Maximum Biomass Research Articles

Maximizing Polysaccharides and Phycoerythrin in Porphyridium purpureum via the Addition of Exogenous Compounds: A Response-Surface-Methodology Approach.

Phycoerythrin and polysaccharides have significant commercial value in medicine, cosmetics, and food industries due to their excellent bioactive functions. To maximize the production of biomass, phycoerythrin, and polysaccharides in Porphyridium purpureum, culture media were supplemented with calcium gluconate (CG), magnesium gluconate (MG) and polypeptides (BT), and their optimal amounts were determined using the response surface methodology (RSM) based on three single-factor experiments. The optimal concentrations of CG, MG, and BT were determined to be 4, 12, and 2 g L-1, respectively. The RSM-based models indicated that biomass and phycoerythrin production were significantly affected only by MG and BT, respectively. However, polysaccharide production was significantly affected by the interactions between CG and BT and those between MG and BT, with no significant effect from BT alone. Using the optimized culture conditions, the maximum biomass (5.97 g L-1), phycoerythrin (102.95 mg L-1), and polysaccharide (1.42 g L-1) concentrations met and even surpassed the model-predicted maximums. After optimization, biomass, phycoerythrin, and polysaccharides concentrations increased by 132.3%, 27.97%, and 136.67%, respectively, compared to the control. Overall, this study establishes a strong foundation for the highly efficient production of phycoerythrin and polysaccharides using P. purpureum.

Development of symmetric monounsaturated triacylglycerols by Rhodosporidium toruloides cell factory for cocoa butter equivalent

AbstractIn the present study, various factors including carbon source, nitrogen source, Mg2+, and pH value were investigated to determine the optimal conditions for producing cocoa butter equivalent using R. toruloides. The maximum of biomass, lipid content, and lipid production were achieved at levels of 7.8 g/L, 61.0%, and 4.4 g/L, respectively. The oil from R. toruloides mainly consisted of 16:0, 18:0, and 18:1 with 18:1 dominating at the sn‐2 position, which was further confirmed by 13C NMR analysis. UPLC‐MS analysis showed that the sum of sn‐POP, sn‐POS, and sn‐SOS accounted for up to 27.11% in the triacylglycerol species of the oil produced, which allows those triacylglycerols to be further separated and isolated from other triacylglycerols and used for cocoa butter equivalent. Notably, the production of cocoa butter equivalent reached 1.13 g/L, demonstrating the scientific feasibility of producing CBE through fermentation. These findings indicate a promising future for the fermentation‐based production of cocoa butter equivalent.

Variability in the relationship between light scattering and chlorophyll a concentration in oligotrophic tropical regions of the Western Pacific Ocean.

It is important to determine the relationship between the concentration of chlorophyll a (Chla) and the inherent optical properties (IOPs) of ocean water to develop optical models and algorithms that characterize the biogeochemical properties and estimate biological pumping and carbon flux in this environment. However, previous studies reported relatively large variations in the particulate backscattering coefficient (bbp(λ)) and Chla from more eutrophic high-latitude waters to clear oligotrophic waters, especially in oligotrophic oceanic areas where these two variables have little covariation. In this study, we examined the variability of bbp(λ) and Chla in the euphotic layer in oligotrophic areas of the tropical Western Pacific Ocean and determined the sources of these variations by reassessment of in-situ measurements and the biogeochemical-argo (BGC-Argo) database. Our findings identified covariation of bbp(λ) and Chla in the water column below the deep Chla maximum (DCM) layer, and indicated that there was no significant correlation relationship between bbp(λ) and Chla in the upper layer of the DCM. Particles smaller than 3.2 µm that were in the water column above the DCM layer had a large effect on the bbp(λ) in the vertical profile, but particles larger than 3.2 µm and smaller than 10 µm had the largest effect on the bbp(λ) in the water column below the DCM layer. The contribution of non-algal particles (NAPs) to backscattering is up to 50%, which occurs in the water depth of 50 m and not consistent with the distribution of Chla. Phytoplankton and NAPs were modeled as coated spheres and homogeneous spherical particles to simulate the bbp(λ) of the vertical profile by Aden-Kerker method and Mie theory, and the results also indicated that the backscattering caused by particles less than 20 µm were closer to the measured data when they were below and above the DCM layer, respectively. This relationship also reflects the bbp(λ) of particles in the upper water was significantly affected particle size, but bbp(λ) in the lower water was significantly affected by Chla concentration. This effect may have relationship with phytoplankton photoacclimation and the relationship of a phytoplankton biomass maximum with particle size distribution in the water column according to the previous relevant studies. These characteristics also had spatial and seasonal variations due to changes of Chla concentration at the surface and at different depths. There was mostly a linear relationship between Chla and bbp(700) during winter. During other seasons, the relationship between these two variables was better characterized by a power function (or a logarithmic function) in the lower layer of the DCM. The spatial and vertical relationships between the bbp(λ) and Chla and the corresponding variations in the types of particles described in this study provide parameters that can be used for accurate estimation of regional geochemical processes.

