Nitrogen Source Concentration Research Articles

Efficient production of biomass and exopolysaccharide from P. ostreatus and physio-chemical characterization of biomass powder

Mycelium biomass and exopolysaccharides (EPS) from Pleurotus ostreatus origin have gained peculiar attention because of their myriad applications in the food and pharmaceutical industries. Mycelial growth is greatly dependent on fermentation media and physical conditions. This study aims to optimize mycelium biomass and EPS using one factor at a time (OFAT) approach. The current study investigates the effect of the concentration of various carbon, nitrogen sources, metal ions, and cell numbers in inoculum for biomass and EPS production. The results revealed that the 5% w/v malt extract and 2% w/v glucose combined with 0.05% w/v of Mg+ ions gave the maximum yield of biomass and EPS as 31.55 g/L and 6.65 g/L respectively. A high protein and total phenolics content have been obtained in the supernatant of media as 5.178 g/L and 104.18 mg GAE/g dry weight respectively. Furthermore, the obtained lyophilized biomass powder was investigated by FTIR which showed the presence of proteins and polysaccharides. The morphology and elemental composition were observed by SEM-EDS. XRD pattern showed the amorphous nature of biomass but the presence of chitin was also observed.

Pengaruh Perbedaan Jenis dan Konsentrasi Sumber Nitrogen (NaNO3 dan urea) terhadap Produksi Biomasa Spirulina Platensis

The goal of this study was to investigate the effect of the concentration and the type of nitrogen sources in the cultivation medium on the production of biomass and biochemical content (carbohydrates, proteins, fats) in the Spirulina platensis biomass. Types of nitrogen sources included NaNO3 and urea, where the concentrations were varied from 0.5 to 3.5 g/L. The results showed that the use of urea tended to produce more S. platensis biomass than the use of NaNO3. The best concentrations that produced the highest biomass were NaNO3 2.5 g/L (biomass 0.6745 g/L) and urea 0.5 g/L (biomass 0.7158 g/L). The use of urea also tended to produce a higher specific growth rate and a shorter doubling time than the use of NaNO3. The high concentration of nitrogen sources caused the pH of the medium to increase more rapidly due to the accumulation of ammonium in the medium. Using NaNO3 can produce biomass with a higher protein content (28.34-36.98%) than using urea (25.86-33.52%).

Utilization of non-pathogenic bacteria to obtain optimum biofilm production for beneficial applications.

Depending on the bacteria embedded in the extracellular polymeric layer, biofilms can be advantageous or harmful. The isolated strains used in this investigation are already established to be beneficial biofilm-producing bacteria. In order to use them effectively in various domains, it is necessary to characterize them and understand their ideal physiological characteristics for maximumbiofilm growth. This study used genome sequence analysis to identify and characterize strains isolated from water samples in Raipur, Chhattisgarh, India. The nucleotide sequences were submitted to NCBI GenBank under the accession numbers Bacillus tequilensis (MN889418) and Pseudomonas beteli (MN889419) and the strains were further characterized using some advanced techniques (phase contrast microscopy, Raman spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscope). For maximum biofilm formation by isolated bacterial strains, many physiochemical factors including incubation duration, temperature, pH, carbon source concentration, and nitrogen source concentration were further examined and optimized. The fact that these non-pathogenic strains were found in public water supplies is another important part of this research because there is a chance that they could change into pathogenic state in future and cause disease in humans.

