Biomass Production Research Articles

Effect of incident light and light gradients on eicosapentaenoic acid distribution between lipid classes in Nannochloropsis oceanica

AbstractCommercial production of eicosapentaenoic acid (EPA) from photoautotrophic microalgae like Nannochloropsis oceanica requires higher productivity and larger scales to reduce costs. Improving productivity can be achieved by increasing biomass concentrations, which creates light gradients in the reactor depending on the culture’s acclimation and the reactor geometry. These light gradients affect physiology, lipid synthesis, but also the distribution of fatty acids between lipid classes. In this study we evaluated the combined effect of the incident light intensity and light gradient on growth, biochemical composition, and fatty acid distribution between lipid classes. A total of 13 cultivations were performed in continuous mode using three different incident light intensities (200, 670, and 1550 μmol photons m−2 s−1) and four dilution rates (from 0.29 to 0.75 day−1). Reducing dilution rates resulted in higher biomass concentrations, steeper light gradients, and lower average light intensities. Increasing incident light intensity improved biomass productivity from 0.5 to 1.8 g L−1 day−1, while the biomass yield on light decreased from 1.05 to 0.44 g mol−1. Lowering average light intensities decreased the triglyceride content from 11.1 to 1.5% w/w, and increased the galactolipid content, mainly monogalactosyldiacylglycerol, up from 3.1 to 5.1% w/w. Total EPA contents did not decrease at low incident light but decreased by 28% at highly saturating light, both relative to medium incident light. The EPA content in polar lipids increased at lower average light intensities, and decreased in the neutral fraction simultaneously. These results highlight the tight regulation of EPA content between lipid polar and neutral fractions under different light regimes. Graphical Abstract

Uncovering novel functions of the enigmatic, abundant, and active Anaerolineae in a salt marsh ecosystem.

Anaerolineae, particularly uncultured representatives, are one of the most abundant microbial groups in coastal salt marshes, dominating the belowground rhizosphere, where over half of plant biomass production occurs. However, this class generally remains poorly understood, particularly in a salt marsh context. Here, novel Anaerolineae metagenome-assembled genomes (MAGs) were generated from the salt marsh rhizosphere representing Anaerolineales, Promineifilales, JAAYZQ01, B4-G1, JAFGEY01, UCB3, and Caldilineales orders. Metagenome and metatranscriptome reads were mapped to annotated MAGs, revealing nearly all Anaerolineae encoded and transcribed genes required for oxidation of carbon compounds ranging from simple sugars to complex polysaccharides, fermentation, and carbon fixation. Furthermore, the majority of Anaerolineae expressed genes involved in anaerobic and aerobic respiration and secondary metabolite production. The data revealed that the belowground salt marsh Anaerolineae in the rhizosphere are important players in carbon cycling, including degradation of simple carbon compounds and more recalcitrant plant material, such as cellulose, using a diversity of electron acceptors and represent an unexplored reservoir of novel secondary metabolites.IMPORTANCEGiven that coastal salt marshes are recognized as biogeochemical hotspots, it is fundamentally important to understand the functional role of the microbiome in this ecosystem. In particular, Anaerolineae are abundant members of the salt marsh rhizosphere and have been identified as core microbes, suggesting they play an important functional role. Yet, little is known about the metabolic pathways encoded and expressed in this abundant salt marsh clade. Using an 'omics-based approach, we determined that Anaerolineae are capable of oxidizing a range of carbon compounds, including simple sugars to complex carbon compounds, while also encoding fermentation and carbon fixation. Surprisingly, Anaerolineae encoded and transcribed genes involved in aerobic respiration, which was unexpected given the reduced nature of the salt marsh rhizosphere. Finally, the majority of Anaerolineae appear to be involved in secondary metabolite production, suggesting that this group represents an unexplored reservoir of novel and important secondary metabolites.

Effect of Light Intensity on Growth and Primary Metabolites Content of <i>Navicula </i>sp.