Reforming CO2 bio-mitigation utilizing Bacillus cereus from hypersaline realms in pilot-scale bubble column bioreactor.

The bubble column reactor of 10 and 20L capacity was designed to bio-mitigate 10% CO2 (g) with 90% air utilizing thermophilic bacteria (Bacillus cereus SSLMC2). The maximum biomass yield during the growth phase was obtained as 9.14 and 10.78gL-1 for 10 and 20L capacity, respectively. The maximum removal efficiency for CO2 (g) was obtained as 56% and 85% for the 10 and 20L reactors, respectively. The FT-IR and GC-MS examination of the extracellular and intracellular samples identified value-added products such as carboxylic acid, fatty alcohols, and hydrocarbons produced during the process. The total carbon balance for CO2 utilization in different forms confirmed that B. cereus SSLMC2 utilized 1646.54g C in 10L and 1587g of C in 20L reactor out of 1696.13g of total carbon feed. The techno-economic assessment established that the capital investment required was $286.21 and $289.08 per reactor run of 11days and $0.167 and $0.187 per gram of carbon treated for 10 and 20L reactors, respectively. The possible mechanism pathways for bio-mitigating CO2 (g) by B. cereus SSLMC2 were also presented utilizing the energy reactions. Hence, the work presents the novelty of utilizing thermophilic bacteria and a bubble column bioreactor for CO2 (g) bio-mitigation.

Mechanistic insights into chemical conditioning on transformation of dissolved organic matter and plant biostimulants production during sludge aerobic composting

Inorganic coagulants (aluminum and iron salt) are widely used to improve sludge dewaterability, resulting in numerous residues in dewatered sludge. Composting refers to the controlled microbial process that converts organic wastes into fertilizer, and coagulant residues in dewatered sludge can affect subsequent compost efficiency and resource recycling, which remains unclear. This work investigated the effects of two typical metal salt coagulants (poly aluminum chloride [PAC] and poly ferric sulfate [PFS]) conditioning on sludge compost. Our results revealed that PAC conditioning inhibited composting with decreased peak temperature, microbial richness, enzymatic reaction intensities, and compost quality, associated with decreased pH and microbial toxicity of aluminum. Nevertheless, PFS conditioning selectively enriched Pseudoxanthomonas sp. and resulted in more fertile compost with increased peak temperature, enzymatic reaction intensities, and humification degree. Spectroscopy and mass difference analyses indicated that PFS conditioning enhanced reaction intensities of labile biopolymers at the thermophilic stage, mainly comprising hydrolyzation (H2O), dehydrogenation (-H2, -H4), oxidation (+O1H2), and other reactions (i.e., +CH2, C2H4O1, C2H6O1). Unlike the common composting process primarily conducts humification at the cooling stage, PFS conditioning changed the main occurrence stage to the thermophilic stage. Non-targeted metabolomics revealed that indole (a humification intermediate) is responsible for the increased humification degree and indoleacetic acid content in the PFS-conditioned compost, which then promoted compost quality. Plant growth experiments further confirmed that the dissolved organic matter (DOM) in PFS-conditioned compost produced the maximum plant biomass. This study provided molecular-level evidence that PFS conditioning can promote humification and compost fertility during sludge composting, enabling chemical conditioning optimization for sustainable management of sludge.

