Search

AbstractThe present study aims at the isolation of Cr (VI) tolerant microalgae from wastewater collected from local bike garages. The wastewater had a continued spillage of engine oil, petrol, grease, and chain lube waste. The isolated microalgae were first sequenced by using 18S rRNA sequencing method. The nucleotide sequence obtained was analyzed via BLAST, the isolated microalga showed maximum similarity with Scenedesmus species. The sequence was submitted to NCBI, and the microalgae was identified as Scenedesmus species GTAF1 IU accession no. OM903800. The bioremediation potential of the isolated microalgae was evaluated for the removal of Cr (VI) in synthetic wastewater. The Cr (VI) removal efficiency was estimated at 0.2, 0.4, 0.6, and 0.8 g L−1 of inoculum concentration under autotrophic and heterotrophic modes. The highest removal efficiency of 98.9% and 99.9% was obtained at 0.8 g L−1 inoculum concentration under autotrophic and heterotrophic modes of operation respectively. On increasing the metal concentration from 5 to 10 ppm, a decrease in the biomass quality and quantity was observed. This increased metal stress resulted in an enhanced carbohydrate and lipid concentration. However, the protein concentration was found to be decreased. Cr (VI) removal efficiency was highest in heterotrophic conditions. This study provides a novel insight for removing Cr (VI) and concomitantly enhancing the lipid content of isolated strains under heterotrophic conditions. Owing to enhanced lipid content, the reported curation of wastewater may also be used in harnessing the potential of isolated microalga in biofuel production. [ABSTRACT FROM AUTHOR]

Abstract Background The development of alternative carbon sources is important for reducing the cost of heterotrophic microalgae cultivation. Among cheap feedstocks, galactose is one of the most abundant sugars and can be easily obtained from many natural biomasses. However, it is generally difficult to be utilized by microalgae. In addition, the mechanism of its low utilization efficiency in heterotrophic cultivation is still unknown. Results Among seven tested carbon sources, only glucose and acetate could be efficiently utilized by C. sorokiniana in heterotrophic cultivation while there were no apparent signs of utilization of other carbohydrates, including galactose, in regular heterotrophic cultivation. However, galactose could be utilized in cultures with high inoculation sizes. This confirmed that C. sorokiniana has a complete pathway for transporting and assimilating galactose under dark conditions, but the rate of galactose utilization is quite low. In addition, the galactose utilization was greatly enhanced in mixotrophic cultures, which indicated that galactose utilization could be enhanced by additional pathways that can enhance cell growth. Based on above results, a mixed carbon source culture strategy was proposed to improve the utilization rate of galactose, and a significant synergistic effect on cell growth was achieved in cultures using a mixture of galactose and acetate. Conclusions This study indicated that the galactose metabolism pathway may not be inherently deficient in Chlorophyta. However, its utilization rate was too low to be detected in regular heterotrophic cultivation. Mixed carbon source culture strategy was confirmed effective to improve the utilization rate of galactose. This study contributes to a deeper understanding of the utilization ability of difficultly utilized substrates in the heterotrophic cultivation of microalgae, which is of great significance for reducing the cost of heterotrophic cultivation of microalgae.

Protoperidinium claudicans is a planktonic, heterotrophic, bioluminescent dinoflagellate species commonly found in neritic waters. It has long been considered to display phenotypic variation in its second anterior intercalary plate, which could vary between quadra, penta and hexa. The equivalent spinose, cordate cyst goes under the name of Votadinium spinosum. Here we perform incubation experiments with cysts from France, Canada, China and Japan, which demonstrate that P. claudicans forms a species complex, with at least two ribotypes with a penta configuration (P. claudicans) and one with a quadra configuration (P. carriae sp. nov.). A fossil-based cyst, V. multispinosum sp. nov., is described as the equivalent of P. carriae. Molecular phylogenetics using large subunit ribosomal DNA supports these observations. The cyst–theca relationships for Votadinium psilodora and another, undescribed, cordate, spineless Votadinium species are also reported from China. Macromolecular analyses of the cyst wall of V. multispinosum reveal it is comprised of a protein-rich carbohydrate compound. We show that this compound is not uncommon in dinoflagellate and ciliate cysts and that it is unlikely to preserve very well upon sedimentation and burial. [ABSTRACT FROM AUTHOR]

Heterotrophic cultivation of microalgae is vastly studied for the potential it offers as a scalable, space- and time-efficient way to produce biodiesel. From the perspective of economic feasibility, it is understood that renewable, waste-based sources of nutrients must be used to support the cultivation process. In this study, carrot pomace, a waste by-product of the juice industry, was utilized to fully replace synthetic growth medium in the heterotrophic cultivation of Auxenochlorella protothecoides. The carrot pomace underwent minimal pre-treatment to avoid incurring excessive costs. With carrot medium (CM) alone, 4.9 g/L total lipids (9.9 g lipid/kg wet carrot pomace), and with a 5 g/L addition of glucose to the CM, 5.9 g/L (11.8 g lipid/kg wet carrot pomace) could be produced, the latter of which was equivalent to the lipid output achieved with the optimized synthetic growth medium (control). The 5 g/L glucose addition improved the triacylglycerol (TAG) content of the lipids to 78.4%, which was equivalent to the control (76.4%). Growth medium prepared using carrot pomace alone as the sole source of carbon and nutrients was demonstrated to successfully support the growth and lipid production of A. protothecoides. The addition of 5 g/L glucose to the CM improved the lipid output by 19% and the TAG content by 18% and might be preferred for more efficient processing — at only a fraction of the cost of a completely synthetic growth medium, containing 30 g/L glucose in addition to other minerals and trace elements. [ABSTRACT FROM AUTHOR]