Global energy demand is steadily rising, necessitating the exploration of sustainable alternatives. Microalgae, such as Navicula sp., offer a promising solution. This study investigated the impact of light intensity on the growth, and biochemical composition (carbohydrates, lipids, proteins, and carotenoids) of Navicula sp. Cultures were grown in f/2 medium under four light intensity treatments: 2100 lux (control), 3500 lux, 4500 lux, and 5500 lux. Cell growth was measured through optical density analysis. Carbohydrate, lipid, protein, and carotenoid assays were performed using phenol-sulfuric acid, Bligh and Dyer, Bradford, and spectrophotometric methods. Maximum growth was observed on the eighth day of cultivation at 4500 lux light intensity. The best specific growth rate was achieved at 5500 lux. The highest biomass, carbohydrate, lipid, and protein productivity were attained at 5500 lux (24.65 mg/mL, 0.374 mg/mL/day, 0.399±0.204 mg/mL/day, and 0.025±0.018 mg/mL/day). Conversely, the highest carotenoid productivity was recorded at 2100 lux, 0.278±0.085 mg/mL/day. By those means, the increase in light intensity was positively correlated with microalgal cell growth, biomass, carbohydrate content, and carbohydrate, lipid, and protein productivity. However, a negative correlation was found with carotenoid pigment productivity. From this research, it is evident that a light intensity of 5500 lux offers a feasible option for the industrial-scale cultivation of Navicula sp. microalgae for biomass, carbohydrate, and protein production, while 2100 lux is more suitable for carotenoid production. This research compares the findings to previous studies, emphasizing the unique way Navicula sp. responds to different light levels.

Experimental analysis of genetic and environmental interactions on leaf elongation and reproductive development in Lolium perenne

Abstract Background and Aims Perennial grasses’ reproductive phenology profoundly impacts plant morphogenesis, biomass production and perenniality in natural ecosystems and cultivated grasslands. Complex interactions between vegetative and reproductive development complicate grass phenology prediction for various environments and genotypes. This work aims to analyse genetic x environment interactions effects on tiller growth and reproductive development in Lolium perenne. Methods Three perennial ryegrass cultivars, Bronsyn, Carvalis and Tryskal, were grown from seedling to heading under four inductive conditions. T0 plants were continuously exposed to high temperatures and long days (HT–LD). T1, T2 and T3, plants were initially exposed to low temperatures and short days (LT-SD) for 9 weeks. Then, T1 plants were immediately transferred to high temperature and long days (HT–LD). Before their exposure to HT–LD, T2 and T3 plants were first transferred to high temperature and short days (HT–SD) for 3 and 6 weeks, respectively. Leaf length, leaf emergence and heading were regularly monitored. Key Results Floral transition and heading only occurred in T1, T2 and T3, i.e. after successive exposure to low temperature and long photoperiod. Bronsyn had higher heading earliness and proportion of reproductive tillers than Carvalis and Tryskal. The duration of HT–SD exposure affected the final number of leaves and spikelet. The rate of leaf and spikelets production significantly increased once plants were exposed to LD. Our results suggest an additive effect of the photoperiod and floral transition on leaf elongation rate. Conclusions These findings enhance our understanding of the genetic x environment interactions on the vegetative and reproductive development in perennial ryegrass.

Growing in red: impact of different light spectra and lighting conditions on lentil microgreens growth in vertical farming

Vertical Farming Systems (VFS) emerge as an approach to optimize plant growth in urban and controlled environments, by enabling sustainable and intensive production in reduced spaces. VFS allow for greater control over growing conditions, such as light, temperature and humidity, resulting in higher quality crops and with less use of resources, such as water and fertilizers. This research investigates the effects of different lighting regimes (Constant and Gaussian) and spectral qualities (white, RBW, blue and red) on the growth, photosynthesis, and biomass accumulation of lentil microgreens (Lens culinaris) in VFS. The results demonstrate that constant lighting regimes, particularly under red, white, and RBW lights, significantly increase biomass production and energy efficiency. On the other hand, the Gaussian regime promotes the accumulation of bioactive compounds such as carotenoids, especially under red light. Chlorophyll content and the photochemical coefficient (qP) also varied across treatments, with significant variations between lighting regimes and spectral combinations. Tailored lighting strategies, adjusted to specific production goals, have the potential to enhance both productivity and nutritional quality in VFS. The analysis contained in the research provides relevant information for optimizing lighting management in controlled agricultural environments, providing practical applications to improve harvest performance.

