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Aspergillus oryzae, commonly known as koji mold, has been widely used for the large-scale production of food products (sake, makgeolli, and soy sauce) and can accumulate a high level of lipids. In the present study, we showed the dynamic changes in A. oryzae mycelium growth and conidia formation under nitrogen and phosphorus nutrient stress. The fatty acid profile of A. oryzae was determined and the content of unsaturated fatty acid was found increased under nitrogen and phosphorus limitation. Oleic acid (C18:1), linoleic acid (C18:2), and γ-linolenic acid (C18:3) production were increased on five nitrogen and phosphorus limitation media, especially on nitrogen deep limitation and phosphorus limitation group, showing a 1. 2–, 1. 6–, and 2.4-fold increment, respectively, compared with the control. Transcriptomic analysis showed the expression profile of genes related to nitrogen metabolism, citrate cycle, and linoleic acid synthesis, resulting in the accumulation of unsaturated fatty acid. qRT-PCR results further confirmed the reliability and availability of the differentially expressed genes obtained from the transcriptome analysis. Our study provides a global transcriptome characterization of the nitrogen and phosphorus nutrient stress adaptation process in A. oryzae. It also revealed that the molecular mechanisms of A. oryzae respond to nitrogen and phosphorus stress. Our finding facilitates the construction of industrial strains with a nutrient-limited tolerance.

Aspergillus oryzae , commonly known as koji mold, has been widely used for the large-scale production of food products (sake, makgeolli, and soy sauce) and can accumulate a high level of lipids. In the present study, we showed the dynamic changes in A. oryzae mycelium growth and conidia formation under nitrogen and phosphorus nutrient stress. The fatty acid profile of A. oryzae was determined and the content of unsaturated fatty acid was found increased under nitrogen and phosphorus limitation. Oleic acid (C18:1), linoleic acid (C18:2), and γ-linolenic acid (C18:3) production were increased on five nitrogen and phosphorus limitation media, especially on nitrogen deep limitation and phosphorus limitation group, showing a 1. 2–, 1. 6–, and 2.4-fold increment, respectively, compared with the control. Transcriptomic analysis showed the expression profile of genes related to nitrogen metabolism, citrate cycle, and linoleic acid synthesis, resulting in the accumulation of unsaturated fatty acid. qRT-PCR results further confirmed the reliability and availability of the differentially expressed genes obtained from the transcriptome analysis. Our study provides a global transcriptome characterization of the nitrogen and phosphorus nutrient stress adaptation process in A. oryzae. It also revealed that the molecular mechanisms of A. oryzae respond to nitrogen and phosphorus stress. Our finding facilitates the construction of industrial strains with a nutrient-limited tolerance. [ABSTRACT FROM AUTHOR]

Microalgae are a promising renewable resource with high biomass yields. They can grow in non-potable water and do not compete with the use of agricultural land. The environmental sustainability of processing microalgae biomass in hydrothermal liquefaction (HTL) to obtain biopetroleum and co-products was evaluated using the life cycle assessment technique. The cultivation step in open raceway ponds was considered in scenarios with nutrient availability for high protein content (HP) biomass and with nutrient limitation for high carbohydrate content (HC) and high lipid content (HL) biomass for the species Scenedesmus acutus (SC), Chlorella vulgaris (CV) and Nannochloropsis granulata (NG), followed by harvesting and HTL processing. The biomass productivity in the evaluated scenarios was 18 g (m2 day)−1 on average over the year. The reference flow of 1 kg of microalgae biomass (in total solids) processed in HTL and the biopetroleum yield were used to estimate the results for 1 kg biopetroleum from HTL. The ecoinvent™ 3.6 database and assessment methods for cumulative energy demand (CED) in megajoules (MJ) and global warming potential (GWP of IPCC-2021 for 100 years) in kilograms of carbon dioxide equivalent (kg CO 2 eq) were used in openLCA® 1.11.0. The most favorable scenario was NG-HL with the lowest energy demand and carbon footprint, respectively, 19 MJ kg−1 and 0.85 kg CO 2 eq kg−1 of biopetroleum and the highest biopetroleum yield (68 % w/w) with a higher heating value (HHV) of 42 MJ kg−1. SC-HP achieved the highest energy demand and carbon footprint due to the larger supply of fertilizers. The energy return on investment (EROI in MJ MJ CED −1) ranged from 0.8 to 2.2 in the evaluated scenarios. The sensitivity analysis of the cultivation period from early (2 days) to late (7.5 days) harvesting time increased the energy demand by 85 % and the carbon footprint by 70 % in NG-HL. The heat demand in HTL is a key parameter in the energy and environmental performance of biopetroleum production, which ranged from −19 % to 30 % in the sensitivity analysis of the evaluated categories when changing from 5.7 MJ kg−1 biomass in HTL to 3–10 MJ kg−1. Therefore, microalgae biomass composition control, nutrient demand, harvesting time and HTL heat should be optimized to increase the competitiveness of HTL biopetroleum on a commercial scale, while reducing the energy demand and carbon footprint. [Display omitted] • LCA of microalgae bioproducts from HTL was evaluated. • Different microalgae biomass composition and productivity were investigated. • Lower heat use in HTL reduced up to 15 % in energy demand and 19 % in carbon footprint. • Longer harvesting time raised up to 87 % in energy demand and 72 % in carbon footprint. • Higher yields of microalgae biomass and biopetroleum support commodity production. [ABSTRACT FROM AUTHOR]

