Production Of Photosynthetic Pigments Research Articles

Microalga-bacteria interaction mitigates adverse effects on microalga produced by ZnO nanoparticles

Zinc oxide nanoparticles (ZnO NPs) used in myriad industries have become an emerging contaminant in various environments. Interactions of microalgae and bacteria, in suspension systems and immobilized, have been proposed for several biotechnology applications, such as wastewater treatment. However, the presence of NPs can affect the performance of these microorganisms during nutrient removal. This study assessed the effect of metal NPs on microalgae˗bacteria interaction, immobilized or in suspension. The effect of two concentrations of ZnO NPs (0.1 and 0.5 ppm) on the growth and photosynthetic pigments of the microalga Chlorella sorokiniana cultured in suspension or immobilized in alginate beads, alone or in the presence of the microalgae growth-promoting bacterium Azospirillum brasilense, was evaluated, and the effect of these NPs on indole-3-acetic acid (IAA) production by A. brasilense was also tested. The presence of ZnO NPs affected the growth of both microorganisms when cultured alone in suspension, and the IAA production by A. brasilense was reduced by 98 %. Nevertheless, when the two microorganisms were co-cultured in suspension, the negative effect of 0.1 ppm of ZnO NPs in C. sorokiniana was mitigated by A. brasilense, indicating a positive interaction between the two microorganisms. Furthermore, adding synthetic IAA enhances microalgae growth and photosynthetic pigment production regardless of NP concentration. On the other hand, immobilization of the cells produces a dose-response effect in the microorganisms, regardless of the partnerʼs presence. The results showed the positive effect of A. brasilense on stress mitigation of C. sorokiniana when 0.1 ppm of ZnO NPs are present and similar to the effect produced by synthetic IAA when the microorganisms are present in a suspension system. On the other hand, the immobilization of cells in alginate beads represents a physical barrier that acts as protection against the stress produced by ZnO NPs.

Effect of Light Conditions on Polyphenol Production in Transformed Shoot Culture of Salvia bulleyana Diels.

Various strategies have been used to increase the efficiency of secondary metabolite production in Salvia plants. This report is the first to examine the spontaneous development of Salvia bulleyana shoots transformed by Agrobacterium rhizogenes on hairy roots and the influence of light conditions on the phytochemical profile of this shoot culture. The transformed shoots were cultivated on solid MS medium with 0.1 mg/L of IAA (indole-3-acetic acid) and 1 mg/L of m-Top (meta-topolin), and their transgenic characteristic was confirmed by PCR-based detection of the rolB and rolC genes in the target plant genome. This study assessed the phytochemical, morphological, and physiological responses of the shoot culture under stimulation by light-emitting diodes (LEDs) with different wavelengths (white, WL; blue, B; red, RL; and red/blue, ML) and under fluorescent lamps (FL, control). Eleven polyphenols identified as phenolic acids and their derivatives were detected via ultrahigh-performance liquid chromatography with diode-array detection coupled to electrospray ionization tandem mass spectrometry (UPLC-DAD/ESI-MS) in the plant material, and their content was determined using high-performance liquid chromatography (HPLC). Rosmarinic acid was the predominant compound in the analyzed extracts. The mixed red and blue LEDs gave the highest levels of polyphenol and rosmarinic acid accumulation (respectively, 24.3 mg/g of DW and 20.0 mg/g of DW), reaching two times greater concentrations of polyphenols and three times greater rosmarinic acid levels compared to the aerial parts of two-year-old intact plants. Similar to WL, ML also stimulated regeneration ability and biomass accumulation effectively. However, the highest total photosynthetic pigment production (1.13 mg/g of DW for total chlorophyll and 0.231 mg/g of DW for carotenoids) was found in the shoots cultivated under RL followed by BL, while the culture exposed to BL was characterized as having the highest antioxidant enzyme activities.

