Production Of Secondary Metabolites Research Articles

Accumulation of secondary metabolites in the family Lamiaceae as influenced by foliar micronutrients

The Lamiaceae family is rich in secondary metabolites, such as essential oils comprising flavonoids, phenolic compounds, and terpenoids. Micronutrients play a crucial role in plant metabolism and secondary metabolites production. This review summarizes and emphasizes the significance of foliar micronutrient nutrition in facilitating the accumulation of secondary metabolites in the Lamiaceae family, based on research literature from 2010 to 2023 using dependable databases like Scopus, Google Scholar, PubMed, and Science Direct. Spraying micronutrients notably enhanced the biosynthesis of various secondary metabolites in Lamiaceae species, especially for nutrients that do not move easily (Fe, Zn, Mn, Cu, B, and Si). Using nano-micronutrients as foliar application on Lamiaceae medicinal plants was more effective than traditional soil treatment. This review highlighted the importance of additional investigation on Cerium, Titanium, and Boron. Genera such as Lavandula, Satureja, Origanum, Lippia, and Hyssopus require more research in the future.

Crystalline deposit in lichens: Determination of crystals with regard to practical application in standard taxonomic studies

The presence of various crystal forms is quite often noticed in lichens from manytaxonomic groups. The crystalline deposit may be linked with the production of secondary metabolites or metal oxalates as well as to the uptake of calcium carbonate from the host substrate. Although the crystals are clearly visible under a microscope employing polarized light, their detailed determination is very difficult without the use of specialized equipment and analytical methods. On the other hand, it is not uncommon for the surface of lichen thalli to be covered with apparent pruina, which is formed by masses of calcium oxalate crystals. Regardless of their origin and distribution, crystalline products can perform an important functional role and enhance the adaptation of a given species to a specific habitat. Moreover, the presence and kind of crystals can be species-specific or characteristic of a certain group of species and, therefore, may constitute a useful diagnostic feature. We intended to examine the extent to which standard methods used in lichen taxonomy, such as solubility tests in chemical reagents, allow for the basic determination of crystals. We indicate the basic differences between various crystal deposits that can be observed inside or outside the lichen thallus. The presented results are based on examining selected specimens representing various lichen genera.

Genetic Engineering in Bacteria, Fungi, and Oomycetes, Taking Advantage of CRISPR

Genetic engineering has revolutionized our ability to modify microorganisms for various applications in agriculture, medicine, and industry. This review examines recent advances in genetic engineering techniques for bacteria, fungi, and oomycetes, with a focus on CRISPR-Cas systems. In bacteria, CRISPR-Cas9 has enabled precise genome editing, enhancing applications in antibiotic production and metabolic engineering. For fungi, despite challenges associated with their complex cell structures, CRISPR/Cas9 has advanced the production of enzymes and secondary metabolites. In oomycetes, significant plant pathogens, modified Agrobacterium-mediated transformation, and CRISPR/Cas12a have contributed to developing disease-resistant crops. This review provides a comparative analysis of genetic engineering efficiencies across these microorganisms and addresses ethical and regulatory considerations. Future research directions include refining genetic tools to improve efficiency and expand applicability in non-model organisms. This comprehensive overview highlights the transformative potential of genetic engineering in microbiology and its implications for addressing global challenges in agriculture, medicine, and biotechnology.

Comprehensive genome analysis of two novel Saccharopolyspora strains—Saccharopolyspora montiporae sp. nov. and Saccharopolyspora galaxeae sp. nov. isolated from stony corals in Hainan

