Breeding of high protein Chlorella sorokiniana using protoplast fusion

Physiological and molecular mechanisms of the inhibitory effects of artemisinin on Microcystis aeruginosa and Chlorella pyrenoidosa

Artemisinin, a novel plant allelochemical, has attracted attention for its potential selective inhibitory effects on algae, yet to be fully explored. This study compares the sensitivity and action targets of Microcystis aeruginosa (M. aeruginosa) and Chlorella pyrenoidosa (C. pyrenoidosa) to artemisinin algaecide (AMA), highlighting their differences. Results indicate that at high concentrations, AMA displaces the natural PQ at the QB binding site within M. aeruginosa photosynthetic system, impairing the D1 protein repair function. Furthermore, AMA disrupts electron transfer from reduced ferredoxin (Fd) to NADP+ by interfering with the iron-sulfur clusters in the ferredoxin-NADP+ reductases (FNR) domain of Fd. Moreover, significant reactive oxygen species (ROS) accumulation triggers oxidative stress and interrupts the tricarboxylic acid cycle, hindering energy acquisition. Notably, AMA suppresses arginine synthesis in M. aeruginosa, leading to reduced microcystins (MCs) release. Conversely, C. pyrenoidosa counters ROS accumulation via photosynthesis protection, antioxidant defenses, and by regulating intracellular osmotic pressure, accelerating damaged protein degradation, and effectively repairing DNA for cellular detoxification. Additionally, AMA stimulates the expression of DNA replication-related genes, facilitating cell proliferation. Our finding offer a unique approach for selectively eradicating cyanobacteria while preserving beneficial algae, and shed new light on employing eco-friendly algicides with high specificity.

Nutritional Supplements for Skin Health-A Review of What Should Be Chosen and Why

Supplementation of micronutrients is considered to be crucial in the reinforcement of the skin's barrier. In this paper, 14 nutritional compounds commonly used in food or pharmaceutic industries were analyzed in terms of influencing skin conditions. The major objective of this paper was to provide a narrative review of the available literature regarding several chosen compounds that are currently widely recommended as supplements that aim to maintain proper and healthy skin conditions. We conducted a review of the literature from PubMed, Scopus, and Web of Science until September 2023 without any other restrictions regarding the year of the publication. Ultimately, we reviewed 238 articles, including them in this review. Each of the reviewed compounds, including vitamin A, vitamin C, vitamin D, vitamin E, curcumin, chlorella, Omega-3, biotin,Ppolypodium leucotomos, Simmondsia chinesis, gamma oryzanol, olive leaf extract, spirulina, and astaxanthin, was observed to present some possible effects with promising benefits for a skin condition, i.e., photoprotective radiation. Adding them to the diet or daily routine might have a positive influence on some skin inflammatory diseases such as atopic dermatitis or psoriasis. Further, UV radiation protection facilitated by some supplements and their impact on human cells might be helpful during chemotherapy or in preventing melanoma development. Further research is needed because of the lack of clear consensus regarding the doses of the described compounds that could provide desirable effects on the skin.

Developing algae as a sustainable food source

Current agricultural and food production practices are facing extreme stress, posed by climate change and an ever-increasing human population. The pressure to feed nearly 8 billion people while maintaining a minimal impact on the environment has prompted a movement toward new, more sustainable food sources. For thousands of years, both the macro (seaweed and kelp) and micro (unicellular) forms of algae have been cultivated as a food source. Algae have evolved to be highly efficient at resource utilization and have proven to be a viable source of nutritious biomass that could address many of the current food production issues. Particularly for microalgae, studies of their large-scale growth and cultivation come from the biofuel industry; however, this knowledge can be reasonably translated into the production of algae-based food products. The ability of algae to sequester CO₂ lends to its sustainability by helping to reduce the carbon footprint of its production. Additionally, algae can be produced on non-arable land using non-potable water (including brackish or seawater), which allows them to complement rather than compete with traditional agriculture. Algae inherently have the desired qualities of a sustainable food source because they produce highly digestible proteins, lipids, and carbohydrates, and are rich in essential fatty acids, vitamins, and minerals. Although algae have yet to be fully domesticated as food sources, a variety of cultivation and breeding tools exist that can be built upon to allow for the increased productivity and enhanced nutritional and organoleptic qualities that will be required to bring algae to mainstream utilization. Here we will focus on microalgae and cyanobacteria to highlight the current advancements that will expand the variety of algae-based nutritional sources, as well as outline various challenges between current biomass production and large-scale economic algae production for the food market.

