Biomolecules from Microalgae and Cyanobacteria: Applications and Market Survey

Enhancing the Biological Effects of Bioactive Compounds from Microalgae through Advanced Processing Techniques: Pioneering Ingredients for Next-Generation Food Production

The heightened interest in healthy dietary practices and the preference for fresh, minimally processed foods with reduced additives have witnessed a significant surge among consumers. Within this context, bioactive compounds have garnered attention as potent agents offering beneficial biological effects when integrated into food formulations. Nevertheless, the efficacy of these bioactive compounds in product development encounters numerous challenges during various processing and storage stages due to their inherent instability. Addressing these limitations necessitates exploring novel technological approaches tailored explicitly to the application of bioactive compounds in food production. These approaches should not only focus on preserving the bioactive compounds within food matrices but also on retaining the sensory attributes (color, taste, and aroma) of the final food products. The impact of microalgae and their bioactive compounds on human health and well-being has been extensively reported in the literature. However, there is still a gap regarding the processing and stability of microalgal bioactive compounds to improve their application in the food industry. The main goal of the present work is to point out how to overcome technological challenges in enhancing the stability of bioactive compounds from microalgae for optimal food applications.

Perspectives on cultivation and harvesting technologies of microalgae, towards environmental sustainability and life cycle analysis

The development of algae is seen as a potential and ecologically sound approach to address the increasing demands in multiple sectors. However, successful implementation of processes is highly dependent on effective growing and harvesting methods. The present study provides a complete examination of contemporary techniques employed in the production and harvesting of algae, with a particular emphasis on their sustainability. The review begins by examining several culture strategies, encompassing open ponds, closed photobioreactors, and raceway ponds. The analysis of each method is conducted in a systematic manner, with a particular focus on highlighting their advantages, limitations, and potential for expansion. This approach ensures that the conversation is in line with the objectives of sustainability. Moreover, this study explores essential elements of algae harvesting, including the processes of cell separation, dewatering, and biomass extraction. Traditional methods such as centrifugation, filtration, and sedimentation are examined in conjunction with novel, environmentally concerned strategies including flocculation, electro-coagulation, and membrane filtration. It evaluates the impacts on the environment that are caused by the cultivation process, including the usage of water and land, the use of energy, the production of carbon dioxide, and the runoff of nutrients. Furthermore, this study presents a thorough examination of the current body of research pertaining to Life Cycle Analysis (LCA) studies, presenting a perspective that emphasizes sustainability in the context of algae harvesting systems. In conclusion, the analysis ends up with an examination ahead at potential areas for future study in the cultivation and harvesting of algae. This review is an essential guide for scientists, policymakers, and industry experts associated with the advancement and implementation of algae-based technologies.

Physico-chemical treatments for the removal of cyanotoxins from drinking water: Current challenges and future trends

Cyanobacteria are highly prevalent blue-green algae that grow in stagnant and nutrient-rich water bodies. Environmental conditions, such as eutrophication and human activities, increased the cyanobacterial blooms in freshwater resources worldwide. The excessive bloom formation has also resulted in an alarming surge of cyanobacterial toxins. Prolonged exposure to cyanotoxins is a potential threat to natural ecosystems, animal and human health by the spoilage of the quality of bathing and drinking water. Various molecular and analytical methods have been proposed to monitor their occurrence and understand their global distribution. Moreover, different physical, chemical, and biological approaches have been employed to control cyanobacterial blooms and their toxins to mitigate their occurrence. Numerous strategies have been engaged in drinking water treatment plants (DWTPs). However, the degree of treatment varies greatly and is primarily determined by the source, water properties, and operating parameters such as temperature, pH, and cyanotoxin variants and levels. A comprehensive compilation of methods, from traditional approaches to more advanced oxidation processes (AOPs), are presented for the removal of intracellular and extracellular cyanotoxins. This review discusses the effectiveness of various physicochemical operations and their limitations in a DWTP, for the removal of various cyanotoxins. These operations span from simple to advanced treatment levels with varying degrees of effectiveness and differing costs of implementation. Furthermore, mitigation measures applied in other toxin systems have been considered as alternative strategies.