Enhanced spirulina platensis growth for photosynthetic pigments production in oil palm empty fruit bunch medium

S. platensis is a cyanobacterium known for its richness in protein and bioactive compounds, with very captivating therapeutic and nutritional properties. In Cameroon, the medium commonly used for the cultivation of S. platensis is Jourdan's medium which is expensive and less available. Thus, it is necessary to find an alternative medium that is more efficient, less expensive and more available. Nutrients present in agro-industrial by-products can be used to enhance the production of biomass and photosynthetic pigments of S. platensis. Therefore, this study was conducted to evaluate the growth and Photosynthetic pigments productivity of S. platensis on the Oil Palm Empty Fruit Bunch (OPEFB) medium. The culture medium was formulated by distilling different concentrations (0; 2; 4; 6; 8 and 10 g L-1) of ash from previously dried and incinerated OPEFB medium in distilled water. The highest optical density (1.01 ± 0.09), dry biomass (1.35 ± 0.10 g L-1) and productivity (0.032 g L-1d-1) were recorded on the medium formulated with 8 g L-1 of the OPEFB compared to the standard (Jourdan medium). The same medium showed the highest content of chlorophyll a (4.96 ± 0.31 mg L-1), chlorophyll b (2.21 ± 0.16 mg L-1) and carotenoids (1.43 ± 0.01 mg L-1). However, the protein (156.1 ± 0.70 mg L-1) and sugar (4.50 ± 0.43 mg L-1) contents recorded on the standard medium were significantly high (P < 0.05). These results suggest that the OPEFB medium is a potential medium for S. platensis culture that can replace the expensive and less accessible Jourdan medium.

Sustainable, quality biofertilizer produced from Nile perch (Lates niloticus) wastewater using three Bacillus species: Demonstration in barley hydroponics

Although substantial quantities of Nile perch waste/wastewater are generated in Northeastern and Central Africa, only a small fraction of Nile perch waste is reutilized, with the resultant environmental pollution threatening aquatic life. Therefore, it was investigated whether Nile perch wastewater (NPWW) can be processed to produce a quality biofertilizer and thus completely reused. To achieve this purpose, NPWW degradation was conducted in a 1 L flask for 72 h using a microbial consortium of three Bacillus species. After 72 h biodegradation, the number of viable cells was 5.6 × 107 CFU/mL, the degree of protein hydrolysis was 48.7%, and the removal efficiency of chemical oxygen demand concentration and total nitrogen in NPWW was 52.5% and 44.0%, respectively, with C/N ratios of 5.5−6.4. Small molecules resulting from biodegradation comprised 52.9% hydrophilic amino acids and exhibited 73.9%, 98.9%, and 93.3% of free radical-scavenging activity for DPPH, ABTS, and OH-, respectively. The resultant biofertilizer was non-phytotoxic beyond a 50-fold dilution, and a 1000-fold dilution of the biofertilizer in barley hydroponics resulted in significantly higher stem and leaf growth than the control and commercial fertilizer. The biofertilizer-fed barley leaves exhibited a higher production of photosynthetic pigments and significantly higher antioxidant activity (92.5% for DPPH and 91.8% for ABTS) than the leaves in the control and commercial fertilizer groups. These findings indicate that the biodegraded NPWW rich in small molecules can be used as a biostimulant for sustainable agriculture.

Development of economical and sustainable cultivation system for biomass production and simultaneous treatment of municipal wastewater using Tetraselmis indica BDUG001

ABSTRACT Microalgal-based bioprocess offers several advantages including wastewater reclamations, therefore present study assessed the usability of the combination of untreated municipal sewage wastewater (UTMSWW) and secondary treated municipal sewage wastewater (STSWW) for nutrient removal and recovery by Tetraselmis indica (T. indica) BDUG001. The present study optimized the additional nutrient supplementations (e.g. ASN-III) percentage and day-night cycle, pH and pH with aeration for monitoring high-rate biomass production and nutrient recovery. The study results showed that the combination of 75% UTMSWW + 25% ASN-III supported maximum biomass production (2.65 ± 0.07 g/L). In the optimized day-night cycle (12:12 h), T. indica BDUG001 showed improved biomass production (2.75 ± 0.07 g/L), biomass productivity (165.63 ± 4.42 mg/L/d), and photosynthetic pigments production. Under optimized pH∼ 7.0 with aeration, maximum total nitrate (TN) removal efficiency (87.67 ± 3.08–91.55 ± 1.92%) was observed, while COD and TP removal was maximum at pH ∼ 9.0. The maximum biomass production (2.35 ± 0.07–2.77 ± 0.04 g/L) with biomass productivity (93.75 ± 167.19 ± 2.21 mg/L/d) and lipid content (42.98 ± 1.86–47.85 ± 0.21% DCW) were also at pH 7.0. with aeration. The present study verified the utilization of UTMSWW with the combination of conventional medium, optimized day-night cycle, pH with aeration along with designing low-cost PBR. It was the ideal system for the cultivation of T. indica BDUG001 for the recovery of nutrients from wastewater, production of biofuels and value-added feedstock.

