Pigment Production Research Articles

Sustainable cultivation of Porphyridium cruentum via agro-industrial by-products: A study on biomass and lipid enhancement

This study explored the cultivation of Porphyridium cruentum using beet molasses and corn steep liquor (CSL) as alternative agri-waste substrates. The objective was to enhance the biomass and lipid production of P. cruentum, known for its potential as an industrial EPA producer. Using a Box-Behnken Design (BBD) as part of the response surface methodology (RSM), we investigated the effects of beet molasses, CSL, and F/2 nutrients on the microalga's cultivation. The results demonstrated a significant influence of these factors on the final cell count and lipid content over an 8-day cultivation period. Specifically, optimal growth conditions were identified at approximately 1.78 g/L of molasses and 1.89 g/L of CSL, yielding a cell count of 12.1 × 106 cells/mL and a lipid content of 24.48%. Validation experiments reaffirmed these findings, with observed results closely aligning with predicted values. Optimized media achieved also a significant higher content of carotenoids and phycobiliproteins compared to the standard media. This research highlights the potential of using agro-industrial by-products for large-scale cultivation of P. cruentum, offering a sustainable approach for enhancing lipid and pigment production.

Winery wastewater treatment by microalgae Chlorella sorokiniana and characterization of the produced biomass for value-added products.

The microalgae Chlorella sorokiniana was used for the treatment of winery wastewater (WWW). Batch experiments were initially conducted to investigate how biomass acclimatization in different media, dilution of wastewater, and addition of ammonium nitrogen (NH4-N) affect the growth of microalgae and the removal of major pollutants. Afterwards, two sequencing batch reactor (SBR) systems were tested applying different configurations and hydraulic retention times. The biomass collected at the end of the experiments was characterized for proteins, lipids, carbohydrates, amino acid profile, and the existence of lutein, β-carotene, chlorophyll a, and tocopherols. Batch experiments showed that Chlorella sorokiniana acclimatization to urban wastewater enhanced the removal of NH4-N and total phosphorus (TP). The operation of a two-stage SBR system achieved COD and NH4-N removal equal to 85 ± 9% and 91 ± 20%, respectively, while the use of a single-stage system feeding with anaerobically pretreated WWW resulted to COD and NH4-N removal of 78 ± 9% and 95 ± 9%, respectively. Analyses of biomass showed higher protein content (up to 58.8%) in batch experiments with NH4-N addition as well as in SBR experiments. The cultivation of microalgae under SBR conditions enhanced the production of pigments and tocopherols. The maximum concentrations of 1075mgkg-1, 45.5mgkg-1, and 131.2mgkg-1 were achieved for lutein, β-carotene, and tocopherols, respectively, in the one-stage system. Our findings suggested that Chlorella sorokiniana cultivation in WWW not only removed nutrients from WWW but also could potentially serve for the production of value-added ingredients used in food industry, cosmetics, and animal feedstock.

Ecotoxicological assessment, in freshwater environment, of wastewater sludge coupled and uncoupled with micro-polyvinyl chlorideon algae and water fleas.

In the frame of bioeconomy and circular economy, wastewater sludge (WS) could be a good candidate for its use in agriculture as fertilizer, due to its high content of organic matter, N and P, but on the other hand, it is full of toxicants such as heavy metal, microplastics, detergent, antibiotics, and so on that can reach groundwater and water bodies in leachate form. In this study, we have investigated different sludge concentrations in the eluate form, combined and not with PVC on two different freshwater organisms Selenastrum capricornutum and Daphnia magna, using ecotoxicity tests. At the endpoint, we have evaluated inhibition growth rate, oxidative stress, and pigments production for S. capricornutum, while in case of D. magna, we have assessed organism immobilization and development. From our results, it emerged that at the higher WS concentration, there was not inhibition growth rate, while at oxidative stress, it was higher in algae treated with WS and PVC. Higher Chl-a production was shown for algae treated with 0.3 g/L of sludge coupled withPVC, where higher phaeopigments production were recorded for algae treated with 0.3 g/L of WS. D.magna has shown an opposite trend when compared with algae, where at the highest WS concentrations supplied was corresponding to an increased mortality explaned as the highest immobility percentage. PRACTITIONER POINTS: Wastewater sludge is used in agriculture as fertilizer. PVC microplastic presence and associate ecotoxicity was tested. PVC presence increased oxidative stress in S. capricornutum. D. magna was significantly affected by sludge concentrations supplied.

