Cyanobacteria: an emerging source for drug discovery

Development of a base editor for convenient and multiplex genome editing in cyanobacteria

Cyanobacteria are important primary producers, contributing to 25% of the global carbon fixation through photosynthesis. They serve as model organisms to study the photosynthesis, and are important cell factories for synthetic biology. To enable efficient genetic dissection and metabolic engineering in cyanobacteria, effective and accurate genetic manipulation tools are required. However, genetic manipulation in cyanobacteria by the conventional homologous recombination-based method and the recently developed CRISPR-Cas gene editing system require complicated cloning steps, especially during multi-site editing and single base mutation. This restricts the extensive research on cyanobacteria and reduces its application potential. In this study, a highly efficient and convenient cytosine base editing system was developed which allows rapid and precise C → T point mutation and gene inactivation in the genomes of Synechocystis and Anabaena. This base editing system also enables efficient multiplex editing and can be easily cured after editing by sucrose counter-selection. This work will expand the knowledge base regarding the engineering of cyanobacteria. The findings of this study will encourage the biotechnological applications of cyanobacteria.

Diving into freshwater microbial metabolites: Pioneering research and future prospects

In practically every facet of life, especially nutrition, agriculture, and healthcare, microorganisms offer a prospective origin for abundant natural substances and products. Among these microorganisms, bacteria also possess the capability to rapidly acclimate to diverse environments, utilize varied resources, and effectively respond to environmental fluctuations, including those influenced by human activities like pollution and climate change. The ever-changing environment of freshwater bodies influences bacterial communities, offering opportunities for improving health and environmental conservation that remain unexplored. Herein, the study discusses the bacterial taxa along with specialised metabolites with antioxidant, antibacterial, and anticancer activity that have been identified from freshwater environments, thus achieving Sustainable Development Goals addressing health and wellbeing (SDG-3), economic growth (SDG-8) along with industrial development (SDG-9). The present review is intended as a compendium for research teams working in the fields of medicinal chemistry, organic chemistry, clinical research, and natural product chemistry.

Microbial lectins as a potential therapeutics for the prevention of certain human diseases

Lectins are protein or glycoprotein molecules with a specific ability to bind to carbohydrates. From viruses to mammals, they are found in various organisms and exhibit remarkable diverse structures and functions. They are significant contributors to defense mechanisms against microbial attacks in plants. They are also involved in functions such as controlling lymphocyte migration, regulating glycoprotein biosynthesis, cell-cell recognition, and embryonic development in animals. In addition, lectins serve as invaluable molecular tools in various biological and medical disciplines due to their reversible binding ability and enable the monitoring of cell membrane changes in physiological and pathological contexts. Microbial lectins, often referred to as adhesins, play an important role in microbial colonization, pathogenicity, and interactions among microorganisms. Viral lectins are located in the bilayered viral membrane, whereas bacterial lectins are found intracellularly and on the bacterial cell surface. Microfungal lectins are typically intracellular and have various functions in host-parasite interaction, and in fungal growth and morphogenesis. Although microbial lectin studies are less extensive than those of plants and animals, they provide insights into the infection mechanisms and potential interventions. Glycan specificity, essential functions in infectious diseases, and applications in the diagnosis and treatment of viral and bacterial infections are critical aspects of microbial lectin research. In this review, we will discuss the application and therapeutic potential of viral, bacterial and microfungal lectins.

Optimizing Luminous Transmittance of a Three-Dimensional-Printed Fixed Bed Photobioreactor

The development of innovative production processes and the optimization of photobioreactors play an important role in generating industrial competitive production technologies for phototrophic biofilms. With emerse photobioreactors a technology was introduced that allowed efficient surface attached cultivation of terrestrial cyanobacteria. However, the productivity of emerse photobioreactors depends on the available cultivation surface. By the implementation of biocarriers to the bioreactor volume, the cultivation surface can be increased which potentially improves productivity and thus the production of valuable compounds. To investigate the surface attached cultivation on biocarriers new photobioreactors need to be developed. Additive manufacturing (AM) offers new opportunities for the design of photobioreactors but producing the needed transparent parts can be challenging using AM techniques. In this study an emerse fixed bed photobioreactor was designed for the use of biocarriers and manufactured using different AM processes. To validate the suitability of the photobioreactor for phototrophic cultivation, the optical properties of three-dimensional (3D)-printed transparent parts and postprocessing techniques to improve luminous transmittance of the components were investigated. We found that stereolithography 3D printing can produce parts with a high luminous transmittance of over 85% and that optimal postprocessing by sanding and clear coating improved the clarity and transmittance to more than 90%. Using the design freedom of AM resulted in a bioreactor with reduced part count and improved handling. In summary, we found that modern 3D-printing technologies and materials are suitable for the manufacturing of functional photobioreactor prototypes.

Bioactive substances of cyanobacteria and microalgae: Sources, metabolism, and anticancer mechanism insights

Cyanobacteria and microalgae contain various phytochemicals, including bioactive components in the form of secondary metabolites, namely flavonoids, phenolic acids, terpenoids, and tannins, with remarkable anticancer effects. This review highlights the recent advances in bioactive compounds, with potential anticancer activity, produced by cyanobacteria and microalgae. Previous in vitro investigations showed that many of these bioactive compounds exhibit potent effects against different human cancer types, such as leukemia and breast cancers. Multiple mechanisms implicated in the antitumor effect of these compounds were elucidated, including their ability to target cellular, subcellular, and molecular checkpoints linked to cancer development and promotion. Recent findings have highlighted various mechanisms of action of bioactive compounds produced by cyanobacteria and microalgae, including induction of autophagy and apoptosis, inhibition of telomerase and protein kinases, as well as modulation of epigenetic modifications. In vivo investigations have demonstrated a potent anti-angiogenesis effect on solid tumors, as well as a reduction in tumor volume. Some of these compounds were examined in clinical investigations for certain types of cancers, making them potent candidates/scaffolds for antitumor drug development.

Prospective Phycocompounds for Developing Therapeutics for Urinary Tract Infection

Antibiotic resistance of bacteria is causing clinical and public health concerns that are challenging to treat. Infections are becoming more common in the present era, and patients admitted to hospitals often have drug-resistant bacteria that can spread nosocomial infections. Urinary tract infections (UTIs) are among the most common infectious diseases affecting all age groups. There has been an increase in the proportion of bacteria that are resistant to multiple drugs. Herein is a comprehensive update on UTI-associated diseases: cystitis, urethritis, acute urethral syndrome, pyelonephritis, and recurrent UTIs. Further emphasis on the global statistical incidence and recent advancement of the role of natural products in treating notorious infections are described. This updated compendium will inspire the development of novel phycocompounds as the prospective antibacterial candidate.

Stalling the Course of Neurodegenerative Diseases: Could Cyanobacteria Constitute a New Approach toward Therapy?

Neurodegenerative diseases (NDs) are characterized by progressive and irreversible neuronal loss, accompanied by a range of pathological pathways, including aberrant protein aggregation, altered energy metabolism, excitotoxicity, inflammation, and oxidative stress. Some of the most common NDs include Alzheimer's Disease (AD), Parkinson's Disease (PD), Multiple Sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS), and Huntington's Disease (HD). There are currently no available cures; there are only therapeutic approaches that ameliorate the progression of symptoms, which makes the search for new drugs and therapeutic targets a constant battle. Cyanobacteria are ancient prokaryotic oxygenic phototrophs whose long evolutionary history has resulted in the production of a plethora of biomedically relevant compounds with anti-inflammatory, antioxidant, immunomodulatory, and neuroprotective properties, that can be valuable in this field. This review summarizes the major NDs and their pathophysiology, with a focus on the anti-neurodegenerative properties of cyanobacterial compounds and their main effects.