Copyright of German International Journal of Modern Science / Deutsche Internationale Zeitschrift für Zeitgenössische Wissenschaft is the property of Artmedia24 and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the course of this work, the total numbers of heterotrophic microorganisms and the numbers of microbes participating in the nitrogen cycle (ammonifying, denitrifying, nitrifying, and nitrogen-fixing ones) in urban and natural (background) soils of Kogalym were estimated. A relation between the results obtained and the geochemical indicators was revealed. Our microbiological analysis showed the predominance of nitrogen-fixing microorganisms in urban soils (5.0 × 104– 2.0 × 106 CFU/g of soil), which were, on average, 44 less than in natural soils. In the last ones, the average number of denitrifying microorganisms was 7.0 × 104 CFU/g of soil, exceeding 1.3 times their number in urban soils. Based on the information obtained, the microbial contents in the soils of Kogalym were established as a series: nitrogen fixators > ammonifiers > heterotrophs > denitrifiers; in background samples: denitrifiers > ammonifiers > heterotrophs > nitrogen fixators. According to the data of ecological and geochemical analysis, an excess of the MPC of mobile forms of heavy metals, such as Cu, Ni, and Zn, was revealed in the Eastern Industrial Zone of the city. A significant inverse correlation was revealed between the number of denitrifying microorganisms in the Kogalym soil microbiocenoses and the content of mobile Ni and Cu forms, which points to a possible negative effect of these metals on the development of denitrifiers. The minimum number of ammonifying, denitrifying, and nitrogen-fixing microorganisms was found in the Eastern Industrial Zone, especially in the soil samples that were taken near the railway. On the whole, the absence of noticeable differences in the microorganisms' content of the studied groups in urban and natural soils indicates a low level of soil pollution in Kogalym. The results obtained represent the basis for subsequent ecological monitoring of the soils in the city and adjacent oil-producing areas, forecasting the environmental consequences of anthropogenic activities on these territories. [ABSTRACT FROM AUTHOR]

The use of functional feed additives is an important approach to both, prevent and fight, viral diseases in aquaculture. In this regard, microalgae-derived products, and, more specifically, microalgal exopolysaccharides (EPSs), have attracted attention, since multiple biotechnological applications are being described for these molecules. Furthermore, depending on culture conditions, the composition and, therefore, properties of EPSs can vary. In the present study, the antiviral activity of EPSs from Tetraselmis suecica and Porphyridium cruentum cultured under autotrophic and heterotrophic conditions has been evaluated in vitro against Viral Haemorrhagic Septicaemia Virus (VHSV), an important pathogen in fish farming. Results showed that EPSs from both species have anti-VHSV activity. T. suecica EPSs from autotrophic cultures showed the strongest effect, since both, adsorption and post-adsorption phases of the VHSV multiplication cycle were affected. In contrast, both, autotrophic and heterotrophic P. cruentum EPSs showed anti-VHSV activity only after the adsorption phase. These results pave the way to use these EPSs to fight VHSV infections, and animate to evaluate the EPS antiviral activity against other viral pathogens relevant to the aquaculture industry. [ABSTRACT FROM AUTHOR]

The green microalga Chlamydomonas reinhardtii is a model microorganism for several areas of study. Among the different microalgae species, it presents advantageous characteristics, such as genomes completely sequenced and well‐established techniques for genetic transformation. Despite that, C. reinhardtii production is still not easily commercially viable, especially due to the low biomass yield. So far there are no reports of scientometric study focusing only on C. reinhardtii biomass production process. Considering the need for culture optimization, a scientometric research was conducted to analyze the papers that investigated the growth regimes effects in C. reinhardtii cultivation. The search resulted in 130 papers indexed on Web of Science and Scopus platforms from 1969 to December 2022. The quantitative analysis indicated that the photoautotrophic regime was the most employed in the papers. However, when comparing the three growth regimes, the mixotrophic one led to the highest production of biomass, lipids, and heterologous protein. The production of bioproducts was considered the main objective of most of the papers and, among them, biomass was the most frequently investigated. The highest biomass production reported among the papers was 40 g L−1 in the heterotrophic growth of a transgenic strain. Other culture conditions were also crucial for C. reinhardtii growth, for instance, temperature and cultivation process. [ABSTRACT FROM AUTHOR]

Euglena gracilis is one of the few permitted edible microalgae. Considering consumer acceptance, E. gracilis grown heterotrophically with yellow appearances have wider food industrial applications such as producing meat analogs than green cells. However, there is much room to improve the protein content of heterotrophic culture cells. In this study, the effects of nitrogen sources, temperature, initial pH, and C/N ratios on the protein production of E. gracilis were evaluated under heterotrophic cultivation. These results indicated that ammonium sulfate was the optimal nitrogen source for protein production. The protein content of E. gracilis cultured by ammonium sulfate increased by 113% and 44.7% compared with that cultured by yeast extract and monosodium glutamate, respectively. The manipulation of the low C/N ratio further improved E. gracilis protein content to 66.10% (w/w), which was 1.6-fold of that in the C/N = 25 group. Additionally, amino acid analysis revealed that the nitrogen-to-protein conversion factor (NTP) could be affected by nitrogen sources. A superior essential amino acid index (EAAI) of 1.62 and a balanced amino acid profile further confirmed the high nutritional value of E. gracilis protein fed by ammonium sulfate. This study highlighted the vast potency of heterotrophic cultured E. gracilis as an alternative dietary protein source. [ABSTRACT FROM AUTHOR]

Microalgae are considered to have great potential as a source of biodiesel. Currently, algae culture has three different trophic modes, i.e., autotrophic, heterotrophic, and mixotrophic, but not all kinds of algae are suitable for heterotrophic and mixotrophic cultivation. In this study, Parachlorella kessleri TY, screened from the soil of Shanxi Province, was heterotrophically and mixotrophically treated with glucose as an organic carbon source, and the physiological and biochemical levels of its growth and lipid accumulation were measured. The results showed that the highest biomass and biomass productivity (1.53 g·L−1 and 218.57 mg·L−1d−1) were attained by P. kessleri TY under mixotrophic cultivation. In comparison, the lowest (0.55 g·L−1 and 78.57 mg·L−1d−1) were attained under heterotrophic culture. Furthermore, heterotrophic and mixotrophic conditions could accumulate more lipids (total lipid contents: 39.85% and 42.92%, respectively), especially the neutral lipids. Additionally, the contents of fatty acids suitable for use as biodiesel raw materials in both heterotrophic and mixotrophic cultures increased, especially the content of C18:1. Moreover, due to the lower biomass of heterotrophic cultivation compared with that from mixotrophic cultivation, the total lipid productivity of heterotrophic conditions decreased. In summary, the conditions of mixotrophic cultivation are more conducive to the accumulation of lipids in P. kessleri TY. [ABSTRACT FROM AUTHOR]