Impact of host species on assembly, composition, and functional profiles of phycosphere microbiomes.

As the main primary producers of the oceans, microalgae serve as cornerstones of the ecosystems they are part of. Additionally, they are increasingly used for biotechnological purposes such as the production of nutraceuticals, pigments, and antioxidants. Since the bacterial microbiomes of microalgae can affect their hosts in beneficial and detrimental ways, understanding these microbiomes is crucial to both the ecological and applied roles of microalgae. The present study advances the understanding of microalgal microbiome assembly, composition, and functionality across microalgal phyla, which may inform the modeling and engineering of microalgal microbiomes for biotechnological purposes.

The application of PAHs-Degrading Pseudomonas aeruginosa to mitigate the phytotoxic impact of pyrene on barley (Hordeum vulgare L.) and broad bean (Vicia faba L.) plants

Mitigating the negative impacts of polycyclic aromatic hydrocarbons (PAHs) is an urgent need due to their toxicity and persistence in the environment. This study investigated the use of Pseudomonas aeruginosa ASU-B6 to detoxify pyrene (PY). The bacterium P. aeruginosa ASU-B6 is capable of degrading PY by 92% as a sole carbon source after 15 days of incubation with phthalate being the major metabolic product. In this regard, the impact of pyrene (PY), P. aeruginosa ASU-B6 (ASU-B6), the bacterial strain combined with pyrene (ASU-B6/PY) and the metabolites produced after pyrene degradation (PY-metabolites) on the germination and physiological attributes of Hordeum vulgare and Vicia faba seedlings were studied. A single application of PY or ASU-B6 showed a toxic effect on the germination of both tested seeds. Interestingly, broad bean seedlings exhibited less sensitivity to PY stress in terms of growth and metabolism compared to barley. Notably, ASU-B6 inhibited fresh and dry weight of shoots and roots of barley and, to a lesser extent, reduced the germination of broad beans compared to the control. However, the combined PY-metabolites and ASU-B6/PY showed a mutual ameliorative effect on seedlings growth, alleviating the phytotoxic impact of each component. Pyrene reduced the virulence of ASU-B6 by inhibiting the production of pyocyanin pigment, while bacteria ameliorated pyrene toxicity through its degradation. Heatmap and principal component analyses highlighted that increasing the contents of hydrogen peroxide, superoxide anion, hydroxyl radical, and lipid peroxidation positively correlated to the toxicity of PY or ASU-B6. However, improving the antioxidant system which buffers the oxidative stress induced by different combinations of PY and ASU-B6 enhanced the growth of germinated seedlings corresponding to PY or ASU-B6. This study reflected the role of ASU-B6 in ameliorating PY-phytotoxicity. In addition, the application of ASU-B6 strain is recommended as a prospective candidate for remediation of PAHs-contaminated environment with a positive impact on the plant growth and metabolic products.

Impact of legacy and unintentionally produced polychlorinated biphenyls (PCBs) in effluents from two wastewater treatment plants in rivers near Barcelona, Spain

Polychlorinated biphenyls (PCBs) are a family of 209 congeners listed as Persistent Organic Pollutants in the Stockholm Convention. Although there has been a lot of focus on those congeners present in the Aroclor or Clophen technical mixtures commercialized in the past (legacy PCBs), other industrial processes such as paint and pigment production can generate other congeners as byproducts (Unintentionally Produced PCBs or UP-PCBs). The present study focuses on the analysis of 72 PCB congeners (including 42 UP-PCBs) in the two major rivers surrounding the city of Barcelona -Llobregat and Besós rivers-, and their levels in two wastewater treatment plants during the production of effluents and reclaimed water. It was observed that WWTP can efficiently remove PCBs from untreated water during sludge production where concentrations are six orders of magnitude higher than in water (in the ng g−1 and pg L−1 ranges, respectively). Although PCB levels in the effluent and reclaimed water replenishing the rivers are not negligible, these do not significantly increase the concentrations already found in the studied rivers, and in most cases PCB concentrations in river water are reduced after merging with the reclaimed water due to dilution effect. The presence of UP-PCB-11 (not present in the Aroclor technical mixtures) in the analyzed water and sludge samples is significant (ranging from 22 to 25 % of the total PCB amount in the Besós river), being often one of the most abundant PCB congeners.