Isolation and Identification of Endophytic Bacteria Bacillus sp. ME9 That Exhibits Biocontrol Activity against Xanthomonas phaseoli pv. manihotis

In recent years, the bacterial blight of cassava has caused substantial economic losses to the Chinese cassava industry. Chemical control methods have become the primary approach to control this disease; however, their widespread usage and harmful residues have raised concerns about environmental pollution. In order to avoid this, it is urgent to seek a green ecological method to prevent and control it. Biological control through the utilization of microorganisms not only effectively inhibits the disease, but also gives consideration to environmental friendliness. Therefore, investigating an endophytic biological control method for cassava bacterial blight is of great importance. In this study, cassava leaf tissues were used as test specimens in order to isolate endophytic bacteria by using dilution and separation methods. Bacillus ME9, derived from cassava endophytic bacteria, exhibits good antagonism against a diverse range of pathogens, including Xpm11. Its genome consists of a series of genes encoding antibacterial lipopeptides, which may be directly related to its antibacterial capabilities. Furthermore, inoculation resulted in a substantial change in the diversity of the endophytic bacterial community, characterized by improved diversity, and displayed an obvious inhibition of pathogenic bacterial growth, demonstrating successful colonization within plants. The results laid a foundation and provided theoretical support for the development and utilization of cassava endophytic bacterial diversity and endogenous disease control strategies.

Tolyporphins-Exotic Tetrapyrrole Pigments in a Cyanobacterium-A Review

Tolyporphins were discovered some 30 years ago as part of a global search for antineoplastic compounds from cyanobacteria. To date, the culture HT-58-2, comprised of a cyanobacterium-microbial consortium, is the sole known producer of tolyporphins. Eighteen tolyporphins are now known-each is a free base tetrapyrrole macrocycle with a dioxobacteriochlorin (14), oxochlorin (3), or porphyrin (1) chromophore. Each compound displays two, three, or four open β-pyrrole positions and two, one, or zero appended C-glycoside (or -OH or -OAc) groups, respectively; the appended groups form part of a geminal disubstitution motif flanking the oxo moiety in the pyrroline ring. The distinct structures and repertoire of tolyporphins stand alone in the large pigments-of-life family. Efforts to understand the cyanobacterial origin, biosynthetic pathways, structural diversity, physiological roles, and potential pharmacological properties of tolyporphins have attracted a broad spectrum of researchers from diverse scientific areas. The identification of putative biosynthetic gene clusters in the HT-58-2 cyanobacterial genome and accompanying studies suggest a new biosynthetic paradigm in the tetrapyrrole arena. The present review provides a comprehensive treatment of the rich science concerning tolyporphins.

Identification, Heterologous Expression, and Characterization of the Tolypodiol Biosynthetic Gene Cluster through an Integrated Approach

Cyanobacteria are tremendous producers of biologically active natural products, including the potent anti-inflammatory compound tolypodiol. However, linking biosynthetic gene clusters with compound production in cyanobacteria has lagged behind that in other bacterial genera. Tolypodiol is a meroterpenoid originally isolated from the cyanobacterium HT-58-2. Here we describe the identification of the tolypodiol biosynthetic gene cluster through heterologous expression in Anabaena and in vitro protein assays of a methyltransferase found in the tolypodiol biosynthetic gene cluster. We have also identified similar biosynthetic gene clusters in cyanobacterial and actinobacterial genomes, suggesting that meroterpenoids with structural similarity to the tolypodiols may be synthesized by other microbes. We also report the identification of two new analogs of tolypodiol that we have identified in both the original and heterologous producer. This work further illustrates the usefulness of Anabaena as a heterologous expression host for cyanobacterial compounds and how integrated approaches can help to link natural product compounds with their producing biosynthetic gene clusters.

Cyanometabolites: molecules with immense antiviral potential

Cyanometabolites are active compounds derived from cyanobacteria that include small low molecular weight peptides, oligosaccharides, lectins, phenols, fatty acids, and alkaloids. Some of these compounds may pose a threat to human and environment. However, majority of them are known to have various health benefits with antiviral properties against pathogenic viruses including Human immunodeficiency virus (HIV), Ebola virus (EBOV), Herpes simplex virus (HSV), Influenza A virus (IAV) etc. Cyanometabolites classified as lectins include scytovirin (SVN), Oscillatoria agardhii agglutinin (OAAH), cyanovirin-N (CV-N), Microcystis viridis lectin (MVL), and microvirin (MVN) also possess a potent antiviral activity against viral diseases with unique properties to recognize different viral epitopes. Studies showed that a small linear peptide, microginin FR1, isolated from a water bloom of Microcystis species, inhibits angiotensin-converting enzyme (ACE), making it useful for the treatment of coronavirus disease 2019 (COVID-19). Our review provides an overview of the antiviral properties of cyanobacteria from the late 90s till now and emphasizes the significance of their metabolites in combating viral diseases, particularly severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has received limited attention in previous publications. The enormous medicinal potential of cyanobacteria is also emphasized in this review, which justifies their use as a dietary supplement to fend off pandemics in future.

The nanomolar affinity of C-phycocyanin from virtual screening of microalgal bioactive as potential ACE2 inhibitor for COVID-19 therapy

The global pandemic of COVID-19 caused by SARS-CoV-2 has caused more than 400 million infections with more than 5.7 million deaths worldwide, and the number of validated therapies from natural products for treating coronavirus infections needs to be increased. Therefore, the virtual screening of bioactive compounds from natural products based on computational methods could be an interesting strategy. Among many sources of bioactive natural products, compounds from marine organisms, particularly microalgae and cyanobacteria, can be potential antiviral agents. The present study investigates bioactive antiviral compounds from microalgae and cyanobacteria as a potential inhibitor of SARS-CoV-2 by targeting Angiotensin-Converting Enzyme II (ACE2) using integrated in silico and in vitro approaches. Our in silico analysis demonstrates that C-Phycocyanin (CPC) can potentially inhibit the binding of ACE2 receptor and SARS-CoV-2 with the docking score of -9.7 kcal mol^-1. This score is relatively more favorable than the native ligand on ACE2 receptor. Molecular dynamics simulation also reveals the stability interaction between both CPC and ACE2 receptor with a root mean square deviation (RMSD) value of 1.5 Å. Additionally, our in vitro analysis using the surface plasmon resonance (SPR) method shows that CPC has a high affinity for ACE2 with a binding affinity range from 5 to 125 µM, with K_D 3.37 nM. This study could serve as a reference to design microalgae- or cyanobacteria-based antiviral drugs for prophylaxis in SARS-CoV-2 infections.

