A Comparative Study of the Growth and Nutrient Removal Effects of Five Green Microalgae in Simulated Domestic Sewage

Microalgae have shown great potential in wastewater treatment. This study evaluates the growth and nutrient removal characteristics of five different microalgae strains, namely Chlorella vulgaris, Tetradesmus obliquus, Parachlorella kessleri, Hydrodictyon sp., and Scenedesmus quadricauda, in simulated domestic wastewater. The five microalgae could adapt to wastewater, but the growth potential and nitrogen removal capacity were species dependent. The nutrient removal effect of the microalgae used in this experiment was about 50% in the first two days. Parachlorella kessleri, selected from the five strains of green algae, shows good potential in removing nutrients from simulated domestic wastewater. For the simulated domestic sewage treated with Parachlorella kessleri, the chemical oxygen demand was almost completely reduced, and ammonium-N (NH4-N) and total nitrogen (TN) removal exceeded 70% at the end of the 10-day treatment. Total phosphorus (TP) removal was slightly worse, more than 65%. Parachlorella kessleri showed the best growth in sewage with the highest biomass reaching 366.67 mg L−1 and the highest specific growth rate reaching 0.538 d−1. This study can provide a reference for selecting suitable microalgae species to treat actual domestic sewage.

Lacustrine, wastewater, interstitial and fluvial water quality in the Southern Lake Baikal region

The coastal area of the southern Lake Baikal with the population over 35,000 people remains an attractive spot for both tourists and local residents. Despite high anthropogenic impact, a detailed assessment of water quality in this area has not been performed so far. Here, we performed a comprehensive evaluation of the quality of the surface, bottom and interstitial water in rivers, lacustrine water and wastewater in the southern Lake Baikal region. We analyzed 37 samples for the presence of fecal enterococci, Escherichia coli and assessed their hydrochemical parameters: concentrations of nutrients (nitrate-N, nitrite-N, ammonium-N and phosphate-P), dissolved oxygen and amount of ions (HCO3− + SO42− + Cl− + Ca2+ + Mg2+ + Na+ + K+). In addition, the temperature, pH and electrical conductivity were also measured. We found that multiple areas around South Baikal suffer from microbiological and hydrochemical pollution. We conclude that ecological situation in this area requires immediate attention from local authorities, more efficient wastewater management systems should be constructed in the settlements. We also conclude that interstitial waters from the lake's splash zone represent an effective and sensitive indicator of sanitary-microbiological and hydrochemical pollution and their analysis can be included in the standard protocol of water quality assessment for all types of water bodies.

Physicochemical Factors Drive Bacterial Communities in an Aquaculture Environment

The role of microbial ecology in aquaculture is becoming increasingly significant; however, studies on the changes in microbial ecology driven by the culture environment are limited. In the present study, high-throughput sequencing and chemical analysis was used to explore changes in physicochemical factors, bacterial communities, and their relationships between a water source (Bay) and an aquaculture area located in a reclaimed area. Statistical analysis results revealed that operational taxonomic units levels in inlet water and pond water varied significantly (p < 0.05). Non-metric multidimensional scaling (NMDS) analysis revealed the distribution characteristics of bacterial communities with water properties. The abundance of Alphaproteobacteria, Actinobacteria, and Flavobacteria in pond water increased significantly when compared to inlet water. The abundance of heterotrophic bacteria, such as Candidatus Actinomarina, Candidatus Aquiluna, Marivita, and Vibrio genera in pond water was significantly higher (Welch’s t-tests, p < 0.05) than inlet water. Functional prediction analysis primarily revealed an increase in the function that was associated with carbon and nitrogen metabolism in the pond environment. Canonical correlation analysis revealed that the bacterial communities was predominantly influenced by inorganic nutrients. Nitrate-nitrogen (N), nitrite-N, ammonium-N, and phosphate-phosphorous (P) were the key factors influencing bacterial communities in pond environment. A significant correlation was observed between inorganic N and phosphorus (P), and dominant bacterial genera (p < 0.05), demonstrating the potential mechanism of regulation of nutrients in bacterial communities. The present study described the microbial ecology of aquaculture ponds in detail and provides a scientific basis for the management of aquacultural environments.

