High Biomass Production Research Articles

High production of biomass and bioactive compounds by Dendrobium officinale protocorm-like bodies induced by exogenous additives

High production of biomass and bioactive compounds by Dendrobium officinale protocorm-like bodies induced by exogenous additives

Phosphorus leaching in high-P soils under maize silage and interseeding cover crop system

Managing soil phosphorus (P) in agroecosystems with high P levels is crucial to mitigate P loss in water sources without compromising yields. The objective of this study was to assess maize silage (Zea mays L.) + interseeding cover crop of annual ryegrass (Lolium multiforum) or using a relay cover crop and starter P (P0, P10, and P20) on (i) P leaching, (ii) changes in soil P status, and (iii) maize yield, cover crop biomass and P uptake. A six-year study was conducted between 2018 and 2023 in two sites. Leachate samples were collected every two weeks between 2021and 2023. The concentration of P in leachate exceeded 0.5 mg L–1 indicating a high risk of P leaching at the current levels of soil P. High concentration of P in leachate with a peak at 0.9 mg L–1 in August and 1.45 mg L–1 in October during 2021 and 2022 was pronounced under interseeded compared to relay cover crop system due to improve water infiltration contributing to the downward movement of P. In contrast, the concentration of P in leachate was high under relay cover crops in February and March particularly in 2023, which could be attributed to the delay in cover crops establishment and growth in early spring. The concentration of P extracted using anion exchange membranes (PO4AEMs) increased with increasing starter P rate during the first weeks after planting maize silage. There were spikes of PO4AEMs, reaching 1.18 and 1.73 µg cm–2 d–1 during the 4th, 7th, and 8th weeks after planting maize which coincided with high soil moisture content occurring after irrigation or rainfall events. The lack of dry matter yield response to starter P at harvest was due to high initial soil P. The soil P status remained significantly high averaging 196.6 mg kg–1 as Mehlich-3 P, despite negative cumulative P budgets. A close observation of the relationships among soil P indicators shows a trend of rapidly decreasing water extractable P under interseeding compared with relay cover crops. It is possible that the production of high biomass under interseeding cover crops increased the amount of P taken up from the soil. We conclude that interseeding cover crops within cash crops in high P soils could be effective at decreasing soil P, but could enhance P leached in the first years of cropping due to high water infiltration along the soil profile.

Sustainable remediation of piggery wastewater using a novel mixotrophic Chlorella sorokiniana Cbeo for high value biomass production

Piggery wastewater (PW) contains high density of organic carbon (COD), nitrogen (NH4+-N and TN) and phosphorous (TP), which are essential nutrients for microalgae growth. This work was attempted to use a newly isolate Chlorella sorokiniana Cbeo for recovery these compounds into its biomass via mixotrophic cultivation. Critical factors including level of ammonia, C/N ratio, pH, light intensity, sterilized/unsterilized media, and indoor/outdoor cultivations affecting biomass production and nutrients removal efficiencies were investigated. Data revealed that C. sorokiniana Cbeo achieved the optimal growth in the unsterilized medium at NH4+-N concentration, C/N ratio, initial pH, and light intensity of 250 mg/L, 10/1, 7, and 150 μmol/m2/s, respectively. Under the optimal conditions, dry cell weight (DCW) reached the maximal level of 4.30 g/L, which was slightly higher than 4.14 g/L determined for the sterilized medium. In 30 L-scale photobioreactor, C. sorokiniana Cbeo grown under indoor and outdoor achieved DCW of 3.61 and 3.19 g/L, respectively. COD, NH4+-N, TN, TP removal efficiencies for both conditions were determined as 91.9–96.7, 96.6–99.7, 96.2–96.4, and 98.2–100 %, respectively. The C. sorokiniana Cbeo biomass contained 14–27 % lipid, 25–32 % carbohydrate, 44–48 % protein, and 0.25–0.97 % lutein. Interestingly, α-Linolenic acid (C18:3n3) was 19.84 –27.0 % of the total fatty acids. C. sorokiniana Cbeo is the promising algal strain for development of a sustainable biorefinery of PW.