Nannochloris sp. JB17 as a Potential Microalga for Carbon Capture and Utilization Bio-Systems: Growth and Biochemical Composition Under High Bicarbonate Concentrations in Fresh and Sea Water.

Nannochloris sp. JB17 has been identified as an interesting microalgal species that can tolerate high salinity and high bicarbonate concentrations. In this study, Nannochloris sp. JB17 was long-term adapted to increased bicarbonate concentrations (10-60 g NaHCO3 per L) in fresh or sea-water-based growing media. This study aimed to evaluate its growth performance and biochemical composition under different cultivation conditions. The highest biomass production (1.24-1.3 g/L) achieved in the study was obtained in fresh water media supplemented with 40 g/L and 60 g/L NaHCO3, respectively. Total protein content fluctuated at similar levels among the different treatments (32.4-38.5%), displaying good essential amino acids indices of 0.85-1.02, but with low in vitro protein digestibility (15-20%) rates. Total lipids did not show any significant alteration among the different NaHCO3 concentrations in both fresh and sea water (12.6-13.3%) but at increased sodium strength, a significant increase in unsaturated lipids and in particular a-linolenic acid (C18:3) and linoleic acid (C18:2) was observed. Carbohydrate content also ranged at very similar levels among the cultures (26-30.9%). The main fraction of carbohydrates was in the type of neutral sugars ranging from around 72% to 80% (of total carbohydrates), while uronic acids were in negligible amounts. Moreover, Nannochloris sp. showed that it contained around 8-9% sulfated polysaccharides. Since the microalgae display good growth patterns at high bicarbonate concentrations, they could be a potential species for microalgal-based carbon capture and utilization systems.

EFFECT OF LOCALLY ISOLATED <i>SCENEDESMUS</i> SP. TN1 ON BIOMASS PRODUCTION AND NUTRIENT REMOVAL FROM COOKING COCOON WASTEWATER: EFFECTS OF INITIAL ALGAL CELL DENSITY AND TEMPERATURE

Scenedesmus sp. TN1, a local freshwater microalga, was cultivated in cooking cocoon wastewater. The effects of initial algal cell density and temperature on microalgae growth and the removal of total nitrogen (T-N), total phosphorus (T-P), and chemical oxygen demand (COD) were studied. The initial algal cell densities were 5, 10, 15, and 20 mg/l. The experimental temperatures varied from 20 °C to 30 °C. The growth rate increased with the increase in initial algal cell density up to 15 mg/l and was statistically stable thereafter. A similar trend of total nitrogen, total phosphorus, and COD removal efficiency was observed. The optimum temperature for microalgae growth and nutrient removal was 30 °C. After 9 days of cultivation, Scenedesmus sp. TN1 exhibited nutrient removal efficiencies of 88.28%, 82.91%, 92.01%, and 89.16% for T-N, T-P, biological oxygen demand (BOD5), and COD, respectively. The maximum biomass production and nutrient removal efficiencies of Scenedesmus sp. TN1 were observed at cultivation conditions of 15 mg/l initial algal cell density at 30 °C. This study compiled information on the cultivation conditions for cooking cocoon wastewater treatment practices.

Yield Responses to Total Water Input from Irrigation and Rainfall in Six Wheat Cultivars Under Different Climatic Zones in Egypt