Abstract Poly-β-hydroxybutyrate (PHB) production from CO2 has the potential to reduce the production cost of this biodegradable polyesters, and also to make the material more sustainable compared to utilization of sugar feedstocks. In this study the unicellular cyanobacterium, Synechocystis sp. PCC 6714 has been identified as an unexplored potential organism for production of PHB. Synechocystis sp. PCC 6714 was studied under various cultivation conditions and nutritional limitations. Combined effects of nitrogen and phosphorus deficiency led to highest PHB accumulation under photoautotrophic conditions. Multivariate experimental design and quantitative bioprocess development methodologies were used to identify the key cultivation parameters for PHB accumulation. Biomass growth and PHB accumulation were studied under controlled defined conditions in a lab-scale photobioreactor. Specific growth rates were fourfold higher in photobioreactor experiments when cultivation conditions were controlled. After 14 days of cultivation in nitrogen and phosphorus, limited media intracellular PHB levels reached up to 16.4% from CO2. The highest volumetric production rate of PHB was 59 ± 6 mg L−1 day−1. Scanning electron microscopy of isolated PHB granules of Synechocystis sp. PCC 6714 cultivated under nitrogen and phosphorus limitations showed an average diameter of 0.7 µm. The results of this study might contribute towards a better understanding of photoautotrophic PHB production from cyanobacteria.

Nitrogen is the main limiting nutrient in boreal ecosystems, but studies in southwest Sweden suggest that certain forests approach phosphorus (P) limitation driven by nitrogen (N) deposition. We added N, P or N + P to a Norway spruce forest in this region, to push the system to N or P limitation. Tree growth and needle nutrient concentrations indicated that the trees are P limited. EMF biomass was reduced only by N + P additions. Soil EMF communities responded more strongly to P than to N. Addition of apatite to ingrowth meshbags altered EMF community composition and enhanced the abundance of Imleria badia in the control and N plots, but not when P was added. The ecological significance of this species is discussed. Effects on tree growth, needle chemistry, and EMF communities indicate a dynamic interaction between EMF fungi and the nutrient status of trees and soils. [ABSTRACT FROM AUTHOR]

The vast majority of terrestrial plants form root symbioses with arbuscular mycorrhizal (AM) fungi to enhance nutrient (particularly phosphorus, P) acquisition. However, some plant species also form dual symbioses involving ectomycorrhizal (ECM) fungi, with a subset of those also forming triple symbioses also involving dinitrogen (N2)‐fixing bacteria. It has been suggested that these plants show plasticity in root symbioses to optimise nutrient acquisition depending on the type and strength of soil nutrient limitation (e.g., N vs. P), yet empirical evidence remains limited. Alternatively, the degree of investment or "preference" in particular root symbioses might simply reflect differences in inoculum potential among soils of contrasting nutrient availability, reflecting adaptations of root symbionts to different edaphic conditions.Here, we grew two co‐occurring plant species forming triple (AM/ECM/N2‐fixing; Acacia rostellifera) or dual (AM/ECM; Melaleuca systena) symbioses in soils of increasing age and contrasting nutrient availability from an Australian long‐term soil chronosequence to disentangle the relative importance of abiotic factors (e.g., soil nutrient availability and stoichiometry) and biotic factors (e.g., soil inoculum potential) in determining root colonisation patterns and functional outcomes of these multiple root symbioses.For both plant species, we found clear hump‐shaped plant growth patterns along the pedogenesis‐driven gradient in soil nutrient availability, with peak growth in intermediate‐aged soils, while high levels of mycorrhizal colonisation by the "preferred" root symbionts were maintained across all soils. We found large increases (540%) in foliar manganese concentrations with increasing soil age and declining P availability, suggesting that plants may be relying on the release of carboxylates to help acquire P in the most P‐impoverished soils. Finally, we found that soil abiotic properties, such as strong differences in soil nutrient availability, are generally more important than soil inoculum potential in explaining these shifts in our plant and root responses.Synthesis. Our study suggests that plants capable of forming multiple root symbioses show plasticity in their nutrient‐acquisition strategies following shifts in soil nutrients during long‐term ecosystem development, yet maintain a preference for certain root symbionts despite changes in soil microbial inoculum. Our study suggests that plants capable of forming multiple root symbioses show plasticity in their nutrient‐acquisition strategies following shifts in soil nutrients during long‐term ecosystem development, yet maintain a preference for certain root symbionts despite changes in soil microbial inoculum. [ABSTRACT FROM AUTHOR]