Enhanced extracellular production of raw starch-degrading α-amylase in Bacillus subtilis through expression regulatory element modification and fermentation optimization

BackgroundRaw starch-degrading α-amylase (RSDA) can hydrolyze raw starch at moderate temperatures, thus contributing to savings in starch processing costs. However, the low production level of RSDA limits its industrial application. Therefore, improving the extracellular expression of RSDA in Bacillus subtilis, a commonly used industrial expression host, has great value.ResultsIn this study, the extracellular production level of Pontibacillus sp. ZY raw starch-degrading α-amylase (AmyZ1) in B. subtilis was enhanced by expression regulatory element modification and fermentation optimization. As an important regulatory element of gene expression, the promoter, signal peptide, and ribosome binding site (RBS) sequences upstream of the amyZ1 gene were sequentially optimized. Initially, based on five single promoters, the dual-promoter Pveg-PylB was constructed by tandem promoter engineering. Afterward, the optimal signal peptide SPNucB was obtained by screening 173 B. subtilis signal peptides. Then, the RBS sequence was optimized using the RBS Calculator to obtain the optimal RBS1. The resulting recombinant strain WBZ-VY-B-R1 showed an extracellular AmyZ1 activity of 4824.2 and 41251.3 U/mL during shake-flask cultivation and 3-L fermenter fermentation, which were 2.6- and 2.5-fold greater than those of the original strain WBZ-Y, respectively. Finally, the extracellular AmyZ1 activity of WBZ-VY-B-R1 was increased to 5733.5 U/mL in shake flask by optimizing the type and concentration of carbon source, nitrogen source, and metal ions in the fermentation medium. On this basis, its extracellular AmyZ1 activity was increased to 49082.1 U/mL in 3-L fermenter by optimizing the basic medium components as well as the ratio of carbon and nitrogen sources in the feed solution. This is the highest production level reported to date for recombinant RSDA production.ConclusionsThis study represents a report on the extracellular production of AmyZ1 using B. subtilis as a host strain, and achieved the current highest expression level. The results of this study will lay a foundation for the industrial application of RSDA. In addition, the strategies employed here also provide a promising way for improving other protein production in B. subtilis.

Effects of dissolved organic carbon and total ammonia nitrogen concentrations with the same DOC/TAN on biofloc performance

The regulation of the carbon-to‑nitrogen ratio (C/N) is at the core of biofloc technology. This study compared the performance of bioflocs under different dissolved organic carbon (DOC) and total ammonia nitrogen (TAN) concentrations but the same DOC/TAN ratio. Dissolved organic carbon and total ammonium nitrogen were set at 200 mg/L and 10 mg/L (Group 200/10), 100 mg/L and 5 mg/L (Group 100/5), and 50 mg/L and 2.5 mg/L (Group 50/2.5), respectively. The TAN removal rates of groups A, B, and C were 1.89 ± 0.02 mg N/g TSS·h, 1.63 ± 0.03 mg N/g TSS·h, and 1.32 ± 0.02 mg N/g TSS·h, respectively, and the differences were significant (P < 0.05). At the phylum level, the microbial community structure was dominated by Proteobacteria, Bacteroidetes, Actinobacteria, Verrucomicrobia, and Planctomycetes. At the genus level, Gemmobacter, Hydrogenophaga, and Microbacterium were the dominant genera. Most of bacteria community differed significantly among the three groups. As the concentration of carbon and nitrogen sources increased, the Shannon index showed a decrease in bacterial diversity, and the number of heterotrophic bacteria significantly increased. The crude protein content of flocs in group A ((29.22 ± 0.20)%) was significantly lower than that in groups B ((30.56 ± 0.32)%) and C ((30.83 ± 0.20)%). In groups A and B with higher carbon and nitrogen concentrations, the copy numbers of genes related to nitrification were relatively low, but the copy numbers of genes related to denitrification were relatively high. Therefore, it can be concluded that with a ratio of 20 of DOC/TAN, increasing DOC and TAN concentrations led to a significant increase in TAN removal capacity, heterotrophic bacteria count, denitrification function gene copies, and crude protein content of bioflocs, and a decrease in bacterial diversity, nitrification function gene copies, and C/N of bioflocs (P < 0.05). These results suggest that the influence of DOC and TAN concentrations on bioflocs performance may be more significant than that of DOC/TAN, and should be fully considered in practical bioflocs technology systems.