Marine actinomycetes exhibit a high level of biodiversity and possess significant potential for the production of high-value secondary metabolites. During the course of investigation of marine actinobacteria from corals, two Saccharopolyspora strains, namely, HNM0983T and HNM0986T, were isolated from stony corals collected from the coastal area of Hainan Island. The 16S ribosomal RNA (rRNA) gene sequence analysis revealed that these two strains are putative novel taxa of the genus Saccharopolyspora. Whole-genome sequencing comparisons further confirmed the two strains as belonging to two novel Saccharopolyspora species, which can be distinguished phenotypically and chemically from their current closest phylogenetic relatives. Some genomic information of the genus Saccharopolyspora was compared for evaluating the production capacity of secondary metabolites. A total of 519 biosynthetic gene clusters (BGCs) from the genus Saccharopolyspora were used for analysis, and terpene BGCs were found to be widespread and most abundant in this genus. In addition, abundant novel BGCs in the genus Saccharopolyspora are not clustered with the known BGCs in the database, indicating that the metabolites of the genus Saccharopolyspora deserve further exploration. On the basis of these presented results, Saccharopolyspora montiporae sp. nov. (type strain = HNM0983T = CCTCC AA 2020014T = KCTC 49526T) and Saccharopolyspora galaxeae sp. nov. (type strain = HNM0986T = CCTCC AA 2020011T = KCTC 49524T) are proposed as the names for the new strains, respectively.

Calcium Transport and Enrichment in Microorganisms: A Review

Calcium is a vital trace element for the human body, and its deficiency can result in a range of pathological conditions, including rickets and osteoporosis. Despite the numerous types of calcium supplements currently available on the market, these products are afflicted with a number of inherent deficiencies, such as low calcium content, poor aqueous solubility, and low human absorption rate. Many microorganisms, particularly beneficial microorganisms, including edible fungi, lactic acid bacteria, and yeast, are capable of absorbing and enriching calcium, a phenomenon that has been widely documented. This opens the door to the potential utilization of microorganisms as novel calcium enrichment carriers. However, the investigation of calcium-rich foods from microorganisms still faces many obstacles, including a poor understanding of calcium metabolic pathways in microorganisms, a relatively low calcium enrichment rate, and the slow growth of strains. Therefore, in order to promote the development of calcium-rich products from microorganisms, this paper provides an overview of the impacts of calcium addition on strain growth, calcium enrichment rate, antioxidant system, and secondary metabolite production. Additionally, it highlights calcium transport and enrichment mechanisms in microorganism cells and offers a detailed account of the progress made on calcium-binding proteins, calcium transport pathways, and calcium storage and release. This paper offers insights for further research on the relevant calcium enrichment in microorganism cells.

ReaL-MGE is a tool for enhanced multiplex genome engineering and application to malonyl-CoA anabolism.

The complexities encountered in microbial metabolic engineering continue to elude prediction and design. Unravelling these complexities requires strategies that go beyond conventional genetics. Using multiplex mutagenesis with double stranded (ds) DNA, we extend the multiplex repertoire previously pioneered using single strand (ss) oligonucleotides. We present ReaL-MGE (Recombineering and Linear CRISPR/Cas9 assisted Multiplex Genome Engineering). ReaL-MGE enables precise manipulation of numerous large DNA sequences as demonstrated by the simultaneous insertion of multiple kilobase-scale sequences into E. coli, Schlegelella brevitalea and Pseudomonas putida genomes without any off-target errors. ReaL-MGE applications to enhance intracellular malonyl-CoA levels in these three genomes achieved 26-, 20-, and 13.5-fold elevations respectively, thereby promoting target polyketide yields by more than an order of magnitude. In a further round of ReaL-MGE, we adapt S. brevitalea to malonyl-CoA elevation utilizing a restricted carbon source (lignocellulose from straw) to realize production of the anti-cancer secondary metabolite, epothilone from lignocellulose. Multiplex mutagenesis with dsDNA enables the incorporation of lengthy segments that can fully encode additional functions. Additionally, the utilization of PCR to generate the dsDNAs brings flexible design advantages. ReaL-MGE presents strategic options in microbial metabolic engineering.