Perennial Fodder Crops as a Tool for Soil Carbon Management in Agroecosystems

Carbon sequestration, typically referred to as carbon storage is defined as the “long-term storage of carbon in plants, soils, geologic formations and the ocean, which occurs both naturally and as a result of anthropogenic activities”. With respect to agricultural sector, carbon sequestration is viewed as the capability of agriculture lands to absorb carbon dioxide from the atmosphere. Out of the different ways in play, cultivation of fodder crops turns out to be promising due to its high biomass production, root proliferation, mostly perennial nature, suitability for wastelands and most importantly as the feed for livestock. Restoration of degraded lands, adoption of pasture-based agroforestry systems, inclusion of grasses, sowing of improved forage species, grazing management, nutrient and water management are strategies that aid in improving carbon sequestration in fodder production systems. Perennial fodder grasses and fodder legumes such as alfalfa are excellent for carbon storage as they do not require replanting after each harvest which avoids soil disturbances that usually associate with annual crops. Carbon neutral methods of cultivation is greatly hoped to convert agriculture from a source of carbon to a permanent sink of carbon at a faster pace.

Technosols Made from Iron Mine Tailings and Construction and Demolition Waste as an Alternative for Sustainable Solid Waste Management

ABSTRACTBrazil faces urgent environmental challenges due to large waste production from mining and construction activities particularly regarding the disposal and management of the solid waste generated by these activities. The extraction of iron ore and the storage of tailings in dams, most of which are at imminent risk of rupture, represent foretold environmental disasters. Additionally, the disposal of construction waste raises environmental concerns due to the decreasing vailability of inert landfill space. To address these challenges, we evaluated the potential of Technosols made from construction and demolition waste (CDW) and iron mining tailing (IMT) in different proportions (60:40, 70:30, 80:20, and 100% of IMT and CDW, respectively) to support grass development. The Technosols were compared to a natural soil (Haplic Ferralsol). The soils were cultivated with Urochloa brizantha cv. Marandu in a field experiment conducted for 120 days. At the end of experiment, soil samples were collected and analyzed their chemical, physical, and mineralogical attributes, while plants were analyzed for dry biomass. Plants cultivated in Technosols exhibited dry biomass production 3.3‐fold (825 ± 270 g) greater than those cultivated in the natural soil (251 ± 77 g). Higher biomass production in the Technosols, especially in the TEC70:30, was associated with the favorable chemical conditions of these soils, such as slightly neutral pH (~7.5), higher cation exchange capacity (68.1 ± 12.4 mmol dm−3) and nutrient availability, especially Ca and P (57.8 ± 0.8 and 28.2 ± 0.4 mmol dm−3, respectively). These results aim to provide insights for the effective use of different Technosols in mitigating environmental impacts and promoting sustainable land and waste management practices, primarily to prevent future environmental disasters.

Boron confers salt tolerance through facilitating BnaA2.HKT1-mediated root xylem Na+ unloading in rapeseed (Brassica napus L.).

Boron (B) is an important limiting factor for plant growth and yield in saline soils, but the underlying molecular mechanisms remain poorly understood. In this study, we found that appropriate B supply obviously complemented rapeseed (Brassica napus L.) growth under salinity accompanied by higher biomass production and less reactive oxygen species accumulation. Determination of Na+ content in shoots and roots indicated that B significantly repressed root-to-shoot Na+ translocation, and non-invasive micro-tests of root xylem sap demonstrated that B increased xylem Na+ unloading in the roots of rapeseed plants under salinity. Comparative transcriptomic profiling revealed that B strongly upregulated BnaHKT1s expression, especially BnaA2.HKT1, in rapeseed roots exposed to salinity. In situ hybridizations analysis showed that BnaA2.HKT1 was significantly induced in root stelar tissues by high B (HB) under salinity. Green fluorescent protein and yeast heterologous expression showed that BnaA2.HKT1 functioned as a plasma membrane-localized Na+ transporter. Knockout of BnaA2.HKT1 by CRISPR/Cas9 resulted in hypersensitive of rapeseed plants to salinity even under HB condition, with higher shoot Na+ accumulation and lower biomass production. By contrast, overexpression of BnaA2.HKT1 ameliorated salinity-induced growth inhibition under B deficiency and salinity. Overall, our results proposed that B functioned as a positive regulator for the rapeseed growth and seed production under salt stress through facilitating BnaA2.HKT1-mediated root xylem Na+ unloading. This study may also provide an alternative strategy for the improvement of crop growth and development in saline soils.