Optimised stress – intensification of pyocyanin production with zinc oxide nanoparticles

BackgroundPyocyanin is a blue pigment produced by Pseudomonas aeruginosa. Due to its unique redox properties over the last decade, it has gained more and more interest as a utile chemical. Nevertheless, it remains a rather costly reagent. It was previously shown that the production of pyocyanin can be enhanced by employing various methods. Among them are using statistical methods for planning the experiments or exposing bacterial cultures to stressors such as nanoparticles dosed in sublethal concentrations, e.g. zinc oxide nanoparticles.ResultsThe Design of Experiment (DoE) methodology allowed for calculating the optimal process temperature and nanoparticle concentration to intensify pyocyanin production. Low concentrations of the nanoparticles (6.06 µg/mL) and a temperature of 32℃ enhanced pyocyanin production, whereas higher concentrations of nanoparticles (275.75 µg/mL) and higher temperature stimulated biomass production and caused the abolishment of pyocyanin production. Elevated pigment production in zinc oxide nanoparticles-supplemented media was sustained in the scaled-up culture. Conducted analyses confirmed that observed stimulation of pyocyanin production is followed by higher membrane potential, altered gene expression, generation of reactive oxygen species, and accumulation of zinc in the cell’s biomass.ConclusionsPyocyanin production can be steered using ZnO nanoparticles. Elevated production of pyocyanin due to exposure to nanoparticles is followed by the number of changes in physiology of bacteria and is a result of the cellular stress. We showed that the stress response of bacteria can be optimised using statistical methods and result in producing the desired metabolite more effectively.

Salinity Tolerance of Diplotaxis tenuifolia Varieties Growing in Spring–Summer Season Under Mediterranean Greenhouse and Optimal Growing Conditions

Salinity is one of the principal abiotic stresses that occurs in the Mediterranean area, causing loss of productivity and decrease of vegetable crop quality. The effect of salinity (0, 25, 75, 150 mM NaCl) was evaluated in three Diplotaxis tenuifolia varieties (Dragon Tongue, Capriccio, Piccante), previously selected for salinity tolerance and high glucosinolates production in leaves. The aim of this research was to explore the salinity tolerance of three wild rocket varieties cultivated under optimal temperature conditions and under high temperature that typically characterized the Mediterranean greenhouse. Biometric, biomass, pigment production and physiological parameters were evaluated. Biometric, physiological, and biochemical parameters significantly varied because of variety, salt level used and environmental conditions. PCA analysis highlighted that the two cultivation systems deeply affected the wild rockets response to salt stress. In general, under optimal growing conditions, wild rocket varieties showed higher growth parameters compared to greenhouse conditions. Overall Capriccio was the most susceptible variety to salinity, while Dragon Tongue (V1) and Piccante (V3) were more tolerant to salt stress. Furthermore, in both growing conditions V1 was the less productive variety while V3 showed an opposite trend. Interestingly, gene (DtOxo and DtGst) expression analysis revealed a significant increase of the target gene expression as response of salinity levels, with a clear increase of DtOxo level in V1 and V3. The results obtained in this study can be useful to plan future breeding programs aimed to increase rocket quality grown under Mediterranean conditions.

Recycling potato waste for the production of blue pigments by Streptomyces lydicus PM7 through submerged fermentation

