Algal Research-Biomass Biofuels and Bioproducts最新文献

Green microalgae are increasingly valuable in industries such as food, cosmetics, animal feed, functional foods, and pharmaceuticals due to their ability to produce significant secondary metabolites like carotenoid pigments. Despite the growing demand for microalgae-derived carotenoids, the identification of robust wild-type strains with high biomass productivity under specific growth conditions remains limited. This study introduces Chlamydomonas sp. KIOST-2 (accession number: PP532860), a newly identified wild-type microalgal strain with 99.9 % genetic similarity to Chlamydomonas callosa, characterized through 18S rRNA gene sequence analysis. Notably, Chlamydomonas sp. KIOST-2 demonstrates considerable biomass productivity at 20–30 °C under alkaline (pH 8–10) and freshwater conditions, making it suitable for large-scale cultivation. Under drought stress, this strain forms orange cysts with high concentrations of astaxanthin (5.7 ± 0.6 mg/g) and notable lipid accumulation, primarily of oleic acid (C18:1 n9c), palmitic acid (C16:0), and linoleic acid (C18:2 n6c). The ability of Chlamydomonas sp. KIOST-2 to produce substantial amounts of astaxanthin under drought conditions without genetic modification highlights its potential for biorefinery applications and industrial exploitation. This discovery underscores the strain's unique combination of drought resistance and high astaxanthin productivity, positioning it as a valuable source of bioactive compounds for various industries.

The high-value carotenoid astaxanthin is a powerful antioxidant with various purported health benefits. The alga Haematococcus lacustris (formerly pluvialis) represents the main natural (farmed) source of astaxanthin. Additionally, Chlamydomonas reinhardtii has been engineered to produce ketocarotenoids including canthaxanthin, astaxanthin, and intermediates that accumulate with its native carotenoids and chlorophylls. Carotenoid extraction from biomass conventionally employs organic solvents such as acetone and ethanol. Here, the use of natural deep eutectic solvents (NADES), composed of food-grade components, was explored as green alternative for the extraction of total pigments, including astaxanthin, from engineered C. reinhardtii and wild-type H. lacustris. Hydrophobic menthol-based NADES extracted up to 2.0 mg of astaxanthin g⁻¹ of dry algal biomass from engineered C. reinhardtii and 13.4 mg g⁻¹ of wildtype H. lacustris, respectively, in single two-hour extractions, giving an extraction efficiency of 79 % and 204 % compared to organic-solvents, respectively. The extractions were carried out at room temperature without necessitating additional energy inputs like heating or sonication and without any pretreatments. The food-grade nature of NADES suggests the feasibility of utilizing the extracted materials in supplements and health applications, offering a cost-effective and sustainable means of converting waste biomass into valuable products.

In recent times, microalgae have been recognized as one of the most potential sources of biomolecules with therapeutic potential. Microalgae are rich sources of polyunsaturated fatty acids, proteins, carbohydrates, carotenoids, and vitamins. These compounds have significant anticancer, antioxidant, anti-aging, antidiabetic, hepatoprotective, and anti-inflammatory potentials. Until now, monoculture of microalgae has been the most preferred way to produce these compounds. However, this method faces the challenge of low biomass and biomolecule production and a high risk of contamination. Controlled symbiotic co-culture of microalgae with suitable microorganisms can overcome these challenges. Therefore, it is crucial to explore the compatibility of microalgae with other microorganisms to develop novel consortia to enhance biomass and biomolecule production. The article comprehensively reviews the strategies for the improvement of bioactive compound production using microalgal consortia (SIBCP-MC) viz. microalgae, fungi, bacteria, and cyanobacteria. It also discusses the mechanisms of their interaction, economic viability, and a comparison of expected revenue generation from different types of microalgal consortia. The review mainly focuses on the therapeutic potentials of microalgae biomolecules and the optimization of different factors, such as the selection of consortium partners, inoculum ratio, cultivation types and modes, temperature, pH, light intensity, and photoperiod, that affect the biomass and biomolecule production of microalgal consortia which in future helps in enhancement in biomass and biomolecules production from microalgae and curing chronic diseases. The review discusses various types of microalgal consortia, aiding in selecting the most suitable consortia for future use. The review compares their biomass and biomolecule production with monoculture, outlining microalgal consortia's advantages, challenges, and prospects. Additionally, it discusses advanced artificial intelligence techniques that could assist in the future in the selection of compatible organisms and predict expected revenue generation.

