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Symbiotic partnerships are widespread in nature and in industrial applications yet there are limited examples of laboratory communities. Therefore, using common photobionts and mycobionts similar to those in natural lichens, we create an artificial lichen-like symbiosis. While Aspergillus nidulans and Aspergillus niger could not obtain nutrients from the green algae, Chlorella, and Scenedesmus, the cyanobacteria Nostoc sp. PCC 6720 was able to support fungal growth and also elevated the accumulation of total biomass. The Nostoc–Aspergillus co-cultures grew on light and CO2 in an inorganic BG11 liquid medium without any external organic carbon and fungal mycelia were observed to peripherally contact with the Nostoc cells in liquid and on solid media at lower cell densities. Overall biomass levels were reduced after implementing physical barriers to indicate that physical contact between cyanobacteria and heterotrophic microbes may promote symbiotic growth. The synthetic Nostoc–Aspergillus nidulans co-cultures also exhibited robust growth and stability when cultivated in wastewater over days to weeks in a semi-continuous manner when compared with axenic cultivation of either species. These Nostoc-Aspergillus consortia reveal species-dependent and mutually beneficial design principles that can yield stable lichen-like co-cultures and provide insights into microbial communities that can facilitate sustainability studies and broader applications in the future.Key Points• Artificial lichen-like symbiosis was built with wild-type cyanobacteria and fungi.• Physical barriers decreased biomass production from artificial lichen co-cultures.• Artificial lichen adapted to grow and survive in wastewater for 5 weeks.

Background To overcome the daunting technical and economic barriers of algal biofuels, we evaluated whether seawater can be a viable medium for economically producing filamentous Spirulina subsalsa as feedstock, using monosodium glutamate residue (MSGR) produced by the glutamate extraction process as an inexpensive nutrient source. Results Spirulina subsalsa cannot grow in pure seawater, but exhibited faster biomass accumulation in seawater supplemented with MSGR than in freshwater medium (modified Zarrouk medium). Introducing seawater into media ensured this cyanobacterium obtained high lipid productivity (120 mg/L/day) and suffered limited bacterial infections during growth. Moreover, the yields of protein, carotenoids and phytols were also improved in seawater mixed with MSGR. S. subsalsa exhibited high biomass and lipid productivity in bag bioreactors with 5- and 10-L medium, demonstrating the potential of this cultivation method for scaling up. Moreover, seawater can produce more biomass through medium reuse. Reused seawater medium yielded 72% of lipid content compared to pristine medium. The reason that S. subsalsa grew well in seawater with MSGR is its proficient adaptation to salinity, which included elongation and desaturation of fatty acids, accumulation of lysine and methionine, and secretion of sodium. The nutrients provided by MSGR, like organic materials, played an important role in these responses. Conclusion Spirulina subsalsa has an efficient system to adapt to saline ambiance in seawater. When supplemented with MSGR, seawater is a great potential medium to produce S. subsalsa in large scale as biofuel feedstock. Meanwhile, value-added products can be derived from the ample protein and pigments that can broaden the range of biomass application and improve this biorefinery economics.

Microalgae have great potential for remediating salt-affected soil. In this study, the microalgae species Coelastrella sp. SDEC-28, Dunaliella salina SDEC-36, and Spirulina subsalsa FACHB-351 were investigated for their potential to rehabilitate salt-affected soils. Nylon screens with optimal aperture sizes and layer numbers were identified to efficiently intercept and harvest biomass, suggesting a correlation between underflow capability and the tough cell walls, strong motility, and intertwining characteristics of the algae. Our investigations proved the feasibility of incorporating monosodium glutamate residue (MSGR) into soil extracts at dilution ratios of 1/200, 1/2000, and 1/500 to serve as the optimal medium for the three microalgae species, respectively. After one growth period of these three species, the electrical conductivities of the media decreased by 0.21, 1.18, and 1.78 mS/cm, respectively, and the pH remained stable at 7.7, 8.6, and 8.4. The hypotheses that microalgae can remediate soil and return profits have been verified through theoretical calculations, demonstrating the potential of employing specific microalgal strains to enhance soil conditions in eco-farms, thereby broadening the range of crops that can be cultivated, including those that are intolerant to saline–alkali environments.