Key drivers of investment initiatives in Uganda's pharmaceutical industry

This study examines the key drivers of investment initiatives in Uganda's pharmaceutical industry. We adopted a qualitative research design using an in-depth interview guide to collect data from 12 board chairpersons/assistants at the selected manufacturing, marketing and sales pharmaceutical firms. The theory of Investment Behavior (Jorgenson, 1967) was used to underpin the actors' investment objectives beyond profit maximization locus subject to utility maximization. The results indicate two complementary investment drivers in pharmaceuticals: an investment gap and government policy initiatives. We recommend that the government should formulate an integrated human resource planning policy and further establish a one-in-all-stop hub to support pharmaceutical investments in the country. Besides, the hub should take charge of the operationalization of government policy initiatives intended to close the investment gap in the pharmaceutical industry.

New insights into enhancement of bio-hydrogen production through encapsulated microalgae with alginate under visible light irradiation

The production of green hydrogen is a promising alternative to fossil fuels. The current study focuses on the design of microalgae as a catalyst in bioelectrochemical systems for the generation of biohydrogen. Furthermore, the abovementioned target could be achieved by optimizing different parameters, including strains of microalgae, different optical filters, and their shapes. Synechocystis sp. PAK13 (Ba9), Micractinium sp. YACCYB33 (R4), and Desmodesmus intermedius (Sh42) were used and designed as free cells and immobilized microalgae for evaluating their performance for hydrogen production. Alginate was applied for immobilization not only for protecting the immobilized microalgae from stress but also for inhibiting the agglomeration of microalgae and improving stability. The amount of studied immobilized microalgae was 0.01 g/5 ml algae-dissolved in 10 ml alginate gel at 28 °C, 12 h of light (light intensity 30.4 μmol m-2 s-1), and 12 h of darkness with continual aeration (air bump in every strain flask) at pH = 7.2 ± 0.2 in 0.05 %wuxal buffer which has 3.7 ionic strength. Different modalities, including FTIR, UV, and SEM, were performed for the description of selected microalgae. The surface morphology of Ba9 with alginate composite (immobilized Ba9) appeared as a stacked layer with high homogeneity, which facilitates hydrogen production from water. The conversion efficiencies of the immobilized microalgae were evaluated by incident photon-to-current efficiency (IPCE). Under optical filters, the optimum IPCE value was ∼ 7 % at 460 nm for immobilized Ba9. Also, its number of hydrogen moles was calculated to be 16.03 mmol h-1 cm-2 under optical filters. The electrochemical stability of immobilized Ba9 was evaluated through repetitive 100 cycles as a short-term stability test, and the curve of chrono-amperometry after 30 min in 0.05 %wuxal at a constant potential of 0.9 V for 30 min of all studied samples confirmed the high stability of all sample and the immobilized Ba9 has superior activity than others.

Green Synthesis of Silver Nanoparticles Using the Cell-Free Supernatant of Haematococcus pluvialis Culture

The green synthesis of silver nanoparticles (AgNPs) using the cell-free supernatant of a Haematococcus pluvialis culture (CFS) was implemented in the current study, under illumination conditions. The reduction of Ag+ to AgNPs by the CFS could be described by a pseudo-first-order kinetic equation at the temperature range tested. A high reaction rate during synthesis and stable AgNPs were obtained at 45 °C, while an alkaline pH (pH = 11.0) and a AgNO3 aqueous solution to CFS ratio of 90:10 (v/v) proved to be the most effective conditions in AgNPs synthesis. A metal precursor (AgNO3) at the concentration range tested (1-5 mM) was the limited reactant in the synthesis process. The synthesis of AgNPs was accomplished under static and agitated conditions. Continuous stirring enhanced the rate of reaction but induced aggregation at prolonged incubation times. Zeta potential and polydispersity index measurements indicated stable AgNPs and the majority of AgNPs formation occurred in the monodisperse phase. The X-ray diffraction (XRD) pattern revealed the face-centered cubic structure of the formed AgNPs, while TEM analysis revealed that the AgNPs were of a quasi-spherical shape with a size from 30 to 50 nm. The long-term stability of the AgNPs could be achieved in darkness and at 4 °C. In addition, the synthesized nanoparticles showed antibacterial activity against Escherichia coli.