BackgroundDiscarded potato is the most abundant potato waste and represents a worldwide disposal problem to the potato industry. This agricultural waste contains valuable nutrients that could be used as substrate to obtain diverse high value-added microbial products, such as biopigments. The aim of this work was to evaluate the use of discarded potato as a sole substrate source for producing blue pigments by Streptomyces lydicus PM7 through submerged fermentation.ResultsInitially, the traditional culture medium ISP2 was established as suitable for inoculum preparation, as it allowed high growth rates and consumption of ~ 75% reducing sugar, leading to 1.3 g L−1 dry biomass at 72 h of incubation. The formulated discarded potato broth (DPB) medium was evaluated together with five other traditional liquid culture media (potato dextrose broth, ISP2, ISP3, ISP4, and ISP5) for producing blue pigments by S. lydicus PM7. The highest blue pigment production was obtained by using DPB medium, reaching ~ 0.97 g L−1, followed by ISP5 (~ 0.36 g L−1). In terms of evaluating the concentration of discarded potato powder, the highest concentration of blue pigments was obtained with 16 g L−1, compared to concentrations of 4, 8, and 32 g L−1. In general, a notable increase in total proteins (~ 14 g L−1 in biomass; ~ 8 g L−1 in medium) and reducing sugars (~ 5 g L−1) on the fifth day of DPB fermentation was observed, at which time the production of blue pigments began. These data proved that S. lydicus PM7 is able to degrade potato wastes during submerged fermentation and to direct metabolism towards the formation of biopigments. Chromatographic analysis revealed that the main blue pigment produced by new strain in this complex medium is actinorhodin.ConclusionsDiscarded potato favored the production of blue pigments by S. lydicus PM7 under submerged fermentation, leading to final product concentration almost three times higher than others traditional Streptomyces culture media. To the best of our knowledge, this is the first report on the production of actinorhodin by the specie S. lydicus, as well as on this pigment synthesis based on an agricultural waste as a sole nutrient source for fermentation process. The findings showed that potato waste could be a potential byproduct for replacement of commercial culture media using for this same purpose.Graphical

Isolation and Molecular Characterization of Pigment Producing Bacteria from Soil of Different Locality of Assam

Pigment is the most attractive attribute and integral part of human life. The source of the pigment used for different applications is chemically synthesised. However, pigment produced from natural sources (such as plants and microorganisms) can also be applied as a coloring agent. In addition to being colorants, many natural pigments are also fascinating bioactive substances with possible health benefits. Agrochemicals, food, medicine, pharmacology, cosmetics, and numerous other industries use these compounds. In this study, a total of 7 pigmented colonies were isolated from the soil samples of different areas of Assam. Out of 7 pigmented colonies, 3 colonies showed orange color and 4 colonies showed yellow color. Based on the similarity of growth pattern and high intensity of pigmentation one colony from each pigment was picked for further studies. The isolated orange and yellow pigments were denoted as S1 and S2, respectively. With the help of Bergey’s Manual of Determinative Bacteriology the isolated pigmented strains were preliminary identified based on their morphological, microscopic, and biochemical characteristics and after that 16S rRNA gene sequencing helped to identify the bacteria at the species level and the strains were identified as (S1) Micrococcus aloeverae ON377368 and (S2) Exiguobacterium aestuarii ON377409. The identified strains Micrococcus aloeverae and Exiguobacterium aestuarii showed a high pigment production rate at specific optimized conditions such as at temperature 37°C, pH 6, and NaCl concentrations at 1.5-2% and strains also showed a good characteristic growth pattern at a specific time interval. Therefore, the present study may be a helpful step towards the large-scale manufacture of pigments and the extraction, purification, and characterization of the pigment extracted from these strains will lead to provide a potent eco-friendly natural dye in the industrial sector.

Impact of ultra-high dilutions from Iranian endemic and commercial calendula on the germination and growth quality of Oryza sativa L.

PurposeThis article deals with producing ultra-diluted compounds (UHDs) prepared from Iranian calendula's characteristic and endemic species. It compares their chemical, biological and biochemical characteristics with the commercial sample of calendula species (grown in the Alps). In the following, these UHDs have been used to improve the quality of germination and growth and reduce contamination of rice (Oryza sativa) seeds in the laboratory environment. MethodsHigh-performance thin-layer chromatography (HPTLC) is used to isolate the active compounds. On the separated results, antioxidant and antibacterial were identified directly on the plate (Bio-autographic method). Direct on the plate)DESI mass spectrometry was used to identify the active compounds. ResultsThe HPTLC reveals that the chromatogram of native C. percica and C. officinalis extract is the most similar to the commercial compounds. The highest antioxidant activity is related to C. officinalis. The best antibacterial activity of the extracts against Staphylococcus aureus and Escherichia coli belongs to C. officinalis and C. tripterocarpa. Rutin, quercitrin, β-campstrole and di-o-caffeoylquinic acid, which are among the flavonoid and terpenoid categories were identified as active compounds. The prepared UHDs from native calendula are biologically more effective than the commercial ones in increasing seed germination efficiency, improving rooting quality and reducing contamination. ConclusionUsing UHDs increases the production of photosynthetic pigments the root length and the number of lateral roots. Also, the amount of protein, gibberellic acid and abscisic acid in seedlings treated using native UHDs of C. officinalis (native or commercial) is higher than the others.