In Egypt, wheat is the most consumed cereal grain, and its availability and affordability are important for social stability. Irrigation plays a vital role in wheat cultivation, despite intense competition for water resources from the River Nile across various societal sectors. To explore how grain and above-ground biomass yields respond to total seasonal water input from sowing to maturity in six bread wheat cultivars, eight field irrigation experiments were performed at four locations representative of three agro-climatic zones in two consecutive cropping seasons. A three-replicate strip-plot design was used with cultivars nested within the main plots featuring five irrigation treatments, ranging from six to two applications. Overall, irrigation treatment significantly affected nine agronomic traits. Compared with the six irrigation applications treatment (T1), the two irrigation applications treatment (T5) decreased the times to heading and maturity by 6.6 (7.3%) and 8.6 (6.3%) days, respectively. Similarly, T5 reduced the plant height by 14.9 cm (14.3%), flag leaf area by 12.0 cm2 (27.2%), number of spikes per square metre by 77.7 (20.1%), number of kernels per spike by 13.9 (25.2%) and thousand grain weight by 10.0 g (19.6%). T5 also decreased the overall mean grain yield and above-ground biomass yield by 2834.9 (32.0%) and 7910.4 (32.86%) kg/ha, respectively. The grain yield and above-ground biomass production were consistently greater for all six cultivars at Al Mataenah and Sids than at Nubaria and Ismailia in the two cropping seasons. All six cultivars showed significantly greater responses to total seasonal water input for the grain yield and above-ground biomass at Al Mataenah and Ismailia. These results emphasise the necessity for choosing regions with favourable soil and climatic conditions to grow wheat cultivars that respond better to irrigation to enhance the large-scale production of wheat in Egypt. The grain and above-ground biomass yields were mostly linearly and positively associated with the total seasonal water input for all six cultivars at all four locations. This suggests that maintaining the current irrigation schedule of six irrigations is valid and should be practised to maximise productivity, particularly in areas similar to the three representative agro-climatic zones in Egypt.

Lipid production from biofilms of Marinobacter atlanticus in a fixed bed bioreactor

BackgroundBiotechnologies that utilize microorganisms as production hosts for lipid synthesis will enable an efficient and sustainable solution to produce lipids, decreasing reliance on traditional routes for production (either petrochemical or plant-derived) and supporting a circular bioeconomy. To realize this goal, continuous biomanufacturing processes must be developed to maximize productivity and minimize costs compared to traditional batch fermentation processes.ResultsHere, we utilized biofilms of the marine bacterium, Marinobacter atlanticus, to produce wax esters from succinate (i.e., a non-sugar feedstock) to determine its potential to serve as a production chassis in a continuous flow, biofilm-based biomanufacturing process. To accomplish this, we evaluated growth as a function of protein concentration and wax ester production from M. atlanticus biofilms in a continuously operated 3-D printed fixed bed bioreactor. We determined that exposing M. atlanticus biofilms to alternating nitrogen-rich (1.8 mM NH4+) and nitrogen-poor (0 mM NH4+) conditions in the bioreactor resulted in wax ester production (26 ± 5 mg/L, normalized to reactor volume) at a similar concentration to what is observed from planktonic M. atlanticus cells grown in shake flasks previously in our lab (ca. 25 mg/L cell culture). The wax ester profile was predominated by multiple compounds with 32 carbon chain length (C32; 50–60% of the total). Biomass production in the reactor was positively correlated with dilution rate, as indicated by protein concentration (maximum of 1380 ± 110 mg/L at 0.4 min−1 dilution rate) and oxygen uptake rate (maximum of 4 mmol O2/L/h at 0.4 min−1 dilution rate) measurements at different flow rates. Further, we determined the baseline succinate consumption rate for M. atlanticus biofilms to be 0.16 ± 0.03 mmol/L/h, which indicated that oxygen is the limiting reactant in the process.ConclusionThe results presented here are the first step toward demonstrating that M. atlanticus biofilms can be used as the basis for development of a continuous flow wax ester biomanufacturing process from non-sugar feedstocks, which will further enable sustainable lipid production in a future circular bioeconomy

Microalgae bioprospecting for the food industry: insights into the autotrophic biomass production and macromolecular accumulation of four microalgal species.