Behind the plant-bacteria system: The role of zucchini and its secondary metabolite in shaping functional microbial diversity in MCPA-contaminated soil

MCPA (2-methyl-4-chlorophenoxyacetic acid) contamination is an emerging problem, especially in water reservoirs. The early removal of MCPA residues from soil can prevent its spread to untreated areas. It has been found that the growth of cucurbits and the addition of selected plant secondary metabolites (PSMs) can stimulate MCPA removal from soil. However, the effect of these treatments on soil microbial activity remains poorly studied. Hence, the aim of this research was to evaluate the influence of zucchini (C. pepo cv Atena Polka) and its characteristic PSM: syringic acid (SA) on the functional diversity of soil microorganisms in MCPA-contaminated soil using Biolog® EcoPlates™. It also examines soil physicochemical properties and the growth parameters of zucchini.Microbial activity was enhanced by both zucchini cultivation and SA. All unplanted variants showed significantly lower microbial activity (average well color development, AWCD, ranging from 0.35 to 0.51) than the planted ones (AWCD ranging from 0.77 to 1.16). SA also stimulated microbial activity in the soil: a positive effect was observed from the beginning of the experiment in the unplanted variants, but over a longer time span in the planted variants. SA ameliorated the toxic effect of MCPA on the studied plants, especially in terms of photosynthetic pigment production: the MCPA+SA group demonstrated significantly increased chlorophyll content (401 ± 4.83 μg/g), compared to the MCPA group without SA (338 ± 50.1 μg/g).Our findings demonstrated that zucchini and the amendment of soils with SA, the characteristic PSM of cucurbits, can shape functional diversity in MCPA-contaminated soil. The changes of soil properties caused by the application of both compounds can trigger changes in functional diversity. Hence, both SA and MCPA exert indirect and direct effects on soil microbial activity.

Plant-growth-promoting bacteria from rhizosphere of Chilean common bean ecotype (Phaseolus vulgaris L.) supporting seed germination and growth against salinity stress.

Salinity abiotic stress is increasing day by day due to continuous global warming and climate change. This is also becoming one of the major causes behind the reduction in crop production. Plant-bacteria interaction plays an essential role in improving crop yield without using any chemical fertilizers. The present study aims to characterize the interaction between plant-growth-promoting bacteria (PGPB) and their role in mitigating salinity stress for local variety crops. Therefore, in this work, two PGPB, namely, Bacillus proteolyticus Cyn1 and Bacillus safensis Cyn2, were isolated from rhizospheric soil of the Chilean common bean ecotype "Sapito" (Phaseolus vulgaris L.), and their PGPB traits were analyzed. Cyn1 can produce NH3 and HCN and also secrete siderophores, whereas Cyn2 produced NH3 and siderophores but responded negatively to HCN production. Both the isolated bacteria have shown a positive result for ACC deaminase production, phosphate solubilization, and catalase enzyme secretion. Under all three tested abiotic stresses, i.e., temperature, water, and salinity, both the bacteria and their consortium have demonstrated positive responses. Cyn1 under temperature stress and water stress can produce a biofilm network to combat the stress. While under salinity stress, both the PGPB isolates indicated the production of stress components and cytoplasmic inclusion bodies. Based on the response, among all other abiotic stresses, salinity stress was chosen for further plant-bacteria interaction study and growth. Visible root colonization of the bacteria has been observed in comparison to the control. The germination index was 100% for all experimental setups of seed bacterization, both under control conditions and salinity stress. Both bacteria responded with good PGP traits that helped in the growth of healthy plants after the bacterial treatment in final pot experiments. Additionally, the consortium and the plants treated with Cyn1 have demonstrated high production of photosynthetic pigments in both experimental setups. Both B. proteolyticus Cyn1 and B. safensis Cyn2 have shown promising PGP characters and efficient response against toxicity related to salinity. Hence, both of these bacteria and consortium can be used for improved agricultural production of Chilean native common beans in the near future.