Freshwater filamentous algae have potential for wastewater bioremediation and bioproduct generation. This study investigated the separate and combined effects of growth irradiance regime (300 ± 25 μmol.m⁻².s⁻¹ with 13:11 dark:light cycle or 775 ± 25 μmol.m⁻².s⁻¹ with 8:16 dark:light cycle) and temperature (15 ± 1 or 25 ± 1 °C) during acclimation on the adaptive biochemistry and photosynthetic activity of Oedogonium with the higher and lower levels representing average outdoor conditions in summer and winter in Melbourne, Australia, respectively. Photoprotective pigments were upregulated in response to either high irradiance regime or temperature, while the chlorophyll content was also reduced when both stressors were combined. The upregulation of protective adaptations slightly lowered photosynthetic efficiency, which was more dramatically impaired by the reduced chlorophyll at high temperature and irradiance. The polar lipid content increased from ~10% to ~30% of total lipid content, the protein content decreased by ~10% and the starch content increased by 30% in response to higher irradiance and temperature, with implications for biomass utilisation. These changes in biochemical composition due to long-term acclimation suggests the potential for compositional stratification in stable floating filamentous algae mats due to the presence of self-shading. Further, the shading created by the upper layers in the mat can be expected to provide further protection to the biomass at the lower levels against photooxidative stress. The results reveal the impact of variations on seasonal growth conditions and filamentous mat depth on the composition and productivity of the algae.

This study investigated Chlorella's capacity to treat cheese whey (CW) effluent and produce a high-nutritional value biomass, by using a systematic sequential experimental design. Physicochemical analysis of CW revealed its high pollution load, characterized by elevated levels of lactose, phosphorus, and nitrogen, as well as high turbidity due to the presence of whey solids. Screening experiments demonstrated that trace mineral addition and continuous air supply are essential factors for Chlorella biomass production in CW (>800 mg·mL⁻¹). Furthermore, whey solids did not hinder Chlorella growth, with notable biomass production observed even in undiluted CW, demonstrating this microalga's ability to adapt metabolically to the complex environment. Laboratory-scale photobioreactor experiments confirmed Chlorella's ability to produce biomass in CW, outperforming controls (>800 mg·mL⁻¹). Bioremediation potential assessment exhibited significant reductions in organic pollutants (>14 g·L⁻¹ COD), nitrogen (>400 mg·L⁻¹), phosphorus (>140 mg·L⁻¹) and sodium (>650 mg·L⁻¹). CW solids were also removed with Chlorella harvesting (>99 %). Harvested algal biomass was enriched with proteins (>40 g·100 g⁻¹), polyunsaturated fatty acids (>9 % TFA) and pigments, offering potential applications in nutraceutical and pharmaceutical industries. Overall, this study highlights Chlorella's efficacy in CW treatment and biomass valorization, offering a sustainable solution for dairy wastewater management while producing valuable resources.

Cyanobacteria are photosynthetic microorganisms widely distributed in diverse environments, including Antarctica, one of the most extreme ecosystems on the planet. These microorganisms have the unique ability to produce a variety of secondary metabolites with bioactive properties. The cyanobacteria that thrive in Antarctica hold exceptional biotechnological promise as they consistently meet and overcome the challenges of this demanding environment by producing a range of diverse secondary metabolites tailored for survival and adaptation. Therefore, this review article aims to explore the secondary metabolites produced by Antarctic cyanobacteria and their potential application in different industries, including pharmacology, cosmetics, and agriculture. Four hundred and twenty-one data were collected from articles reporting the search for metabolites produced by Antarctic cyanobacteria, published between 1989 and 2023, with the years 2000, 2008, and 2014 contributing more than half of this data. Around 29.2 % of the articles surveyed focused on secondary metabolites, 61 % on biotechnological potential, and 9.7 % on specific genes. These results demonstrate that Antarctica's unique and extreme environment is as a remarkable natural laboratory for studying cyanobacteria and their diverse secondary metabolites.

ETT (Glu-Met-Phe-Gly-Thr-Ser-Ser-Glu-Thr) isolated from Isochrysis zhanjiangensis was an antioxidant nonapeptide with the highest active site on Met 2. In this study, the investigated the anti-skin aging effect of ETT on both keratinocytes and fibroblasts, took ultraviolet B (UVB)-induced human immortalized keratinocytes (HaCaT) and hydrogen peroxide (H₂O₂)-induced human skin fibroblasts (BJ cells). The results showed the anti-photoaging effect of ETT on UVB-induced HaCaT cells by declining an increasing level of intracellular reactive oxygen species (ROS), activating antioxidant system via nuclear factor erythroid 2 (Nrf2)/ heme oxgenase-1 (HO-1) signaling pathway, promoting autophagy to enhancing mitochondrial membrane potential and inhibiting apoptosis. Moreover, ETT also against skin aging on H₂O₂-induced BJ cells by attenuating senescence and improving collagen generation via transforming growth factor β1 (TGF-β1)/Smad signaling pathway. In general, these results indicated ETT is potential to against skin aging by maintaining keratinocytes homeostasis, reducing apoptosis, attenuating fibroblasts senescence and enhancing content of collagen.