Experimental Study on the Effective Production of Biocement for Soil Solidification and Wind Erosion Control

Biocement can be achieved through the microbially induced carbonate precipitation (MICP) process. Such a method can potentially be utilized as an eco-friendly method for civil and environmental engineering applications such as soil ground improvement and wind erosion control of surface soil. In this method, one key step is the effective production of ureolytic bacteria. In previous laboratory and field studies, the cultivation and production of the bacteria used for the MICP were usually expensive and time-consuming. The purpose of this study was to optimize the cultivation method of the ureolytic bacteria (Sporosarcina pasteurii), and soil stabilization tests were conducted to verify the effectiveness of the cultured bacteria used to strengthen soil against the wind-induced erosion. Bacterial cultivation methods were studied by investigating the effects of different cultivation media and conditions. Testing variables included the types and concentrations of nitrogen sources (urea or NH4Cl), pH values (7.5–9.5), cultivation conditions (batch or chemostat condition), and different carbon sources. It was found that, with the same amount of nitrogen source, the test with pure urea had the highest biomass yield, urease activity, and specific urease activity than the other tests with pure NH4Cl or both NH4Cl and urea. The use of urea as the nitrogen source in the media also led to an increase in pH, which was not found in the test with pure NH4Cl. As for the factor of urea concentration, the tests with a higher urea concentration had a higher biomass yield, urease activity, and pH. The factor of pH values also played an important role. The test with an 8.5 initial pH value had a higher biomass yield, urease activity, and specific urease activity than the tests with 7.5 and 9.5 initial pH values. In the chemostat condition, the ureolytic bacteria could be effectively produced with urease activity up to 7 mmol/L/min, as compared with around 12 mmol/L/min activity in the batch condition. Thus, the optimum nitrogen source, pH value, and cultivation condition for the cultivation of Sporosarcina pasteurii was urea, 8.5, and batch condition, respectively. In addition, when soybean milk powder or milk powder was used as the carbon source, the urease activity was around 2.5 mmol/L/min, which is also high enough to be used for biocement.

Effects of Nitrogen Source and Concentration on the Growth and Biochemical Composition of the Red Seaweed Grateloupia turuturu (Halymeniaceae, Rhodophyta)

Seaweeds, as biofilters that remediate seawater eutrophication, have been widely applied in integrated cultivations for both ecological and economic benefits. Although Grateloupia turuturu (Rhodophyta) is considered as a qualified species in integrated maricultivation, its growth and biochemical performance under different nitrogen conditions are still unknown. Here, we cultured G. turuturu under two nitrogen sources (nitrate and ammonium) at six concentrations (0, 25, 50, 100, 200, and 400 µM) to investigate its growth and nitrogenous compounds (total and inorganic nitrogen, soluble protein, amino acids, and pigments) as well as the allocation pattern of nitrogen storage pools. Our results showed that G. turuturu was well acclimated to high concentrations of both nitrogen sources, and algal age played an important role in the preference of nitrogen sources. Most of the biochemical compositions in G. turuturu increased significantly with the increased concentrations of nitrogen, except for the protein and nitrate contents. Protein and residual organic nitrogen (RON, mainly amino acids) were found to be the two main nitrogen storage pools in G. turuturu. Our study revealed that G. turuturu can produce more profitable compositions at high nitrogen concentrations, making it a profitably promising biofilter to remediate eutrophication.

Isolation and Characterization of Biosurfactant Producing Pseudomonas aeruginosa YLA03 and its Diesel Degradation Potentials