Identification of pigmented extremophilic bacteria from mangrove soil with antibiofilm activity on food pathogens

Mangrove ecosystems and associated microorganisms are always a source of curiosity for researchers. Pigment producing bacteria were isolated from the mangrove soil in Kadamakkudi, Cochin, Kerala. The bacteria were biochemically identified and by 16 S rRNA gene sequence. The pigments extracted had been tested for antibiofilm activity against food pathogens Pseudomonas aeruginosa (NCIM 2863), Klebsiella pneumoniae (NCIM 5215), and Escherichia coli (NCIM 2343). Antibiofilm activity was further confirmed by fluorescent and scanning electron microscopy. Six yellow-orange pigmented bacteria (KDR2, KDR3, KDR7, KDR8, KDR14 and KDS1) were isolated. KDR2 was identified as Cellulosimicrobium funkei, KDR7 and KDS1 as Cytobacillus depressus, KDR8 as Bacillus aquimaris, and KDR3 and KDR14 as Halobacillus sp. All of these organisms are known to be extremophiles. The UV-Visible absorption spectrum of all the pigments ranged from 400 nm to 550 nm with different absorbance maxima. All the pigments showed antibiofilm activity against the food pathogens tested.

Enhancing content and decreasing production costs of phycocyanin through phytohormone supplementation in Spirulina cultivations

This study explores the potential of fractional supplementation of the phytohormone indole-3-acetic acid (IAA) to enhance phycocyanin production in Spirulina cultures. Microalgae cultures were supplemented with IAA at specific time points (days 0, 5, 10, 15, 20, and 25), reaching the same supplementation concentration (0.1 mg L−1) in the final 30-day cultivation period. The continuous daily supplementation resulted in a remarkable 229 % (106.41 mg g−1) increase in phycocyanin concentration and a 251 % (8.3 mg L−1 d−1) improvement in productivity compared to the control group without phytohormone addition (32.30 mg g−1 and 2.4 mg L−1 d−1, respectively). Additionally, the strategy successfully reduced the production cost of the pigment by 71 %. This approach can potentially make microalgae-based products more accessible to the population while addressing the industry's need for cost-effective pigment production. The study offers a novel strategy for optimizing natural pigment production and microalgae cultivation.

Antimicrobial resistance pattern of Klebsiella species isolated from various clinical specimens

Objective: The present study was carried out to identify Klebsiella species and their antimicrobial resistance pattern from various clinical specimens. Methods: This cross study was conducted at a tertiary care hospital, Dhaka, Bangladesh from July2020 to June 2021. Written consent was taken from the concerned authority. A total 6739 clinical samples including urine, wound swab/ pus, sputum, blood and endotracheal aspirates were collected and processed for isolation of bacteria by following standard guidelines from adult patients. All the urine, wound swab, blood and endotracheal aspirates were inoculated in both blood agar and MacConkey agar media, for blood samples blood culture was done in BacT/ALERT 3D 60 aerobic bottles irrespective to antibiotics administration. After incubation at 370C aerobically for 24 hours incubated plates were examined. Phenotypic identification of the organisms were done by observing colony morphology, hemolytic properties, pigment production, Gram staining and biochemical tests (oxidase test, catalase test and biochemical reactions after inoculation in TSI, MIU, citrate agar media). The Kirby - Bauer disk diffusion method was used for antimicrobial susceptibility testing of the isolated organism using Mueller-Hinton agar and commercially available antibiotic discs (Oxoid Ltd, UK). The data were analyzed using SPSS software Version-20 (SPSS Inc., Chicago, IL, USA). Categorical variables were expressed as numbers (n) and percentages (%). Results: A total 6739 samples were included in the present study. Of which, 170 were urine, 162 were wound swabs, 71 were sputum, 52 were endotracheal aspirates and 45 were blood samples. Culture positivity among the samples is shown in table I. Conclusion: Most of the Klebsiella species are highly resistant to commonly used antibiotics. This higher resistance is the major cause morbidity and mortality related with infections in hospitalized patients. So, a regular surveillance of antibiotic susceptibility pattern is needed to prevent indiscriminate use of antibiotics. CME J 2024; 3(2); 12-15

Phyllosphere Microbiome in Ecosystem Management and Plant Growth Promotion for Agricultural Sustainability