Microbial communities in aerosol generated from cyanobacterial bloom-affected freshwater bodies: an exploratory study in Nakdong River, South Korea

Toxic blooms of cyanobacteria, which can produce cyanotoxins, are prevalent in freshwater, especially in South Korea. Exposure to cyanotoxins via ingestion, inhalation, and dermal contact may cause severe diseases. Particularly, toxic cyanobacteria and their cyanotoxins can be aerosolized by a bubble-bursting process associated with a wind-driven wave mechanism. A fundamental question remains regarding the aerosolization of toxic cyanobacteria and cyanotoxins emitted from freshwater bodies during bloom seasons. To evaluate the potential health risk of the aerosolization of toxic cyanobacteria and cyanotoxins, the objectives of this study were as follows: 1) to quantify levels of microcystin in the water and air samples, and 2) to monitor microbial communities, including toxic cyanobacteria in the water and air samples. Water samples were collected from five sites in the Nakdong River, South Korea, from August to September 2022. Air samples were collected using an air pump with a mixed cellulose ester membrane filter. Concentrations of total microcystins were measured using enzyme-linked immunosorbent assay. Shotgun metagenomic sequencing was used to investigate microbial communities, including toxic cyanobacteria. Mean concentrations of microcystins were 960 μg/L ranging from 0.73 to 5,337 μg/L in the water samples and 2.48 ng/m³ ranging from 0.1 to 6.8 ng/m³ in the air samples. In addition, in both the water and air samples, predominant bacteria were Microcystis (PCC7914), which has a microcystin-producing gene, and Cyanobium. Particularly, abundance of Microcystis (PCC7914) comprised more than 1.5% of all bacteria in the air samples. This study demonstrates microbial communities with genes related with microcystin synthesis, antibiotic resistance gene, and virulence factors in aerosols generated from cyanobacterial bloom-affected freshwater body. In summary, aerosolization of toxic cyanobacteria and cyanotoxins is a critical concern as an emerging exposure route for potential risk to environmental and human health.

Microalgae Produce Antioxidant Molecules with Potential Preventive Effects on Mitochondrial Functions and Skeletal Muscular Oxidative Stress

In recent years, microalgae have become a source of molecules for a healthy life. Their composition of carbohydrates, peptides, lipids, vitamins and carotenoids makes them a promising new source of antioxidant molecules. Skeletal muscle is a tissue that requires constant remodeling via protein turnover, and its regular functioning consumes energy in the form of adenosine triphosphate (ATP), which is produced by mitochondria. Under conditions of traumatic exercise or muscular diseases, a high production of reactive oxygen species (ROS) at the origin of oxidative stress (OS) will lead to inflammation and muscle atrophy, with life-long consequences. In this review, we describe the potential antioxidant effects of microalgae and their biomolecules on mitochondrial functions and skeletal muscular oxidative stress during exercises or in musculoskeletal diseases, as in sarcopenia, chronic obstructive pulmonary disease (COPD) and Duchenne muscular dystrophy (DMD), through the increase in and regulation of antioxidant pathways and protein synthesis.

Marine Cyanobacterial Peptides in Neuroblastoma: Search for Better Therapeutic Options

Neuroblastoma is the most prevalent extracranial solid tumor in pediatric patients, originating from sympathetic nervous system cells. Metastasis can be observed in approximately 70% of individuals after diagnosis, and the prognosis is poor. The current care methods used, which include surgical removal as well as radio and chemotherapy, are largely unsuccessful, with high mortality and relapse rates. Therefore, attempts have been made to incorporate natural compounds as new alternative treatments. Marine cyanobacteria are a key source of physiologically active metabolites, which have recently received attention owing to their anticancer potential. This review addresses cyanobacterial peptides' anticancer efficacy against neuroblastoma. Numerous prospective studies have been carried out with marine peptides for pharmaceutical development including in research for anticancer potential. Marine peptides possess several advantages over proteins or antibodies, including small size, simple manufacturing, cell membrane crossing capabilities, minimal drug-drug interactions, minimal changes in blood-brain barrier (BBB) integrity, selective targeting, chemical and biological diversities, and effects on liver and kidney functions. We discussed the significance of cyanobacterial peptides in generating cytotoxic effects and their potential to prevent cancer cell proliferation via apoptosis, the activation of caspases, cell cycle arrest, sodium channel blocking, autophagy, and anti-metastasis behavior.