Isolation and identification of thermophilic cyanobacterium inhabiting Shiv Kund (Sohna hot spring), India through polyphasic approach: Bioprospecting in varying nitrogen environment for biotechnological interest particularly for biofuel potential

Identifying a potential candidate having optimal growth characteristics and high-value biotechnological attributes, especially biofuel profile in the era of high rising renewable energy demands is necessary for a sustainable algal-biorefinery perspective. Thermophilic cyanobacteria are scarcely investigated for their industrial potential. In this regard, a preliminary study was performed to isolate a thermophilic cyanobacterium from Shiv Kund, Sohna hot spring, Gurugram, India. The polyphasic approach with molecular identification through 16SrRNA and phylogenetic analysis identified the isolated thermophilic cyanobacterium as Fischerella thermalis PCC 7521 based on the 99.15 % similarity in the NCBI-BLASTn results. Further, the phenotypic visualization under light microscopy and Scanning Electron Microscope (SEM) confirms the true-branching filamentous nitrogen fixing cyanobacterium. To examine its potential for a biotechnological perspective, the effect of different nitrogen concentrations in the growth medium on the biochemical profiling was studied. The highest biomass production and biomass productivity per day obtained was 1041.6 mg/L and 42.33 ± 1.52 mg/L/d⁎⁎(p < 0.01) in 0.1875 g/L (N/8) and 1.5 g/L (N) sodium nitrate concentration respectively. The effect of the growth phase on the biochemical profiling was also prominent and studying optimization helps in the cost-effective production of the required product. Surprisingly, nitrogen starvation has resulted in the increased production of pigments (chlorophyll, phycocyanin and carotenoids), proteins and lipids. The maximum carbohydrate production observed was under complete nitrogen availability (N) in the growth medium with 37.4 % more production in N than complete nitrogen starvation (N0) on 15th day of the growth cycle. Interestingly, the total lipid production observed was 457.41 ± 18.3 μg/mg ⁎(p ≤ 0.05) in N0 condition and 519.28 ± 21.3 μg/mg ⁎⁎(p < 0.01) in N/8 condition on 15th and 20th day of the growth cycle respectively. The effect of nitrogen concentrations on the C/N ratio and different functional groups were also examined. Overall, the results indicated F. thermalis PCC 7521 is a promising candidate for different biotechnological fields, especially biofuel production.

Enhanced Production of Microalgal Metabolites Through Aeration Coupled with Stirring

Adequate mixing is a key factor for microalgal cultivation to achieve high biomass production, so it is essential to clarify the comparative effects of different mixing methods on microalgal productivity, which has rarely been studied previously. This work therefore aimed to investigate the effects of different mixing methods (stirring, aeration, and aeration coupled with stirring) on the growth and metabolite composition of Chlorella sorokiniana SDEC-18, a strain with potential for large-scale application. The results showed that mixing was beneficial for carbohydrate accumulation, while dual mixing (aeration coupled with stirring) promoted growth and achieved the highest dry mass and metabolite productivities (including carbohydrates, proteins, and lipids) through enhancement of light energy capture in the entire system. The stirring speed in the dual mixing approach of aeration coupled with stirring was also considered: the optimal condition was found to be 800 rpm. The maximum biomass was 3.56 g L−1, and the carbohydrate productivity was as high as 119.45 mg L−1 d−1, which was the highest metabolite productivity (higher than proteins or lipids), obtained from aeration coupled with stirring at 800 rpm. Our study suggests that aeration coupled with stirring provides a feasible strategy for microalgal production, due to the optimal availability of CO2 and light achieved through effective mixing.

Phytoremediation of lead polluted mine soil by synergistic effect of chelating agents and nitrogen in hemp