Phenolic compounds have become a severe environmental concern due to water contamination, affecting the sustainability of the ecosystem. The microalgae enzymes have enticed for the efficient involvement in the biodegradation of phenolics compound in metabolic processes. In this investigation, the oleaginous microalgae Chlorella sorokiniana was cultured heterotrophically under the influence of phenol and p-nitrophenol. The enzymatic assays of algal cell extracts were used to decipher the underlying mechanisms for phenol and p-nitrophenol biodegradation. A reduction of 99.58% and 97.21% in phenol and p-nitrophenol values, respectively, was recorded after the 10th day of microalgae cultivation. Also, the biochemical components in phenol, p-nitrophenol, and control were found to be 39.6 ± 2.3%, 36.7 ± 1.3%, and 30.9 ± 1.8% (total lipids); 27.4 ± 1.4%, 28.3 ± 1.8%, and 19.7 ± 1.5% (total carbohydrates); and 26.7 ± 1.9%, 28.3 ± 1.9%, and 39.9 ± 1.2% (total proteins), respectively. The GC–MS and 1H-NMR spectroscopy attested the incidence of fatty acid methyl esters in the synthesized microalgal biodiesel. The activity of catechol 2,3-dioxygenase and hydroquinone 1,2-dioxygenase in microalgae under heterotrophic conditions has conferred the ortho- and hydroquinone pathways for phenol and p-nitrophenol biodegradation, respectively. Also, the acceleration of fatty acid profiles in microalgae is deliberated under the impact of the phenol and p-nitrophenol biodegradation process. Thus, microalgae enzymes in the metabolic degradation process of phenolic compounds encourage ecosystem sustainability and biodiesel prospects due to the increased lipid profiles of microalgae. [ABSTRACT FROM AUTHOR]

Municipal wastewater treatment saves fresh water resources from contamination and provides a sustainable approach for reuse in water-stress regions. Herein, the impact of ferric chloride addition to cloth-media MBR treating municipal wastewater was tested for treatment performance, membrane filterability and sludge particle size distribution. Dosing of 7.5 and 15 mg/l of FeCl3 did not show any significant impacts on the removal of chemical oxygen demand and ammonia compared to the control test. However, the addition of ferric chloride increases percentage removal of total phosphorous from 33.5 to 39.5 and 46.5% at doses of 7.5 and 15 mgFeCl3/l, respectively. The ferric chloride addition did not enhance membrane filterability or flocculation of the sludge particles. On batch and Jar test experiments, the removal of total phosphorous reached up to 86% at dose of 120 mgFeCl3/l which shows that each mg of P needs 8 mg of Fe (22 mgFeCl3). The batch and jar test experiments did not show any significant impacts of ferric chloride up to 120 mg/l on the biological activity and particle size distribution of the sludge. To enhance phosphorus removal in the MBR systems, coagulant addition to the final permeate is recommended to avoid any negative impacts on the flux rate and to minimize coagulant addition. [ABSTRACT FROM AUTHOR]

Fish consumption has been growing since 1961. Indeed, the fisheries sector is essential to prevent hunger and malnutrition. However, this sector has its challenges. Fish stocks are being depleted beyond biological sustainability, with diseases and biosecurity risks to production and harm to the environment and ecosystems. There is a clear need to improve fish farming with minimum occupation and environmental impact. Heterotrophic and aquaponics systems are being utilized and modified to address these needs. However, environmental factors can affect the innate immunity of fish raised in these systems. Understanding how these systems affect fish’s immunity is critical to prevent potential hazards and the breakdown of these production methods. The goal of this research was to evaluate the performance, growth, and phagocytic indexes of silver catfish (Rhamdia quelen) juveniles reared in water recirculation, biofloc, and aquaponics systems in consortium with watercress seedlings (Nasturtium officinale). In each system, 12 juveniles weighing 15.2 g±7,6 were randomly divided into three replicates, fed with commercial feed. The following physical-chemical parameters - temperature, total and toxic ammonia, nitrite, and water pH - were daily assessed. Fishes were weighed monthly for six months. It was observed that R. quelen juveniles reared in the aquaponic system achieved higher average weight, but no statistical significance was detected (p>0.05) when compared to those reared in the recirculated and biofloc systems. At the end of the experiment, the phagocytic index was lower only in the recirculating system. The phagocytic capacity was lower in all systems. Although the aquaponic system presented low average weight gain/animal the performance of this system was effective in reducing the concentrations of total ammonia and nitrite in the water, in consortium with the production of vegetables.

Abstract Background Microalgae protein is considered as a sustainable alternative to animal protein in the future. Using waste for microalgal culture can upgrade low-value raw materials into high-value products, helping to offset the cost of microalgal protein production. In this study we explored the feasibility of using microalgae heterotrophic fermentation to convert broken rice hydrolysate (BRH) into protein. Results The results showed that the increase of BRH supplemental ratio was beneficial to the increase of biomass production but not beneficial to the increase of intracellular protein content. To further improve protein production, the effect of C/N ratio on intracellular protein accumulation was studied. It was found that low C/N ratio was beneficial to the synthesis of glutamate in microalgae cells, which in turn promoted the anabolism of other amino acids and further the protein. When the C/N ratio was 12:1, the biomass productivity and protein content could reach a higher level, which were 0.90 g/L/day and 61.56%, respectively. The obtained Chlorella vulgaris biomass was rich in essential amino acids (41.80%), the essential amino acid index was as high as 89.07, and the lysine content could reach up to 4.05 g/100 g. Conclusions This study provides a theoretical basis and guidance for using Chlorella vulgaris as an industrial fermentation platform to convert broken rice into products with high nutritional value.