Carbon neutrality in wastewater treatment plants: An integrated biotechnological-based solution for nutrients recovery, odour abatement and CO2 conversion in alternative energy drivers

Wastewater treatment plants play a crucial role in water security and sanitation, ensuring ecosystems balance and avoiding significant negative effects on humans and environment. However, they determine also negative pressures, including greenhouse gas and odourous emissions, which should be minimized to mitigate climate changes besides avoiding complaints. The research has been focused on the validation of an innovative integrated biological system for the sustainable treatment of complex gaseous emissions from wastewater treatment plants. The proposed system consists of a moving bed biofilm reactor coupled with an algal photobioreactor, with the dual objective of: i) reducing the inlet concentration of the odourous contaminants (in this case, hydrogen sulphide, toluene and p-xylene); ii) capturing and converting the carbon dioxide emissions produced by the degradation process into exploitable algal biomass. The first reactor promoted the degradation of chemical compounds up to 99.57% for an inlet load (IL) of 22.97 g m−3 d−1 while the second allowed the capture of the CO2 resulting from the degradation of gaseous compounds, with biofixation rate up to 81.55%. The absorbed CO2 was converted in valuable feedstocks, with a maximum algal biomass productivity in aPBR of 0.22 g L−1 d−1. Dairy wastewater has been used as alternative nutrient source for both reactors, with a view of reusing wastewater while cultivating biomass, framing the proposed technology in a context of a biorefinery within a circular economy perspective. The biomass produced in the algal photobioreactor was indeed characterized by a high lipid content, with a maximum percentage of lipids per dry weight biomass of 35%. The biomass can therefore be exploited for the production of alternative and clean energy carrier. The proposed biotechnology represents an effective tool for shifiting the conventional plants in carbon neutral platform for implementing principles of ecological transition while achieving high levels of environmental protection.

Enhanced production of mycelium biomass and exopolysaccharides of Pleurotus ostreatus by integrating response surface methodology and artificial neural network

This study aimed to enhance the production of mycelium biomass and exopolysaccharides (EPS) of Pleurotus ostreatus in submerged fermentation. Response Surface Methodology (RSM)sought to optimize culture conditions, whereas Artificial Neural Network (ANN)aimed to predict the mycelium biomass and EPS. After optimization of RSM model conditions, the maximum biomass (36.45 g/L) and EPS (6.72 g/L) were obtained at the optimum temperature of 22.9 °C, pH 5.6, and agitation of 138.9 rpm. Further, the Genetic Algorithm (GA) was employed to optimize the cultivation conditions in order to maximize the mycelium biomass and EPS production. The ANN model with an optimized network structure gave the coefficient of determination (R2) value of 0.99 and the least mean squared error of 1.9 for the validation set. In the end, a graphical user interface was developed to predict mycelium biomass and EPS production.

Extraction and separation of astaxanthin with the help of pre-treatment of Haematococcus pluvialis microalgae biomass using aqueous two-phase systems based on deep eutectic solvents