Aqueous Seaweed Extract Alleviates Salinity-Induced Toxicities in Rice Plants (Oryza sativa L.) by Modulating Their Physiology and Biochemistry

Around the world, salinity a critical limiting factor in agricultural productivity. Plant growth is affected by salt stress at all stages of development. The contemporary investigation focused on Chaetomorpha antennina aqueous extracts (SWEs) to decrease the effects of salt strain on rice germination, growth, yield, and the production of key biological and biochemical characters of the rice, Oryza sativa L. (Poaceae). SWE improved the germination capacities of rice seedlings by promoting their emergence 36.27 h prior to those that had been exposed to saline stress. The creation of 79.647% longer radicles by SWE treatment on salt-stressed seeds which boosted the establishment effectiveness of seeds produced under salt stress longer radicles resulted in plants that were 64.8% taller. SWE treatment was effective in revoking the levels of protein (26.9%), phenol (35.54%), and SOD (41.3%) enzyme levels that were previously constrained by salinity stress. Additionally, SWE were also efficient in retaining 82.6% of leaf water content and enhancing the production of photosynthetic pigments affected by salt exposure earlier. The improvement in plant functionality was evident from the display of increase in tiller numbers/hill (62.36%), grain yield (58.278%), and weight (56.502%). The outcome of our research shows that SWEs protected the plants from the debarring effects of salinity by enhancing the plant functionality and yield by mechanistically enriching their physiological (germination and vegetative growth) and biochemical attributes (leaf RWC, photosynthetic pigments, protein, phenol, and SOD). Despite the increase in TSS and starch levels in rice grain exposed to salinity stress, SWE improved the grain protein content thus cumulatively enhancing rice nutrition and marketability. The current investigation reveals that the extracts of C. antennina can help alleviate rice plants from salt stress in an efficient, eco-friendly, as well as economical way.

Effects of Algal Utilization of Dissolved Organic Phosphorus by Microcystis Aeruginosa on Its Adaptation Capability to Ambient Ultraviolet Radiation

Phosphorus (P) plays an important role in eutrophication and algal adaptation to environmental stresses; therefore, a better understanding of the impact of P is essential to control cyanobacterial bloom. In this study, Microcystis aeruginosa is treated with 5 h of ambient irradiation in the culture medium with different availabilities of dissolved organic P (DOP) and dissolved organic matter (DOM) to explore algal physiological responses. Compared to photosynthetically active radiation (PAR), ambient UV-A and UV-B radiation exerted oxidative stresses and has inhibitive effects on the growth and photosynthesis of M. aeruginosa. However, M. aeruginosa had a strong adaptation capability, and the negative effects of UV radiation can be alleviated with DOM addition in the DOP-rich medium. The adaptation of M. aeruginosa to UV radiation in the DOP-rich waters can be mainly achieved through hydrolysis of DOP and metabolism of dissolved inorganic P (DIP), and the DOP utilization behaviors of M. aeruginosa might greatly affect algal UV adaptation capability. In the DOP-rich medium without DOM, the great inactivation of algal alkaline phosphatase (APase) after UV radiation could result in worse affinity for DOP, slower DOP uptake and lower cellular P quota. Consequently, the P demand of M. aeruginosa could not be satisfied for UV adaptation processes, including decreasing UV-induced damages and promoting self-repair. However, DOM could act as an antioxidant and significantly decrease APase inactivation of UV-radiated M. aeruginosa. In the DOP-rich medium with DOM, DOP utilization by M.aeruginosa in the UV-A and UV-B treatments is promoted and algal demand for P is satisfied for its adaptation, such as enhanced production of photosynthetic pigments, increased superoxide dismutase (SOD) activity, recovery of photosynthetic efficiency, etc. Overall, our findings indicate the close relationship between algal DOP utilization and the adaptation to ambient UV radiation of typical cyanobacteria in DIP-limited and DOP-enriched natural waters.

Enantioselective aquatic toxicity and degradation in soil of the chiral fungicide oxathiapiprolin.

Oxathiapiprolin is an efficient and chiral fungicide for peronosporomycetes. The enantioselective environmental behavior and ecotoxicity of oxathiapiprolin are still unclear. The enantioselectivity of oxathiapiprolin enantiomers was explored, including their acute toxicity toward aquatic plants (Auxenochlorella pyrenoidosa and Soirodela polyrhiza) along with their influence on photosynthetic pigment production, the acute toxicity and morphological differences for the embryos, larvae and adult stages of zebrafish (Danio rerio), and the degradation in four typical soils (aerobic, anaerobic and sterilized conditions). The enantioselective toxicity of oxathiapiprolin showed that the toxicity of R-oxathiapiprolin was 1.8-2.1 times higher than that of S-oxathiapiprolin toward the two aquatic plants. In particular, the content of photosynthetic pigments decreased significantly stronger after exposure to R-oxathiapiprolin compared with S-oxathiapiprolin. The LC50 values of R-oxathiapiprolin in zebrafish in the different life stages were 1.6-2.1 times higher than those of S-oxathiapiprolin. The zebrafish embryos were most sensitive to the oxathiapiprolin enantiomers. After exposure to R-oxathiapiprolin, zebrafish embryos showed noticeable hatching delays, inhibition or deformation. R-oxathiapiprolin degraded preferentially in all four soils, with an enantiomeric fraction (EF) ranging from 0.28 to 0.42 under aerobic conditions. Enantioselective degradation was not found under anaerobic and sterilized conditions. The enantioselectivity of new chiral pesticides should be fully considered in risk assessments to provide a basis for the development and preparation of pure optical enantiomers.