Industry chain and challenges of microalgal food industry-a review

Currently, the whole world is facing hunger due to the increase in the global population and the rising level of food consumption. Unfortunately, the impact of environmental, climate, and political issues on agriculture has resulted in limited global food resources. Thus, it is important to develop new food sources that are environmentally friendly and not subject to climate or space limitations. Microalgae represent a potential source of nutrients and bioactive components for a wide range of high-value products. Advances in cultivation and genetic engineering techniques provide prospective approaches to widen their application for food. However, there are currently problems in the microalgae food industry in terms of assessing nutritional value, selecting processes for microalgae culture, obtaining suitable commercial strains of microalgae, etc. Additionally, the limitations of real data of market opportunities for microalgae make it difficult to assess their actual potential and to develop a better industrial chain. This review addresses the current status of the microalgae food industry, the process of commercializing microalgae food and breeding methods. Current research progress in addressing the limitations of microalgae industrialization and future prospects for developing microalgae food products are discussed.

Enhancement of Carbon Conversion and Value-Added Compound Production in Heterotrophic Chlorella vulgaris Using Sweet Sorghum Extract

High-cost carbon sources are not economical or sustainable for the heterotrophic culture of Chlorella vulgaris. In order to reduce the cost, this study used sweet sorghum extract (SE) and its enzymatic hydrolysate (HSE) as alternative carbon sources for the heterotrophic culture of Chlorella vulgaris. Under the premise of the same total carbon concentration, the value-added product production performance of Chlorella vulgaris cultured in HSE (supplemented with nitrogen sources and minerals) was much better than that in the glucose medium. The conversion rate of the total organic carbon and the utilization rate of the total nitrogen were both improved in the HSE system. The biomass production and productivity using HSE reached 2.51 g/L and 0.42 g/L/d, respectively. The production of proteins and lipids using HSE reached 1.17 and 0.35 g/L, respectively, and the production of chlorophyll-a, carotenoid, and lutein using HSE reached 30.42, 10.99, and 0.88 mg/L, respectively. The medium cost using HSE decreased by 69.61% compared to glucose. This study proves the feasibility and practicability of using HSE as a carbon source for the low-cost heterotrophic culture of Chlorella vulgaris.

Optimization of Protoplast Preparation and Establishment of Genetic Transformation System of an Arctic-Derived Fungus Eutypella sp

Arctic-derived fungus Eutypella sp. D-1 has attracted wide attention due to its huge ability to synthesize secondary metabolites. However, current studies only focus on stimulating its production of new secondary metabolites by OSMAC strategies, and the relationship between secondary metabolites and biosynthetic gene clusters (BGCs) has not been explored. In this study, the preparation and regeneration conditions of Eutypella sp. D-1 protoplasts were explored to lay a foundation for the study of genetic transformation of this fungus. Orthogonal experiment showed that the optimal preparation conditions were 0.75 M NaCl, 20 g/L of lysing enzyme, and 20 g/L of driselase, 28°C for 6 h. The maximum yield of Eutypella sp. D-1 protoplasts could reach 6.15 × 10⁶ cells·ml⁻¹, and the concentration of osmotic stabilizer NaCl was the most important factor for Eutypella sp. D-1 protoplasts. The results of FDA staining showed that the prepared protoplasts had good activity. Besides, the best protoplasts regeneration medium was YEPS, whose maximum regeneration rate is 36%. The mediums with nitrogen sources, such as SR and RM, also had good effects on the Eutypella sp. D-1 protoplast regeneration, indicating that nitrogen sources played an important role on the Eutypella sp. D-1 protoplast regeneration. Subsequent transformation experiments showed that hygromycin resistance genes (hrg) could be successfully transferred into the genome of Eutypella sp. D-1, indicating that the prepared protoplasts could meet the needs of subsequent gene manipulation and research. This study lays a foundation for the genetic transformation of Eutypella sp. D-1.