The microalgae Haematococcus pluvialis are the main source of the natural antioxidant astaxanthin. However, the effective extraction of astaxanthin from these microalgae remains a significant challenge due to the rigid, non-hydrolyzable cell walls. Energy savings and high-efficiency cell disruption are essential steps in the recovery of the antioxidant astaxanthin from the cysts of H. pluvialis. In the present study, H. pluvialis microalgae were first cultured in Bold's Basal medium under certain conditions to reach the maximum biomass concentration, and then light shock was applied for astaxanthin accumulation. The cells were initially green and oval, with two flagella. As the induction time increases, the motile cells lose their flagellum and become red cysts with thick cell walls. Pre-treatment of aqueous two-phase systems based on deep eutectic solvents was used to decompose the cell wall. These systems included dipotassium hydrogen phosphate salt, water, and two types of deep eutectic solvents (choline chloride–urea and choline chloride–glucose). The results of pre-treatment of Haematococcus cells by the studied systems showed that intact, healthy cysts were significantly ruptured, disrupted, and facilitated the release of cytoplasmic components, thus facilitating the subsequent separation of astaxanthin by liquid–liquid extraction. The system containing the deep eutectic solvent of choline chloride–urea was the most effective system for cell wall degradation, which resulted in the highest ability to extract astaxanthin. More than 99% of astaxanthin was extracted from Haematococcus under mild conditions (35% deep eutectic solvent, 30% dipotassium hydrogen phosphate at 50 °C, pH = 7.5, followed by liquid–liquid extraction at 25 °C). The present study shows that the pre-treatment of two-phase systems based on deep eutectic solvent and, thus, liquid–liquid extraction is an efficient and environmentally friendly process to improve astaxanthin from the microalgae H. pluvialis.

A temperature-based model of biomass accumulation in humid forests of the world

Forests benefit humans in numerous ways. Many of these benefits are greater from forests with large trees and high biomass (i.e., above-ground biomass) than from young forests with small trees. Understanding how the biomass accumulation rate depends on climate is therefore important. According to a classic theory, the biomass accumulation rate first increases until canopy closure, as leaf area and gross primary productivity increase, and decreases thereafter because leaf area cannot increase further and maintaining larger biomass is energetically costlier as living tissue increases even though its proportion of all biomass decreases. We based our modeling on this classic theory and defined relative productivity, pr indicating productivity, and relative maintenance cost, cr, signaling the expense of sustaining a unit of biomass in humid climates of the world. The biomass accumulation rate of low biomass forests is determined by pr − cr and maximal biomass by pr/cr. We then compiled a global data set from the literature, with 3,177 records to fit a parameter for the efficiency of converting surplus carbon into accumulated biomass and another parameter determining biomass at canopy closure. Based on the parameterized models, a constant temperature of 22.3°C leads to the most rapid biomass accumulation in low biomass forests, whereas 16.4°C results in greatest maximal biomass. Our parameterized model can be applied to both climate change adaptation and mitigation by optimizing land use.

Cultivation Of Spirulina Platensis for carbon dioxide bio sequestration in hybrid photobioreactor with real-time monitoring system

Innovative methods for effectively sequestering significant amounts of carbon dioxide (CO2) are required to address the ongoing problem of greenhouse gas emissions, which have increased in tandem with industrial development. Optimisation of the performance of the photobioreactor remains a challenge, despite the potential of using photobioreactors and cyanobacteria for bio sequestration. A potential solution lies in the development of a hybrid photobioreactor design. Thus, this study aims to develop a hybrid design of the photobioreactor equipped with tailor-made real-time monitoring system known as FCB2022 for cultivating Spirulina platensis. The performance is evaluated by monitoring real-time data such as pH, dissolved oxygen (DO), and temperature, alongside assessing the growth kinetic of cyanobacterium, CO2 sequestration, oxygen release rate and mass carbon balance. These assessments are conducted under varying photon flux densities (PFD) of 100µmol/ (m2.s), 200µmol/ (m2.s), and 300µmol/ (m2.s). The result demonstrates that FCB2022 exhibited high hydrodynamic performance with parameters like mixing time, circulation time, Reynold number, and empty bed residence time showing favourable values. The optimal ranges for temperature, pH, and dissolved oxygen are determined to be between 23.56 and 29.11 ⁰C, 9.03–9.58, and 6.57–6.89 mgO2/L, respectively. Under the conditions of 15% CO2 and PFD of 300µmol/ (m2.s), the specific growth rates reach 0.36±0.004 /day and maximum biomass concentration attains 1.52±0.03 kg/m3. Notably, the PFD of 300µmol/ (m2.s) yields the highest conversion of carbon into biomass, ranging from 1.09×10−02 kg to 1.26×10−02 kg, representing the yield of 31–83% in each CO2 injection treatment.

No recovery in the biomass of flying insects over the last decade in German nature protected areas.