Application of Arthrospira platensis for Medicinal Purposes and the Food Industry: A Review of the Literature

Arthrospira platensis is a filamentous cyanobacterium of the class Cyanophyceae and is the most cultivated photosynthetic prokaryote. It is used in the pharmaceutical sector, medicine and the food industry. It has a rich micro- and macro-element composition, containing proteins, lipids, carbohydrates, essential amino acids, polyunsaturated fatty acids, minerals and raw fibers. It is a commonly used ingredient in food products and nutritional supplements. The wide range of biologically active components determines its diverse pharmacological properties (antioxidant, antidiabetic, antimicrobial, antineoplastic, antitumor, anti-inflammatory, photoprotective, antiviral, etc.). This review summarizes research related to the taxonomy, distribution and chemical composition of Arthrospira platensis as well as its potential application in the food and pharmaceutical industries. Attention is drawn to its various medical applications as an antidiabetic and antiobesity agent, with hepatoprotective, antitumor, antimicrobial and antiviral effects as well as regulatory effects on neurodegenerative diseases.

Computational modeling of cyanobacterial phytoconstituents against toll-like receptors of skin cancer

Melanoma is an extremely dangerous disease. The diagnosis and treatment of it may be difficult because of its diversity and complexity. More than 90% of the marine biomass (microflora and microalgae) constitutes the natural biodiversity reserves. TLR-related research developments indicate possible cancer therapeutic possibilities. In addition to its significant function in innate immunity, TLR activation is connected to the start of pyroptosis, apoptosis, or autophagy in malignance cells. For these reasons, TLR agonists are appealing candidates for the production of cancer medications. From the web databases, the ternary structures of the receptors (TLR3 and TLR4) and ligands are extracted. Sixty-nine compounds were subjected to a drug likeness filter, but only twenty-two were screened further for evaluating ADMET criteria, in which only seven compounds satisfied the pharmacological properties. These compounds are further analyzed for docking parameters against TLRs (TLR3 and TLR4) and molecular simulation investigation of the best cluster to evaluate the complex stability. Molecular docking methodology discovered that Scytonmein has a significant binding potential energy of -5.21 and -7.92 kcal/mol against TLR3 and TLR4, respectively, in comparison to the redock co-crystal structure (-3.98 and -4.30 kcal/mol, respectively). The simulation analysis demonstrates the significant stability of the Scytonemin and TLR4 complexes in terms of average RMSD and RMSF compared to the redock complex, while criteria like solvent-accessible surface area (SASA), gyration (Rg) and hydrogen bonding have further supported the significant interaction and stability of the conformations.Communicated by Ramaswamy H. Sarma.

Naturally Occurring Organohalogen Compounds-A Comprehensive Review

The present volume is the third in a trilogy that documents naturally occurring organohalogen compounds, bringing the total number-from fewer than 25 in 1968-to approximately 8000 compounds to date. Nearly all of these natural products contain chlorine or bromine, with a few containing iodine and, fewer still, fluorine. Produced by ubiquitous marine (algae, sponges, corals, bryozoa, nudibranchs, fungi, bacteria) and terrestrial organisms (plants, fungi, bacteria, insects, higher animals) and universal abiotic processes (volcanos, forest fires, geothermal events), organohalogens pervade the global ecosystem. Newly identified extraterrestrial sources are also documented. In addition to chemical structures, biological activity, biohalogenation, biodegradation, natural function, and future outlook are presented.

Four new suomilides isolated from the cyanobacterium Nostoc sp. KVJ20 and proposal of their biosynthetic origin

The suomilide and the banyasides are highly modified and functionalized non-ribosomal peptides produced by cyanobacteria of the order Nostocales. These compound classes share several substructures, including a complex azabicyclononane core, which was previously assumed to be derived from the amino acid tyrosine. In our study we were able to isolate and determine the structures of four suomilides, named suomilide B - E (1-4). The compounds differ from the previously isolated suomilide A by the functionalization of the glycosyl group. Compounds 1-4 were assayed for anti-proliferative, anti-biofilm and anti-bacterial activities, but no significant activity was detected. The sequenced genome of the producer organism Nostoc sp. KVJ20 enabled us to propose a biosynthetic gene cluster for suomilides. Our findings indicated that the azabicyclononane core of the suomilides is derived from prephenate and is most likely incorporated by a proline specific non-ribosomal peptide synthetase-unit.

Crosstalk between biological and chemical diversity with cytotoxic and cytostatic effects of Aphanothece halophytica in vitro

Different solvent extracts from Aphanothece halophytica (A. halophytica) were evaluated for their cytotoxic effects against four human cancer cell lines. The samples demonstrated different percentages of cyanobacteria species populations. The samples containing 100% A. halophytica and 90% A. halophytica showed a significant cytotoxic effect in human breast cancer cells MDA231. The cytostatic effect was demonstrated in MDA231 and human glioblastoma T98G cells regardless of the treatment, resulting in a significant cell cycle arrest in the S phase. The chemical profiles of the extracts were proven to be diverse in qualitative and quantitative compositions. This variability was dependent on the A. halophytica´s abundance in each extract. The 100% A. halophytica extract induced cytotoxic and cytostatic effects in breast cancer cells, and those could be associated with the predominance of fatty acids, hydrocarbons and phthalates, indicating that A. halophytica is an interesting source of novel compound with anticancer effect.

Revisiting the role of cyanobacteria-derived metabolites as antimicrobial agent: A 21st century perspective

Cyanobacterial species are ancient photodiazotrophs prevalent in freshwater bodies and a natural reservoir of many metabolites (low to high molecular weight) such as non-ribosomal peptides, polyketides, ribosomal peptides, alkaloids, cyanotoxins, and isoprenoids with a well-established bioactivity potential. These metabolites enable cyanobacterial survival in extreme environments such as high salinity, heavy metals, cold, UV-B, etc. Recently, these metabolites are gaining the attention of researchers across the globe because of their tremendous applications as antimicrobial agents. Many reports claim the antimicrobial nature of these metabolites; unfortunately, the mode of action of such metabolites is not well understood and/or known limited. Henceforth, this review focuses on the properties and potential application, also critically highlighting the possible mechanism of action of these metabolites to offer further translational research. The review also aims to provide a comprehensive insight into current gaps in research on cyanobacterial biology as antimicrobials and hopes to shed light on the importance of continuing research on cyanobacteria metabolites in the search for novel antimicrobials.

In-vitro anti-Mycobacterium tuberculosis effect of Eugenol

BACKGROUND/OBJECTIVES

Mycobacterium tuberculosis, the causative agent of tuberculosis has developed resistance to most of the available antimicrobials. Therefore research on the detection of new antimicrobials against Mycobacterium tuberculosis is needed urgently. Essential oils extracted from plants have been shown to have anti-Mycobacterium tuberculosis effect in in-vitro experiments. Essential oil contains many chemicals and any one or more than one chemical may have the anti-Mycobacterium tuberculosis effect. Eugenol is one such chemical in the essential oil and the anti-Mycobacterium tuberculosis effect of eugenol is investigated.

METHODS

The anti-Mycobacterium tuberculosis effect of eugenol was evaluated against H37Rv and twelve clinical isolates of Mycobacterium tuberculosis in the BD BACTEC MGIT instrument using different volumes of eugenol.

RESULTS

H37Rv and all the twelve clinical isolates of Mycobacterium tuberculosis were inhibited by eugenol. The minimal inhibitory concentration of H37Rv was 2.5 μl (2.67 mg) and those of the clinical isolates of Mycobacterium tuberculosis ranged from to 2.5 μl (2.67 mg) to 10 μl (10.68 mg).

CONCLUSION

Eugenol has anti-Mycobacterium tuberculosis effect in the in-vitro BD BACTEC MGIT method.