OBTAINING ASEPTIC CULTURE IN VITRO OF RHODIOLA SEMENOWII L. FROM VARIOUS TYPES OF EXPLANTS

In vitro cultivation of callus cells allows for the stable production of secondary metabolites, being an alternative to the use of medicinal plant biomass from natural populations. Standardization of cultivation protocols and technological processes for the synthesis of secondary metabolites in vitro conditions determines significant interest in the use of tissue culture methods (PTC – Plant Tissue Culture). The aim of the study was to obtain an aseptic culture of Rhodiola semenowii in vitro from various types of explants, as well as the effect of the hormonal composition of the nutrient medium on the induction of callusogenesis in the culture of isolated organs of R. semenowii. As a result of the research, the optimal mode of obtaining R. semenovii aseptic cultures from various explants was determined. It has been shown that the use of 70% EtOH in combination with 0.01% HgCl2 or 20% NaClO makes it possible to obtain aseptic cultures from any type of R. semenovii explants. It has been established that the type of explant is R. semenovii influenced both the frequency of callus formation and the beginning of its formation. The least optimal types of R. semenovii explants are stem and rhizome segments, the frequency of callusogenesis varied from 5.8% to 75.6%. The induction of callusogenesis also depended on the hormonal composition of the nutrient medium: the highest percentage of callus formation in all types of explants was on media containing 0.5mg L−1 thidiazuron (TDZ) + 1.0 mg L−1 1-naphthaleneacetic acid (NAA) and 0.5mg L−12,4D + 2.0 mg L−1 6-Benzylaminopurine (BAP).

Novel Differentially Expressed LncRNAs Regulate Artemisinin Biosynthesis in Artemisia annua

Long non-coding RNAs (lncRNAs) are crucial in regulating secondary metabolite production in plants, but their role in artemisinin (ART) biosynthesis, a key anti-malarial compound from Artemisia annua, remains unclear. Here, by investigating high-artemisinin-producing (HAP) and lowartemisinin-producing (LAP) genotypes, we found that the final artemisinin content in A. annua is influenced by the quantity of the precursor compounds. We report on RNA deep sequencing in HAP and LAP genotypes. Based on the application of a stringent pipeline, 1419 novel lncRNAs were identified. Moreover, we identified 256 differentially expressed lncRNAs between HAP and LAP. We then established correlations between lncRNAs and artemisinin biosynthesis genes in order to identify a molecular framework for the differential expression of the pathway between the two genotypes. Three potential lncRNAs (MSTRG.33718.2, MSTRG.30396.1 and MSTRG.2697.4) linked to the key artemisinin biosynthetic genes (ADS: Amorpha-4,11-diene synthase, DXS: 1-deoxy-D-xylulose-5-phosphate synthase, and HMGS: 3-hydroxyl-3-methyglutaryl CoA synthase) were detected. Importantly, we observed that up-regulation of these lncRNAs positively modulates the target artemisinin biosynthetic genes, potentially leading to high artemisinin biosynthesis in HAP. In contrast, BAS (beta-amyrin synthase), which is involved in the artemisinin competing pathway, was strongly down-regulated in HAP compared to LAP, in line with the expression pattern of the linked lncRNA MSTRG.30396.1. By identifying and characterizing lncRNAs that are potentially linked to the regulation of key biosynthetic genes, this work provides new insights into the complex regulatory networks governing artemisinin production in A. annua. Such findings could pave the way for innovative approaches in metabolic engineering, potentially enhancing artemisinin yields and addressing challenges in sustainable production.

Decoding the Impact of a Bacterial Strain of Micrococcus luteus on Arabidopsis Growth and Stress Tolerance