Industrial hemp is a valuable fibrous plant with high biomass production for it can survive under variable environmental stresses including heavy metals and is used in a wide range of products. This research work aimed at determining the growth potential of industrial hemp (Cannabis sativa) developed on lead (Pb) contaminated mine soils using various chelating agents viz., ethylenediaminedisuccinic acid (EDDS), ethylenediaminetetraacetic acid (EDTA), citric acid (CA) and nitrilotriacetic acid (NTA) under various concentrations of nitrogen (N) fertilizer such as 0 (control), 50, 150, 250 and 350 kg ha−1. Results indicated that the synergistic effect of chelating agents and rising concentrations of N fertilizer resulted in a linear increase in hemp growth and dry biomass. The chelating agent and N mediated showed better response in the photosynthetic, antioxidative, and osmolytic potential of hemp as compared with control. The concentration of N and Pb plants showed a differential response such as N accumulation was maximum in plant leaf and shoot portions as compared to the roots. In contrast, Pb enrichment was higher in the roots than in the plant’s leaves and stems when exposed to varying concentrations of N fertilizer and chelating agents in the soil environment. Biomobilizaiton of Pb in the plant continuum enhanced with the rising N fertilizer levels in the soil. The EDTA showed better phytoextraction potential as compared with the rest of the chelating agents. Hence, findings suggest that the synergistic application of chelating agents and N fertilizer is a far more effective technique that increases the bioavailability of Pb for phytoextraction and decreases Pb-induced oxidative injuries by restricting Pb uptake.

A comparative study of yield components and their trade-off in oilseed crops (Brassica napus L. and Brassica carinata A. Braun)

Canola (Brassica napus L.) and carinata (Brassica carinata A. Braun) are two oilseed crops that have seen a surge in demand in recent years. However, current yields achieved by farmers are inconsistent and significantly lower than those achieved in research experiments. Therefore, a better understanding of the trade-off between yield components is crucial to help breeders develop new high-yielding cultivars and for farmers to manage their crops more effectively. Unfortunately, scientific literature focused on trade-offs between yield components in rapeseed is scarce for canola and lacking for carinata. To address this issue, we conducted field experiments in Uruguay over three consecutive seasons (2016–2018) using the cultivars “Rivette” and “Avanza 641” for canola and carinata, respectively. Our goal was to study yield compensation and determine the comparative performance of canola and carinata across a wide range of sowing dates. Our results showed that carinata yields ranged from 854 kg ha−1 to 7283 kg ha−1, while canola yields ranged from 1152 kg ha−1 to 4489 kg ha−1. Higher biomass production was linked to increased yields in carinata, while an increase in biomass did not necessarily result in higher yields in canola due to a harvest index reduction. Carinata yield was positively correlated with grain number, silique number, and grains per silique. In canola, moderate to large yield changes were primarily influenced by grain number and grain weight, as silique number had a negative trade-off with yield, while grains per silique had a neutral relationship with yield. Our study revealed a distinct yield building process in canola and carinata, despite the general belief that they share physiological similarities and can be managed alike. These findings enhance our understanding of crop knowledge and management, potentially leading to increased crop productivity, and generate more effective breeding programs. Enhancing the yield performance of canola and carinata will position them as economically profitable crops, allowing for greater crop diversification and meeting the growing global demand for biofuels.

Current Scenario and Global Perspective of Sustainable Algal Biofuel Production.

Industrialization and globalization have increased the demand for petroleum products that has increased a load on natural energy resources. The escalating fossil fuel utilization has resulted in surpassing the Earth's capacity to absorb greenhouse gases, necessitating the exploration of sustainable bioenergy alternatives to mitigate emissions. Biofuels, derived from algae, offer promising solutions to alleviate fossil fuel dependency. Algae, often regarded as third-generation biofuels, present numerous advantages owing to their high biomass production rates. While algae have been utilized for their bioactive compounds, their capability as biomass for the production of biofuel has gained traction among researchers. Various biofuels such as bio-hydrogen, bio-methane, bio-ethanol, bio-oil, and bio-butanol can be derived from algae through diverse processes like fermentation, photolysis, pyrolysis, and transesterification. Despite the enormous commercial potential of algae-derived biofuels, challenges such as high cultivation costs persist. However, leveraging the utilization of algae byproducts could improve economic viability of biofuel production. Moreover, algae derived biofuels offer environmental sustainability, cost-effectiveness, and waste reduction benefits, promising novel opportunities for a more sustainable energy future.

Comparative assessment of Brassica cultivars for genotypic variability in phytoremediation of soil exposed to lead (Pb) contamination.