The aim of this study was to improve the protein content and yield of heterotrophic microalgal cultivation and establish a simple, economical, and efficient method for microalgal protein production using the novel green alga, Graesiella emersonii WBG-1, which has not been previously reported for heterotrophic cultivation. Through batch heterotrophic cultivation of this alga, we observed that glucose was the optimal carbon source, while it could not use sucrose as a carbon source. Biomass production and protein content were significantly reduced when sodium acetate was used as the carbon source. Compared with nitrate, protein content increased by 93% when urea was used as the nitrogen source. Cultivation temperature had a significant impact on biomass production and protein content. The optimal conditions were glucose as the carbon source at an initial concentration of 10 g/L, urea as the nitrogen source at an initial concentration of 1.62 g/L, and a culture temperature of 35 °C. On the second day of batch cultivation, the highest protein content (66.14%) was achieved, which was significantly higher than that reported in heterotrophic cultures of Chlorella and much higher than that reported for specially established technologies aimed at increasing the protein content, such as two-stage heterotrophic, heterotrophy–dilution–photoinduction, and mixotrophic processes. These results demonstrate the great potential of the heterotrophic cultivation of G. emersonii WBG-1 for protein production. [ABSTRACT FROM AUTHOR]

Eicosapentaenoic acid (EPA) could be extracted from diatoms such as Amphora sp. present abundantly in the ecosystems. In view of the key environmental and nutritional factors governing the diatoms growth rate, culture conditions were optimized for the biomass yield, total lipid content, EPA yield, and fatty acid composition under two main cultivation regimes: photoautotrophic and heterotrophic. The fastest growth rate about 0.20 ± 0.02 g/L and the highest EPA yield about 9.19 ± 3.56 mg EPA/g biomass were obtained by adding 10 g/L glucose and sucrose, respectively. Under photoautotrophic culture conditions, Amphora sp. rendered higher EPA yield at 100 rpm and 16:8 light/dark cycle. Total fatty acids produced predominantly comprised of an approximate 40–70% of saturated fatty acids, followed by 10–27% of monounsaturated fatty acids and then 8–25% of polyunsaturated fatty acids. These findings were able to pave a way for huge‐scale microalgal biomass production in commercial EPA production. [ABSTRACT FROM AUTHOR]

The relevance of inland waters in the global carbon cycle has been stressed recently, particularly because of a reassessment of their capacity for carbon exportation to the atmosphere and to the sediments. Global surveys have also highlighted the acute lack of information on tropical systems, which are exposed to crescent problems in the Global Change panorama, such as contamination and eutrophication, as well as important impacts related to water management strategies and water supply (e.g., water level fluctuations). Oxygen dynamics, a method left behind in the past, has been revised and is now being increasingly implemented to estimate primary production and ecosystemic respiration due to the urgency to understand carbon fluxes in aquatic systems. Therefore the details (advantages and disadvantages) of modern implementation of oxygen dynamics are revised and discussed here, particularly oriented to facilitate and promote their aplication in tropical aquatic systems (where it seems an adequate strategy). We suggest a unifying method pipeline in order to obtain comparable results among systems, towards the construction of a carbon flux inventory at larger (spatial and temporal) scales. This effort would contribute to understand the role and responses of tropical aquatic systems and regions (particularly as carbon sources or sinks) facing Global Change.

The relevance of inland waters in the global carbon cycle has been stressed recently, particularly because of a reassessment of their capacity for carbon exportation to the atmosphere and to the sediments. Global surveys have also highlighted the acute lack of information on tropical systems, which are exposed to crescent problems in the Global Change panorama, such as contamination and eutrophication, as well as important impacts related to water management strategies and water supply (e.g., water level fluctuations). Oxygen dynamics, a method left behind in the past, has been revised and is now being increasingly implemented to estimate primary production and ecosystemic respiration due to the urgency to understand carbon fluxes in aquatic systems. Therefore the details (advantages and disadvantages) of modern implementation of oxygen dynamics are revised and discussed here, particularly oriented to facilitate and promote their aplication in tropical aquatic systems (where it seems an adequate strategy). We suggest a unifying method pipeline in order to obtain comparable results among systems, towards the construction of a carbon flux inventory at larger (spatial and temporal) scales. This effort would contribute to understand the role and responses of tropical aquatic systems and regions (particularly as carbon sources or sinks) facing Global Change.

In recent years, microalgal biomass cultivation has been growing in importance, not only related to the production of alternative foods and nutritional supplements but also for its usage for energy purposes or as a natural solution for wastewater treatment. Regarding these cases, the practical potential associated with the circular economy is evident. However, this is not an option for microalgal food and supplements due to strict hygiene requirements for microalgae cultivation used for these purposes. Currently, the most common cultivation options for microalgae include phototrophic cascades, photobioreactors, and heterotrophic fermenters. Generally, the higher requirements for the purity of the resulting biomass, the higher the consumption of energy and nutrients needed. These are the main operational parameters that significantly shape the total environmental and economic performance of microalgae cultivation processes. The comparative Life Cycle Assessment (LCA) of environmental aspects in the operational phases of three selected cultivation systems, located in the Czech Republic and used for pure microalgae biomass production, confirmed that the impacts of these systems in the assessed categories are fundamentally dependent on the amount of electricity needed and nutrient consumption, as well as their sources. For this reason, the heterotrophic fermenter was evaluated as being the most damaging in the comparison of the three cultivation systems, while the phototrophic cascade showed a lower total environmental impact by 15% and the flat photobioreactor was lower still, by 95%, mainly due to energy production from biomass. The major impact categories observed were climate change, depletion of fossil fuels, human toxicity, and freshwater and marine ecotoxicity. The environmental impacts of microalgae cultivation systems could be further reduced if cycling practices, such as process water recycling and reprocessing of generated sewage sludge, were addressed. [ABSTRACT FROM AUTHOR]

Microalgae are considered to have great potential as a source of biodiesel. Currently, algae culture has three different trophic modes, i.e., autotrophic, heterotrophic, and mixotrophic, but not all kinds of algae are suitable for heterotrophic and mixotrophic cultivation. In this study, Parachlorella kessleri TY, screened from the soil of Shanxi Province, was heterotrophically and mixotrophically treated with glucose as an organic carbon source, and the physiological and biochemical levels of its growth and lipid accumulation were measured. The results showed that the highest biomass and biomass productivity (1.53 g·L−1 and 218.57 mg·L−1d−1) were attained by P. kessleri TY under mixotrophic cultivation. In comparison, the lowest (0.55 g·L−1 and 78.57 mg·L−1d−1) were attained under heterotrophic culture. Furthermore, heterotrophic and mixotrophic conditions could accumulate more lipids (total lipid contents: 39.85% and 42.92%, respectively), especially the neutral lipids. Additionally, the contents of fatty acids suitable for use as biodiesel raw materials in both heterotrophic and mixotrophic cultures increased, especially the content of C18:1. Moreover, due to the lower biomass of heterotrophic cultivation compared with that from mixotrophic cultivation, the total lipid productivity of heterotrophic conditions decreased. In summary, the conditions of mixotrophic cultivation are more conducive to the accumulation of lipids in P. kessleri TY.