A review on current advances in the energy and cost effective pretreatments of algal biomass: Enhancement in liquefaction and biofuel recovery

The main downside of utilizing algal biomass for biofuel production is the rigid cell wall which confines the availability of soluble organics to hydrolytic microbes during biofuel conversion. This constraint reduces the biofuel production efficiency of algal biomass. On the other hand, presenting various pretreatment methods before biofuel production affords cell wall disintegration and enhancement in biofuel generation. The potential of pretreatment methods chiefly relies on the extent of biomass liquefaction, energy, and cost demand. In this review, different pretreatments employed to disintegrate algal biomass were conferred in depth with detailed information on their efficiency in enhancing liquefaction and biofuel yield for pilot-scale implementation. Based on this review, it has been concluded that combinative and phase-separated pretreatments provide virtual input in enhancing the biofuel generation based on liquefaction potential, energy, and cost. Future studies should focus on decrement in cost and energy requirement of pretreatment in depth.

Fluorescence inner filters of Arthrospira platensis: Novel perspective for precise fluorescence-based sensors

Microalgae have been reputed as novel biological materials due to their unique structure, surface functionality and optical activity, making them worthwhile agents in biosensing and theranostic applications. However, further scrutiny is required for utilizing them in routine optical techniques due to their complex structure and diverse chemical components. Here, laser induced fluorescence (LIF) features of a bio-compatible microalgae i. e. Arthrospira platensis (Spirulina) have been assessed. Typical fluorescence properties as well as the inner filter effects (IFEs) were examined and revealed to be strongly dependent on concentration, excitation wavelength, and detection geometry as well. IFEs and resulting spectral shifts have been analyzed considering various SP chromophores, reabsorption processes, and resonance energy transfer (RET) mainly from "Carotenoids to Phycobilisomes" as well as "Phycobilisomes to Chlorophyll-a". As a result, LIF spectral shift due to the re-absorption events (secondary-IFE) is introduced as a credible parameter for design of precise fluorescence-based sensors, due to being less dependent on ambient noises. We hope that the findings provide novel features regarding the LIF of Spirulina (SP) that could be utilized to design and develop optical sensors in the field of photonics, material diagnosis and biomedical theranostics.

Plant and Microbial Approaches as Green Methods for the Synthesis of Nanomaterials: Synthesis, Applications, and Future Perspectives

The unique biological and physicochemical characteristics of biogenic (green-synthesized) nanomaterials (NMs) have attracted significant interest in different fields, with applications in the agrochemical, food, medication delivery, cosmetics, cellular imaging, and biomedical industries. To synthesize biogenic nanomaterials, green synthesis techniques use microorganisms, plant extracts, or proteins as bio-capping and bio-reducing agents and their role as bio-nanofactories for material synthesis at the nanoscale size. Green chemistry is environmentally benign, biocompatible, nontoxic, and economically effective. By taking into account the findings from recent investigations, we shed light on the most recent developments in the green synthesis of nanomaterials using different types of microbes and plants. Additionally, we cover different applications of green-synthesized nanomaterials in the food and textile industries, water treatment, and biomedical applications. Furthermore, we discuss the future perspectives of the green synthesis of nanomaterials to advance their production and applications.

Bioactive Compounds from Red Microalgae with Therapeutic and Nutritional Value

Red microalgae represent a natural reservoir of beneficial substances with applications in different industrial sectors. They are rich in natural biomolecules known for their antihypertensive, antioxidant, antimicrobial, antiviral, anti-inflammatory, antitumor, and anticoagulant activities. Many red microalgae are a source of vitamins, minerals, photochemicals, polyunsaturated fatty acids, and a wide spectrum of polysaccharides. The content of their valuable compounds and their activities have turned red microalgae into cellular factories of special interest in food, nutraceutical, and pharmaceutical industries. Like all microalgae, the red ones are superior to traditional crops for the aims of biotechnology as they are renewable sources widely available in great quantities and are easy to culture. Moreover, some of the most studied red microalgae are generally recognized as safe. This review summarizes the valuable biochemicals from red microalgae and highlights their health and nutritional benefits.