Cultivation of Chlorella sorokiniana in a bubble-column bioreactor coupled with cooking cocoon wastewater treatment: effects of initial cell density and aeration rate

Previous studies have documented that Chlorella sorokiniana could grow well on cooking cocoon wastewater (CCW) with a maximum biomass of 0.49 g/L. In order to further enhance the biomass production and nutrient removals, a bubble-column bioreactor was designed and performed to cultivate C. sorokiniana in CCW, and two main cultivation parameters were investigated in this work. Results showed that a maximum algal biomass, specific growth rate, and biomass productivity of 2.83 g/L, 0.854 d^-1, and 476.25 g/L/d, respectively, were achieved when this alga was cultivated in the bioreactor with an initial cell density of 0.8 g/L and an aeration rate of 3.34 L air/L culture/min; meanwhile, removal efficiencies of ammonium, total nitrogen, total phosphorus, and chemical oxygen demand reached 97.96, 85.66, 97.96, and 86.43%, respectively, which were significantly higher than that obtained in our previous studies. Moreover, chemical compositions in the algal cells varied with the changes of cultivation conditions (i.e., initial cell density and aeration rate). Thus, it is concluded that (1) the bubble-column bioreactor was suitable for cultivation of C. sorokiniana coupled with the CCW treatment and (2) initial cell density and aeration rate affected the biomass production, nutrient removals and chemical compositions of this alga.

Protoplast fusion between Blakeslea trispora 14,271 (+) and 14,272 (-) enhanced the yield of lycopene and β-carotene

Blakeslea trispora, a heterothallic Zygomycota with two mating types (termed "plus" and "minus"), is an ideal source of lycopene and β-carotene. The lycopene and β-carotene yields when the two type strains are used for fermentation separately are lower than those when they are joint together. To enhance the yield of lycopene and β-carotene in B. trispora, protoplast fusion technology was carried out between ATCC 14,271 (+) and ATCC 14,272 (-). After protoplast preparation, protoplast fusion, fusion sorting, fusion regeneration, and high-throughput screening, two fusions (Fu-1and Fu-2) with high lycopene and β-carotene yields were obtained. The lycopene yields of Fu-1 and Fu-2 were increased to 0.60 mg/gDW and 0.90 mg/gDW, which were respectively 3.62- and 5.44-fold those of 14,271 and 1.76- and 2.64-fold those of 14,272. The β-carotene yields of Fu-1 and Fu-2 were increased to 22.07 mg/gDW and 36.93 mg/gDW, which were respectively 1.72- and 2.89-fold those of 14,271 and 1.23- and 2.06-fold those of 14,272. In this study, the protoplast fusion technique was successfully used in Blakeslea trispora, providing new ideas for improving lycopene and β-carotene production.

Recent advancements in mixotrophic bioprocessing for production of high value microalgal products

Recently, microalgal biomass has become an attractive and sustainable feedstock for renewable production of various biochemicals and biofuels. However, attaining required productivity remains a key challenge to develop industrial applications. Fortunately, mixotrophic cultivation strategy (MCS) is leading to higher productivity due to the metabolic ability of some microalgal strain to utilise both photosynthesis and organic carbon compared to phototrophic or heterotrophic processes. The potential of MCS is being explored by researchers for maximized biochemicals and biofuels production however it requires further development yet to reach commercialization stage. In this review, recent developments in the MCS bioprocess for selective value-added (carotenoids) products have been reviewed; synergistic mechanism of carbon and energy was conferred. Moreover, the metabolic regulation of microalgae under MCS for utilized carbon forms and carbon recycling was demonstrated; Additionally, the opportunities and challenges of large-scale MCS have been discussed.