The ammonia removal ability of heterotrophic bacteria Alcaligenes faecalis strain No.4 isolated from sewage sludge was examined in a batch operation to mitigate ammonia from piggery wastewater, consequently preventing pollution by the inflow of wastewater from piggeries adjacent to rivers. If this process works functionally, it can be effective in controlling nitrous oxide (N2O) and nitrate (NO3−) emissions derived from animal agriculture, the heterotrophic nitrifying and the aerobic denitrifying effect of A. faecalis strain No.4 on high-strength ammonium (NH4+-N) were evaluated in wastewater collected from a piggery. The removal rate by A. faecalis strain No.4 on high-strength ammonium (NH4+-N) was 0.97 kg N/m3/day which was more than 100 fold greater than that achieved using conventional aerobic nitrification and anaerobic denitrification processes. An aerobic one-step denitrification system using A. faecalis strain No.4 can be proposed to remove ammonia and phytopathogens from piggery wastewater with high efficiency and prevent water pollution in adjacent rivers. [ABSTRACT FROM AUTHOR]

A tobacco chloroplast hypothetical open reading frame 4 (YCF4) has been reported as a non-essential assembly factor for photosynthesis based on an incomplete knockout of YCF4, just 93 of 184 amino acids from the N-terminus were knocked out. On the other hand, we removed the complete sequence of YCF4 from tobacco chloroplasts and observed that DYCF4 plants were unable to survive photoautotrophically as their growth was hampered in the absence of an external carbon supply, clearly showing that the YCF4 is essential for photosynthesis. Initially, the aadA gene was introduced into the tobacco plastome replacing the complete YCF4 gene through homologous recombination events. The replacement of YCF4 with aadA was confirmed by PCR and Southern blot analysis in DYCF4 plants. Homoplasmic DYCF4 plants had a light green phenotype, and the leaves became pale yellow as the plants grew older. The structure of chloroplasts of DYCF4 mutants of light green phenotype was studied using a transmission electron microscope (TEM), and the micrographs demonstrated structural anomalies in the chloroplasts; including shape, size, and grana stacking compared to the wild-type plants. Further, transcriptome analysis revealed that the expression of PSI, PSII, and ribosomal genes remained unchanged in ΔYCF4 plants. On the other hand, transcriptome levels of rbcL (Ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit), LHC (Light-Harvesting Complex), and ATP Synthase (atpB and atpL) decreased, indicating that the YCF4 has the function(s) in addition to assembling the photosynthetic complex. This was confirmed by in-silico protein-protein interactions of full-length YCF4 as well as 93 and 91 of 184 amino acids from N- and C-termini of the full-length protein, which revealed that the C-terminus (91 aa) of YCF4 is important in interacting with other chloroplast proteins. These findings provide genetic support for the plastid YCF4 gene's critical role in regulating the plastid gene expression and assembling the photosynthetic complex. [ABSTRACT FROM AUTHOR]

The unicellular flagellate algae Poterioochromonas malhamensis is a potential fucoxanthin-rich resource for sustainable and cost-effective fucoxanthin production. Light and nutrients are critical regulators for the accumulation of fucoxanthin in P. malhamensis. In this study, the maximum fucoxanthin yield of 50.5 mg L−1 and productivity of 6.31 mg L−1 d−1 were achieved by coupling high-cell-density fermentation with illumination. It was found that the combined use of organic and inorganic nitrogen (N) nutrition could improve the fucoxanthin yield as single inorganic or organic N had limitation to enhance cell growth and fucoxanthin accumulation. White light was the optimal light quality for fucoxanthin accumulation. Under white light and a moderate light intensity of 150 μmol m−2 s−1, the highest biomass concentration and fucoxanthin content reached 32.9 g L−1 and 1.56 mg g−1 of dry cell weight (DCW), respectively. This is the first study on effective fucoxanthin production in P. malhamensis by integrating illumination with high-cell-density fermentation, which paved the way for further development of P. malhamensis as a potential source for commercial fucoxanthin production.

A tobacco chloroplast hypothetical open reading frame 4 (YCF4) has been reported as a non-essential assembly factor for photosynthesis based on an incomplete knockout of YCF4, just 93 of 184 amino acids from the N-terminus were knocked out. On the other hand, we removed the complete sequence of YCF4 from tobacco chloroplasts and observed that ΔYCF4 plants were unable to survive photoautotrophically as their growth was hampered in the absence of an external carbon supply, clearly showing that the YCF4 is essential for photosynthesis. Initially, the aadA gene was introduced into the tobacco plastome replacing the complete YCF4 gene through homologous recombination events. The replacement of YCF4 with aadA was confirmed by PCR and Southern blot analysis in ΔYCF4 plants. Homoplasmic ΔYCF4 plants had a light green phenotype, and the leaves became pale yellow as the plants grew older. The structure of chloroplasts of ΔYCF4 mutants of light green phenotype was studied using a transmission electron microscope (TEM), and the micrographs demonstrated structural anomalies in the chloroplasts; including shape, size, and grana stacking compared to the wild-type plants. Further, transcriptome analysis revealed that the expression of PSI, PSII, and ribosomal genes remained unchanged in ∆YCF4 plants. On the other hand, transcriptome levels of rbcL (Ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit), LHC (Light-Harvesting Complex), and ATP Synthase (atpB and atpL) decreased, indicating that the YCF4 has the function(s) in addition to assembling the photosynthetic complex. This was confirmed by in-silico protein-protein interactions of full-length YCF4 as well as 93 and 91 of 184 amino acids from N- and C-termini of the full-length protein, which revealed that the C-terminus (91 aa) of YCF4 is important in interacting with other chloroplast proteins. These findings provide genetic support for the plastid YCF4 gene’s critical role in regulating the plastid gene expression and assembling the photosynthetic complex.