This review paper attempts to interpret the various role of phyllosphere microbiome, survival, resistant mechanisms to confront the adverse environmental conditions, production of pigment, extracellular polysaccharides, biosurfactants to promote surface attachment desiccation protection, volatile organic compounds, phytoalexins, as a defensive role to compete for space and nutrients. The beneficial phyllosphere microbes contributing to promotion of plant growth by facilitating nutrient acquisition, modulating hormonal signaling, biocontrol for plant pathogens in multi-various crops is discussed in detail. Phyllobacteria show encouraging interactions with host plants in improving plant health and biometric traits by regulating nutrient acquisition, phytohormones production, biotic and abiotic stress management. The members of genera Bacillus, Enterobacter, Microbacterium, Methylobacterium, Stenotrophomonas, Pseudomonas, Pseudarthrobacter, and Kocuria were the most dominant plant growth promoting bacteria reported in phyllosphere. The beneficial phyllosphere microorganism enhances crop yield while reducing the environmental footprint associated with synthetic fertilizers and pesticides. The review focuses and thrust on the development as well as commercialization of biostimulants derived from phyllosphere microbiomes. These biostimulants, and their metabolites, can be tapped to enhance plant growth, nutrient uptake, and overall crop performance in organic farming. Furthermore, this review paper focus on certain drawbacks that there have been few researches on phyllosphere yeast and its symbiotic association with bacteria, thereby emphasizing subsequent research in this area.

Bioprospecting Hypoxylon fendleri for pigment production and assessment of its dyeing efficacy on silk fabric

Fungal dyes are promising natural source of pigment for the textile industry due to their environmentally friendly production process. The present study evaluated the efficacy of buffy brown pigment extracted from Hypoxylon fendleri for dyeing silk fabric following fungal identification using morphological features coupled with sequence analysis of the internal transcribed spacer region. The physiochemical parameters namely, pH, temperature, and incubation time along with glucose and peptone concentrations were optimized for in vitro pigment production using the desirability function. A pH of 7 at 28 °C temperature, 75 g/L glucose and 10 g/L peptone with an incubation time of 17 d was found to be optimum with a desirability value of 0.56. The chromatic properties of the dyed fabric were characterized on the basis of CIELAB coordinates. The fastness of color produced on silk fabric was assessed using standard tests for washing, perspiration, and rubbing fastness. Finally, the dye (pigmented liquid extract) obtained from H. fendleri showed good and uniform dyeing properties on silk fabric and could be an alternative natural source for dyeing silk fabric. Moreover, the use of natural dyes will aid in mitigating the hazardous environmental impacts of the synthetic dyeing industry.

A deoxyviolacein-based transposon insertion vector for pigmented tracer studies.

Pigments provide a simple means to rapidly visually ascertain the quantities or presence of specific microbes in a complex community. The selection of pigment-producing colonies that are simple to differentiate from common colony phenotypes provides a high degree of certainty for the identity of pigment-tagged strains. Successful employment of pigment production is dependent on various intrinsic factors related to proper levels of gene expression and pigment production that are not always easy to predict and vary within each microbe. We have constructed a simple transposon system that incorporates the genes for the production of deoxyviolacein, a pigment produced from intracellular reserves of the amino acid tryptophan, to randomly insert these genes throughout the genome. This tool allows the user to select from many thousands of potential sites throughout a bacterial genome for an ideal location to generate the desired amount of pigment. We have applied this system to a small selection of endophytes and other model bacteria to differentiate these strains from complex communities and confirm their presence after several weeks in natural environments. We provide two examples of applications using the pigments to trace strains following introduction into plant tissues or to produce a reporter strain for extracellular nitrogen compound sensing. We recognize that this tool could have far broader utility in other applications and microbes, and describe the methodology for use by the greater scientific community.

An RNA interference approach for functional studies in the sea urchin and its use in analysis of Nodal signaling gradients.