Assessment of the Impacts of Green Synthesized Silver Nanoparticles on Maerua oblongifolia Shoots under In Vitro Salt Stress.

Salinity is one of the major abiotic stresses that affect the plant’s growth and development. Recently, the contribution of nanoparticles (NPs) to ameliorating salinity stresses has become the new field of interest for scientists due to their special physiochemical properties in the biological system. This study is designed to examine the effects of biosynthesized silver nanoparticles (AgNPs) spherical in shape (size range between 9 and 30 nm) on morphophysiological characteristics and the antioxidant defense system of in vitro raised Maerua oblongifolia under four levels of salt stress (0, 50, 100, and 200 mM NaCl). Our findings reveal that the application of AgNPs (0, 10, 20, and 30 mg/L) to M. oblongifolia shoots significantly alleviates the adverse effects of salt stress and ameliorates plant developmental-related parameters and defense systems. High salinity elevates the oxidative damage by over-accumulation of the levels of total soluble sugars, proline, hydrogen peroxide (H2O2), and malondialdehyde (MDA). In addition, enhancing the activity of the antioxidant enzymes, total phenolic, and flavonoid content over the control. Interestingly, the application of AgNPs to salinized plants improved the growth traits and photosynthetic pigment production and caused higher enhancement in antioxidant enzyme activities. Furthermore, mitigating the oxidative damage by lowering the accumulation of proline, soluble sugars, H2O2, MDA, and total phenolic and flavonoid contents in salt-stressed plants. In general, AgNPs augmented the growth of M. oblongifolia shoots under saline conditions through different strategies; thus, AgNPs can be used as an appropriate eco-friendly approach that enhances salinity tolerance in plants.

Fluoride mitigates aluminum-toxicity in barley: morpho-physiological responses and biochemical mechanisms

BackgroundTo our knowledge, the role of exogenous fluoride (F–) on aluminum (Al)-stress mitigation in plants has not been investigated yet. In this experiment, barley (Hordeum vulgaris) seedlings were exposed to excessive Al3+ concentrations (aluminum chloride, 0.5, 1.0, 2.0, 3.0, and 4.0 mM) with and without fluoride (0.025% sodium fluoride) to explore the possible roles of fluoride on the alleviation of Al-toxicity.ResultsOverall, Al-stress caused inhibition of growth and the production of photosynthetic pigments. Principal component analysis showed that the growth inhibitory effects were driven by increased oxidative stress and the interruption of water balance in barley under Al-stress. Fluoride priming, on the other hand, enhanced growth traits, chlorophyll a and b content, as well as invigorated the protection against oxidative damage by enhancing overall antioxidant capacity. Fluoride also improved osmotic balance by protecting the plasma membrane. Fluoride reduced endogenous Al3+ content, restored Al-induced inhibition of glutathione-S-transferase, and increased the contents of phytochelatins and metallothioneins, suggesting that fluoride reduced Al3+ uptake and improved chelation of Al3+.ConclusionsAluminum chloride-induced harmful effects are abridged by sodium fluoride on barely via enhancing antioxidative responses, the chelation mechanism causing reduction of Al uptake and accumulation of barely tissues. Advanced investigations are necessary to uncover the putative mechanisms underpinning fluoride-induced Al-stress tolerance in barley and other economically significant crops, where our results might serve as a solid reference.