Serratia sp. ZM is a plant growth-promoting (PGP) bacterial strain isolated from the rhizospheric soil of Populus euphratica in northwestern China. In this study, low nitrogen supply significantly stimulated the production of indole-3-acetic acid (IAA) in Serratia sp.ZM. The inoculation of the bacterium to wheat seedlings improved plant growth compared with the uninoculated group, and the stimulating effect was more prominent under low nitrogen stress. Inactivation of the predicted key gene in the IAA biosynthesis pathway impaired IAA production and significantly hampered mutant growth in poor medium. Furthermore, the IAA-deficient mutant lost the PGP effect under either normal or low nitrogen conditions in plant experiments. This study revealed the significant impact of environmental nitrogen levels on IAA production in the PGP strain and the vital effect of IAA on resistance physiology of both the bacterium and host plant. The characteristics of Serratia sp. ZM also indicated its application potential as a biofertilizer for plants, especially those suffering from poor nitrogen soil.

Phaeodactylum tricornutum and Nannochloropsis oceanica, with their satisfactory performance in accumulating lipids and other high-value products, have been successfully used for commercial production in recent years. However, costly chemicals in culture media greatly increase the price of the resulting bioproducts. To control the cultivation cost, this paper assessed the potential of seawater supplemented with monosodium glutamate residue wastewater at a ratio of 1/500 (S-MSGR) to serve as a growing medium for these two marine species. Compared with the standard chemical culture medium, Erdschreiber’s medium (EM), both the algal growth and metabolite accumulation of P. tricornutum and N. oceanica were greatly promoted in S-MSGR. The maximum biomass concentrations of P. tricornutum and N. oceanica reached 0.93 and 0.36 g/L, which were, respectively, 1.5 and 1.9 times higher than those in EM medium. For lipid accumulation, P. tricornutum exhibited an excellent lipid productivity of 22.9 mg/L/day in S-MSGR, a 64% increase compared to EM medium. Furthermore, the average yield coefficients indicated good performance of P. tricornutum and N. oceanica in transferring the nitrogen in S-MSGR to the biomass, at 74.8 and 174.8 mg/g of nitrogen. In addition, compared with EM, the costs of the medium for lipid production of P. tricornutum and N. oceanica cultured in S-MSGR were USD 2.3 and 5.8/(kg lipid), which saved 96.9% and 97.6%, respectively. Therefore, this paper demonstrates that S-MSGR is a suitable nutrient resource for P. tricornutum and N. oceanica, and it has a great potential to cut the cultivation cost during real commercial production.

Amorphous Al2O3-Y2O3:Er nanolaminate films are fabricated on silicon by atomic layer deposition, and ~1530 nm electroluminescence (EL) is obtained from the metal-oxide-semiconductor light-emitting devices based on these nanofilms. The introduction of Y2O3 into Al2O3 reduces the electric field for Er excitation and the EL performance is significantly enhanced, while the electron injection of devices and the radiative recombination of doped Er3+ ions are not impacted. The 0.2 nm Y2O3 cladding layers for Er3+ ions increase the external quantum efficiency from ~3% to 8.7% and the power efficiency is increased by nearly one order of magnitude to 0.12%. The EL is ascribed to the impact excitation of Er3+ ions by hot electrons, which stem from Poole-Frenkel conduction mechanism under sufficient voltage within the Al2O3-Y2O3 matrix.

Salt-affected soil and carbon emissions are worldwide problems. Tiny microalgae hold huge power to remediate soil and reduce carbon. An eco-friendly and cost-effective approach is proposed to remediate salt-affected soils using microalgal eco-farms, which would deliver threefold benefits: salt-affected soil amelioration, CO2 reduction, and agricultural production.

Spirulina subsalsa represents a promising candidate for commercial production. Yet, due to its unique pattern of attached growth followed by upward flotation, there is an urgent need to find a suitable cultivation strategy and achieve scale-up. In the low-cost medium of seawater plus monosodium glutamate wastewater, this study initially investigated the influence of aeration rate (0, 0.3, 0.6 L/min) and reactor geometry ( D 24 d 4.5 , D 18 d 8 , D 12 d 18 , D : diameter, cm; d : depth, cm) on microalgal growth, indicating that Spirulina subsalsa was suited for culturing in non-aerated, wide-shallow reactors. Then, in the single plastic reactor, diverse depths (2.25, 4.50, 9.00 cm) and surface areas (1000, 2000, and 3000 cm 2 ) for culturing Spirulina subsalsa were optimised to 4.5 cm and 2000 cm 2 . Subsequently, a pilot-scale cultivation system with a volume of 162 L was constructed, adopting a semi-continuous culture mode. The average dry mass productivity was 0.12 g/L/d and 816.48 g of algal powder was harvested within 41 days. The mean contents of protein, carbohydrate and lipid were respectively 46.50%, 14.95% and 10.87%. Moreover, economic analysis demonstrated that the cost of produced algal powder was 8.30 USD/kg. In the future, Spirulina subsalsa has the potential to be developed into multiple products.