Molecular Docking and In-Silico Analysis of Natural Biomolecules against Dengue, Ebola, Zika, SARS-CoV-2 Variants of Concern and Monkeypox Virus

The emergence and rapid evolution of human pathogenic viruses, combined with the difficulties in developing effective vaccines, underline the need to develop innovative broad-spectrum antiviral therapeutic agents. The present study aims to determine the in silico antiviral potential of six bacterial antimicrobial peptides (AMPs), two phytochemicals (silvestrol, andrographolide), and two bacterial secondary metabolites (lyngbyabellin A, hapalindole H) against dengue virus, Zika virus, Ebola virus, the major variants of SARS-CoV-2 and monkeypox virus. The comparison of docking scores obtained with natural biomolecules was performed with specific neutralizing antibodies (positive controls for ClusPro) and antiviral drugs (negative controls for Autodock Vina). Glycocin F was the only natural biomolecule tested to show high binding energies to all viral surface proteins and the corresponding viral cell receptors. Lactococcin G and plantaricin ASM1 also achieved high docking scores with all viral surface proteins and most corresponding cell surface receptors. Silvestrol, andrographolide, hapalindole H, and lyngbyabellin A showed variable docking scores depending on the viral surface proteins and cell receptors tested. Three glycocin F mutants with amino acid modifications showed an increase in their docking energy to the spike proteins of SARS-CoV-2 B.1.617.2 Indian variant, and of the SARS-CoV-2 P.1 Japan/Brazil variant, and the dengue DENV envelope protein. All mutant AMPs indicated a frequent occurrence of valine and proline amino acid rotamers. AMPs and glycocin F in particular are the most promising biomolecules for the development of broad-spectrum antiviral treatments targeting the attachment and entry of viruses into their target cell.

Bioprospecting microalgae and cyanobacteria for biopharmaceutical applications

Microalgae and cyanobacteria have sparked a lot of interest due to their potential in various industries like biorefineries, biopharmaceuticals, food supplements, nutraceuticals, and other high-value products. Polysaccharides, vitamins, proteins, enzymes, and steroids are valuable products isolated from microalgae and cyanobacteria and potentially used in health and biomedical applications. Bioactive compounds derived from microalgae and cyanobacteria exhibit various pharmaceutical properties like antibacterial, anticancer, antiviral, antialgal, and antioxidant. From the properties listed above, the research for novel antibiotics has become particularly appropriate. In addition, the possible emergence of resistance against pathogens, as well as the potential decline in antibiotic efficacy, has prompted researchers to look for a new source of antibiotics. Microalgae and cyanobacteria have indicated a great and unexplored potential among these sources. For this reason, microalgae and cyanobacteria have been highlighted for their efficiency in different industrial sectors, as well as for their potential uses in the betterment of human and environmental health. This review gives an overview of bioactive compounds and metabolites with several biological properties isolated from microalgae and cyanobacteria for treating different animal and human diseases.

Oscillatoria sp. as a Potent Anti-phytopathogenic Agent and Plant Immune Stimulator Against Root-Knot Nematode of Soybean cv. Giza 111

BACKGROUND

Plant-parasitic nematodes are one of the major constraints to soybean production around the world. Plant-parasitic nematodes cause an estimated $78 billion in annual crop losses worldwide, with a 10-15% crop yield loss on average. Consequently, finding and applying sustainable methods to control diseases associated with soybean is currently in serious need.

METHODS

In this study, we isolated, purified, characterized, and identified a novel cyanobacterial strain Oscillatoria sp. (blue-green alga). Based on its microscopic examination and 16S rRNA gene sequence, the aqueous and methanolic extracts of Oscillatoria were used to test their nematicidal activity against Meloidogyne incognita hatchability of eggs after 72 h of exposure time and juvenile mortality percentage in vitro after 24, 48, and 72 h of exposure time and reduction percentage of galls, eggmass, female number/root, and juveniles/250 soil. Also, the efficacy of the extract on improving the plant growth parameter and chlorophyll content under greenhouse conditions on soybean plant cv. Giza 111 was tested. Finally, the expression of PR-1, PR-2, PR-5, and PR15 (encoding enzymes) genes contributing to plant defense in the case of M. incognita invasion was studied and treated with Oscillatoria extract.

RESULTS

The aqueous and methanolic extracts of Oscillatoria sp. had nematicidal activity against M. incognita. The percentage of mortality and egg hatching of M. incognita were significantly increased with the increase of time exposure to Oscillatoria extract 96.7, 97, and 98 larvae mortality % with S concentration after 24, 48, and 72 h of exposure time. The aqueous extract significantly increased the percentage of Root-Knot nematodes (RKN) of egg hatching, compared with Oxamyl and methanol extract at 96.7 and 97% after 72 h and 1 week, respectively. With the same concentration in the laboratory experiment. Furthermore, water extracts significantly reduced the number of galls in soybean root, egg masses, and female/root by 84.1, 87.5, and 92.2%, respectively, as well as the percentage of J2s/250 g soil by 93.7%. Root, shoot lengths, dry weight, number of pods/plant, and chlorophyll content of soybean treated with Oscillatoria water extract were significantly higher than the control increasing by 70.3, 94.1, 95.5, and 2.02%, respectively. The plant defense system's gene expression was tracked using four important pathogenesis-related genes, PR-1, PR-2, PR-5, and PR15, which encode enzymes involved in plant defense.

CONCLUSIONS

Oscillatoria extract is a potential nematicide against root-knot nematode invasion in soybean.

Insights into cyanobacterial alkane biosynthesis

Alkanes are high-energy molecules that are compatible with enduring liquid fuel infrastructures, which make them highly suitable for being next-generation biofuels. Though biological production of alkanes has been reported in various microorganisms, the reports citing photosynthetic cyanobacteria as natural producers have been the most consistent for the long-chain alkanes and alkenes (C15-C19). However, the production of alkane in cyanobacteria is low, leading to its extraction being uneconomical for commercial purposes. In order to make alkane production economically feasible from cyanobacteria, the titre and yield need to be increased by several orders of magnitude. In the recent past, efforts have been made to enhance alkane production, although with a little gain in yield, leaving space for much improvement. Genetic manipulation in cyanobacteria is considered challenging, but recent advancements in genetic engineering tools may assist in manipulating the genome in order to enhance alkane production. Further, advancement in a basic understanding of metabolic pathways and gene functioning will guide future research for harvesting the potential of these tiny photosynthetically efficient factories. In this review, our focus would be to highlight the current knowledge available on cyanobacterial alkane production, and the potential aspects of developing cyanobacterium as an economical source of biofuel. Further insights into different metabolic pathways and hosts explored so far, and possible challenges in scaling up the production of alkanes will also be discussed.

Discovery of Anticancer Agents of Diverse Natural Origin

Research progress from mainly over the last five years is described for a multidisciplinary collaborative program project directed toward the discovery of potential anticancer agents from a broad range of taxonomically defined organisms. Selected lead compounds with potential as new antitumor agents that are representative of considerable structural diversity have continued to be obtained from each of tropical plants, terrestrial and aquatic cyanobacteria, and filamentous fungi. Recently, a new focus has been on the investigation of the constituents of U.S. lichens and their fungal mycobionts. A medicinal chemistry and pharmacokinetics component of the project has optimized structurally selected lead natural products, leading to enhanced cytotoxic potencies against selected cancer cell lines. Biological testing has shown several compounds to have in vivo activity, and relevant preliminary structure-activity relationship and mechanism of action studies have been performed. Several promising lead compounds worthy of further investigation have been identified from the most recent collaborative work performed.