Polycyclic aromatic hydrocarbon sequestration by intertidal phototrophic biofilms cultivated in hydrophobic and hydrophilic biofilm-promoting culture vessels

Phototrophic biofilms collected from intertidal sediments of the world’s largest tidal mangrove forest were cultured in two sets of a biofilm-promoting culture vessel having hydrophilic glass surface and hydrophobic polymethyl methacrylate surface wherein 16 priority polycyclic aromatic hydrocarbons (PAHs) were spiked. Biofilms from three locations of the forest were most active in sequestering 98–100% of the spiked pollutants. PAH challenge did not alter the biofilm phototrophic community composition; rather biofilm biomass production and synthesis of photosynthetic pigments and extracellular polymeric substances (EPS) were enhanced. Photosynthetic pigment and EPS synthesis were sensitive to vessel-surface property. The lowest mean residual amounts of PAHs in the liquid medium as well as inside the biofilm were recorded in the very biofilm cultivated in the hydrophobic flask where highest values of biofilm biomass, total chlorophyll, released polysaccharidic (RPS) carbohydrates, RPS uronic acids, capsular polysaccharidic (CPS) carbohydrates, CPS proteins, CPS uronic acids and EPS hydrophobicity were obtained. Ratios of released RPS proteins: polysaccharides increased during PAH sequestration whereas the ratios of CPS proteins: polysaccharides remained constant. Efficacious PAH removal by the overlying phototrophic biofilm will reduce the entry of these contaminants in the sediments underneath and this strategy could be a model for “monitored natural recovery”.

Comparative Study of Algal Responses and Adaptation Capability to Ultraviolet Radiation with Different Nutrient Regimes.

Frequent outbreaks of harmful algal blooms (HABs) represent one of the most serious outcomes of eutrophication, and light radiation plays a critical role in the succession of species. Therefore, a better understanding of the impact of light radiation is essential for mitigating HABs. In this study, Chlorella pyrenoidosa and non-toxic and toxic Microcystis aeruginosa were mono-cultured and co-cultured to explore algal responses under different nutrient regimes. Comparisons were made according to photosynthetically active radiation (PAR), UV-B radiation exerted oxidative stresses, and negative effects on the photosynthesis and growth of three species under normal growth conditions, and algal adaptive responses included extracellular polymeric substance (EPS) production, the regulation of superoxide dismutase (SOD) activity, photosynthetic pigments synthesis, etc. Three species had strain-specific responses to UV-B radiation and toxic M. aeruginosa was more tolerant and showed a higher adaptation capability to UV-B in the mono-cultures, including the lower sensitivity and better self-repair efficiency. In addition to stable μmax in PAR ad UV-B treatments, higher EPS production and enhanced production of photosynthetic pigments under UV-B radiation, toxic M. aeruginosa showed a better recovery of its photosynthetic efficiency. Nutrient enrichment alleviated the negative effects of UV-B radiation on three species, and the growth of toxic M. aeruginosa was comparable between PAR and UV-B treatment. In the co-cultures with nutrient enrichment, M. aeruginosa gradually outcompeted C. pyrenoidosa in the PAR treatment and UV-B treatment enhanced the growth advantages of M. aeruginosa, when toxic M. aeruginosa showed a greater competitiveness. Overall, our study indicated the adaptation of typical algal species to ambient UV-B radiation and the stronger competitive ability of toxic M. aeruginosa in the UV-radiated waters with severer eutrophication.

Use of Piriformospora indica to Promote Growth of Strawberry Daughter Plants

As an endophytic fungus, the growth-promoting effects of Piriformospora indica have been widely confirmed in many of its host plants. In this study, we investigated the influences of P. indica colonization on the growth of the daughter plants of two strawberry cultivars, ‘Benihoppe’ and ‘Sweet Charlie.’ The results showed that the fungus colonization significantly promoted the growth of the daughter plants of both of the two strawberry varieties. Its colonization greatly improved almost all of the growth parameters of the ‘Benihoppe’ daughter plants, including the above-ground fresh weight, above-ground dry weight, root fresh weight, root dry weight, plant height, petiole length, leaf area, number of roots and chlorophyll content. However, the fungus colonization showed significant improving effects on only the above-ground fresh weight, root fresh weight and root dry weight of ‘Sweet Charlie.’ Surprisingly, the average root length of ‘Benihoppe’ and ‘Sweet Charlie’ was suppressed by about 14.3% and 24.6%, respectively, by P. indica. Moreover, after P. indica colonization, the leaf nitrate reductase activity and root activity upregulated by 30.12% and 12.74%, and 21.85% and 21.16%, respectively, for the ‘Benihoppe’ and ‘Sweet Charlie’ daughter plants. Our study indicated that P. indica could promote the growth of strawberry daughter plants by improving rooting, strengthening photosynthetic pigments production and nutrient absorption and accelerating biomass accumulation. The fungus shows great potential to be used in the strawberry industry, especially in the breeding of daughter plants.