Euglena gracilis is one of the few permitted edible microalgae. Considering consumer acceptance, E. gracilis grown heterotrophically with yellow appearances have wider food industrial applications such as producing meat analogs than green cells. However, there is much room to improve the protein content of heterotrophic culture cells. In this study, the effects of nitrogen sources, temperature, initial pH, and C/N ratios on the protein production of E. gracilis were evaluated under heterotrophic cultivation. These results indicated that ammonium sulfate was the optimal nitrogen source for protein production. The protein content of E. gracilis cultured by ammonium sulfate increased by 113% and 44.7% compared with that cultured by yeast extract and monosodium glutamate, respectively. The manipulation of the low C/N ratio further improved E. gracilis protein content to 66.10% (w/w), which was 1.6-fold of that in the C/N = 25 group. Additionally, amino acid analysis revealed that the nitrogen-to-protein conversion factor (NTP) could be affected by nitrogen sources. A superior essential amino acid index (EAAI) of 1.62 and a balanced amino acid profile further confirmed the high nutritional value of E. gracilis protein fed by ammonium sulfate. This study highlighted the vast potency of heterotrophic cultured E. gracilis as an alternative dietary protein source.

The goal of this research is to produce bio-alcohol and biodiesel from S. quadricauda and C. pyrenoidosa microalgae in a sustainable manner using phototrophic and heterotrophic pathways. Experimental and statistical approaches are used to assess the viability of the bioenergy produced as a prospective alternative to diesel fuel. On analysis, it was observed that the %age weight of the dry cell of C. pyrenoidosa cultures on scaling-up resulted lipid content of 44.1%, 46.7%, and 41%, respectively. On scaling up, the cultures' biomass concentrations reached 5.15 g L −1, 4.24 g L −1, and 4.36 g L −1. Similarly, upscaling S. quadricauda cultures resulted in yield rates of 4.2 g L −1 and 2.96 g L −1 d −1 and a lipid productivity of 2.96 g L −1 d −1, respectively. On engine testing, AA20D80 and AA30D70 blend combinations shows an improvement of 4.84% and 6.9% in BTE with a reduction of 88.6% and 72.41% in fuel consumption. Similarly, as compared to amyl alcohol blends and diesel fuel at full load, CP20D80 and CP30D70 efficiently lower HC, NOx, and smoke emissions. The statistical analysis revealed that the similarity index of the 20% and 30% proportions were ideal in achieving optimal engine output characteristics. [Display omitted] • Phototrophic and heterotrophic upscaling of third generation microalgae feedstock. • Biosynthesis of long-chain bio-alcohol and low-density biodiesel from microalgae. • Higher yield and conversion rates for heterotrophic upscaling of C. pyrenoidosa. • S. quadricauda based bio-alcohol shows superior engine output characteristics. • Statistical COA identified the optimal mixtures as CP20D80 and AA20D80. [ABSTRACT FROM AUTHOR]

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The microalga Chlorella sorokiniana has attracted much attention for lipid production and wastewater treatment. It can perform photosynthesis and organic carbon utilization concurrently. To understand its phototrophic metabolism, a biomass compositional analysis, a 13C metabolic flux analysis, and metabolite pool size analyses were performed. Under dark condition, the oxidative pentose phosphate pathway (OPP) was the major route for glucose catabolism (88% carbon flux) and a cyclic OPP–glycolytic route for glucose catabolism was formed. Under light condition, fluxes in the glucose catabolism, tricarboxylic acid (TCA) cycle, and anaplerotic reaction (CO2 fixation via phosphoenolpyruvate carboxylase) were all suppressed. Meanwhile, the RuBisCO reaction became active and the ratio of its carbon fixation to glucose carbon utilization was determined as 7:100. Moreover, light condition significantly reduced the pool sizes of sugar phosphate metabolites (such as E4P, F6P, and S7P) and promoted biomass synthesis (which reached 0.155 h−1). In addition, light condition increased glucose consumption rates, leading to higher ATP and NADPH production and a higher protein content (43% vs. 30%) in the biomass during the exponential growth phase. [ABSTRACT FROM AUTHOR]

The effect of temperature on the phosphorous, nitrogen, and organic matter removal in an activated sludge system(ASS) has been assessed in this research. Benchmark Simulation Model No.1 (BSM1-P) with an ASS (ASM3bioP) is used and the temperature is chosen between 10 to 35°C. The kinetic expressions for the maximum growth rate of heterotrophic biomass, autotrophic, and phosphate accumulating organisms and their decay rates are considered. Total ammonia, nitrogen, and phosphorous in the effluent are analysed and when the range of temperature is less than 15°C and greater than 30°C, the effluent quality deviates from the legal requirements. [ABSTRACT FROM AUTHOR]

The influence of algal cell size on nutrient absorption, and the time delay in reproduction is paramount in biological terms. Furthermore, the control is necessary during algal flocculation harvesting and sewage treatment. Therefore, we investigated the properties of a single cell algal flocculation model with time delay, size structure and control. First, we introduced a dimensionless model. Then, we analyzed the existence of positive equilibrium states and studied the equilibrium states of the model. Finally, the numerical simulation revealed that the model exhibits backward bifurcation. [ABSTRACT FROM AUTHOR]

The aim of this study was to improve the protein content and yield of heterotrophic microalgal cultivation and establish a simple, economical, and efficient method for microalgal protein production using the novel green alga, Graesiella emersonii WBG-1, which has not been previously reported for heterotrophic cultivation. Through batch heterotrophic cultivation of this alga, we observed that glucose was the optimal carbon source, while it could not use sucrose as a carbon source. Biomass production and protein content were significantly reduced when sodium acetate was used as the carbon source. Compared with nitrate, protein content increased by 93% when urea was used as the nitrogen source. Cultivation temperature had a significant impact on biomass production and protein content. The optimal conditions were glucose as the carbon source at an initial concentration of 10 g/L, urea as the nitrogen source at an initial concentration of 1.62 g/L, and a culture temperature of 35 °C. On the second day of batch cultivation, the highest protein content (66.14%) was achieved, which was significantly higher than that reported in heterotrophic cultures of Chlorella and much higher than that reported for specially established technologies aimed at increasing the protein content, such as two-stage heterotrophic, heterotrophy–dilution–photoinduction, and mixotrophic processes. These results demonstrate the great potential of the heterotrophic cultivation of G. emersonii WBG-1 for protein production.