Five years after a German study on insect biomass described a multi-decade decline in nature protected habitats, the DINA (Diversity of Insects in Nature protected Areas) project has investigated the status of insects in 21 selected nature reserves across Germany in the years 2020 and 2021. We used the same methods and protocols for trapping and measuring the biomass of flying insects as in the earlier study. Across two vegetation periods, we accumulated a comprehensive data set of 1621 data points of two-week emptying intervals to evaluate the insect biomass along gradients from arable land into nature reserves through transects of Malaise traps. On average, we observed an increase in maximum insect biomass per day along the transect from the edge to the centre of the nature reserve. Overall, the measured insect biomass remained at low levels, consistent with previous findings from the years 2007-2016. There were no significant regional differences. The results show that protected habitats have higher insect biomass compared to farmland and are therefore essential for insects but are unlikely to be sufficient to sustain insect biodiversity. Further measures need to be taken for better protection and sustainment of insects, which fulfil key functions in all terrestrial ecosystems.

Controls on use efficiency of plant nutrients along subtropical to alpine gradients on the Tibetan Plateau

AbstractQuestionKnowledge of how nutrient use strategies differ between forest trees and alpine shrubs/grasses is important to understand the mechanisms of vegetation changes from montane forests to alpine shrubs/grasslands along altitudinal gradients. We tested the hypothesis that, to maximize the nitrogen use efficiency (NUE) of canopy production, forest trees tend to have a higher mean residence time (MRT) of nitrogen in the plants through increased leaf life span, whereas alpine shrublands and grasslands tend to have higher nitrogen productivity through increased below‐ground biomass fraction. We further tested whether similar patterns are found in phosphorus use efficiency (PUE).LocationTwenty‐one sampling sites along Tibetan Alpine Vegetation Transects (TAVT) at altitudes from 1900 m to 4900 m.MethodsWe measured the maximum biomass of new canopy leaves and twigs and the concentrations of their nutrients N and P and associated ecosystem variables along the TAVT. NUE (PUE) was calculated as the product of nutrient productivity (dry matter production per unit N or P in new canopy leaves and twigs) and MRT (the ratio of foliage nutrient pool to annual nutrient uptake).ResultsWith increasing altitude, leaf life span increased in forest trees but decreased in shrublands and grasslands, while below‐ground fraction increased when vegetation changed from montane forests to alpine shrubs/grasslands. In forest trees, higher N‐MRT and P‐MRT and lower P productivity were associated with longer leaf life span and lower below‐ground fraction, while N productivity varied little. In alpine shrublands and grasslands, N‐MRT, P‐MRT and P productivity varied little with leaf life span and below‐ground fraction, while N productivity was positively correlated with below‐ground fraction.ConclusionsOur data supported the hypothesis, suggesting that NUE of canopy production would be a measure of changes in ecosystem functioning from montane forests to alpine shrublands and grasslands along altitudinal gradients. The findings provide an insight into the linkage between biogeochemistry and phytogeographic processes across ecosystems.

Controls on Polar Southern Ocean Deep Chlorophyll Maxima: Viewpoints From Multiple Observational Platforms

AbstractDeep Chlorophyll Maxima (DCMs) are ubiquitous in low‐latitude oceans, and of recognized biogeochemical and ecological importance. DCMs have been observed in the Southern Ocean, initially from ships and recently from profiling robotic floats, but with less understanding of their onset, duration, underlying drivers, or whether they are associated with enhanced biomass features. We report the characteristics of a DCM and a Deep Biomass Maximum (DBM) in the Inter‐Polar‐Frontal‐Zone (IPFZ) south of Australia derived from CTD profiles, shipboard‐incubated samples, a towbody, and a BGC‐ARGO float. The DCM and DBM were ∼20 m thick and co‐located with the nutricline, in the vicinity of a subsurface ammonium maximum characteristic of the IPFZ, but ∼100 m shallower than the ferricline. Towbody transects demonstrated that the co‐located DCM/DBM was broadly present across the IPFZ. Large healthy diatoms, with low iron requirements, resided within the DCM/DBM, and fixed up to 20 mmol C m−2 d−1. The BGC‐ARGO float revealed that DCM/DBM persisted for >3 months. We propose a dual environmental mechanism to drive DCM/DBM formation and persistence within the IPFZ: sustained supply of both recycled iron within the subsurface ammonium maxima, and upward silicate transport from depth. DCM/DBM cell‐specific growth rates were considerably slower than those in the overlying mixed layer, implying that phytoplankton losses such as herbivory are also reduced, possibly because of heavily silicified diatom frustules. The light‐limited seasonal termination of the observed DCM/DBM did not result in a “diatom dump”, rather ongoing diatom downward export occurred throughout its multi‐month persistence.