Seaweeds are considered a promising source of phytochemical compounds, including polyphenols. The Australian shoreline hosts a diverse array of seaweeds; however, the phenolic profile and the antioxidant potential of most species remain unclear, necessitating further exploration. To this end, ten red seaweeds were collected, identified using molecular testing, and their phenolic compounds were extracted using acidified ethanol and subjected to ten in vitro assays. The Relative Antioxidant Capacity Index (RACI) was calculated for each sample to compare the overall results. The results indicated that Phacelocarpus peperocarpos exhibited the highest overall phenolic and antioxidant potential, followed by Callophyllis sp. and Rhodophyllis sp.. A total of 365 phenolic compounds were screened, comprising 85 phenolic acids, 164 flavonoids, and 118 other polyphenols. Correlation analysis displayed a positive correlation between phenolic content, antioxidant activity, and the identified phenolic compounds. Overall, this study sheds light on the polyphenol content and antioxidant potential of ten red seaweed species from Queenscliff, Victoria, through various in vitro assays and LC-ESI-QTOF-MS/MS characterization. The findings indicate that Australian red seaweeds are a promising source of polyphenols and exhibit considerable antioxidant properties, underscoring their potential in providing substantial health benefits and functional food products.

Fast hydrothermal liquefaction (HTL) shows great potential for producing biocrude. This research examined the influences of mixing ratios of sludge and Chlorella during both isothermal (300 °C, 1800 s) and fast (500 °C, 20 s) co-HTL. Adding Chlorella could efficiently retard repolymerization reaction and increase the biocrude production. The highest co-liquefaction effect was achieved from a sludge to Chlorella ratio of 2:6 by fast HTL, producing a biocrude yield of 29.65 wt%, closely approaching the calculated yield of 29.39 wt% and demonstrating an additive effect. However, for the high ash content of sludge, all isothermal and other fast HTL conditions presented an antagonistic effect on biocrude production. Meanwhile, co-liquefaction also exhibited a slight antagonistic effect on the heating value and energy recovery of biocrude, with experimental values reaching 32.73 MJ·kg⁻¹ and 52.74 %, respectively. FT-IR and maturity analyses indicated that compared to isothermal co-HTL, fast co-HTL biocrude was more favorable for the conversion into gasoline/diesel due to its lower paleo-temperature. GC–MS analysis identified amides (isothermal co-HTL) and nitrogen heterocycles (fast co-HTL) as the dominant components, suggesting that the holding time significantly influenced the competition of Maillard and amidation reactions. Besides biocrude, the major composition of aqueous phase products (APs) was also nitrogen heterocycles. Notably, fast co-HTL induced a substantial decrease in COD, NH₃-N, and TN contents of APs, reducing the discharge challenge of the by-products.

Microalgae and cyanobacteria biomass can be cultivated in large amounts, producing a variety of bioactive compounds. As a result, various industries have begun to study the potential of this biomass in a wide range of applications such as biofuel production, environmental remediation for contaminated soil and water, food supplements, and as a source of feed for aquaculture. The cultivation conditions have a profound impact on microalgae biochemical composition. Therefore, the culture conditions must be tailored to the specific application of the biomass. This entails careful control of factors such as light exposure, nutrient concentration, and the application of stress conditions. To further enhance the value of microalgae biomass beyond its nutritional analysis, this review aims to explore the potential of the biomass as biofactories for producing antioxidant enzymes and inhibitors targeting Alzheimer's and diabetes diseases. Both chronic diseases are a growing concern due to an aging population and an increase in obesity rates. Microalgae when exposed to stressful conditions enhance the activity of antioxidant enzymes. However, further studies in the isolation and storage of these enzymes need to be performed. From the literature reviewed microalgae exhibited great potential in inhibiting key enzymes involved in Alzheimer's and Diabetes. The inhibitory potential was observed both in vitro and at a cellular level making them a promising natural alternative to current medication used to inhibit these enzymes.