Potential of the microalgae Chlorella fusca (Trebouxiophyceae, Chlorophyta) for biomass production and urban wastewater phycoremediation

The present work focuses on: (1) the evaluation of the potential of Chlorella fusca to grow and synthesize metabolites of biotechnological interest, after being exposed for fourteen days to urban wastewater (UW) from Malaga city (UW concentrations: 25%, 50%, 75%, and 100%); (2) the study of the capacity of C. fusca to bioremediate UW in photobioreactors at laboratory scale; and (3) the evaluation of the effect of UW on the physiological status of C. fusca, as photosynthetic capacity by using in vivo Chl a fluorescence related to photosystem II and the production of photosynthetic pigments. C. fusca cell density increased in treatments with 50% UW concentration, followed by the treatment with 100% UW, 75% UW, the control, and finally 25% UW. Protein content increased to 50.5% in 75% UW concentration. Stress induced to microalgal cultures favored the increase of lipid production, reaching a maximum of 16.7% in 100% UW concentration. The biological oxygen demand (BOD5) analysis indicated a 75% decrease in 100% UW concentration. Dissolved organic carbon (DOC) levels decreased by 41% and 40% in 50% UW and 100% UW concentration, and total nitrogen (TN) decreased by 55% in 50% UW concentration. The physiological status showed the stressful effect caused by the presence of UW on photosynthetic activity, with increasing impact as UW concentration grew. In the framework of circular economy, we seek to deepen this study to use the biomass of C. fusca to obtain metabolites of interest for biofuel production and other biotechnological areas.Graphical

Impact of parabens on microalgae bioremediation of wastewaters: A mechanistic study

The rising concerns from environmental contamination by emerging contaminants (ECs) pushes the need to develop efficient removal technologies in wastewater (WW) treatment plants. Parabens are synthetic estrogens belonging to the ECs group of endocrine disrupting chemicals. Microalgae-based bioremediation is gaining attention as a compelling solution for a cost-effective and sustainable WW treatment. However, there is a lack of scientific data regarding the capacity of microalgae for the removal of parabens at different concentrations as well as the removal mechanisms involved. This work aims to study the effects from methylparaben (MetP) exposure at 0.796 and 7.96 mg/L (10 and 100 × higher than the maximum found in a WW influent) on the ability of Chlorella vulgaris to remove MetP and nutrients from a WW. This mechanistic study was undertaken using different physiological endpoints: cellular hydrophobicity (as extracellular interaction), metabolic activity, intracellular reactive oxygen species (ROS) accumulation and photosynthetic efficiency. The presence of MetP did not alter the hydrophobicity of C. vulgaris cells, which suggests that bioadsorption did not occur. Moreover, for 0.796 mg MetP/L no effects were observed in the metabolism or biomass production. However, for 7.96 mg/L, a decrease in the esterase activity and photosynthetic pigments production was observed, linking these metabolic effects with a decrease in cellular growth. After 168 h, MetP was partly removed: 33.16% and 14.10%, for initial concentrations of 0.796 and 7.96 mg/L, respectively. For the lower concentration, removal was achieved through biodegradation and photodegradation, however, for the extreme concentration, C. vulgaris was not capable to biodegrade MetP, being photodegradation the main removal mechanism. Furthermore, C. vulgaris showed satisfactory growth and removal of the main nutrients (≥73%), which were not affected by the presence of MetP at the lower concentration, highlighting the ability of this microalga for the treatment of WW contaminated with parabens, even with extreme concentrations.

Priming with copper-chitosan nanoparticles elicit tolerance against PEG-induced hyperosmotic stress and salinity in wheat