Microbes produce various bioactive metabolites that can influence plant growth and stress tolerance. In this study, a plant growth-promoting rhizobacterium (PGPR), strain S14, was identified as Micrococcus luteus (designated as MlS14) using de novo whole-genome assembly. The MlS14 genome revealed major gene clusters for the synthesis of indole-3-acetic acid (IAA), terpenoids, and carotenoids. MlS14 produced significant amounts of IAA, and its volatile organic compounds (VOCs), specifically terpenoids, exhibited antifungal activity, suppressing the growth of pathogenic fungi. The presence of yellow pigment in the bacterial colony indicated carotenoid production. Treatment with MlS14 activated the expression of β-glucuronidase (GUS) driven by a promoter containing auxin-responsive elements. The application of MlS14 reshaped the root architecture of Arabidopsis seedlings, causing shorter primary roots, increased lateral root growth, and longer, denser root hairs; these characteristics are typically controlled by elevated exogenous IAA levels. MlS14 positively regulated seedling growth by enhancing photosynthesis, activating antioxidant enzymes, and promoting the production of secondary metabolites with reactive oxygen species (ROS) scavenging activity. Pretreatment with MlS14 reduced H2O2 and malondialdehyde (MDA) levels in seedlings under drought and heat stress, resulting in greater fresh weight during the post-stress period. Additionally, exposure to MlS14 stabilized chlorophyll content and growth rate in seedlings under salt stress. MlS14 transcriptionally upregulated genes involved in antioxidant defense and photosynthesis. Furthermore, genes linked to various hormone signaling pathways, such as abscisic acid (ABA), auxin, jasmonic acid (JA), and salicylic acid (SA), displayed increased expression levels, with those involved in ABA synthesis, using carotenoids as precursors, being the most highly induced. Furthermore, MlS14 treatment increased the expression of several transcription factors associated with stress responses, with DREB2A showing the highest level of induction. In conclusion, MlS14 played significant roles in promoting plant growth and stress tolerance. Metabolites such as IAA and carotenoids may function as positive regulators of plant metabolism and hormone signaling pathways essential for growth and adaptation to abiotic stress.

Priming with multiwalled carbon nanotubes improved biomass accumulation, biological activityand metabolism of four horticultural plants during the sprouting stage.

It is imperative to enhance the quality of sprouts since they are a rich source of various primary and secondary metabolites. The objective of this work was to examine how multiwalled carbon nanotubes (MWCNTs) priming at various concentrations affected the nutritional qualities of four horticultural plants (T. foenum-graecum, L. grandiflorum, L. sativum and A. graveolens) and their sprouting processes. Among the four applied concentrations (10-60 mgL-1), MWCNTs at 10 and 40 mg L⁻¹ induced the highest biomass accumulation in L. grandiflorum and T. foenum-graecum, respectively, while 60 mg L⁻¹ was most effective for L. sativum and A. graveolent. MWCNTs induced growth by enhancing photosynthesis, as shown by increased chlorophyll content and rubisco activity, which rose by 27%, 17%, 23% and 12% in T. foenum-graecum, L. grandiflorum, L. sativum, and A. graveolens, respectively. Enhanced photosynthesis by MWCNTs improved sugar metabolism as indicated by increased activity of sugar metabolic enzymes such as amylase, starch synthase and invertase. This also supplied the carbon necessary for the production of primary (amino acids, fatty acids and organic acids) and secondary (flavonoids and polyphenols) metabolites. There was consistently higher activity of antioxidant enzymes (catalase and peroxidase). Interestingly, species-specific reactions to MWCNT priming were observed, where L. sativum sprouts showed the highest antioxidant activity, followed by A. graveolens. MWCNT priming improves sprout growth and nutritional quality by boosting metabolic processes and antioxidant activity, presenting a promising approach for sustainable agriculture. © 2024 Society of Chemical Industry.

Characterization of an aminotransferase TlBCAT from Trichoderma longibrachiatum UN32 involved in dendrobine-type total alkaloids biosynthesis.