Poly-β-hydroxybutyrate (PHB) production from CO has the potential to reduce the production cost of this biodegradable polyesters, and also to make the material more sustainable compared to utilization of sugar feedstocks. In this study the unicellular cyanobacterium, Synechocystis sp. PCC 6714 has been identified as an unexplored potential organism for production of PHB. Synechocystis sp. PCC 6714 was studied under various cultivation conditions and nutritional limitations. Combined effects of nitrogen and phosphorus deficiency led to highest PHB accumulation under photoautotrophic conditions. Multivariate experimental design and quantitative bioprocess development methodologies were used to identify the key cultivation parameters for PHB accumulation. Biomass growth and PHB accumulation were studied under controlled defined conditions in a lab-scale photobioreactor. Specific growth rates were fourfold higher in photobioreactor experiments when cultivation conditions were controlled. After 14 days of cultivation in nitrogen and phosphorus, limited media intracellular PHB levels reached up to 16.4% from CO. The highest volumetric production rate of PHB was 59 ± 6 mg L day. Scanning electron microscopy of isolated PHB granules of Synechocystis sp. PCC 6714 cultivated under nitrogen and phosphorus limitations showed an average diameter of 0.7 µm. The results of this study might contribute towards a better understanding of photoautotrophic PHB production from cyanobacteria. [ABSTRACT FROM AUTHOR]

Abstract: Calcifying green macroalgae of the genus Halimeda are widely distributed on coral reefs and may become more abundant under higher nutrient availability. To determine how nutrient enrichment affects the physiological performance of Halimeda opuntia (Linnaeus) J.V.Lamouroux in relation to different water depths, we carried out in situ nutrient enrichment experiments in Curaçao, Netherlands Antilles. H. opuntia was collected in 5m and then incubated at 5 and 15m in clear acrylic cages with or without addition of N and P. Growth, algal tissue composition (internal C, N, and P content, δ15N signatures, protein content), photosynthetic performance and pigment content were measured after 14 days of incubation. Growth rates and total C increased with nutrients and were higher in 5m water depth. N and P content were higher and δ15N signatures were lighter with nutrients in both depths. Photosynthetic performance, concentrations of the main and accessory photosynthetic pigments, and photoprotection also increased with nutrients and showed some response to depth. These results indicate that nutrient enrichment supported a rapid increase in physiological performance of H. opuntia, but with differences in depth. In 5m, more C was allocated to growth, where light levels were sufficient, while in 15m C was allocated to photosynthetic pigments. These results suggest that nutrient enrichment may influence their abundance and depth distribution on the reef. [Copyright &y& Elsevier]

The diatom Achnanthes brevipes C.A. Ag. was cultured in the presence of limiting concentrations of nitrogen (N) or inorganic phosphate (Pi). Growth, in terms of final yield, was more affected by N limitation than Pi limitation; N limitation had a greater effect also on protein and chlorophyll content. Carbohydrate concentrations increased under both nutrient starvation treatments, but N or Pi limitation had different effects. Total (intracellular plus extracellular) sugar content increased when cells were exposed to both types of nutrient limitation, but the extracellular polysaccharide fraction increased only in the presence of Pi starvation. Analyses were performed to identify the metabolic changes occurring in cells exposed to low phosphate because this was the main condition that affected carbohydrate extrusion. Activities of several enzymes involved in carbohydrate metabolism showed that under Pi limitation there was no activation of alternative reactions that were found to result in Pi liberation, instead of its consumption, in some higher plants and in the green alga Selenastrum minutum Naeg. Collins. Results showed that activities of pyruvate kinase, phosphorylating NAD-dependent 3-phosphate-glyceraldehyde dehydrogenase, and 3-phospho-glycerate kinase were inhibited under Pi-limited conditions compared with control cells, indicating limited glucose catabolism. Activity of uridine diphosphate glucose pyrophosphorylase, a key enzyme for the biosynthesis of the storage compound crysolaminarin, was also partly inhibited in Pi-stressed cells. Our findings suggest that carbohydrate catabolism in A. brevipes is limited under Pi deficiency, whereas extracellular extrusion of carbohydrate is favored. [ABSTRACT FROM AUTHOR]