In this study, four microalgal strains were evaluated for their biomass production capacity and macromolecule biosynthesis. These include three strains from the phylum Chlorophyta: Monoraphidium sp. LB2PC 0120, Stichococcus sp. LB2PC 0117, and Tetraselmis sp. LB2PC 0320, and one strain from the phylum Haptophyta: Isochrysis sp. LB2PC 0220. The experiments were conducted under typical laboratory-scale setups. Additionally, phylogenetic analysis based on the 18-28S rRNA internal transcribed spacer (ITS) was performed to validate the taxonomic identity of the strains. Each strain was exposed to four different cultivation conditions based on two levels of illumination intensity [25-(LI) and 50-(HI) µmol m- 2 s- 1] and nitrogen loading [100-(LΝ) and 300-(HΝ) mg NaNO3 L- 1] in a full factorial design. All the microalgae achieved maximum biomass production under HI-HN conditions, which amounted to 1495, 919, 844, and 708mg/L for Monoraphidium sp. LB2PC 0120, Stichococcus sp. LB2PC 0117, Tetraselmis sp. LB2PC 0320 and Isochrysis sp. LB2PC 0220, respectively, after 16 days of cultivation. Among them, Stichococcus sp. LB2PC 0117 had the highest protein content (49.9% wt.) under LI-HN conditions and Monoraphidium sp. LB2PC 0120 had the highest lipid content (44.3% wt.) under HI-LN conditions. Both Monoraphidium sp. LB2PC 0120 and Tetraselmis sp. LB2PC 0320 accumulated the highest carbohydrate content (~ 37% wt.) under LI-LN and HI-LN conditions, respectively. Based on biomass and macromolecule production, Monoraphidium sp. LB2PC 0120 was identified as the most promising candidate for upscaling studies, expecting its highly manipulatable compositional profile to support multiple applications in the food industry, rendering this microalga a valuable resource.

Good practices for the industrial cultivation of the cyanobacterium Arthrospira platensis under a greenhouse in a temperate zone (northern Italy)

Arthrospira, Spirulina, and Limnospira are cyanobacteria widely known as food supplements or additives and cultivated worldwide under the commercial name of spirulina. Many studies have been focused on the improvement of operational conditions for optimizing cell growth and harvesting. At present, greater attention is paid to obtaining a good-quality, possibly food-grade, product that can be added to different food formulations and to reducing the environmental impact by saving water and avoiding or minimizing the release of mineral salts in the environment. A few studies have addressed these aspects although, in most cases, through laboratory experiments or pilot plants. This study focused on the effects of medium recycling, monitored at each harvesting step, and nutrient replenishment on Arthrospira platensis growth, biomass, biochemical composition, and extracellular polysaccharide (EPS) production, in a production plant located in a temperate zone (northeastern Italy). Four out of the seven largest ponds (11,000 L each) of the plant were followed for a three-month semi-continuous cultivation, which included the period with the highest biomass productivity. Recycling the culture medium after biomass harvest effectively allowed the best nutritional status of the cells. Biomass productivity increased from June to August 2023 (mean values: 0.029 and 0.038 g L-1 d-1 at 25–26 °C and 27–29 °C, respectively). Protein, polysaccharides, and C-phycocyanin contents were 62, 22, and 12%, respectively, while EPS was < 7 mg L-1. The biochemical composition did not vary during the cultivation period, differently from previous studies performed with small culture volumes and for a short time.

Comparative Analysis of the Biochemical and Molecular Responses of Nannochloropsis gaditana to Nitrogen and Phosphorus Limitation: Phosphorus Limitation Enhances Carotenogenesis.

Nannochloropsis gaditana is well known for its potential for biofuel production due to its high lipid content. Numerous omics and biochemical studies have explored the overall molecular mechanisms underlying the responses of Nannochloropsis sp. to nutrient availability, primarily focusing on lipid metabolism. However, N. gaditana is able to synthesize other valuable products such as carotenoids, including violaxanthin, which has various biological functions and applications. In this study, we comparatively investigated the physiological, biochemical, and molecular responses of N. gaditana to nitrogen and phosphorus limitation, examining biomass production, photosynthetic activity, lipid, chlorophyll, and carotenoids content, and RNA-seq data. Nitrogen limitation decreased photosynthetic activity, chlorophyll content, and biomass production but increased lipid content. Phosphorus limitation substantially increased carotenoids content, with violaxanthin productivity of 10.24 mg/L, 3.38-fold greater than under the control condition, with little effect on biomass production or photosynthetic function. These results were generally consistent with the gene expression pattern observed in transcriptomic analysis. This integrated analysis shows that phosphorus limitation can be an economically competitive solution by enhancing valuable carotenoids while maintaining lipid and biomass production in N. gaditana.