Quantifying the Spatial Distribution of Soil Nitrogen Under Long-Term Drip Fertigation

Quantifying the spatial distribution of nitrogen (N) in the soil under long-term drip fertigation events is essential for the optimal regulation of drip fertigation systems. In this study, a greenhouse soil that has been under drip irrigation for 20 years was selected as the research object, and soil samples were collected from 0-50 cm soil depth. The concentrations of N in soil samples were measured and their spatial distribution characteristics were quantified by classical statistical analysis and multifractal analysis. The results showed that long-term drip fertigation and the influence of natural factors resulted in the nitrate N mainly accumulating in the shallow layer of the soil and within a distance from the drip irrigation belt, and the spatial heterogeneity gradually decreased with increasing depth. The content of ammonium N was low and its distribution was observed in the whole section. Multifractal analysis indicated that the Δα value of nitrate N and inorganic N gradually increased with the increase of research scale, i.e., the spatial heterogeneity gradually increased, and it did not appreciably change for ammonium N. Meanwhile, the local high value region was the main factor leading to the spatial heterogeneity of N, and this dominant effect gradually increased with increasing depth. Multifractal analysis can effectively reflect the local information of N spatial distribution in the soil and provide a more detailed description of the spatial heterogeneity of soil properties.

Repression of Carotenoid Accumulation by Nitrogen and NH4+ Supply in Carrot Callus Cells In Vitro

The effect of mineral nutrition on the accumulation of the main health beneficial compounds in carrots, the carotenoid pigments, remains ambiguous; here, a model-based approach was applied to reveal which compounds are responsible for the variation in carotenoid content in carrot cells in vitro. For this purpose, carotenoid-rich callus was cultured on either BI (modified Gamborg B5) or R (modified Murashige and Skoog MS) mineral media or on modified media obtained by exchanging compounds between BI and R. Callus growing on the BI medium had abundant carotene crystals in the cells and a dark orange color in contrast to pale orange callus with sparse crystals on the R medium. The carotenoid content, determined by HPLC and spectrophotometrically after two months of culture, was 5.3 higher on the BI medium. The replacement of media components revealed that only the N concentration and the NO3:NH4 ratio affected carotenoid accumulation. Either the increase of N amount above 27 mM or decrease of NO3:NH4 ratio below 12 resulted in the repression of carotenoid accumulation. An adverse effect of the increased NH4+ level on callus growth was additionally found. Somatic embryos were formed regardless of the level of N supplied. Changes to other media components, i.e., macroelements other than N, microelements, vitamins, growth regulators, and sucrose had no effect on callus growth and carotenoid accumulation. The results obtained from this model system expand the range of factors, such as N availability, composition of N salts, and ratio of nitrate to ammonium N form, that may affect the regulation of carotenoid metabolism.

Influence of the Nitrate-N to Ammonium-N Ratio on Relative Growth Rate and Crude Protein Content in the Duckweeds Lemna minor and Wolffiella hyalina

In order to produce protein-rich duckweed for human and animal consumption, a stable cultivation process, including an optimal nutrient supply for each species, must be implemented. Modified nutrient media, based on the N-medium for duckweed cultivation, were tested on the relative growth rate (RGR) and crude protein content (CPC) of Lemna minor and Wolffiella hyalina, as well as the decrease of nitrate-N and ammonium-N in the media. Five different nitrate-N to ammonium-N molar ratios were diluted to 10% and 50% of the original N-medium concentration. The media mainly consisted of agricultural fertilizers. A ratio of 75% nitrate-N and 25% ammonium-N, with a dilution of 50%, yielded the best results for both species. Based on the dry weight (DW), L. minor achieved a RGR of 0.23 ± 0.009 d−1 and a CPC of 37.8 ± 0.42%, while W. hyalina’s maximum RGR was 0.22 ± 0.017 d−1, with a CPC of 43.9 ± 0.34%. The relative protein yield per week and m2 was highest at this ratio and dilution, as well as the ammonium-N decrease in the corresponding medium. These results could be implemented in duckweed research and applications if a high protein content or protein yield is the aim.

Cyanobacterial growth and cyanophycin production with urea and ammonium as nitrogen source

Several technologies have aimed to recover nitrogen directly from urine. Nitrogen recovery in these technologies was limited by the mismatch of the nitrogen-phosphorus molar ratio (N:P) of urine, being 30–46:1, and that of the final product, e.g., 1:1 in struvite and 16–22:1 in microalgae biomass. Additionally, the high nitrogen concentrations found in urine can be inhibitive for growth of microorganisms. Cyanobacteria were expected to overcome phosphorus (P) limitation in urine given their ability to store an N-rich polymer called cyanophycin. In this study, it was found that the model cyanobacterium Synechocystis sp. PCC6803 did not experience significant growth inhibition when cultivated in synthetic medium with concentrations of 0.5 g ammonium-N L−1. In the case of urea, no inhibition was observed when having it as sole nitrogen source, but it resulted in chlorosis of the cultures when the process reached stationary phase. Synechocystis was successfully cultivated in a medium with 0.5 g ammonium-N L−1 and a N:P ratio of 276:1, showing the N:P flexibility of this biomass, reaching biomass N:P ratios up to 92:1. Phosphorus starvation resulted in cyanophycin accumulation up to 4%. Dilution of the culture in fresh medium with the addition of 118 mg N L−1 and 1.5 mg P L−1 (N:P of 174:1) resulted in a rapid and transient cyanophycin accumulation up to 11%, after which cyanophycin levels rapidly decreased to 3%.