The soil pollution caused with accretion of pollutant elements like lead (Pb) is the major environmental concern nowadays. Phytoremediation of contaminated soils using Brassica cultivars that act as hyperaccumulator plants for Pb emerges as an important technique for decontamination of Pb spiked soils. Therefore, pot study was carried out to compare the efficiency of three Brassica cultivars and select the most efficient cultivar for phytoremediation of Pb spiked soils. The experimental soil was contaminated with Pb applied @ 0, 125, 250, 500, 750, and 1,000 mg kg-1 soil. Our outcomes reflected that increased rates of Pb pollution in soil from 125 to 1,000 mg kg-1 soil resulted in decline of yield but enhanced the Pb acquisition of all Brassica cultivars. Comparison of cultivars indicated the highest biomass production (16.7 g pot-1), Pb acquisition (4,011.7 μg pot-1), contamination indices i.e., tolerance index (70.6), and bioaccumulation coefficient (17.03) by Brassica juncea produced thereby proving it as the most efficient cultivar for phytoremediation of Pb spiked soil.

Potential of a novel brine-struvite-based growth medium for sustainable biomass and phycocyanin production by Arthrospira platensis.

Nutrient recovery is crucial for sustainability as it helps to recycle valuable resources, reduce environmental pollution, and promote the efficient use of natural materials in various agricultural and industrial processes. The present study investigated the impact of using brine and struvite as sustainable nutrient sources on the growth and c-phycocyanin (C-PC) production by the cyanobacterium Arthrospira platensis. Three modified growth media were compared to the standard SAG-spirul medium under yellow-white light [YLT], and blue-white light [BLT]. In the modified medium BSI, a struvite solution was utilized to replace dipotassium phosphate, while diluted brine was used to replace NaCl and de-ionized H2O. For BSII, struvite and brine were used as in BSI, with elimination of the micronutrient from the solution. In BSIII, no other nutrient sources than bicarbonate-buffer were used in addition to struvite and brine. For each medium, A. platensis was cultivated and incubated under YLT or BLT till the stationary phase. The results showed that the combinations of brine and struvite did not have any significant negative impact on the growth rates in BSIII. However, adding struvite as a phosphorus source boosted C-PC production just as effectively as YLT, with boosting biomass yield, unlike when only BLT was used. In conclusion, the brine/struvite-based media resulted in high biomass productivity with higher C-PC yields, making it an ideal growth medium for commercial sustainable C-PC production.

Enhancement of Mycelial Biomass Production and Bioactive Properties Related to Cosmeceuticals of Calocybe indica (Milky Mushroom) by Optimization of Submerged Culture Conditions

Calocybe indica or milky mushroom grown in submerged culture was investigated as a new source of antioxidants and anti-collagenase substances, and for its ability to inhibit three bacteria that trigger inflammatory acne, Cutibacterium acnes, Staphylococcus epidermidis, and S. aureus. To facilitate C. indica submerged cultivation and achieve high productivity, a three-level four-factor Box-Behnken design was utilized to find the optimal culture conditions for its mycelial biomass production. The model estimated the optimal conditions as 30 °C, a medium pH of 5.9, and incubation for 14 days under static culture, with results verifi ed by validation experiments. The optimal conditions gave mycelial biomass of 7.12 g/L, which is 5-fold higher than the original condition. This statistical method facilitated rapid identification and integration of key factors for C. indica high mycelial biomass production with significantly improved cosmeceutical properties in terms of antioxidant and antibacterial activities against acne-causing bacteria, especially C. acnes at 19-fold and 18-fold, respectively, compared to the original condition. An ethanolic extract derived from C. indica mycelia was nontoxic to human skin keratinocytes (HaCaT). These diverse functionalities indicate that the mycelial extract of C. indica may represent a promising source of bioactive substances for cosmeceutical applications.

Assessing Fire Regimes in the Paraguayan Chaco: Implications for Ecological and Fire Management

This study analyzed the fire regime in the highly diverse Paraguayan Chaco, focusing on different aspects of fire patterns, including spatial (area burned) and temporal (frequency) aspects and magnitude (severity). We focused on fire as it is a natural phenomenon that drives ecosystem change and has significant economic, ecological and social impacts of particular concern in vulnerable ecosystems. Using the K-means clustering technique, we identified four distinct fire regimes in the study region: High (H), Moderately High (MH), Moderately Low (ML) and Low (L). On the one hand, the Dry Chaco predominantly featured Low and Moderately High regimes, characterized by a low fire frequency due to arid conditions. On the other hand, the Humid Chaco was particularly affected by agricultural burning, driven by extensive livestock activity and higher biomass productivity. Finally, in the Pantanal, the variations in fire intensity were influenced by flood pulses and rainfall patterns. Our findings highlight the distinct fire regimes across the Paraguayan Chaco and detail the differences in the regimes. The study’s findings are valuable for developing efficient management strategies that account for fire behaviour during agricultural burning in this poorly studied region.