Genomic analysis and biochemical profiling of an unaxenic strain of Synechococcus sp. isolated from the Peruvian Amazon Basin region

Cyanobacteria are diverse photosynthetic microorganisms able to produce a myriad of bioactive chemicals. To make possible the rational exploitation of these microorganisms, it is fundamental to know their metabolic capabilities and to have genomic resources. In this context, the main objective of this research was to determine the genome features and the biochemical profile of Synechococcus sp. UCP002. The cyanobacterium was isolated from the Peruvian Amazon Basin region and cultured in BG-11 medium. Growth parameters, genome features, and the biochemical profile of the cyanobacterium were determined using standardized methods. Synechococcus sp. UCP002 had a specific growth rate of 0.086 ± 0.008 μ and a doubling time of 8.08 ± 0.78 h. The complete genome of Synechococcus sp. UCP002 had a size of ∼3.53 Mb with a high coverage (∼200x), and its quality parameters were acceptable (completeness = 99.29%, complete and single-copy genes = 97.5%, and contamination = 0.35%). Additionally, the cyanobacterium had six plasmids ranging from 24 to 200 kbp. The annotated genome revealed ∼3,422 genes, ∼ 3,374 protein-coding genes (with ∼41.31% hypothetical protein-coding genes), two CRISPR Cas systems, and 61 non-coding RNAs. Both the genome and plasmids had the genes for prokaryotic defense systems. Additionally, the genome had genes coding the transcription factors of the metalloregulator ArsR/SmtB family, involved in sensing heavy metal pollution. The biochemical profile showed primary nutrients, essential amino acids, some essential fatty acids, pigments (e.g., all-trans-β-carotene, chlorophyll a, and phycocyanin), and phenolic compounds. In conclusion, Synechococcus sp. UCP002 shows biotechnological potential to produce human and animal nutrients and raw materials for biofuels and could be a new source of genes for synthetic biological applications.

Microalgae-based wastewater treatment for developing economic and environmental sustainability: Current status and future prospects

Over the last several decades, concerns about climate change and pollution due to human activity has gained widespread attention. Microalgae have been proposed as a suitable biological platform to reduce carbon dioxide, a major greenhouse gas, while also creating commercial sources of high-value compounds such as medicines, cosmetics, food, feed, and biofuel. Industrialization of microalgae culture and valorization is still limited by significant challenges in scaling up the production processes due to economic constraints and productivity capacities. Therefore, a boost in resource usage efficiency is required. This enhancement not only lowers manufacturing costs but also enhancing the long-term viability of microalgae-based products. Using wastewater as a nutrient source is a great way to reduce manufacturing costs. Furthermore, water scarcity is one of the most important global challenges. In recent decades, industrialization, globalization, and population growth have all impacted freshwater resources. Moreover, high amounts of organic and inorganic toxins in the water due to the disposal of waste into rivers can have severe impacts on human and animal health. Microalgae cultures are a sustainable solution to tertiary and quaternary treatments since they have the ability to digest complex contaminants. This review presents biorefineries based on microalgae from all angles, including the potential for environmental pollution remediation as well as applications for bioenergy and value-added biomolecule production. An overview of current information about microalgae-based technology and a discussion of the associated hazards and opportunities for the bioeconomy are highlighted.

Towards green biomanufacturing of high-value recombinant proteins using promising cell factory: Chlamydomonas reinhardtii chloroplast

Microalgae are cosmopolitan organisms in nature with short life cycles, playing a tremendous role in reducing the pressure of industrial carbon emissions. Besides, microalgae have the unique advantages of being photoautotrophic and harboring both prokaryotic and eukaryotic expression systems, becoming a popular host for recombinant proteins. Currently, numerous advanced molecular tools related to microalgal transgenesis have been explored and established, especially for the model species Chlamydomonas reinhardtii (C. reinhardtii hereafter). The development of genetic tools and the emergence of new strategies further increase the feasibility of developing C. reinhardtii chloroplasts as green factories, and the strong genetic operability of C. reinhardtii endows it with enormous potential as a synthetic biology platform. At present, C. reinhardtii chloroplasts could successfully produce plenty of recombinant proteins, including antigens, antibodies, antimicrobial peptides, protein hormones and enzymes. However, additional techniques and toolkits for chloroplasts need to be developed to achieve efficient and markerless editing of plastid genomes. Mining novel genetic elements and selectable markers will be more intensively studied in the future, and more factors affecting protein expression are urged to be explored. This review focuses on the latest technological progress of selectable markers for Chlamydomonas chloroplast genetic engineering and the factors that affect the efficiency of chloroplast protein expression. Furthermore, urgent challenges and prospects for future development are pointed out.