A Novel Approach for Fast Screening of a Complex Cyanobacterial Extract for Immunomodulatory Properties and Antibacterial Activity

The filamentous cyanobacteria from genus Phormidium are rich natural sources of bioactive compounds that could be exploited as pharmaceuticals or nutraceuticals. In this study, we suggest a novel approach for assessing the immunomodulatory properties of the products derived from cyanobacteria. The influence of Phormidium papyraceum extract on the human leukocyte immunophenotype was evaluated by attempting to link this activity to certain putative compounds identified in the extract. By using three staining panels and flow cytometry, we found that the cyanobacterial extract affected mainly CD4+ T cells upregulating activated CD4+CD152+ T cells (15.75 ± 1.93% treated vs. 4.65 ± 1.41% control) and regulatory CD4+CD25+ T cells (5.36 ± 0.64% treated vs. 1.03 ± 0.08% control). Furthermore, P. papyraceum extract can modulate T cell subpopulations with a CD4+ effector/memory phenotype. Extract-treated cells showed increased production of IL-2 (55 ± 12 pg/mL) and IL-6 (493 ± 64 pg/mL) compared to the untreated, 21 ± 7 pg/mL and 250 ± 39 pg/mL, respectively. No significant changes were observed in the secretion of TNF-α. In addition, P. papyraceum extract displayed antibacterial activity against both Gram-negative (inhibition zone from 18.25 ± 0.50 mm to 20.28 ± 1.50 mm) and Gram-positive (inhibition zone from 10.86 ± 0.85 mm to 17.00 ± 0.82 mm) bacteria. The chemical profile of the cyanobacterial extract was determined using LC–ESI–MS/MS analysis, where at least 112 putative compounds were detected. Many of these compounds have proven different biological activities. We speculated that compounds such as betulin and the macrolide azithromycin (or their analogues) could be responsible for the immunomodulatory potential of the investigated extract. More studies are needed to determine and validate the biological activities of the determined putative compounds.

Influence of wettability and surface design on the adhesion of terrestrial cyanobacteria to additive manufactured biocarriers

Productive biofilms are gaining growing interest in research due to their potential of producing valuable compounds and bioactive substances such as antibiotics. This is supported by recent developments in biofilm photobioreactors that established the controlled phototrophic cultivation of algae and cyanobacteria. Cultivation of biofilms can be challenging due to the need of surfaces for biofilm adhesion. The total production of biomass, and thus production of e.g. bioactive substances, within the bioreactor volume highly depends on the available cultivation surface. To achieve an enlargement of surface area for biofilm photobioreactors, biocarriers can be implemented in the cultivation. Thereby, material properties and design of the biocarriers are important for initial biofilm formation and growth of cyanobacteria. In this study, special biocarriers were designed and additively manufactured to investigate different polymeric materials and surface designs regarding biofilm adhesion of the terrestrial cyanobacterium Nostoc flagelliforme (CCAP 1453/33). Properties of 3D-printed materials were characterized by determination of wettability, surface roughness, and density. To evaluate the influence of wettability on biofilm formation, material properties were specifically modified by gas-phase fluorination and biofilm formation was analyzed on biocarriers with basic and optimized geometry in shaking flask cultivation. We found that different polymeric materials revealed no significant differences in wettability and with identical surface design no significant effect on biomass adhesion was observed. However, materials treated with fluorination as well as optimized biocarrier design showed improved wettability and an increase in biomass adhesion per biocarrier surface.

Antimicrobial Compounds from Microorganisms

Antimicrobial resistance is an exigent public health concern owing to the emergence of novel strains of human resistant pathogens and the concurrent rise in multi-drug resistance. An influx of new antimicrobials is urgently required to improve the treatment outcomes of infectious diseases and save lives. Plant metabolites and bioactive compounds from chemical synthesis have found their efficacy to be dwindling, despite some of them being developed as drugs and used to treat human infections for several decades. Microorganisms are considered untapped reservoirs for promising biomolecules with varying structural and functional antimicrobial activity. The advent of cost-effective and convenient model organisms, state-of-the-art molecular biology, omics technology, and machine learning has enhanced the bioprospecting of novel antimicrobial drugs and the identification of new drug targets. This review summarizes antimicrobial compounds isolated from microorganisms and reports on the modern tools and strategies for exploiting promising antimicrobial drug candidates. The investigation identified a plethora of novel compounds from microbial sources with excellent antimicrobial activity against disease-causing human pathogens. Researchers could maximize the use of novel model systems and advanced biomolecular and computational tools in exploiting lead antimicrobials, consequently ameliorating antimicrobial resistance.

Some Natural Photosensitizers and Their Medicinal Properties for Use in Photodynamic Therapy

Despite significant advances in early diagnosis and treatment, cancer is one of the leading causes of death. Photodynamic therapy (PDT) is a therapy for the treatment of many diseases, including cancer. This therapy uses a combination of a photosensitizer (PS), light irradiation of appropriate length and molecular oxygen. The photodynamic effect kills cancer cells through apoptosis, necrosis, or autophagy of tumor cells. PDT is a promising approach for eliminating various cancers but is not yet as widely applied in therapy as conventional chemotherapy. Currently, natural compounds with photosensitizing properties are being discovered and identified. A reduced toxicity to healthy tissues and a lower incidence of side effects inspires scientists to seek natural PS for PDT. In this review, several groups of compounds with photoactive properties are presented. The use of natural products has been shown to be a fruitful approach in the discovery of novel pharmaceuticals. This review focused on the anticancer activity of furanocoumarins, polyacetylenes, thiophenes, tolyporphins, curcumins, alkaloid and anthraquinones in relation to the light-absorbing properties. Attention will be paid to their phototoxic and anti-cancer effects on various types of cancer.

Identification and characterization of the novel bioactive compounds from microalgae and cyanobacteria for pharmaceutical and nutraceutical applications

Microalgae and cyanobacteria (blue-green algae) are used as food by humans. They have gained a lot of attention in recent years because of their potential applications in biotechnology. Microalgae and cyanobacteria are good sources of many valuable compounds, including important biologically active compounds with antiviral, antibacterial, antifungal, and anticancer activities. Under optimal growth condition and stress factors, algal biomass produce varieties of potential bioactive compounds. In the current review, bioactive compounds production and their remarkable applications such as pharmaceutical and nutraceutical applications along with processes involved in identification and characterization of the novel bioactive compounds are discussed. Comprehensive knowledge about the exploration, extraction, screening, and trading of bioactive products from microalgae and cyanobacteria and their pharmaceutical and other applications will open up new avenues for drug discovery and bioprospecting.

Phycochemistry and bioactivity of cyanobacterial secondary metabolites

Microbes are a huge contributor to people's health around the world since they produce a lot of beneficial secondary metabolites. Cyanobacteria are photosynthetic prokaryotic bacteria cosmopolitan in nature. Adaptability of cyanobacteria to wide spectrum of environment can be contributed to the production of various secondary metabolites which are also therapeutic in nature. As a result, they are a good option for the development of medicinal molecules. These metabolites could be interesting COVID-19 therapeutic options because the majority of these compounds have demonstrated substantial pharmacological actions, such as neurotoxicity, cytotoxicity, and antiviral activity against HCMV, HSV-1, HHV-6, and HIV-1. They have been reported to produce a single metabolite active against wide spectrum of microbes like Fischerella ambigua produces ambigols active against bacteria, fungi and protozoa. Similarly, Moorea producens produces malygomides O and P, majusculamide C and somocystinamide which are active against bacteria, fungi and tumour cells, respectively. In addition to the above, Moorea sp. produce apratoxin A and dolastatin 15 possessing anti cancerous activity but unfortunately till date only brentuximab vedotin (trade name Adcetris), a medication derived from marine peptides, for the treatment of Hodgkin lymphoma and anaplastic large cell lymphoma has been approved by FDA. However, several publications have effectively described and categorised cyanobacterial medicines based on their biological action. In present review, an effort is made to categorize cyanobacterial metabolites on the basis of their phycochemistry. The goal of this review is to categorise cyanobacterial metabolites based on their chemical functional group, which has yet to be described.