Background During inevitable light/dark cycle, lipid productivity of outdoor microalgae photoautotrophic cultivation is lowered by nightly biomass and lipid loss. To minimize, or even reverse the nightly lipid loss, it was expected that lipid accumulation would not cease, even if at night. Without relying on photosynthesis and organic matter in media, endogenous lipid accumulation that consumes energy and carbon sources derived from cells themselves, namely endogenous accumulation, is the only way for lipid production. The main aims of the present study was to characteristic endogenously accumulated lipid, confirm feasibility to reverse nightly lipid loss, and determine optimal conditions and its quality suitability for biodiesel feedstock production under stress conditions. Results Chlorella vulgaris SDEC-3M ability to rapidly accumulated lipid under stress conditions was cultivated for 12 h in darkness, and the effects of various conditions on lipid accumulation and biomass loss were analyzed. Under non-stress conditions, lipid contents dropped. Under certain stress conditions, conversely, the lipid contents were substantially improved so that net nightly endogenous lipid accumulation was observed. Under the optimal conditions (aeration mode with 0.10 vvm and 15% CO2, 5–10 mg L−1 of NO3−-N, 30–35 °C, approximate 2500 mg L−1 of biomass), the lipid content was doubled and increased lipid was approximately 180 mg L−1. Among stress conditions, N-deficiency had the most significant effect on endogenous lipid accumulation, and the optimum results were characterized under relatively low-N concentrations. Higher consistency between loss in carbohydrate and gain in lipid confirmed accumulated lipid endogenously conversed from carbohydrate. Based on the analyses of fatty acids profiles and prediction of kinematic viscosity, specific gravity, cloud point, cetane number and iodine value, it was confirmed that the quality of lipid obtained under optimal conditions complied with biodiesel quality standards. Conclusion Via triggering endogenous lipid accumulation by stress conditions, even in darkness, SDEC-3M can synthesize enough lipid suitable for biodiesel feedstock. It implies that the lipid accumulation phase in two-phase strategy can be scheduled at night, and following biomass production stage in light, which should be a solution to improve the lipid yield and quality of large-scale outdoor photoautotrophic microalgae cultivation for biodiesel production.

Dongping Lake is the final adjusting and storing lake in the east route of the South-to-North Water Diversion Project in China, and there has been serious concern regarding the water quality. Understanding the process of phytoplankton variation can be particularly useful in water quality improvement and management decisions. In this study, the phytoplankton taxonomic composition, abundance, temporal variations, spatial distribution, and diversity were studied based on a monthly sampling campaign from three sampling stations between May 2010 and May 2011. A total of 132 species (8 phyla, 72 genera), including 64 species of Chlorophyta, 26 species of Bacillariophyta, 21 species of Cyanophyta, 12 species of Euglenophyta, 3 species of Cryptophyta, 2 species of Xanthophyta, 1 species of Pyrrophyta, and 3 species of Chrysophyta were identified. Average phytoplankton diversity index and evenness values were 3.83 and 0.77, respectively, revealing a high biodiversity of phytoplankton community. The phytoplankton abundance averaged 5.11 × 10 6  cells/L, with Bacillariophyta dominant in winter and spring, but Cyanophyta in summer and autumn. There were 14 predominant species including Pseudanabaena limnetica , Chlamydomonas simplex , Cyclotella stelligera , and Chroomonas acuta . Phytoplankton community structure and water quality variables changed substantially over the survey period; redundancy analysis, Pearson correlations, and regression analysis as an integrated approach were applied to analyze the relationships among them. Total phosphorus and ammonium played governing roles in the phytoplankton dynamics of Dongping Lake during all periods investigated.