A "love match" score to compare root exudate attraction and feeding of the plant growth-promoting rhizobacteria Bacillus subtilis, Pseudomonas fluorescens, and Azospirillum brasilense.

The rhizosphere is the zone of soil surrounding plant roots that is directly influenced by root exudates released by the plant, which select soil microorganisms. The resulting rhizosphere microbiota plays a key role in plant health and development by enhancing its nutrition or immune response and protecting it from biotic or abiotic stresses. In particular, plant growth-promoting rhizobacteria (PGPR) are beneficial members of this microbiota that represent a great hope for agroecology, since they could be used as bioinoculants for sustainable crop production. Therefore, it is necessary to decipher the molecular dialog between roots and PGPR in order to promote the establishment of bioinoculants in the rhizosphere, which is required for their beneficial functions. Here, the ability of root exudates from rapeseed (Brassica napus), pea (Pisum sativum), and ryegrass (Lolium perenne) to attract and feed three PGPR (Bacillus subtilis, Pseudomonas fluorescens, and Azospirillum brasilense) was measured and compared, as these responses are directly involved in the establishment of the rhizosphere microbiota. Our results showed that root exudates differentially attracted and fed the three PGPR. For all beneficial bacteria, rapeseed exudates were the most attractive and induced the fastest growth, while pea exudates allowed the highest biomass production. The performance of ryegrass exudates was generally lower, and variable responses were observed between bacteria. In addition, P. fluorescens and A. brasilense appeared to respond more efficiently to root exudates than B. subtilis. Finally, we proposed to evaluate the compatibility of each plant-PGPR couple by assigning them a "love match" score, which reflects the ability of root exudates to enhance bacterial rhizocompetence. Taken together, our results provide new insights into the specific selection of PGPR by the plant through their root exudates and may help to select the most effective exudates to promote bioinoculant establishment in the rhizosphere.

Phenotyping of the nickel metal crop Bornmuellera emarginata for establishing breeding selection criteria

AbstractNickel is a crucial metal widely used in various industrial applications, such as lithium‐ion batteries and stainless‐steel production. The increasing demand for nickel and resource depletion challenges highlight the need for sustainable extraction methods. Agromining employs hyperaccumulator plants to extract nickel from soils that are either contaminated or naturally enriched in nickel. Bornmuellera emarginata is a nickel hyperaccumulator originating from Greece and a promising candidate for nickel agromining. This study aimed to identify suitable genotypes for a successful “domestication” breeding program, focusing on phenotypic traits. Seeds from 35 plants across six wild populations were cultivated under controlled conditions for 7 months to complete a full life cycle. In this period, growth parameters (e.g., plant height (PH), leaf size, and biomass) were determined. Geographically proximate populations displayed greater phenotypic similarity than those from distant locations. Substantial morphological variations, including PH (40–126 cm) and leaf length (6–13 cm), were observed. Nickel concentrations in plants ranged from 290 to 6250 mg kg−1 dry weight, resulting in nickel yields of 10–145 mg/plant. The notable phenotypic differences among genotypes provide a valuable biological resource for initiating a breeding program to enhance overall nickel yield in B. emarginata agromining crops. Selection and breeding efforts should prioritize genotypes with high biomass production and nickel concentrations. This research lays the foundation for targeted breeding to optimize the potential of B. emarginata in nickel agromining.