Dicer substrate interfering RNAs (DsiRNAs) destroy targeted transcripts using the RNA-Induced Silencing Complex (RISC) through a process called RNA interference (RNAi). This process is ubiquitous among eukaryotes. Here we report the utility of DsiRNA in embryos of the sea urchin Lytechinus variagatus (Lv). Specific knockdowns phenocopy known morpholino and inhibitor knockdowns, and DsiRNA offers a useful alternative to morpholinos. Methods for designing and obtaining specific DsiRNAs that lead to destruction of targeted mRNA are described. DsiRNAs directed against pks1, an enzyme necessary for pigment production, show how successful DsiRNA perturbations are monitored by RNA in situ analysis and by qPCR to determine relative destruction of targeted mRNA. DsiRNA-based knockdowns phenocopy morpholino- and drug-based inhibition of nodal and lefty. Other knockdowns demonstrate that the RISC operates early in development as well as on genes that are first transcribed hours after gastrulation is completed. Thus, DsiRNAs effectively mediate destruction of targeted mRNA in the sea urchin embryo. The approach offers significant advantages over other widely used methods in the urchin in terms of cost, and ease of procurement, and offers sizeable experimental advantages in terms of ease of handling, injection, and knockdown validation.

Physiological and transcriptomic analysis reveals the toxicological mechanisms of polystyrene micro- and nano-plastics in Chlamydomonas reinhardtii

With the accumulation of plastic waste in the environment, the toxicity of micro- and nano-plastics (MNPs) to microalgae has attracted increasing attention. However, the underlying toxic mechanisms of MNPs remain to be elucidated. In this study, we synthesized micro- and nano-scale of polystyrene MNPs (PS MNPs) to investigate their toxicity and toxic mechanisms in Chlamydomonas reinhardtii. We found that PS MNPs significantly inhibit the production of photosynthetic pigments and increase soluble protein content. The detailed analysis of results shows that both materials affect photosynthetic efficiency by damaging the donor side, reaction center, and electron transfer of photosystem II. Moreover, compared to PS MPs, PS NPs have a greater negative impact on algal cells. Analyzing the transcriptome of cells suggests that the most sensitive metabolic pathways in response to PS MNPs involve oxidative phosphorylation, biosynthesis of secondary metabolites, and photosynthesis. Especially, genes related to photosynthesis and oxidative phosphorylation showed significant changes in expression after exposure to PS MNPs. This study provided molecular-level insights into the toxic mechanisms of PS MNPs on microalgae.

Sequential two-stage cultivation system using novel microalga consortia for treatment of municipal wastewater and simultaneous biomass production: Sustainable environmental management

Monoculture-based microalgae cultivation systems to treat wastewater are well-reported. Despite that, this method has some limitations in terms of nutrient removal potential, environment adaptation, and low biomass productivity. Conversely, microalgae co-cultivation and a two-stage sequential cultivation system (TSSCS) recently emerged as a promising approach to improve the treatment process and biomass productivity through better adaptation to the environment. However, no outdoor large-scale experiments were reported using this approach which hinders the viability of the process. Thus, in the present study, a sequential two-stage large-scale outdoor novel microalgae consortia experiment was developed. In first stage consortia-assisted sequential cultivation, two ratios of Tetraselmis indica (TS) and one ratio of Picochlorum sp. (PC) (2 TS:1 PC) were cultivated in a 1000-L pond containing 75%-municipal wastewater (MWW) + 25%-ASN-III, while in the second stage, 2 PC:1 TS was cultivated in two different ponds, and each containing 375-L 2 TS:1 PC-treated water + 375-L ASN-III. Outdoor parameters and nutrient removal efficiency (NRE), biomass, and biomolecule productivity such as lipid, photosynthetic pigments, astaxanthin, and β-carotene were quantified, and cost analysis was performed. At the end of the first and second stages, 2 TS:1 PC and 2 PC:1 TS showed maximum NRE of COD (68.71 and 86.40%), TN (66.98 and 94.73%), and TP (82.70 and 94.36%), respectively. Moreover, 2 TS:1 PC and 2 PC:1 TS Pond 1 and 2 produced maximum dry biomass production; 2.41 and ∼2.54 g/L contained lipid content; 36.89 and 34.90% that have 86.50 and 55.79% FAME content respectively. Similarly, 2 TS:1 PC and 2 PC:1 TS biomass exhibited valuable pigments production of astaxanthin i.e., 0.56 and 0.35 mg/g, and β-carotene; 4.65 and 2.82 mg/g, respectively. The cost analysis suggested that only microalgal-based MWW treatment was unfeasible, while valorization of produced biomass into co-products could offset the operation costs and could allow the option for the microalgal-based sustainable approach for the treatment of MWW and recovery of valuable resources.