochemistry. The current system explored a new type of nitrogen sources for aminohalogenation of functionalized olefins.