Advances in Biomass and Microbial Lipids Production: Trends and Prospects

Biotechnology is increasingly being used as a tool to replace traditional production methods due to concerns about the increasing damage caused by global warming. Bacteria, yeasts, fungi, and microalgae are microorganisms able to transform residues into value-added bioproducts. They produce microbial biomass that can result in the production of several products, such as biofuels, microbial proteins, fatty acids, bioactive polysaccharides, carotenoids, industrial enzymes, polyhydroxyalkanoates, and biofertilizers, among others. To improve microbial biomass and lipid yield, modern genetic engineering techniques can be applied as a way of optimizing processes and conditions. This review aims to explore the latest trends and technological advances in microbial biomass and lipid production, including optimization strategies for cultivation conditions and the use of genetic engineering to enhance yields and efficiency. It also discusses the challenges and future prospects for scaling up production for industrial applications. The potential of microbial lipids to contribute to a sustainable bioeconomy, as well as their applications in renewable energy and food industries, underscores their importance in a world increasingly seeking alternatives to fossil fuel dependence and unsustainable agricultural practices.

Assessing the Sustainability of Miscanthus and Willow as Global Bioenergy Crops: Current and Future Climate Conditions (Part 1)

Miscanthus (Miscanthus × giganteus) and Willow (Salix spp.) are promising bioenergy crops due to their high biomass yields and adaptability to diverse climatic conditions. This study applies the MiscanFor/SalixFor models to assess the sustainability of these crops under current and future climate scenarios, focusing on biomass productivity, carbon intensity (CI), and energy use efficiency (EUE). Under present conditions, both crops show high productivity in tropical and subtropical regions, with Miscanthus generally outperforming Willow. Productivity declines in less favourable climates, emphasising the crops’ sensitivity to environmental factors at the regional scale. The average productivity for Miscanthus and Willow was 19.9 t/ha and 10.4 t/ha, respectively. Future climate scenarios (A1F1, representing world markets and fossil-fuel-intensive, and B1, representing global sustainability) project significant shifts, with northern and central regions becoming more viable for cultivation due to warmer temperatures and extended growing seasons. However, southern and arid regions may experience reduced productivity, reflecting the uneven impacts of climate change. Miscanthus and Willow are predicted to show productivity declines of 15% and 8% and 12% and 7% under A1F1 and B1, respectively. CI analysis reveals substantial spatial variability, with higher values in industrialised and temperate regions due to intensive agricultural practices. Future scenarios indicate increased CI in northern latitudes due to intensified land use, while certain Southern Hemisphere regions may stabilise or reduce CI through mitigation strategies. Under climate change, CI for Miscanthus is projected to increase by over 100%, while Willow shows an increase of 64% and 57% for A1F1 and B1, respectively. EUE patterns suggest that both crops perform optimally in tropical and subtropical climates. Miscanthus shows a slight advantage in EUE, though Willow demonstrates greater adaptability in temperate regions. Climate change is expected to reduce EUE for Miscanthus by 10% and 7% and for Willow by 9% and 6%. This study underscores the need for region-specific strategies to optimise the sustainability of bioenergy crops under changing climate conditions.

RITA® Temporary Immersion System (TIS) for Biomass Growth Improvement and Ex Situ Conservation of Viola ucriana Erben & Raimondo.

Viola ucriana Erben & Raimondo is a rare and endangered taxon, endemic to a limited area on Mount Pizzuta in northwestern Sicily, Italy. Its population is significantly threatened by anthropogenic activities, including fires, overgrazing, and habitat alterations. Temporary immersion systems (TISs) have proven effective for large-scale propagation in various protected species, offering potential for ex situ conservation and population reinforcement of V. ucriana. This study aimed to establish a bioreactor-based micropropagation protocol for shoot multiplication and compare the efficacy of a TIS with that of conventional solid culture medium (SCM). Three different plant growth regulators (PGRs) were also compared: 6-benzylaminopurine (BA), zeatin, and meta-topolin-9-riboside (mTR). The starting material originated from seeds collected from mother plants in their natural environment. The best growth outcomes (in terms of shoot multiplication, shoot length, and relative growth rate) were achieved using THE RITA® TIS, with BA (0.2 mg/L) and mTR (0.5 or 0.8 mg/L) outperforming SCM. Anomalous or hyperhydric shoots were observed with all zeatin treatments (especially with 0.8 mg/L) in both the TIS and SCM, suggesting that this cytokinin is unsuitable for V. ucriana biomass production. The rooting phase was significantly improved by transferring propagules onto rockwool cubes fertilized with Hoagland solution. This approach yielded more robust roots in terms of number and length compared to the conventional agar-based medium supplemented with indole-3-butyric acid (IBA). Flow cytometry analysis confirmed the genetic fidelity of the regenerants from the optimal PGR treatments, showing that all plantlets maintained the diploid ploidy level of their maternal plants. Over 90% of the in vitro derived plantlets were successfully acclimatized to greenhouse conditions. This paper represents the first report of V. ucriana biomass multiplication using a RITA® bioreactor. The stability of the regenerants, confirmed by nuclei quantification via cytofluorimetry, provides guidance in establishing a true-to-type ex situ population, supporting conservation and future reinforcement efforts.