Productivity and competitive dominance of freshwater filamentous macroalgal cultivars for nutrient bioremediation of primary municipal wastewater

ABSTRACT Algal bioremediation using macroalgae is a promising approach to wastewater treatment. This study compared the productivity and bioremediation performance of the freshwater filamentous algal cultivars; Klebsormidium flaccidum, Oedogonium calcareum, and Oedogonium sp., in primary municipal wastewater in outdoor high-rate filamentous algal pond mesocosms. K. flaccidum had the highest biomass productivity (3.09 g dry weight m−2 day−1 ± 0.20 SE) and bioremediation performance, reducing total ammoniacal-N by 51% to 14.80 mg L−1 (± 0.81 SE), nitrate-N by 59% to 0.30 mg L−1 (± 0.02 SE), and dissolved reactive phosphorous by 15% to 3.52 mg L−1 (± 0.07 SE). This cultivar achieved the greatest reductions in total suspended solids (54%), carbonaceous biochemical oxygen demand (93%), and chemical oxygen demand (74%). K. flaccidum and Oedogonium sp. reduced Escherichia coli by 98%. Competitive dominance of K. flaccidum and Oedogonium sp. was assessed in bicultures at three stocking densities. By day 12, K. flaccidum's proportion increased from 50 to 64% (± 6.1 SE) and 73% (± 5.0 SE) at a stocking density of 0.25 g and 0.5 g FW L−1, respectively. Based on superior biomass productivity, bioremediation performance, and competitive dominance, K. flaccidum was identified as a target cultivar for bioremediation of primary municipal wastewater.

Crop Productivity, Phytochemicals, and Bioactivities of Wild and Grown in Controlled Environment Slender Amaranth (Amaranthus viridis L.)

Amaranthus viridis L. is a wild edible plant that occasionally is cultivated as an alternative crop because of its interest as a functional food and its adaptation to high-saline soils. In this work, leaves from A. viridis were compared with their grown in controlled environment (GCE) counterparts in a soilless system at electrical conductivities (EC) and different light exposures for assessing growth parameters, moisture, total phenolic and total flavonoid content, phenolic compound profiles, vitamin C, antioxidant activity, and antiproliferative activity against the HT–29 human colorectal cancer cell line. The highest biomass production was obtained using EC of 2.5 dS m−1 and the AP67 Milk LED lamp. Vitamin C in wild samples ranged from 83.1 to 104.9 mg 100 g−1 fresh weight (fw), and in GCE ones, it ranged from 112.3 to 236.7 mg 100 g−1 fw. Measured by the DPPH and ABTS assays, the antioxidant activity was higher in wild than in GCE plants: the ranges for wild samples were in the 1.8–4.9 and 2.0–3.9 mmol of Trolox Equivalent (TE) 100 g−1 dry weight (dw) ranges, and for GCE ones in the 1.3–1.9 and 1.5–2.2 mmol TE 100 g−1 dw ranges, respectively. As for phenolic compounds, in wild samples, the range was from 14.65 to 22.70 mg 100 g−1 fw, and these amounts were much higher than those found in their GCE counterparts, in which the range was from 2.58 to 5.95 mg 100 g−1 fw. In wild plants three compounds, namely trans-p-coumaric acid, isorhamnetin-3-O-glucoside, and nicotiflorin, accounted for more than half of the total quantified phenolic compounds. The MTT assay revealed concentration- and time-dependent inhibitory effects on HT–29 cells for all checked extracts. Cancer cells were less influenced by extracts from GCE plants, which showed higher GI50 compared to wild plants. This work improves knowledge on the growth parameters, phytochemical profiles, and biological activities of wild and GCE A. viridis.

Isolation and Selection of Protein-Rich Mutants of Chlorella vulgaris by Fluorescence-Activated Cell Sorting with Enhanced Biostimulant Activity to Germinate Garden Cress Seeds.

Microalgae are a promising feedstock with proven biostimulant activity that is enhanced by their biochemical components (e.g., amino acids and phytohormones), which turns them into an appealing feedstock to reduce the use of fertilisers in agriculture and improve crop productivity and resilience. Thus, this work aimed to isolate protein-rich microalgal mutants with increased biostimulant activity. Random mutagenesis was performed with Chlorella vulgaris, and a selection of protein-rich mutants were sorted through fluorescence-activated cell sorting (FACS), resulting in the isolation of 17 protein-rich mutant strains with protein contents 19-34% higher than that of the wildtype (WT). Furthermore, mutant F4 displayed a 38%, 22% and 62% higher biomass productivity, growth rate and chlorophyll content, respectively. This mutant was then scaled up to a 7 L benchtop reactor to produce biomass and evaluate the biostimulant potential of this novel strain towards garden cress seeds. Compared to water (control), the germination index and the relative total growth increased by 7% and 19%, respectively, after the application of 0.1 g L-1 of this bioproduct, which highlights its biostimulant potential.