This work was aimed at isolating and characterising biosurfactant producing bacteria strain from diesel oil contamination sites. The potential of the strain to degrade diesel oil n-alkanes was further studied. Soil samples were collected from diesel rich areas, and identified strains were grown on minimal media that contained diesel oil as only carbon source. Enrichment culture technique was used to identify bacteria. Seventeen bacteria strains were identified based on their capacity to use diesel oil as carbon source. Other qualitative screening methods were employed to determine the potential to produce biosurfactants. Isolate A03 was the only candidate that shows positive signs for drop collapse, foaming, haemolytic, oil displacement and emulsification tests. The effect of various culture parameters (incubation time, concentration of diesel, nitrogen source, pH and temperature) on biodegradation of diesel was evaluated. Optimum pH was 8.0 at 35° C, while the incubation time at maximum bacteria growth was five (5) days. The favourable diesel oil concentration was 7.5% for the isolate. The isolate has shown degradative ability towards dodecane, Tridecane, tetradecane but was unable to degrade 2, 6, 10-trimethyl- dodecane. It degraded between 10.09% - 45.39% of individual diesel alkanes. The strain has exhibited potential for degrading diesel alkanes and was identified as pseudomonas aeruginosa strain A3 (Accession Number: MZ027605) using the 16S rRNA. Sequencing.

Production of polyhydroxyalkanoate from sesame seed wastewater by sequencing batch reactor cultivation process of Haloferax mediterranei

Due to the high cost of bioplastic production, sesame wastewater, generated from the sesame seed hulling process, was investigated to be used as inexpensive and renewable carbon source for the production of biodegradable polyhydroxyalkanoate (PHA) by extreme Haloferax mediterranei. The sesame wastewater (SWW) was hydrolyzed using different concentrations of hydrochloric acid (0.4. 1.00 and 2.00 M) at different period of times (15, 60 and 90 min). The concentration of salt (NaCl) and nitrogen source (NH4Cl and yeast) required for H. mediterranei cells growth and the accumulation of PHA biopolymer was optimized. A maximum 0.53 g/L concentration of PHA was achieved when the SWW extract media was supplemented with 100 g/L NaCl and 6.0 g/L yeast extract. The cultivation was scaled-up using sequencing batch reactor (SBR) fermentation under non-sterile conditions. The SBR results showed that SWW needs an auxiliary carbon source to obtain high PHA production. Consequently, the system fed with SWW and glucose produced higher PHA (20.9 g/L) than the system fed with SWW.

Optimization of ectoine production from Nesterenkonia xinjiangensis and one-step ectoine purification

In the current study, the optimization of ectoine production byNesterenkonia xinjiangensisand purification of ectoine from the bacterial cell extract were performed for the first time. Various carbon sources (glucose, sucrose, maltose, lactose, mannitol, and xylose) and nitrogen sources (ammonium nitrate, ammonium phosphate, ammonium chloride, ammonium oxalate, ammonium sulphate, and ammonium acetate), were used to optimize ectoine production. Subsequently, the effects of salt, pH and, concentrations of carbon and nitrogen source on ectoine production were optimized by response surface methodology (RSM). Ultimately, high pure (over 99%) and yield (98%) of ectoine from bacterial cells extracted was obtained by a single-step process using cation exchange chromatography. This study provides information that higher ectoine production can be achieved from this bacterial isolate by optimizing the factors influencing ectoine production and thus can be used as a new and alternative ectoine producer.

Optimization of glutathione production in Saccharomyces cerevisiae HBSD-W08 using Plackett–Burman and central composite rotatable designs

BackgroundGlutathione is an important bioactive tripeptide and is widely used in the food, medicine, and cosmetics industries. The aim of this study was to provide an efficient method for producing GSH and to explore its synthesis mechanism. Saccharomyces cerevisiae strain HBSD-W08 was screened for GSH production, and its fermentation medium was optimized using single-factor experiments of the Plackett-Burman and central composite rotatable designs. This method was used to analyze the effects of the presence and concentration of various carbon sources, organic and inorganic nitrogen sources, metal ions, and precursor amino acids on GSH production and catalase, superoxide dismutase, and γ-glutamylcysteine synthetase activity.ResultsThe three most significant factors affecting GSH production were peptone (optimal concentration [OC]: 2.50 g L− 1), KH2PO4 (OC: 0.13 g L− 1), and glutamic acid (OC: 0.10 g L− 1). GSH productivity of HBSD-W08 was obtained at 3.70 g L− 1 in the optimized medium. The activity of γ-GCS, which is a marker for oxidative stress, was found to be highly positively correlated with GSH production.ConclusionsThis finding revealed an underlying relationship between GSH synthesis and oxidative stress, providing useful information for developing effective GSH fermentation control strategies.