Survival of 13 Forage Legumes in Contrasting Environments of Central Otago, New Zealand

ABSTRACTThe lack of suitable perennial and annual forage legumes strongly constrains the productivity and sustainability of upland grasslands in New Zealand. Legumes support sustainable grassland production through nitrogen fixation and increased yields. However, traditional legume species such as white clover (Trifolium repens L.) struggle to persist within New Zealand's upland climatic and edaphic conditions characterised by acid, low fertility soils and short growing seasons. To address this challenge, we assessed the survival of 13 forage legume species over 2 years at three field sites across Central Otago, capturing the districts varied precipitation and temperature profiles. Legume survival rates, biomass and weather data were measured. Notably, lotus (Lotus pedunculatus Cav.) exhibited 100% survival over the 2 years on high altitude acidic, low fertility soils, whereas other perennial legume species showed limited persistence (0%–55% survival) and low biomass production. Crimson clover (Trifolium incarnatum L.) had the greatest Year 1 establishment and biomass of annual legumes species at low and medium rainfall sites. Moreover, strong Year 1 seed set and subsequent regeneration in Year 2 were observed for crimson clover, striated clover (Trifolium striatum L.), and subterranean clover (Trifolium subterraneum L.) (cvs. Denmark and Narrikup). These findings underscore the potential of these annual legume species in dryland environments due to their regeneration capacity before summer drought onset. Climate emerged as a pivotal determinant influencing the viability of less resilient species across all trial locations. Lotus and crimson clover are alternative legume species with the potential to enhance sustainable grassland productivity in New Zealand's upland farming systems.

Thriving in salty environments: Aspergillus niger's halotolerance and BTEX biodegradation potential.

Benzene, toluene, ethylbenzene, and xylene (BTEX) can be found in marine and estuarine waters due to accidental spills of oil and derivatives, as well as in production water and effluents discharged from petrochemical plants. Addressing the bioremediation of these compounds in saline environments and effluents with elevated salinity levels is imperative. In this study, the halotolerance of Aspergillus niger was assessed by subjecting it to a stepwise increase in salinity, achieved through progressive addition of NaCl from 2 to 30‰ (v/v). The fungal strain exhibited optimal growth support up to a salinity concentration of 25‰, accompanied by a biomass production rate of (0.93 ± 0.11) g.d-1. The adapted biomass was employed in batch reactors to evaluate the biodegradation of BTEX (1,500 mg.L-1). In the absence of sucrose, the reactors inoculated with fungi demonstrated almost complete BTEX removal within 7 days, with rates ranked as follows: benzene (1.12 d-1) > toluene (0.78 d-1) > ethylbenzene (0.65 d-1) > xylene (0.63 d-1). Enhanced BTEX removal rates were obtained in the presence of sucrose, notably with 2g.L-1: benzene (3.63 d-1) > toluene (2.10 d-1) > ethylbenzene (1.56 d-1) > xylene (1.50 d-1). Notably, benzene was found to be the sole compound adsorbed onto the fungal mycelium (1.50 ± 0.19) to (13.35 ± 4.72) mg.g-1 of biomass.

Biosynthesis of Bacteriochlorophylls and Bacteriochlorophyllides in Escherichia coli.