Trichoderma longibrachiatum UN32 is an industrially important fungus capable of producing Dendrobine-Type Total alkaloids (DTTAs). Several reports have pointed out that branched-chain amino acid aminotransferases (BCATs) participate in backbone modification or promote the production of secondary metabolites. We previously proposed that cobalt chloride increased DTTAs production in T. longibrachiatum UN32, which was associated with enhanced expression of the gene BCAT, TlBCAT (Genbank accession No. PP465542). Following cloning and characterization, the cDNA of TlBCAT was found to consists of 1191bp, encoding a protein of 397 amino acid residues. The molecular mass of TlBCAT was about 42kDa through SDS-PAGE analysis. The predicted pI value was 5.54. Recombinant TlBCAT can catalyze L-leu with a catalytic efficiency of 15.91 mM- 1S- 1. In the binding pocket, residues interacting with PLP, including Tyr68, Arg93, Tyr136, and Lys194, are highly conserved. TlBCAT exhibits a broad spectrum of substrate specificity, typical for catalyzing the transamination reaction of various branched-chain and hydrophobic amino acids, with α-ketoglutarate as the amino acceptor. Exogenous branched-chain amino acids (BCAAs) positively affect Trichoderma growth and DTTAs production. These findings offer insights into the physiological significance of BCAAs and present a novel approach for enhancing DTTAs production in Trichoderma mycelium cultures.

Recent advances on the impact of protumorigenic dietary‐derived bacterial metabolites on the intestinal stem cell

AbstractThe links between diet, microbiome, immunity, and colorectal cancer are well established. The metabolite output of the microbiome, which has a large influence over host health and disease, is related to the composition of the diet. These metabolites subsequently impact on immune and intestinal epithelial either directly or indirectly via production of secondary metabolites. Here we summarize the latest findings and briefly discuss their potential for managing disease risk.

Metabolomic profiling and 16 S rRNA metabarcoding of endophytes of two Aloe species revealed diverse metabolites

Aloe species are often used interchangeably for medicinal and cosmeceutical applications, presenting a challenge to the biological efficacy consistency of some herbal preparations. Sustainable production of high-quality commonly used medicinal plants remains a limitation for commercialisation. Thus, this study investigated the potential for plant substitution by examining bacterial endophytes capable of producing similar host plant secondary metabolites. The metabolite profiles and endophytic bacterial communities of endangered Aloe lettyae were compared with those of Aloe longibracteata using nuclear magnetic resonance spectroscopy and 16 S rRNA gene sequencing. Only 15 metabolites were significantly different between A. lettyae and A. longibracteata based on metabolite concentrations. However, both plants’ functionality and potential application remain comparable. Phytohormones, including indole-3-acetate and 5-hydroxyindole-3-acetate, were more concentrated in A. lettyae than A. longibracteata. Metabolites such as tyrosine, allantoin, and myo-inositol, with human health benefits, were annotated in both species. Aloe lettyae harboured a phylogenetically diverse bacteria community compared to A. longibracteata, with a higher richness of bacterial species, indicating a likelihood of diverse metabolic capabilities among the bacteria. Dominant endophytes, including Bacillus, Comamonas, and Pseudomonas, possess enzymes contributing to various metabolic pathways. The enzymes have the potential to impact the synthesis, or breakdown of plant metabolites, consequently influencing the overall metabolic composition of the host plant. Therefore, this study supports the interchangeability of A. lettyae and A. longibracteata due to their ability to produce similar metabolites, and although the Aloe species exhibit phylogenetically diverse endophytic communities, the feasibility of utilizing their endophytes as producers of secondary metabolites remains viable.Graphical abstract

Optimization of the Production of Secondary Metabolites from Furanocoumarin and Furoquinoline Alkaloid Groups in In Vitro Ruta corsica Cultures Grown in Temporary Immersion Bioreactors

Optimization of the Production of Secondary Metabolites from Furanocoumarin and Furoquinoline Alkaloid Groups in In Vitro Ruta corsica Cultures Grown in Temporary Immersion Bioreactors

Study on the Mechanism of Flavonoid Enrichment in Black Soybean Sprouts by Abscisic Acid/Melatonin Under Slight Acid Treatment