Cyanobacterial Genome Sequencing, Annotation, and Bioinformatics

Cyanobacteria are collectively a globally important monophyletic phylum of bacteria. They have attracted a lot of attention, not only because they are rich sources of natural bioactive products, including toxic substances, but also because they play an important role in global nitrogen and carbon cycles, and are capable of maintaining versatile environmental niche adaptations. A vast number of cyanobacterial genomes have become available due to fast development of sequencing technologies, but effort is still needed to comprehensively understand the molecular basis of their diversity. Here, we introduce a basic pipeline for the cyanobacterial genome sequencing project that can be employed to complete the whole cyanobacterial genome. The pipeline includes DNA extraction from the cyanobacterial culture of interest, hybrid genome sequencing, and genome assembly and annotation. At the end of the chapter, we briefly introduce genome mining tools and one successful genome mining example from our laboratory. This chapter provides general guidance regarding the sequencing project and thus includes several references for alternative methods and tools so that the reader can easily modify the pipeline according to the needs of the laboratory.

Gut Microbiota-Medication Interaction in Rheumatic Diseases

Besides its contribution to the development of rheumatic diseases, the gut microbiota interact with anti-rheumatic drugs. The intestinal microbiota can directly metabolize many drugs and indirectly change drug metabolism through a complex multi-dimensional interaction with the host, thus affecting individual response to drug therapy and adverse effects. The focus of the current review is to address recent advances and important progress in our understanding of how the gut microbiota interact with anti-rheumatic drugs and provide perspectives on promoting precision treatment, drug discovery, and better therapy for rheumatic diseases.

In-vitro anti-Mycobacterium tuberculosis effect of essential oil of Ocimum sanctum L. (Tulsi/Basil) leaves

BACKGROUND/OBJECTIVES

Mycobacterium tuberculosis, the causative agent of tuberculosis has developed resistance to most of the available antimicrobials. Consequently, it is difficult to cure all the patients with tuberculosis and in future, the incidence of tuberculosis by drug resistant M. tuberculosis is likely to increase, worldwide. Therefore detection and development of new antimicrobials against M. tuberculosis is needed urgently.

METHODS

Essential oil from the leaves of Ocimum sanctum L (Tulsi/Basil) was obtained by hydro distillation. The anti-mycobacterial effect of essential oil was evaluated against H37Rv and nine clinical isolates of M. tuberculosis in the BD BACTEC MGIT instrument using different volumes of essential oil.

RESULTS

The essential oil inhibited the growth of H37Rv and all the nine clinical isolates of M. tuberculosis. The minimal inhibitory concentration of H37Rv was 3 μl (2.931 μg) and those of the clinical isolates of M. tuberculosis ranged from 1.5 μl (1.4655 μg) to 6 μl (5.862 μg).

CONCLUSION

The Essential oil from the leaves of O. sanctum L.(Tulsi/Basil) has anti-M. tuberculosis effect in the in-vitro BD BACTEC MGIT method.

Cyanobacteria derived compounds: Emerging drugs for cancer management

The wide diversity of cyanobacterial species and their role in a variety of biological activities have been reported in the previous few years. Cyanobacteria, especially from marine sources, constitutes a major source of biologically active metabolites that have gained great attention especially due to their anticancer potential. Numerous chemically diverse metabolites from various cyanobacterial species have been recognized to inhibit the growth and progression of tumor cells through the induction of apoptosis in many different types of cancers. These metabolites activate the apoptosis in the cancer cells by different molecular mechanisms, however, the dysregulation of the mitochondrial pathway, death receptors signaling pathways, and the activation of several caspases are the crucial mechanisms that got considerable interest. The array of metabolites and the range of mechanisms involved may also help to overcome the resistance acquired by the different tumor types against the ongoing therapeutic agents. Therefore, the primary or secondary metabolites from the cyanobacteria as well as their synthetic derivates could be used to develop novel anticancer drugs alone or in combination with other chemotherapeutic agents. In this study, we have discussed the role of cyanobacterial metabolites in the induction of cytotoxicity and the potential to inhibit the growth of cancer cells through the induction of apoptosis, cell signaling alteration, oxidative damage, and mitochondrial dysfunctions. Moreover, the various metabolites produced by cyanobacteria have been summarized with their anticancer mechanisms. Furthermore, the ongoing trials and future developments for the therapeutic implications of these compounds in cancer therapy have been discussed.

Evaluation of inducible promoter-riboswitch constructs for heterologous protein expression in the cyanobacterial species Anabaena sp. PCC 7120

Cyanobacteria are promising chassis for synthetic biology applications due to the fact that they are photosynthetic organisms capable of growing in simple, inexpensive media. Given their slower growth rate than other model organisms such as Escherichia coli and Saccharomyces cerevisiae, there are fewer synthetic biology tools and promoters available for use in model cyanobacteria. Here, we compared a small library of promoter–riboswitch constructs for synthetic biology applications in Anabaena sp. PCC 7120, a model filamentous cyanobacterium. These constructs were designed from six cyanobacterial promoters of various strengths, each paired with one of two theophylline-responsive riboswitches. The promoter–riboswitch pairs were cloned upstream of a chloramphenicol acetyltransferase (cat) gene, and CAT activity was quantified using an in vitro assay. Addition of theophylline to cultures increased the CAT activity in almost all cases, allowing inducible protein production with natively constitutive promoters. We found that riboswitch F tended to have a lower induced and uninduced production compared to riboswitch E for the weak and medium promoters, although the difference was larger for the uninduced production, in accord with previous research. The strong promoters yielded a higher baseline CAT activity than medium strength and weak promoters. In addition, we observed no appreciable difference between CAT activity measured from strong promoters cultured in uninduced and induced conditions. The results of this study add to the genetic toolbox for cyanobacteria and allow future natural product and synthetic biology researchers to choose a construct that fits their needs.