Photosynthesis, the most important biological process on Earth, converts light energy into chemical energy with essential pigments like chlorophylls and bacteriochlorophylls. The ability to reconstruct photosynthesis in heterotrophic organisms could significantly impact solar energy utilization and biomass production. In this study, we focused on constructing light-dependent biosynthesis pathways for bacteriochlorophyll (BChl) a and bacteriochlorophyllide (BChlide) d and c in the model strain Escherichia coli. The production of the starting compound, Mg protoporphyrin monomethylester, was optimized by screening the ribosome binding sites for the expression of each of the five genes. By fusing a maltose-binding protein and apolipoprotein A-I domain with the membrane protein BchF, the yield of 3-hydroxyethyl-Chlide a was increased by five-fold. Anaerobic cultivation of the engineered E. coli strains facilitated the reduction of the C7=C8 double bond by chlorophyllide a oxidoreductase, a critical step in BChl a synthesis. We further enhanced BChl a production by adjusting the isopropyl-β-d-thiogalactopyranoside concentration to optimize enzyme production and introducing an exogenous superoxide dismutase to combat oxidative stress. Additionally, fusing BciC with a RIAD tag resulted in an eight-fold increase in the production of 3-vinyl BChlide d. This study lays the foundation for the reconstitution of BChl-based photosynthetic apparatus in heterotrophic model organisms, offering promising avenues for future research and applications in biotechnology.

Evaluation of Vermicompost, Seaweed, and Algal Fertilizers on Soil Fertility and Plant Production of Sunn Hemp

Regenerative agriculture increasingly relies on organic soil amendments to improve soil fertility and crop productivity. This study evaluates the effects of dried algae (DA), vermicompost (VC), liquid hydrolyzed fish and seaweed fertilizer (LA), and a control (S0, untreated soil without amendments) on the soil fertility, growth, nutrient uptake, and physiology of sunn hemp (Crotalaria juncea L.), a key cover crop for soil improvement. Treatments were applied at 1 ton/ha (DA), 3 ton/ha (VC), and 8 mL/L (LA). Plants were grown for 10 weeks, during which plant growth, chlorophyll content, and biomass were measured. Soil and plant samples were analyzed for macro- and micronutrients. S0 and DA treatments produced the highest biomass, with S0 showing the highest total carbon and organic matter content. LA-treated soils exhibited elevated phosphorus, potassium, and sodium levels, while DA and S0 shoots had significantly higher sulfur and zinc concentrations. LA treatment notably increased chlorophyll content by the study’s end. Overall, DA demonstrated strong potential as a nutrient-rich organic amendment, while S0 provided a robust baseline for biomass production. VC enriched phosphorus and potassium but resulted in the lowest total biomass. LA promoted shoot growth and chlorophyll content but required root development and sodium management optimization. These findings highlight the need to align the amendment choice with soil characteristics and environmental conditions to optimize crop productivity and soil health in sustainable farming systems.

Identification of a drought stress response module in tomato plants commonly induced by fungal endophytes that confer increased drought tolerance

Global climate change exacerbates abiotic stresses, as drought, heat, and salt stresses are anticipated to increase significantly in the coming years. Plants coexist with a diverse range of microorganisms. Multiple inter-organismic relationships are known to confer benefits to plants, including growth promotion and enhanced tolerance to abiotic stresses. In this study, we investigated the mutualistic interactions between three fungal endophytes originally isolated from distinct arid environments and an agronomically relevant crop, Solanum lycopersicum. We demonstrated a significant increase in shoot biomass under drought conditions in co-cultivation with Penicillium chrysogenum isolated from Antarctica, Penicillium minioluteum isolated from the Atacama Desert, Chile, and Serendipita indica isolated from the Thar Desert, India. To elucidate plant gene modules commonly induced by the different endophytes that could explain the observed drought tolerance effect in tomato, a comprehensive transcriptomics analysis was conducted. This analysis led to the identification of a shared gene module in the fungus-infected tomato plants. Within this module, gene network analysis enabled us to identify genes related to abscisic acid (ABA) signaling, ABA transport, auxin signaling, ion homeostasis, proline biosynthesis, and jasmonic acid signaling, providing insights into the molecular basis of drought tolerance commonly mediated by fungal endophytes. Our findings highlight a conserved response in the mutualistic interactions between endophytic fungi isolated from unrelated environments and tomato roots, resulting in improved shoot biomass production under drought stress.