Suspension cell cultures of Panax vietnamensis as a biotechnological source of ginsenosides: growth, cytology, and ginsenoside profile assessment.

Panax vietnamensis is a valuable medicinal plant and a source of a broad spectrum of biologically active ginsenosides of different structural groups. Overexploitation and low adaptability to planation cultivation have made this species vulnerable to human pressure and prompted the development of cell cultivation in vitro as a sustainable alternative to harvesting wild plants for their bioactive components. Despite high interest in biotechnological production, little is known about the main factors affecting cell growth and ginsenoside biosynthesis of this species under in vitro conditions. In this study, the potential of cell cultures of P. vietnamensis as a biotechnological source of ginsenosides was was assessed. Six suspension cell lines that were developed from different sections of a single rhizome through a multi-step culture optimization process and maintained for over 3 years on media with different mineral salt base and varying contents of auxins and cytokinins. These cell lines were evaluated for productivity parameters and cytological characteristics. Ginsenoside profiles were assessed using a combination of the reversed-phase ultra-high-performance liquid chromatography-Orbitrap-tandem mass spectrometry (UHPLC-Orbitrap-MS/MS) and ultra-performance liquid chromatography-time of flight-mass spectrometry (UPLC-TOF-MS). All lines demonstrated good growth with a specific growth rate of 0.1-0.2 day-1, economic coefficient of 0.31-0.70, productivity on dry weight (DW) of 0.30-0.83 gDW (L·day)-1, and maximum biomass accumulation varying from 10 to 22 gDW L-1. Ginsenosides of the protopanaxadiol (Rb1, Rb2/Rb3, malonyl-Rb1, and malonyl-Rb2/Rb3), oleanolic acid (R0 and chikusetsusaponin IV), and ocotillol (vinaginsenoside R1) groups and their isomers were identified in cell biomass extracts. Chikusetsusaponin IV was identified in P. vietnamensis cell culture for the first time. These results suggest that suspension cell cultures of Vietnamese ginseng have a high potential for the biotechnological production of biomass containing ginsenosides, particularly of the oleanolic acid and ocotillol groups.

Deciphering biomass contributing traits of interspecific and intergeneric hybrids derived from early generations hybrids of Saccharum and Erianthus Spp. as potential sources of biomass and bioenergy