Use of exogenous substrate in Chlorella cultivation: Strategy for biomass and polyhydroxybutyrate production

The aim of this study was to investigate the influence of exogenous carbon supplementation and nitrogen source reduction on Chlorella fusca LEB 111 growth, biomass composition, and polyhydroxybutyrate accumulation. First, assays were performed with 50 % and 25 % reduced nitrogen source concentrations (NaNO3). In the second stage, the influence of culture supplementation with 10, 20, and 30 mg L−1 D-xylose, associated with 50 and 25 % reductions in NaNO3, was evaluated. The experiments conducted with a 25 % reduction in NaNO3 and supplementation with 10 mg L−1 D-xylose resulted in a positive effect on the biomass productivity of C. fusca LEB 111, with production as high as 354.4 mg L−1 d−1. The maximum concentration of PHB extracted from C. fusca LEB 111 was 3.7 % (w w−1) and was obtained when the microalgae were cultivated with a 25 % of reduction in NaNO3 and supplementation of D-xylose at 20 mg L−1. Therefore, this study brings new perspectives regarding reducing the use of nutritional sources and using exogenous carbon sources in using microalgae to produce molecules of high biotechnological potential.

Complete genome sequence analysis of a novel alkane-degrading bacterial strain, Acinetobacter vivianii KJ-1, and its diesel degradation ability

With the increasing demand for diesel in various countries, the ecological pollution caused by the improper use, storage, and accidental leakage of diesel needs to be addressed urgently. As an environmentally friendly and cost-effective method, bioremediation generally uses various microorganisms to remove pollutants from the environment. Here, the strain KJ-1, obtained through an enrichment culture using n-dodecane from oil-contaminated soil near a gas station as the substrate, was identified as Acinetobacter vivianii according to its morphology, biochemistry, and molecular biology. The isolate KJ-1 was able to use diesel as a sole carbon source and more than 40% of diesel was degraded after 12 days of incubation with strain KJ-1 in mineral salts medium. The most suitable diesel concentration and nitrogen source concentrations were 4,140 mg/L and 350–700 mg/L, respectively, for diesel degradation and bacterial growth. The optimal initial pH and temperature for strain KJ-1 growth and diesel degradation were 6.5–8.0 and 20–37°C, respectively. To investigate the diesel-degrading mechanisms of this strain, the complete genome was sequenced and annotated. The complete genome consists of one chromosome with a total length of 3,927,757 base pairs and a G + C content of 41.5%. The genes related to the two-component regulatory system and alkane degradation were analyzed. In addition, two putative alkane monooxygenases were analyzed, and the protein sequences were characterized and compared with other AlkBs in Acinetobacter spp. using sequences downloaded from NCBI. The results demonstrated that A. vivianii KJ-1 may be particularly useful for future bioremediation of diesel-polluted soil.

Biomass and β-Glucosidase Production by the Cyanobacterium Pseudanabaena sp. under Heterotrophic Conditions

A cyanobacterium producing β-glucosidase was isolated from Lake Pamvotis located in Ioannina in Greece. This microorganism, named Pamv7, was identified as Pseudanabaena sp. using phylogenetic characterization. The high-throughput BiologMicroPlate™ method, used for the rapid assessment of heterotrophic potential, indicates that Pseudanabaena sp. metabolizes a wide range of organic substrates such as amino acids, carbohydrates, and carboxylic acids. When the strain grows in a culture medium containing cellobiose as a carbon source, it produces a significant amount of intracellular β-glucosidase. The effect of cellobiose concentration, nitrogen source, and nitrogen concentration of the growth medium, as well as the temperature of the culture, on biomass and β-glucosidase by Pseudanabaena sp., was studied. Biomass and β-glucosidase production by the strain in a lab-scale bioreactor at optimal conditions (10 g/L cellobiose, 1.5 g/L yeast, and 23 ± 1 °C) reached 2.8 g dry weight/L and 44 U/L, respectively. The protein and lipid content of the produced cyanobacterium biomass were 23% and 43 w/w, respectively. This study is the first report of β-glucosidase production by a cyanobacterial strain and concomitant high production of microalgae biomass, making Pseudanabaena sp. a promising microorganism in the field of enzyme biotechnology.