Genome Streamlining, Plasticity, and Metabolic Versatility Distinguish Co-occurring Toxic and Nontoxic Cyanobacterial Strains of Microcoleus

Harmful cyanobacterial bloom occurrences have increased worldwide due to climate change and eutrophication, causing nuisance and animal deaths. Species from the benthic cyanobacterial genus Microcoleus are ubiquitous and form thick mats in freshwater systems, such as rivers, that are sometimes toxic due to the production of potent neurotoxins (anatoxins). Anatoxin-producing (toxic) strains typically coexist with non-anatoxin-producing (nontoxic) strains in mats, although the reason for this is unclear. To determine the genetic mechanisms differentiating toxic and nontoxic Microcoleus, we sequenced and assembled genomes from 11 cultures and compared these to another 31 Microcoleus genomes. Average nucleotide identities (ANI) indicate that toxic and nontoxic strains are distinct species (ANI, <95%), and only 6% of genes are shared across all 42 genomes, suggesting a high level of genetic divergence among Microcoleus strains. Comparative genomics showed substantial genome streamlining in toxic strains and a potential dependency on external sources for thiamine and sucrose. Toxic and nontoxic strains are further differentiated by an additional set of putative nitrate transporter (nitrogen uptake) and cyanophycin (carbon and nitrogen storage) genes, respectively. These genes likely confer distinct competitive advantages based on nutrient availability and suggest nontoxic strains are more robust to nutrient fluctuations. Nontoxic strains also possess twice as many transposable elements, potentially facilitating greater genetic adaptation to environmental changes. Our results offer insights into the divergent evolution of Microcoleus strains and the potential for cooperative and competitive interactions that contribute to the co-occurrence of toxic and nontoxic species within mats. IMPORTANCE Microcoleus autumnalis, and closely related Microcoleus species, compose a geographically widespread group of freshwater benthic cyanobacteria. Canine deaths due to anatoxin-a poisoning, following exposure to toxic proliferations, have been reported globally. While Microcoleus proliferations are on the rise, the mechanisms underpinning competition between, or coexistence of, toxic and nontoxic strains are unknown. This study identifies substantial genetic differences between anatoxin-producing and non-anatoxin-producing strains, pointing to reduced metabolic flexibility in toxic strains, and potential dependence on cohabiting nontoxic strains. Results provide insights into the metabolic and evolutionary differences between toxic and nontoxic Microcoleus, which may assist in predicting and managing aquatic proliferations.

Total syntheses and antiproliferative activities of prenostodione and its analogues

A high-yielding total synthesis of the indole alkaloid prenostodione was completed in 4 steps and 44% overall yield from 1H-indole-3-carboxylic acid. The expedient syntheses of prenostodiones containing distinct substituents at the para position of the phenyl frame underscored the scope of this methodology. The cytotoxic activities of the tert-butyl esters of prenostodione analogues were tested using six tumor cell lines. Preliminary structure-activity studies revealed the importance of the identity of the aromatic substituent at the C-4 position for cytotoxic activity. The IC50 values of these compounds were found to compare satisfactorily with those of the commercially available drugs etoposide and cisplatin. Furthermore, the compounds with, respectively, -OMe (14d) and -NO2 (14f) groups at C-4 were more selective than these control compounds in PC-3, K-562, and MCF-7 cells. Also, computational studies were carried out to determine the ADMET profiles and passive membrane permeabilities of the compounds. The results suggested the promise of 14d and 14f as hit compounds for the development of new anticancer agents.

Phormidepistatin from the Cyanobacterium UIC 10484: Assessing the Phylogenetic Distribution of the Statine Pharmacophore

A new linear lipopeptide, phormidepistatin (1), containing an epi-statine amino acid was isolated from cf. Phormidium sp. strain UIC 10484. The planar structure was elucidated by 1D and 2D NMR experimentation. The relative configuration was determined by J-based configurational analysis and the absolute configuration by advanced Marfey's analysis. Given that the statine moiety is an established pharmacophore known to inhibit aspartic proteases, phormidepistatin was evaluated against cathepsin D and displayed limited activity. With 1 containing a statine-like moiety, we sought to assess the distribution of this γ-amino acid within the phylum Cyanobacteria. In-depth MS/MS analysis identified the presence of phormidepistatin in cf. Phormidium sp. UIC 10045 and cf. Trichormus sp. UIC 10039. A structure database search identified 33 known cyanobacterial metabolites containing a statine or statine-like amino acid and, along with phormidepistatin, were grouped into 10 distinct compound classes. A phylogenetic tree was built comprising all cyanobacteria with established 16S rRNA sequences known to produce statine or statine-like-containing compound classes. This analysis suggests the incorporation of the γ-amino acid into secondary metabolites is taxonomically widespread within the phylum. Overall, it is our assessment that cyanobacteria are a potential source for statine or statine-like-containing compounds.

Emerging Optical Materials in Sensing and Discovery of Bioactive Compounds

Optical biosensors are used in numerous applications and analytical fields. Advances in these sensor platforms offer high sensitivity, selectivity, miniaturization, and real-time analysis, among many other advantages. Research into bioactive natural products serves both to protect against potentially dangerous toxic compounds and to promote pharmacological innovation in drug discovery, as these compounds have unique chemical compositions that may be characterized by greater safety and efficacy. However, conventional methods for detecting these biomolecules have drawbacks, as they are time-consuming and expensive. As an alternative, optical biosensors offer a faster, simpler, and less expensive means of detecting various biomolecules of clinical interest. In this review, an overview of recent developments in optical biosensors for the detection and monitoring of aquatic biotoxins to prevent public health risks is first provided. In addition, the advantages and applicability of these biosensors in the field of drug discovery, including high-throughput screening, are discussed. The contribution of the investigated technological advances in the timely and sensitive detection of biotoxins while deciphering the pathways to discover bioactive compounds with great health-promoting prospects is envisaged to meet the increasing demands of healthcare systems.

Thirtieth Anniversary of the Discovery of Laxaphycins. Intriguing Peptides Keeping a Part of Their Mystery

Lipopeptides are a class of compounds generally produced by microorganisms through hybrid biosynthetic pathways involving non-ribosomal peptide synthase and a polyketyl synthase. Cyanobacterial-produced laxaphycins are examples of this family of compounds that have expanded over the past three decades. These compounds benefit from technological advances helping in their synthesis and characterization, as well as in deciphering their biosynthesis. The present article attempts to summarize most of the articles that have been published on laxaphycins. The current knowledge on the ecological role of these complex sets of compounds will also be examined.

Identification of Putative Biosynthetic Gene Clusters for Tolyporphins in Multiple Filamentous Cyanobacteria

Tolyporphins A-R are unusual tetrapyrrole macrocycles produced by the non-axenic filamentous cyanobacterium HT-58-2. A putative biosynthetic gene cluster for biosynthesis of tolyporphins (here termed BGC-1) was previously identified in the genome of HT-58-2. Here, homology searching of BGC-1 in HT-58-2 led to identification of similar BGCs in seven other filamentous cyanobacteria, including strains Nostoc sp. 106C, Nostoc sp. RF31YmG, Nostoc sp. FACHB-892, Brasilonema octagenarum UFV-OR1, Brasilonema octagenarum UFV-E1, Brasilonema sennae CENA114 and Oculatella sp. LEGE 06141, suggesting their potential for tolyporphins production. A similar gene cluster (BGC-2) also was identified unexpectedly in HT-58-2. Tolyporphins BGCs were not identified in unicellular cyanobacteria. Phylogenetic analysis based on 16S rRNA and a common component of the BGCs, TolD, points to a close evolutionary history between each strain and their respective tolyporphins BGC. Though identified with putative tolyporphins BGCs, examination of pigments extracted from three cyanobacteria has not revealed the presence of tolyporphins. Overall, the identification of BGCs and potential producers of tolyporphins presents a collection of candidate cyanobacteria for genetic and biochemical analysis pertaining to these unusual tetrapyrrole macrocycles.