In this study Cu-chitosan nanoparticles (Cu-CNP) have been employed as eco-friendly and safer priming agents to induce salt and PEG-induced hyperosmotic stress tolerance in wheat seedlings. Seed priming is a facile on-farm stress management technique that requires a little amount of priming agent and minimizes the eco-toxicological effects on soil fertility. The wheat seeds were primed with 0.12% and 0.16% Cu-CNP for eight hours and were allowed to germinate under normal, PEG-induced hyperosmotic stress (15% PEG-6000 – 3.0 Mpa) and salt stress (150 mM). For comparison, non-primed and hydro-primed seeds were also allowed to germinate as control under the same conditions. The biochemical analyses suggested the priming treatments enhanced the POD activity under salt stress but it was decreased under PEG-induced hyperosmotic stress. Priming with 0.12% Cu-CNP induced a significant increase in CAT while the opposite effect was observed in 0.16% treated seedling under stress and non-stress conditions. Both priming treatments did not allow the over-expression of SOD under both stress conditions. The total phenolic contents were also decreased significantly under all conditions. Except for priming with 0.16% Cu-CNP under PEG-induced hyperosmotic stress, a suppression in MDA was observed under both stress conditions. Surprisingly, the Cu-CNP priming induced a significant increase in β-carotenoids, total carotenoids, chlorophyll a, b and total chlorophyll under normal and stress conditions. In conclusion, the controlled expression of enzymatic antioxidants, low contents of non-enzymatic antioxidants and suppression of MDA mirror the stress mitigating role of Cu-CNP against PEG-induced hyperosmotic stress and salinity. The stress-insulating potential has also been reinforced by the enhanced production of plant and photosynthetic pigments. All these priming-induced biochemical changes produced positive effects on growth and germinating parameters in wheat seedlings under PEG-induced hyperosmotic stress as well as salinity.

Silicon nanoparticles decrease arsenic translocation and mitigate phytotoxicity in tomato plants.

In this study, we simulate the irrigation of tomato plants with arsenic (As)-contaminated water (from 0 to 3.2mg L-1) and investigate the effect of the application of silicon nanoparticle (Si NPs) in the form of silicon dioxide (0, 250, and 1000mg L-1) on As uptake and stress. Arsenic concentrations were determined in substrate and plant tissue at three different stratums. Phytotoxicity, As accumulation and translocation, photosynthetic pigments, and antioxidant activity of enzymatic and non-enzymatic compounds were also determined. Our results show that irrigation of tomato plants with As-contaminated water caused As substrate enrichment and As bioaccumulation (roots > leaves > steam), showing that the higher the concentration in irrigation water, the farther As translocated through the different tomato stratums. Additionally, phytotoxicity was observed at low concentrations of As, while tomato yield increased at high concentrations of As. We found that application of Si NPs decreased As translocation, tomato yield, and root biomass. Increased production of photosynthetic pigments and improved enzymatic activity (CAT and APX) suggested tomato plant adaptation at high As concentrations in the presence of Si NPs. Our results reveal likely impacts of As and nanoparticles on tomato production in places where As in groundwater is common and might represent a risk.

Impacts of elicitors on metabolite production and on antioxidant\xa0potential and tyrosinase inhibition in watercress microshoot cultures

The study has proved the stimulating effects of different strategies of treatments with elicitors on the production of glucosinolates (GSLs), flavonoids, polyphenols, saccharides, and photosynthetic pigments in watercress (Nasturtium officinale) microshoot cultures. The study also assessed antioxidant and anti-melanin activities. The following elicitors were tested: ethephon (ETH), methyl jasmonate (MeJA), sodium salicylate (NaSA), and yeast extract (YeE) and were added on day 10 of the growth period. Cultures not treated with the elicitor were used as control. The total GSL content estimations and UHPLC-DAD-MS/MS analyses showed that elicitation influenced the qualitative and quantitative profiles of GSLs. MeJA stimulated the production of gluconasturtiin (68.34 mg/100 g dried weight (DW)) and glucobrassicin (65.95 mg/100 g DW). The elicitation also increased flavonoid accumulation (max. 1131.33 mg/100 g DW, for 100 μM NaSA, collection after 24 h). The elicitors did not boost the total polyphenol content. NaSA at 100 μM increased the production of total chlorophyll a and b (5.7 times after 24 h of treatment), and 50 μM NaSA caused a 6.5 times higher production of carotenoids after 8 days of treatment. The antioxidant potential (assessed with the CUPRAC FRAP and DPPH assays) increased most after 24 h of treatment with 100 μM MeJA. The assessment of anti-melanin activities showed that the microshoot extracts were able to cause inhibition of tyrosinase (max. 27.84% for 1250 µg/mL).Key points• Elicitation stimulated of the metabolite production in N. officinale microshoots.• High production of pro-health glucosinolates and polyphenols was obtained.• N. officinale microshoots have got tyrosinase inhibition potential.• The antioxidant potential of N. officinale microshoots was evaluated.Graphical abstract