Lampiran 4D Paper Kondisi Kualitas Air dan Perilaku Masyarakat di Sun Daerah Aliran Sungai (DAS) Kali Liliba Kota Kupang

This research aims to; (1) to determine the water quality of Liliba River and to analyse the water quality index of Kali Liliba River using STORET (2) to identify the perceptions of various stakeholders in Kali Liliba to achieve sustainable use of water resources The study was conducted by measuring several water quality parameters such as turbidity, temperature, TDS, turbidity, smell, taste, pH, DO, ammonium, N-Nitrite, phosphate, oils and fats, hardness (CaCO3) in several sampling points and distributing questionnaires to communities living in Kali Liliba River Basin. The results showed that ammonium and phosphate concentrations in Kali Liliba had exceeded the threshold specified in accordance with Government Regulation No.82 of 2001. In addition, water quality status using STORET INDEX analysis showed that sub DAS Kali Liliba was categorized medium contaminated. The waste disposal from septic or greywater, disposal of tofu industry waste, and pig farm waste was the major contribution of water pollution in Kali Liliba.

Nitrogen mineralization in soils cultivated with plantain (Musa AAB Subgroup plátano cv. Hartón), Zulia state, Venezuela

The main source of N in the soil is organic matter; therefore, its availability depends on its quantity and quality, microbial activity, soil characteristics and management. An efficient way to quantify available N is by mineralizing it as ammonium (N-NH ) and nitrate (N-NO ). Therefore, in this study, the total and available N was determined in soil samples 0-20 cm deep from two plots with plantain plants (Musa AAB plantain subgroup cv. Hartón) with high and low vigor (AV and BV, respectively), in the South of Lake Maracaibo. Total N was determined by the Kjeldalh method and the mineralization of available N by incubation under laboratory conditions for 10 weeks. The accumulated mineralized N (Nm), the constant mineralization rate of (k) and the potentially mineralizable N (N0) were calculated. A one-way analysis of variance was applied, when it was significant (p<0.05), a Tukey test was applied for multiple comparisons of means. Total N was low (<0.025 %) and did not present statistical differences (p<0.05) between AV and BV. The accumulated mineralized N-NO was statistically (p<0.05) higher (524.47 mg.kg-1) in BV, while the N-NH did not present differences between AV and BV. Only k was statistically higher (0.07 ± 0.03; p<0.05) in BV. Nitrification was the process that prevailed especially in BV where organic carbon was higher and presented a higher percentage of sand.

Nitrogen Metabolism of an Anoxygenic Filamentous Phototrophic Bacterium Oscillocholris trichoides Strain DG-6

Abstract— The possible nitrogen sources for Osc. trichoides DG6, a typical strain of the Oscillochloridaceae family, are ammonium, N2, glutamate, asparagine, glycine, and glutamine. The assimilation of molecular nitrogen occurs with the participation of nitrogenase, the structural gene of which, nifH, is located in the gene cluster which also includes the genes of the nifD and nifK nitrogenase subunits and the auxiliary nifB gene. Considering that nifHBDK clusters have been also annotated in the genomes of other members of the Oscillochloridaceae family, including uncultured and candidate taxa, it can be assumed that the ability to fix nitrogen is a property immanent for this entire family. The pathways for assimilating ammonium in the cells grown using different nitrogen sources may differ. Osc. trichoides DG6 growing in a medium containing ammonium assimilated it with the participation of glutamate dehydrogenase, which is determined by a single gene. The expression product of this gene has dual functionality and can be used to implement the reaction with both NAD and NADP. With the growth of Osc. trichoides DG6 on a medium with glutamate as the only nitrogen source all the enzymes necessary for the implementation of the GS‑GOGAT pathway were found in the cells. However, for the glutamine synthetase reaction, ammonium, which was absent in the growth medium, was required. The source of ammonium may be glutamate metabolized through glutamate dehydrogenase.