Increased consumer awareness for healthier and more sustainable products has driven the search for naturally sourced compounds as substitutes for chemically synthesized counterparts. Research on pigments of natural origin, such as carotenoids, particularly lutein, has been increasing for over three decades. Lutein is recognized for its antioxidant and photoprotective activity. Its ability to cross the blood-brain barrier allows it to act at the eye and brain level and has been linked to benefits for vision, cognitive function and other conditions. While marigold flower is positioned as the only crop from which lutein is extracted from and commercialized, microalgae are proposed as an alternative with several advantages over this terrestrial crop. The main barrier to scaling up lutein production from microalgae to the commercial level is the low productivity compared to the high costs. This review explores strategies to enhance lutein production in microalgae by emphasizing the overall productivity over lutein content alone. Evaluation of how culture parameters, such as light quality, nitrogen sufficiency, temperature and even stress factors, affect lutein content and biomass development in batch phototrophic cultures was performed. Overall, the total lutein production remains low under this metabolic regime due to the low biomass productivity of photosynthetic batch cultures. For this reason, we describe findings on microalgal cultures grown under different metabolic regimes and culture protocols (fed-batch, pulse-feed, semi-batch, semi-continuous, continuous). After a careful literature examination, two-step heterotrophic or mixotrophic cultivation strategies are suggested to surpass the lutein productivity achieved in single-step photosynthetic cultures. Furthermore, this review highlights the urgent need to develop technical feasibility studies at a pilot scale for these cultivation strategies, which will strengthen the necessary techno-economic analyses to drive their commercial production. [ABSTRACT FROM AUTHOR]

Nowadays, there is an increasing demand for novel feedstocks and alternative protein sources to meet global needs. Because of their rich nutritional profiles and high protein contents, microalgae-based food products and supplements are being developed. Nonetheless, these products present organoleptic characteristics such as taste, smell and colour that are often considered unpleasant by human and animal consumers. To address this constraint, strain improvement approaches such as random mutagenesis have been used, which combined with the right selection strategy, lead to more appealing microalgal biomass. In this work, a novel selection strategy using oxyfluorfen, an inhibitor of the chlorophyll synthesis pathway, was applied for the first time to isolate chlorophyll-deficient strains of Scenedesmus rubescens and Chlorella vulgaris upon treatment with ethyl methanesulfonate (EMS). With this approach, one S. rubescens brownish (37Y01) mutant strain, as well as two C. vulgaris mutant strains, one yellow (31Y15) and one white (31W62), were obtained. S. rubescens 37Y01 displayed a reduced protein content of 19.1% dry weight (DW) compared to that of the wildtype, which presented a protein content of 25.0% DW. C. vulgaris wildtype and mutants exhibited higher protein contents, in the 42.8‐44.3% DW range, compared to Scenedesmus rubescens (p < 0.05). The selective pressure of this inhibitor allowed the selection of S. rubescens and C. vulgaris mutants displaying 55% and 95% decrease in chlorophyll content, respectively. The reduced chlorophyll content greatly improves the sensory properties and consumer acceptance of established mutants, increasing the potential of both strains as feedstocks to develop novel food products. [Display omitted] • Strain improvement enabled the development of appealing microalgal products. • A novel selection method to screen randomly-generated mutants is proposed. • Oxyfluorfen was used to select mutants with up to 55–95% less chlorophyll. • A brownish mutant of S. rubescens was isolated with 19% DW of protein content. • Yellow and white mutants of C. vulgaris with protein of 43–44% DW were isolated. [ABSTRACT FROM AUTHOR]

The increase in mariculture activities worldwide has not only led to a rise of nitrogen compounds in the ecosystem but has also intensified the accumulation of antibiotics in both terrestrial and marine environments. This study focused on the effect of typical antibiotics, specifically sulfamethoxazole (SMX) on nitrate removal from mariculture wastewater by aerobic denitrification process; an aerobic denitrification system feeding with 148.2 mg/L COD, 8.59 mg/L nitrate, 0.72 mg/L nitrite, and 4.75 mg/L ammonium was set up. The hydraulic retention time (HRT) was 8 h. As the aerobic bioreactor started up successfully without SMX dosage, an excellent removal of ammonium, nitrite, and nitrate was achieved at 91.35%, 93.33%, and 88.51%, respectively; the corresponding effluent concentrations were 0.41 mg/L, 0.048 mg/L, and 0.96 mg/L. At the influent SMX doses of 0, 1, 5, and 10 mg/L, the COD removal reached 96.91%, 96.27%, 88.69%, and 85.89%, resulting in effluent concentrations of 4.53, 5.45, 17.38, and 20.6 mg/L, respectively. Nitrification was not inhibited by SMX dosage. However, aerobic denitrification was inhibited by 10 mg/L SMX. Proteobacteria was the most abundant phylum, and surprisingly its abundance increased with the increase in SMX concentration. An excellent SMX degradation was noted at initial SMX dosages of 1, 5, and 10 mg/L; the removal rate was 100%,100%, and 99.8%, respectively. The SMX degrading genera Comamonas sp., Acinetobacter sp., and Thauera sp. are of great validity to wastewater engineers because they have demonstrated efficiency in simultaneous heterotrophic aerobic denitrification and antibiotic degradation as well as COD removal. Practitioner Points: Nitrification was not inhibited by increase in SMX dosage.An increase in SMX dosage inhibited aerobic denitrification.COD removal was not affected by increased SMX dosage.Comamonas, Acinetobacter, and Thauera had high efficiency in COD removal and SMX degradation. [ABSTRACT FROM AUTHOR]

Fungi are heterotrophic organisms possessing cryptic lifestyles and have an individual hierarchy in the evolution of microorganisms on earth. Out of which, Keratinophilic fungi are allied molds that produce keratinase enzymes and diminish the keratin matters in or on the soil. Fifty soil samples were collected from various sites of Jaipur district, India to analyze incidence of keratinophilic fungi. Out of 162 isolates, a total of 24 keratinophilic fungal species of 13 genera were recovered, including Trichophyton sp. (17.90%), Aspergillus sp. (17.90%), Chrysosporium sp. (14.81%). Selective keratinophilic fungi were also discussed about phylogenetic studies. In multiple sequence alignment of sequences, species were reported to have closest relationships between teleomorphic and anamorphic form of keratinophilic fungi which exhibited a reason for phase changes between geophilic and dermatophytic fungi by accident or opportunistic where they may cause infections in both humans and animals on the opportunity. In the anti-fungal activity, Eucalyptus globulus (Inhibition Zone: 23.5 mm; Activity Index: 0.82) and Ocimum tenuiflorum (Inhibition Zone: 20.75 mm; Activity Index: 1.46) were inscribed to dispense a greater potential of antifungal activity against all selected keratinophilic fungi.