Sugarcane (Saccharum spp., hybrids (2 n=100–130)) is one of the industrial crops cultivated mainly for sugar in the tropical and subtropical regions. It has earned the attention of many countries as a prominent energy crop owing to its exceptional biomass production potential. Energy cane is a hybrid of commercial and wild sugarcane, which was bred for high fiber content and low sucrose. Average energy cane biomass production potential is much higher, and brix levels are lower, compared with commercial sugarcane. A total of 138 Saccharum spp. hybrids representing 99 interspecific hybrids (ISH) and 39 intergeneric hybrids (IGH) derived from intercrossing of species clones of S. spontaneum, S. robustum and wild genus, Erianthus arundinaceus were evaluated along with the commercial hybrids for their cane growth and quality parameters, fibre and biomass traits. In general, the ISH and IGH clones recorded higher fibre per cent with maximum of 32% (ISH-562) and maximum biomass yield of 396.16 t/ha (ISH-571), lower values for quality characters such as juice brix 10.68% (ISH-571), sucrose 6.65% (ISH-579) and commercial cane sugar (CCS) 3.66% (ISH-579). Total biomass showed a significant positive correlation with the number of tillers (‘000/ha) at 120 days (r =0.176), number of shoots (‘000/ha) at 240 days (r = 0.129), number of stalks (‘000/ha) at 360 days (r = 0.249), cane height (r = 0.163) and single cane weight (SCW) (r = 0.508) and positive correlation with quality traits indicates the possibility of simultaneous improvement for biomass and quality traits. However, the fibre per cent has showed a significant negative correlation with quality traits viz., extraction % (r = −0.616), juice brix % (r = −0.419), sucrose % (r = −0.422), CCS % (r = −0.409), cane diameter (r = −0.600) and SCW (r = −0.475) suggests difficulty in combining both the traits. In the cluster analysis, the cluster III with 12 clones is more similar to commercial cultivars for juice quality (20.16% juice brix and 18.08% of sucrose) and cane traits, however the cluster V consist of 4 clones (ISH-557, ISH-563, ISH-571 and ISH-572) recorded highest total biomass yield of 368.72 t/ha and a mean fibre of 19.50% could be exploited for green energy purposeor as parental stocks in breeding programme.

Establishing an efficient membrane bioreactor for simultaneous pollutant removal and purple bacteria production under salinity stress

Recovering resources from wastewater to alleviate the energy crisis has become the prevailing trend of technological development. Purple phototrophic bacteria (PPB), a group of fast-growing microbes, have been widely noticed for their potential in producing value-added products from waste streams. However, saline contents in these waste streams, such as food processing wastewater pose a big challenge, which not only restrain the pollutant removal efficiency, but also hinder the growth of functional microbes. To overcome this, a photo anaerobic membrane bioreactor cultivating PPB (PPB-MBR) was constructed and its performance upon long-term salinity stress was investigated. PPB-MBR achieved desirable pollutants removal performance with the average COD and NH4+ removal efficiency being 87% (±8%, n = 87) and 89% (±10%, n = 87), respectively during long-term exposure to salinity stress of 1–80 g NaCl L−1. PPB were predominant during the entire operation period of 87 days (60%–80%), obtaining maximum biomass yield of 0.67 g biomass g−1 CODremoved and protein productivity of 0.18 g L−1 d−1 at the salinity level of 20 g NaCl L−1 and 60 g NaCl L−1, respectively. The sum of value-added products in proportion to the biomass reached 58% at maximum at the salinity level of 60 g NaCl L−1 with protein, pigments and trehalose contributing to 44%, 8.7%, and 5%, respectively. Based on economic analysis, the most cost-saving scenario treating food processing wastewater was revealed at salinity level of around 20 g NaCl L−1. However, more optimization tools are needed to boost the production efficiency so that the profit from value-added products can outweigh the additional cost by excess salinity in the future implication.

Response of Arthrospira platensis to different temperatures regarding growth and biochemical composition.

The growth of cyanobacteria can vary considerably depending on the ambient temperature. Since the optimal growth temperature for Arthrospira platensis (strain SAG21.99) is not yet known, this was investigated in the present study. The study revealed that a process temperature of 30 °C seems to be optimal for the Arthrospira strain SAG21.99 cultivation in terms of a maximum biomass productivity. This was also true for the phycocyanin content which was at 30 °C significantly higher than at 20 or 40 °C.

Growth of Scenedesmus obliquus in anaerobically digested swine wastewater from different cleaning processes for pollutants removal and biomass production