Arthrospira platensis Mutagenesis for Protein and C-Phycocyanin Improvement and Proteomics Approaches

Arthrospira (Spirulina) platensis is known for its use as a food supplement, with reported therapeutic properties including antiviral, anti-inflammatory and antioxidant activity. Arthrospira is also an excellent source of proteins and C-phycocyanin. The latter is a light-harvesting pigment-protein complex in cyanobacteria, located on the outer surface of the thylakoid membrane and comprising 40 to 60% of the total soluble protein in cells. Random mutagenesis is a useful tool as a non-genetically modified mutation method that has been widely used to generate mutants of different microorganisms. Exposure of microalgae or cyanobacteria to chemical stimuli affects their growth and many biological processes. Chemicals influence several proteins, including those involved in carbohydrate and energy metabolisms, photosynthesis and stress-related proteins (oxidative stress-reactive oxygen species (ROS) scavenging enzymes). Signal transduction pathways and ion transportation mechanisms are also impacted by chemical treatment, with changes causing the production of numerous biomolecules and stimulation of defence responses. This study compared the protein contents of A. platensis control and after mutagenesis using diethyl sulphate (DES) under various treatment concentrations for effective mutation of A. platensis. Results identified 1152 peptides using proteomics approaches. The proteins were classified into 23 functional categories. Random mutagenesis of A. platensis by DES was found to be highly effective for C-phycocyanin and protein production.

Emerging Trends in Genetic Engineering of Microalgae for Commercial Applications

Recently, microalgal biotechnology has received increasing interests in producing valuable, sustainable and environmentally friendly bioproducts. The development of economically viable production processes entails resolving certain limitations of microalgal biotechnology, and fast evolving genetic engineering technologies have emerged as new tools to overcome these limitations. This review provides a synopsis of recent progress, current trends and emerging approaches of genetic engineering of microalgae for commercial applications, including production of pharmaceutical protein, lipid, carotenoids and biohydrogen, etc. Photochemistry improvement in microalgae and CO2 sequestration by microalgae via genetic engineering were also discussed since these subjects are closely entangled with commercial production of the above mentioned products. Although genetic engineering of microalgae is proved to be very effective in boosting performance of production in laboratory conditions, only limited success was achieved to be applicable to industry so far. With genetic engineering technologies advancing rapidly and intensive investigations going on, more bioproducts are expected to be produced by genetically modified microalgae and even much more to be prospected.

The Effect of Variable Light Source and Light Intensity on the Growth of Three Algal Species

Light is the essential energy source for autotrophically growing organisms, including microalgae. Both light intensity and light quality affect cell growth and biomass composition. Here we used three green algae—Chlamydomonas reinhardtii, Desmodesmus quadricauda, and Parachlorella kessleri—to study the effects of different light intensities and light spectra on their growth. Cultures were grown at three different light intensities (100, 250, and 500 µmol m⁻² s⁻¹) and three different light sources: fluorescent lamps, RGB LEDs, and white LEDs. Cultures of Desmodesmus quadricauda and Parachlorella kessleri were saturated at 250 µmol m⁻² s⁻¹, and further increasing the light intensity did not improve their growth. Chlamydomonas reinhardtii cultures did not reach saturation under the conditions used. All species usually divide into more than two daughter cells by a mechanism called multiple fission. Increasing light intensity resulted in an increase in maximum cell size and division into more daughter cells. In Parachlorella kessleri cells, the concentration of photosynthetic pigments decreased with light intensity. Different light sources had no effect on algal growth or photosynthetic pigments. The results show a species-specific response of algae to light intensity and support the use of any white light source for their cultivation without negative effects on growth.