Abstract—In a long-term model experiment, the abundance dynamics of soil microorganisms was studied as affected by the pollution of southern chernozem soils with various concentrations and combinations of iron, nickel, and copper ions. In the course of this study, soil microbiocenoses were plated on solid nutrient media and the following values were estimated: the total number of heterotrophic microorganisms on a meat–peptone agar and the numbers of iron-oxidizing microorganisms on a selective medium 0, 30, 90, and 210 days after the introduction of heavy metal ions into the soil. A characteristic diverse impact of heavy metal ions on soil microorganisms was established, and the degree of stability of soil microbiocenoses of the southern chernozem was revealed. Iron and copper concentrations of 10 and 50 RGB/MPC 30 days after soil contamination by individual metal ions or their combinations stimulated the growth of heterotrophic microorganisms in the soil microbiocenoses, and 90 days later the number of this microbial group decreased to the control levels and below. After 210 days, the microbiocenoses returned to a stable state. Nickel ions, introduced into the soil at a concentration of 50 MPC separately and in a number of combinations with other heavy metal ions, did not stimulate the growth of heterotrophic microorganisms. Opposing trends were observed in the abundance dynamics of iron-oxidizing microorganisms. With the exception of some model variants such as 10 and 50 MPC of copper, iron, nickel, and their combinations in various concentrations inhibited the growth of iron-oxidizing microorganisms in the first month after soil contamination. The inhibitory effect of a combination of heavy metal ions was stronger than that of individual metals. After 90 days, the numbers of iron-oxidizing microorganisms returned to the control level or even exceeded it. After 210 days, inhibition of the growth of iron-oxidizing microorganisms was observed in the microbiocenoses or their abundance corresponded to the value in the control soil sample. [ABSTRACT FROM AUTHOR]

Soil respiration (Rs) is the second largest carbon (C) flux to the atmosphere and our understanding of how Rs and its components shift with plant-community composition remains an important question. We used high-frequency soil respiration measurements and root exclusion to evaluate how Rs, autotrophic respiration (Ra) and heterotrophic respiration (Rh) vary between a semi-arid perennial shrub community and annual invasive community. Over two growing seasons, total Rs was 40% higher under annual vegetation compared to shrubs. Partitioning revealed consistently higher Ra under annual vegetation which accounted for most of the difference in Rs. Under annual vegetation, Ra increased soon after the first rain events and remained high despite cooling temperatures while shrub Ra increased only when soil temperature began to warm up. The Rh rates were similar between vegetation types when daily soil temperatures were lower than 20 °C. As soil temperatures increased and soil moisture dropped below 10%, Rh was consistently higher under annual vegetation than shrubs. Seasonal dynamics of Rs and Rh were best modeled with an interaction term between soil moisture and temperature with significantly different model parameters for each vegetation type. Differences in the timing and magnitude of Rs and Ra between vegetation types are consistent with phenological differences between shrubs and annuals. Under annuals, larger Rh at high temperatures suggests that expansion of annual vegetation and future hotter and drier conditions could lead to greater C losses from this semi-arid shrub system. [ABSTRACT FROM AUTHOR]

The genus Spumella , established by Cienkowsky in 1870, is characterized by omnivory, two (rarely three) flagella, a short stick-like structure beneath the flagella, a threadlike stalk, cell division via constriction and cyst formation. Since the first phylogenetic study of Spumella -like flagellates, their paraphyly has consistently been shown, with separation into several genera. More recently, Spumella was carefully investigated using molecular and morphological data to propose seven new species. Classification of this genus and knowledge of its species diversity remain limited because Spumella -like flagellates are extremely difficult to identify based on limited morphological characters. To understand the phylogeny and taxonomy of Spumella , we analyzed molecular and morphological data from 47 strains, including 18 strains isolated from Korean ponds or swamps. Nuclear SSU, ITS and LSU rDNA data were used for maximum likelihood and Bayesian analyses. The molecular data divided the strains into 15 clades, including seven new lineages, each with unique molecular signatures for nuclear SSU rRNA from the E23-2 to E23-5 domains, the spacer between the E23-8 and E23-9 domains of the V4 region and domain 29 of the V5 region. Our results revealed increased species diversity in Spumella. In contrast to the molecular phylogeny results, the taxa showed very similar cell morphologies, suggesting morphological convergence into simple nanoflagellates to enable heterotrophy. Three new species produced stomatocysts in culture. Aspects of stomatocyst morphology, including collar structure, surface ornamentation, and cyst shape, were very useful in differentiating the three species. The general ultrastructure of Spumella bureschii strain Baekdongje012018B8 and S. benthica strain Hwarim032418A5 showed the typical chrysophyte form for the leucoplast, a vestigial chloroplast surrounded by four envelope membranes, supporting the hypothesis that Spumella evolved from a phototroph to a heterotroph via the loss of its photosynthetic ability. Seven new species are proposed: S. benthica , S. communis , S. longicolla , S. oblata , S. rotundata , S. similis , and S. sinechrysos. [ABSTRACT FROM AUTHOR]

In the present study, three conditions of photoautotrophic (Case 1), heterotrophic (Case 2), and mixotrophic (Case 3) on the microalgal growth, lipid accumulation, and content of chlorophyll a and phycocyanin pigment in Anabaena vaginicola ISC90 have been investigated. Results shown that the specific growth rate (µmax) of case 1 compared to cases 2 and 3, had an increase of 30% and 26%, respectively. Additionally, the productivity rate (P) of case 3 in comparison with cases 1 and 2 grew by 30% and 92%, sequentially. Lipid and chlorophyll a content in case 3 were found to be significantly higher than other cases at the end of cultivation time. Also, during the first week phycocyanin pigment content in case 2 reached a massive increase compared to other cultures. In spite of the low rate of growth parameters in heterotrophic condition, this culture was found to be a great potential for phycocyanin pigment content production. Also, three kinetic growth models (Logistic, Gompertz and Richards) were evaluated, among which Gompertz showed the best fit for all conditions.