Plant hormones play a critical role in the physiological and biochemical mechanisms of plants, with functions such as regulating the metabolic pathways of secondary metabolite production and alleviating external stresses. In this study, the synthesis of flavonoids in black soybean sprouts was induced by slight acid combined with the plant hormones abscisic acid (ABA) and melatonin (MT). The results indicated that the contents of daidzin, genistin, daidzein, and genistein in black soybean sprouts treated with slight acid were increased by 10 μM ABA and 75 μM MT, and the total flavonoid content was significantly enhanced. Compared with the slight acid treatment, the H2O2 and malondialdehyde (MDA) contents in black soybean sprouts were increased after ABA treatment, and the black soybean sprouts were further stressed. However, the H2O2 and MDA contents in black soybean sprouts were significantly decreased after MT treatment, indicating that the stress of black soybean sprouts can be alleviated by MT. Under slight acid stress, the genes related to flavonoid synthesis in black soybean sprouts were induced by exogenous ABA, promoting the accumulation of flavonoids; under exogenous MT treatment, the activity of phenylpropanoid metabolism enzymes was significantly increased, the genes related to flavonoid synthesis were upregulated, and flavonoid synthesis was induced. These results suggest that the combination of slight acid and plant hormone treatments promotes the accumulation of flavonoid substances during the germination of black soybeans. This research lays the foundation for improving the growth conditions of black soybeans and promoting the enrichment of flavonoid substances in black soybeans.

Whole Genome Sequencing and Biocontrol Potential of Streptomyces luteireticuli ASG80 Against Phytophthora Diseases

Phytophthora-induced crop diseases, commonly known as “plant plagues”, pose a significant threat to global food security. In this study, strain ASG80 was isolated from sisal roots and demonstrated a broad-spectrum antagonistic activity against several Phytophthora species and fungal pathogens. Strain ASG80 was identified as Streptomyces luteireticuli via phylogenetic analysis, digital DNA–DNA hybridization (dDDH), and average nucleotide identity (ANI). Whole-genome sequencing identified 40 biosynthetic gene clusters (BGCs) related to secondary metabolite production, including antimicrobial compounds. Strain ASG80 extract exhibited broad-spectrum inhibitory activity against Phytophthora nicotianae, P. vignae, P. cinnamomi, and P. sojae. Pot experiments showed that strain ASG80 extract significantly reduced sisal zebra disease incidence, with an efficacy comparable to the fungicide metalaxyl. These findings suggest that strain ASG80 is a promising biocontrol agent with substantial potential for managing Phytophthora-related diseases in agriculture.

Revealing the metabolic potential and environmental adaptation of nematophagous fungus, Purpureocillium lilacinum, derived from hadal sediment

The extreme environment shapes fungi in deep-sea sediments with novel metabolic capabilities. The ubiquity of fungi in deep-sea habitats supports their significant roles in these ecosystems. However, there is limited research on the metabolic activities and adaptive mechanisms of filamentous fungi in deep-sea ecosystems. In this study, we investigated the biological activities, including antibacterial, antitumor and nematicidal activity of Purpureocillium lilacinum FDZ8Y1, isolated from sediments of the Mariana Trench. A key feature of P. lilacinum FDZ8Y1 was its tolerance to high hydrostatic pressure (HHP), up to 110 MPa. We showed that HHP affected its vegetative growth, development, and production of secondary metabolites, indicating the potential for discovering novel natural products from hadal fungi. Whole-genome sequencing of P. lilacinum FDZ8Y1 revealed the metabolic potential of this piezotolerant fungus in carbon (carbohydrate metabolism), nitrogen (assimilatory nitrate reduction and protein degradation) and sulfur cycling processes (assimilatory sulfate reduction). Transcriptomic analysis under elevated HHP showed that P. lilacinum FDZ8Y1 may activate several metabolic pathways and stress proteins to cope with HHP, including fatty acid metabolism, the antioxidant defense system, the biosynthetic pathway for secondary metabolites, extracellular enzymes and membrane transporters. This study provides valuable insights into the metabolic potential and adaptation mechanisms of hadal fungi to the challenging conditions of the hadal environment.