Preparation of polyhydroxyalkanoates using &lt;i&gt;Pseudomonas helmanticensis&lt;/i&gt; in non-sterile media containing glycerol and sodium dodecyl sulfate

Biosynthetically-produced Pseudomonas poly-3-hydroxyalkanoates (PHAs) are a promising substitute for conventional plastics. Costs involved with the production of PHAs can be reduced by optimizing power consumption, which can be achieved using nutrient media without preliminary steam sterilization. Cultivation of Pseudomonas bacteria resistant to sodium dodecyl sulfate (SDS) on SDS-containing non-sterile media yields a biomass consisting predominantly of a PHA producer. SDS plays the role of an antimicrobial agent that inhibits the growth of foreign microorganisms. In this work, an SDS-resistant culture of Pseudomonas helmanticensis and media containing glycerol and SDS were used. The concentrations of carbon (glycerol) and nitrogen sources were optimized using an experiment performed according to a central composite rotatable design. The concentration of substrate C and the C/N ratio between the glycerol and nitrogen content were varied. The dependence of the degree of substrate conversion in PHA on C and C/N was derived in the R programming environment. The constructed model adequately describes the experimental data at a significance level of 0.05 (adequacy variance of the regression equation 4.1×10-2; R2 =0.98). According to the constructed model, the conversion of glycerol to PHA equals 6.9±0.4%. Under optimized conditions (0.61 g/L nitrogen source; 8.4 g/L glycerol; 96 h), P. helmanticensis converts 7.0% of the substrate to PHA with an average monomer unit length. Using a 16S rRNA metagenomic assay, the proportion of foreign bacteria in P. helmanticensis cultures on non-sterile media containing 0.5 g/L SDS was shown to be 2%.

Effect of Nitrogen Sources on L-Dopa and Dopamine Production Using Citrobacter freundii (NRRL B-2643)

Microbial production of L-dopa and dopamine which is an important substrance for the treatment of Parkinson's disease were investigated by using Citrobacter freundii (NRRL B-2643). The effects of nitrogen source such as peptone, yeast extract, casein, soy protein, whey, ammonium sulfate on L-dopa and dopamine production were investigated and extracellular L-dopa and dopamine concentrations were determined by usign HPLC. Optimum nitrogen source concentrations were found to be (peptone 12.5 g/L, yeast extract 10.0 g/L, casein 0.1 g/L, soy protein 0.75g/L, whey 5% v/v and ammonium sulfate 1.0 g /L) for the production of L-dopa and dopamine. At this condition L-dopa and dopamine concentrations were found to be 342 and 467 mg/L, respectively. Although the experiments were continued for 60 hours, maximum production of L-dopa and dopamine concentration was reached at around the 30 th hour of the experiments.

Influence of hydrochloric acid concentration and type of nitrogen source on the electrochemical performance of TiO2/N-MoS2 for energy storage applications