Anaerobically digested swine wastewater (ASW) purification by microalgae provides a promising strategy for nutrients recovery, biomass production and CO2 capture. However, the characteristics of ASW from different cleaning processes vary greatly. At present, the cultivation of microalgae in ASW from different manure cleaning processes is rarely investigated and compared. That may bring uncertainty for microalgae growth using different ASW in large-scale application. Thus, the ASW from three cleaning processes were tested for cultivating microalgae, including manure dry collection (I), water flushing (II) and water submerging processes (III). The characteristics of ASW from three manure cleaning processes varied greatly such as nutrient and heavy metals levels. High concentration of ammonia and copper in ASW significantly inhibited microalgae growth. Fortunately, the supply of high CO2 (10%) effectively alleviated negative influences, ensuring microalgal growth at low dilution ratio. The characteristics of three ASW resulted in significant differences in microalgae growth and biomass components. The maximal biomass production in optimal diluted ASW-I, II and III reached 1.46 g L−1, 2.19 g L−1 and 2.47 g L−1, respectively. The removal of organic compounds, ammonia and phosphorus by optimal microalgae growth in diluted ASW-I, II and III was 50.6%/94.2%/64.7%, 63.7%/82.3%/57.6% and 83.2%/91.7%/59.7%, respectively.The culture in diluted ASW-I, II and III obtained the highest lipids production of 12.1 mg L−1·d−1, 16.5 mg L−1·d−1 and 19.4 mg L−1·d−1, respectively. The analysis of lipids compositions revealed that the proportion of saturated fatty acids accounted for 36.4%, 32.4% and 27.9 % in optimal diluted ASW-I, II and III, as ideal raw materials for biodiesel production.

A robust multinutrient kinetic model for enhanced lutein and biomass yields in mixotrophic microalgae cultivation: A step towards successful large-scale productions.

Mixotrophic cultivation holds great promise to significantly enhance the productivities of biomass and valuable metabolites from microalgae. In this study, a new kinetic model is developed, explicitly describing the effect of the most influential environmental factors on both biomass growth and the production of the high-value product lutein. This extensive study of multinutrient kinetics for Tetradesmus obliquus in a mixotrophic regime covers various nutritional conditions. Crucial nutrients governing the model include nitrate, phosphate, and glucose. Using seven state variables and 13 unknown parameters, the model's accuracy was ensured through a well-designed two-factor, four-level experimental setup, providing ample data for reliable calibration and validation. Results accurately predict dynamic concentration profiles for all validation experiments, revealing broad applicability. Optimizing nitrogen availability led to significant increases in biomass (up to fourfold) and lutein production (up to 12-fold), with observed maximum biomass concentration of 6.80 g L-1 and lutein reaching 25.58 mg L-1. Noticeably, the model exhibits a maximum specific growth rate of 4.03 day-1, surpassing reported values for photoautotrophic and heterotrophic conditions, suggesting synergistic effects. Valuable guidance is provided for applying the method to various microalgal species and results are large-scale production-ready. Future work will exploit these results to develop real-time photobioreactor operation strategies.

Effects of water-nitrogen coupling on water and salt environment and root distribution in Suaeda salsa.

Understanding the spatial distribution of crop roots is crucial for effectively managing crop water and fertilizer. We investigate the effects of water-nitrogen coupling on the water-salt environment and root distribution in the root zone of S. salsa. Three irrigation levels were established, calculated according to 0.35 (W1), 0.50 (W2), and 0.65 (W3) of local ET0. The three nitrogen levels were 150 (N1), 250 (N2), and 350 (N3) kg·hm-2 in a complete combination design. With the augmentation of irrigation water and nitrogen application, the total root weight density of the root system of Suaeda salsa increased from 17.18×10-3 g·cm-3 to 27.91×10-3 g·cm-3. The distribution of soil water suction significantly influences the root distribution of Suaeda salsa in saline soil, causing a transition from a narrow deep type to a wide shallow type. Under the W2 irrigation level, soil water suction ranges from 1485.60 to 1726.59 KPa, which can provide water for S. salsa.it becomes feasible to attain the necessary water and salt environment for the growth and development of S. salsa, resulting in the attainment of maximum biomass, ash content, and salt uptake. No significant differences in the biomass, ash content, and salt uptake of S. salsa was noted between N2 and N3 nitrogen application levels (p > 0.05).The optimal irrigation volume and nitrogen application level were 0.50 ET0 and 250 kg·hm-2, respectively. The results of this study provide a scientific basis for the large-scale planting of S. salsa in extreme arid areas to improve and utilize saline wastelands.