Heterologous Expression of MYB Gene (Rosea1) or bHLH Gene (Delila) from Antirrhinum Increases the Phenolics Pools in Salvia miltiorrhiza

Phenolic acids have health-promoting properties, however, but their low concentrations in Salvia miltiorrhiza limit broader medicinal applications. MYB and bHLH transcription factors activate multiple target genes involved in phenylpropanoid metabolism, thereby enhancing the production of various secondary metabolites. We introduced the MYB transcription factor Antirrhinum Rosea1 (AmROS1) or Delila (AmDEL) into S. miltiorrhiza and observed that antioxidant activity in transgenic plants increased by 1.40 to 1.80-fold. The total content was significantly higher in transformants compared to the controls. Furthermore, heterologous expression of AmROS1 or AmDEL triggered moderate accumulations of rosmarinic acid and salvianolic acid at various growth stages. Levels of total phenolics, total flavonoids, and anthocyanins were significantly elevated. These biological and phytochemical alterations were correlated with the upregulated expression of genes involved in phenolic acid biosynthesis. Our findings demonstrate that AmROS1 and AmDEL function as a transcriptional activator in phenolic acids biosynthesis. This study offers further insights into the heterologous or homologous regulation of phenolics production, potentially enabling its engineering in S. miltiorrhiza.

Evaluating stress resilience of cyanobacteria through flow cytometry and fluorescent viability assessment.

Cyanobacteria are prokaryotic organisms characterised by their complex structures and a wide range of pigments. With their ability to fix CO2, cyanobacteria are interesting for white biotechnology as cell factories to produce various high-value metabolites such as polyhydroxyalkanoates, pigments, or proteins. White biotechnology is the industrial production and processing of chemicals, materials, and energy using microorganisms. It is known that exposing cyanobacteria to low levels of stressors can induce the production of secondary metabolites. Understanding of this phenomenon, known as hormesis, can involve the strategic application of controlled stressors to enhance the production of specific metabolites. Consequently, precise measurement of cyanobacterial viability becomes crucial for process control. However, there is no established reliable and quick viability assay protocol for cyanobacteria since the task is challenging due to strong interferences of autofluorescence signals of intercellular pigments and fluorescent viability probes when flow cytometry is used. We performed the screening of selected fluorescent viability probes used frequently in bacteria viability assays. The results of our investigation demonstrated the efficacy and reliability of three widely utilised types of viability probes for the assessment of the viability of Synechocystis strains. The developed technique can be possibly utilised for the evaluation of the importance of polyhydroxyalkanoates for cyanobacterial cultures with respect to selected stressor-repeated freezing and thawing. The results indicated that the presence of polyhydroxyalkanoate granules in cyanobacterial cells could hypothetically contribute to the survival of repeated freezing and thawing.

Genomic insights into the cold adaptation and secondary metabolite potential of Pseudoalteromonas sp. WY3 from Antarctic krill

In the Antarctic marine ecosystem, krill play a pivotal role, yet the intricate microbial community intertwined with these diminutive crustaceans remains largely unmapped. In this study, we successfully isolated and characterized a unique bacterial strain, Pseudoalteromonas sp. WY3, from Antarctic krill. Genomic analysis revealed that WY3 harbors a multitude of genes associated with cold shock proteins, oxidoreductases, and enzymes involved in the osmotic stress response, equipping it with a robust molecular arsenal to withstand frigid Antarctic conditions. Furthermore, the presence of two distinct biosynthesis-related gene clusters suggests that WY3 has the potential to synthesize diverse secondary metabolites, including aryl polyenes and ribosomally synthesized and post-translationally modified peptides. Notably, the identification of genes encoding enzymes crucial for biological immunity pathways, such as apeH and ubiC, hints at a complex symbiotic relationship between WY3 and its krill host. This comprehensive study highlights the robust potential of WY3 for secondary metabolite production and its remarkable ability to thrive at extremely low temperatures in the Antarctic ecosystem, shedding light on the interplay between culturable microorganisms and their hosts in harsh environments, and providing insights into the underexplored microbial communities associated with Antarctic marine organisms and their role in environmental adaptation and biotechnological applications.