In this work, nitrogen-doped molybdenum sulfide was directly deposited on titanium dioxide nanotubes substrate (TiO2/N-MoS2) during hydrothermal synthesis. The study focuses on the influence of hydrochloric acid concentration used for the synthesis, with the results indicating its essential role in thioacetamide hydrolysis and thus in the effectiveness of the N-MoS2 deposition. The electrode material itself is characterized by an initial capacitance of 320 mF cm−2 with 76 % capacitance retention after 10000 cycles. Moreover, the effect of nitrogen source on the physical and capacitive properties is investigated, revealing that the simultaneous addition of aniline and ammonium persulfate contributes to the improvement of crystallinity and overall electrochemical performance of the electrode material. The analysis of charge storage mechanisms also indicates that the introduction of nitrogen atoms significantly affects the contribution of diffusion-controlled processes. In the construction of a symmetrical device, the specific capacitance of 76 F g−1 and areal capacitance of 70 mF cm−2 with the superior coulombic efficiency and 84 % of capacitance retention after 15,000 cycles is observed, with 11.1 W kg−1 and 5193.4 Wh kg−1 of energy and power density of the device, respectively.

Effect of cultural conditions and physical factors on production of antibiotic metabolites by selected actinomycetes

Antibiotic resistance is one of the biggest global problem of our times. The leading producers of antibiotics that can be used to curb this problem are actinomycetes. This study was conceived to isolate antibiotic producing actinomycetes from the soils of Menengai crater and identify the cultural and physical factors that favoured production of antibiotics by selected actinomycetes. Soil samples were collected from 32 randomly selected sampling points within Menengai crater. The actinomycetes were isolated using serial dilution technique. The actinomycetes were tested for antagonism against selected bacterial and fungal pathogens using primary and secondary screening bioassays. Based on broad spectrum of activity and the size of zone of inhibition, four potent actinomycetes were selected for further studies. The effect of growth media, pH, temperature, incubation period, aeration, inoculum concentration, carbon source, nitrogen source and salt concentration on growth and production of antibiotic metabolites was determined. The actinomycetes isolated presented varying morphological characteristics. There was a significant difference in the diameters of zones of inhibition produced by the test pathogens when subjected to the antibiotic metabolites from the selected actinomycetes (F = 6.6046 P = 0.001338). The growth and production of antibiotics by the selected actinomycetes was favoured by use of Luria Bertani as the culture medium, a pH of 6, incubation temperature of 28oC, incubation period of 7d, aeration rate of 200rpm, inoculum concentration of 1%, glycerol as carbon source, oat meal as nitrogen source and a salt concentration of 1.5%. The growth and production of antibiotics by the selected actinomycetes is affected by culture medium, pH, incubation temperature, incubation period, aeration rate, inoculum concentration, carbon source, nitrogen source and salt concentration. There is need to curry out structure elucidation of the antibiotics from the selected actinomycetes.

Effect of Nitrogen Concentration on the Biosynthesis of Citric Acid, Protein, and Lipids in the Yeast Yarrowia lipolytica.

Yarrowia lipolytica yeast is well known to be able to synthesize citric acid (CA) in large amounts. This study deals with CA biosynthesis, the production of biomass, as well as the accumulation and composition of proteins and lipids in Y. lipolytica VKM Y-2373 grown in media with glucose at different concentrations of ammonium sulfate (from 2 to 10 g/L). It was found that these concentrations of nitrogen source are limiting for the growth of Y. lipolytica and that nitrogen deficiency is the main cause of CA excretion. At the high concentration of (NH4)2SO4 (10 g/L), the accumulation of cell biomass, biomass yield (YX/S), and protein concentration was higher than in the medium with 2 g/L ammonium sulfate by 4.3 times, 143%, and 5.1 times, respectively. CA was accumulated in meaningful quantities only in media containing 3–10 g/L (NH4)2SO4 with the maximum concentration of CA (99.9 g/L) at 4 g/L ammonium sulfate. Also of interest is the technological mode with 6 g/L (NH4)2SO4, which is characterized by high productivity (1.11 g/L × h). It should be noted that biomass contains large amounts of essential amino acids and unsaturated fatty acids and can be used in food biotechnologies and agriculture.

Effect of nitrogen source and nickel concentration on green microalga Botryococcus braunii growth and its remediation potential

Effect of nitrogen source and nickel concentration on green microalga Botryococcus braunii growth and its remediation potential