Anti-enterococcal and anti-oxidative potential of a thermophilic cyanobacterium, Leptolyngbya sp. HNBGU 003

Enterococci, the opportunistic pathogens, pose several serious and life-threatening infections such as urinary tract infections, sepsis, and endocarditis. The situation is worsening due to the development of drug resistance in these pathogens against several antibiotics. The addition of anti-enterococcal compounds with antioxidant activity in fermented and packaged food may help prevent the transmission of food-borne enterococcal infections. Scientists are in continuous search of such compounds from various sources. Hence, the present study has tested the diethyl ether extracts of thermophilic cyanobacteria, selected based on a previous study, against the multidrug-resistant and -sensitive strains of Enterococcus faecium. Out of the eleven tested extracts, 72% have shown anti-enterococcal activity against both strains. Among the extracts with anti-enterococcal activity, the diethyl ether extract of Leptolyngbya sp. (DEEL-3) inhibited the growth of VRE in a dose-dependent manner with a minimum inhibitory concentration of 2.0 mg mL^-1. The DEEL-3 has also shown its antioxidant potential in terms of DPPH scavenging with an IC₅₀ of 3.16 mg mL^-1. The organism was named Leptolyngbya sp. HNBGU 003 based on 16SrRNA sequence homology analysis and morphological features. Further, the GC–MS analysis of the DEEL-3 has revealed the predominance of two phenolic compounds, phenol, 2,4-bis(1,1-dimethylethyl)-, phosphite (3:1) and tris(2,4-di-tert-butylphenyl) phosphate, in it. Thus, the anti-enterococcal and antioxidant activity of DEEL-3 may be attributed to these phenolics, which may be isolated and developed as food additives.

Alkaloids in Contemporary Drug Discovery to Meet Global Disease Needs

An overview is presented of the well-established role of alkaloids in drug discovery, the application of more sustainable chemicals, and biological approaches, and the implementation of information systems to address the current challenges faced in meeting global disease needs. The necessity for a new international paradigm for natural product discovery and development for the treatment of multidrug resistant organisms, and rare and neglected tropical diseases in the era of the Fourth Industrial Revolution and the Quintuple Helix is discussed.

Recent advances in hapalindole-type cyanobacterial alkaloids: biosynthesis, synthesis, and biological activity

Covering: 1984 up to the end of 2020Hapalindoles, fischerindoles, ambiguines and welwitindolinones are all members of a class of indole alkaloid natural products that have been isolated from the Stigonematales order of cyanobacteria. These compounds possess a polycyclic ring system, unique functional groups and various stereo- and regiochemical isomers. Since their initial isolation in 1984, they have been explored as potential therapeutics due to their wide variety of biological activities. Although numerous groups have pursued total syntheses of these densely functionalized structures, hapalindole biosynthesis has only recently been unveiled. Several groups have uncovered a wide range of novel enzymes that catalyze formation and tailoring of the hapalindole-type metabolites. In this article, we provide an overview of these natural products, their biological activities, highlight general synthetic routes, and provide an extensive review on the surprising biosynthetic processes leading to these structurally diverse metabolites.

CyanoMetDB, a comprehensive public database of secondary metabolites from cyanobacteria

Harmful cyanobacterial blooms, which frequently contain toxic secondary metabolites, are reported in aquatic environments around the world. More than two thousand cyanobacterial secondary metabolites have been reported from diverse sources over the past fifty years. A comprehensive, publically-accessible database detailing these secondary metabolites would facilitate research into their occurrence, functions and toxicological risks. To address this need we created CyanoMetDB, a highly curated, flat-file, openly-accessible database of cyanobacterial secondary metabolites collated from 850 peer-reviewed articles published between 1967 and 2020. CyanoMetDB contains 2010 cyanobacterial metabolites and 99 structurally related compounds. This has nearly doubled the number of entries with complete literature metadata and structural composition information compared to previously available open access databases. The dataset includes microcytsins, cyanopeptolins, other depsipeptides, anabaenopeptins, microginins, aeruginosins, cyclamides, cryptophycins, saxitoxins, spumigins, microviridins, and anatoxins among other metabolite classes. A comprehensive database dedicated to cyanobacterial secondary metabolites facilitates: (1) the detection and dereplication of known cyanobacterial toxins and secondary metabolites; (2) the identification of novel natural products from cyanobacteria; (3) research on biosynthesis of cyanobacterial secondary metabolites, including substructure searches; and (4) the investigation of their abundance, persistence, and toxicity in natural environments.

Effects of fluctuating temperature in open raceway ponds on the biomass accumulation and harvest efficiency of Spirulina in large-scale cultivation

It is of great significance to select strains with wide adaptability to temperature range for large-scale commercial cultivation of Spirulina. The aim of this study was to comprehend how the strain H-208 grew and whether this strain had any advantages in temperature adaptation compared with local production strain during the large-scale cultivation in Inner Mongolia. The results showed that the strain H-208 could adapt to the new environmental condition quickly, and the daily average biomass dry weight of strain H-208 was 49% and 52% more than that of production strain M-1 in first cycle (20.24 g/m2/day) and second cycle (16.90 g/m2/day) of acclimation experiment, respectively. The growth rate of strain H-208 was 0.055 and 0.066 g/L/day from July 22 to July 25 and from July 26 to July 29, respectively, while the growth rate of strain M-1 was only 0.036 and 0.032 g/L/day, respectively, during the same cultured days in 605-m2 raceway ponds before high temperature. The harvesting efficiency of H-208 and M-1 was 95.1% and 72.1% before high temperature, and that was 95.3% and 52.5% after being stressed by high temperature, respectively. Meanwhile, it was also observed that the filaments of the two strains contracted and their pitches were smaller than that before high temperature stress, especially the strain M-1. In 20-m2 raceway ponds of recovery experiment after high temperature, the percentage of daily average biomass dry weight of strain H-208 was 68% more than that of strain M-1, which demonstrated that strain H-208 could recover and grow rapidly, and its self-regulation ability was superior to that of strain M-1.

Cyanobacterial natural products as sources for antiviral drug discovery against COVID-19

The recent Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), positive-sense RNA viruses, originated from Wuhan City in December 2019 and propagated widely globally. Hence, the disease caused by this virus has been declared as a global pandemic by the WHO. As of 18th February 2021, at least seven different vaccines across three platforms have been rolled out in countries and more than 200 additional vaccine candidates have been in development, of which more than 60 are at the stage of the clinical development. So far, Most of the approved vaccine manufacturers are Pfizer, AstraZeneca, and Serum Institute of India, which have been finalized by WHO. Synthetic drug-associated complications have evoked scientific attention for natural product-based drugs. There has been a surge in the antiviral compounds from natural resources along with some therapies. Cyanobacteria are the fruitful reservoir of many metabolites like sulfated polysaccharides and lectins that possess strong antiviral activities and immunity boosting effects. However, the research in this field has been relatively under-developed. The current research highlights important features of cyanobacterial antiviral biomaterials, benefits and drawbacks of cyanobacterial drugs, challenges, future perspectives as well as overview of drugs against COVID-19. In addition, we have described mutated variants and transmission rate of coronaviruses. The current research suggests that cyanobacterial species and their extracts have promising applications as potentially antiviral drug biomaterials against COVID-19.Communicated by Ramaswamy H. Sarma.

Isolation and Structure Elucidation of a Novel Symmetrical Macrocyclic Phthalate Hexaester

A novel symmetrical macrocyclic phthalate hexaester (1) and a known macrocyclic phthalate tetraester (2) were isolated during a natural product-exploring program on the cyanobacterium Moorea producens. Their structures were elucidated based on spectroscopic data, including nuclear magnetic resonance and high-resolution mass spectra. In the antibacterial activity test, compounds 1 and 2 showed no bioactivity at the concentrations tested.