Production Of Secondary Metabolites Research Articles

Construction of a beneficial microbes-enriched rhizosphere system assists plants in phytophagous insect defense: current status, challenges and opportunities.

The construction of a plant rhizosphere system enriched with beneficial microbes (BMs) can efficiently help plants defend against phytophagous insects. However, our comprehensive understanding of this approach is still incomplete. In this review, we methodically analyzed the progress made over the last decade, identifying both challenges and opportunities. The main methods for developing a BMs-enriched rhizosphere system include inoculating exogenous BMs into plants, amending the existing soil microbiomes with amendments, and utilizing plants to shape the soil microbiomes. BMs can assist plants in suppressing phytophagous insects across many orders, including 13 Lepidoptera, seven Homoptera, five Hemiptera, five Coleoptera, four Diptera, and one Thysanoptera species by inducing plant systemic resistance, enhancing plant tolerance, augmenting plant secondary metabolite production, and directly suppressing herbivores. Context-dependent factors such as abiotic and biotic conditions, as well as the response of insect herbivores, can affect the outcomes of BM-assisted plant defense. Several challenges and opportunities have emerged, including the development of synthetic microbial communities for herbivore control, the integration of biosensors for effectiveness assessment, the confirmation of BM targets for phytophagous insect defense, and the regulation of outcomes via smart farming with artificial intelligence. This study offers valuable insights for developing a BM-enriched rhizosphere system within an integrated pest management approach. © 2024 Society of Chemical Industry.

Effect of ozone treatment on phenylpropanoid metabolism in harvested cantaloupes.

Phenylpropanoid metabolism plays an important role in cantaloupe ripening and senescence, but the mechanism of ozone regulation on phenylpropanoid metabolism remains unclear. This study investigated how ozone treatment modulates the levels of secondary metabolites associated with phenylpropanoid metabolism, the related enzyme activities, and gene expression in cantaloupe. Treating cantaloupes with 15mg/m3 of ozone after precooling can help maintain postharvest hardness. This treatment also enhances the production and accumulation of secondary metabolites, such as total phenols, flavonoids, and lignin. These metabolites are essential components of the phenylpropanoid metabolic pathway, activating enzymes like phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, 4CL, chalcone synthase, and chalcone isomerase. The results of the transcriptional expression patterns showed that differential gene expression related to phenylpropanoid metabolism in the peel of ozone-treated cantaloupes was primarily observed during the middle and late storage stages. In contrast, the pulp exhibited significant differential gene expression mainly during the early storage stage. Furthermore, it was observed that the level of gene expression in the peel was generally higher than that in the pulp. The correlation between the relative amount of gene changes in cantaloupe, activity of selected enzymes, and concentration of secondary metabolites could be accompanied by positive regulation of the phenylpropanoid metabolic pathway. Therefore, ozone stress induction positively enhances the biosynthesis of flavonoids in cantaloupes, leading to an increased accumulation of secondary metabolites. Additionally, it also improves the postharvest storage quality of cantaloupes.

Co-regulatory network analysis of the main secondary metabolite (SM) biosynthesis in Crocus sativus L.

Saffron (Crocus sativus L.) is being embraced as the most important medicinal plant and the commercial source of saffron spice. Despite the beneficial economic and medicinal properties of saffron, the regulatory mechanism of the correlation of TFs and genes related to the biosynthesis of the apocarotenoids pathway is less obvious. Realizing these regulatory hierarchies of gene expression networks related to secondary metabolites production events is the main challenge owing to the complex and extensive interactions between the genetic behaviors. Recently, high throughput expression data have been highly feasible for constructing co-regulation networks to reveal the regulated processes and identifying novel candidate hub genes in response to complex processes of the biosynthesis of secondary metabolites. Herein, we performed Weighted Gene Co-expression Network Analysis (WGCNA), a systems biology method, to identify 11 regulated modules and hub TFs related to secondary metabolites. Three specialized modules were found in the apocarotenoids pathway. Several hub TFs were identified in notable modules, including MADS, C2H2, ERF, bZIP, HD-ZIP, and zinc finger protein MYB and HB, which were potentially associated with apocarotenoid biosynthesis. Furthermore, the expression levels of six hub TFs and six co-regulated genes of apocarotenoids were validated with RT-qPCR. The results confirmed that hub TFs specially MADS, C2H2, and ERF had a high correlation (P < 0.05) and a positive effect on genes under their control in apocarotenoid biosynthesis (CCD2, GLT2, and ADH) among different C. sativus ecotypes in which the metabolite contents were assayed. Promoter analysis of the co-expressed genes of the modules involved in apocarotenoids biosynthesis pathway suggested that not only are the genes co-expressed, but also share common regulatory motifs specially related to hub TFs of each module and that they may describe their common regulation. The result can be used to engineer valuable secondary metabolites of C. sativus by manipulating the hub regulatory TFs.

Copy number variation introduced by a massive mobile element facilitates global thermal adaptation in a fungal wheat pathogen

Copy number variation (CNV) can drive rapid evolution in changing environments. In microbial pathogens, such adaptation is a key factor underpinning epidemics and colonization of new niches. However, the genomic determinants of such adaptation remain poorly understood. Here, we systematically investigate CNVs in a large genome sequencing dataset spanning a worldwide collection of 1104 genomes from the major wheat pathogen Zymoseptoria tritici. We found overall strong purifying selection acting on most CNVs. Genomic defense mechanisms likely accelerated gene loss over episodes of continental colonization. Local adaptation along climatic gradients was likely facilitated by CNVs affecting secondary metabolite production and gene loss in general. One of the strongest loci for climatic adaptation is a highly conserved gene of the NAD-dependent Sirtuin family. The Sirtuin CNV locus localizes to an ~68-kb Starship mobile element unique to the species carrying genes highly expressed during plant infection. The element has likely lost the ability to transpose, demonstrating how the ongoing domestication of cargo-carrying selfish elements can contribute to selectable variation within populations. Our work highlights how standing variation in gene copy numbers at the global scale can be a major factor driving climatic and metabolic adaptation in microbial species.

Harnessing the Potential of Harpin Proteins: Elicitation Strategies for Enhanced Secondary Metabolite Accumulation in Grapevine Callus Cultures

Grapes and grape products are rich in secondary metabolites such as phenolic compounds and anthocyanins, which have antioxidant properties. These compounds possess health-promoting attributes, including cardioprotective, antimicrobial, and anticancer effects. In recent years, biotechnological methods have been employed to produce high quantities and purity of secondary metabolites under in vitro conditions, aiming to elucidate their complex functions and optimize production methods. However, the potential effects of harpin proteins on the accumulation of secondary compounds in callus cultures have not been investigated thus far. Harpin proteins, encoded by the hrp gene clusters in Gram-negative phytopathogens, are known to trigger defense responses in various plant species by promoting the accumulation of secondary compounds. These findings suggest that harpin proteins may have the potential to enhance secondary metabolite accumulation in callus cultures. This study therefore investigated the potential of applying different concentrations of harpin protein (0, 0.1, 1, 10, and 100 ppm) to increase secondary metabolite production in calluses derived from petioles of the “Horoz Karası” grape cultivar. Our findings revealed that 1 and 10 ppm harpin treatments resulted in the highest anthocyanin accumulations, with 17.21 and 16.57 CV/g, respectively, representing 1.95- and 1.87-fold increases compared to control treatments, respectively. Total phenolic content peaked at 0.39 mg GAE g−1 FW with the 1 ppm harpin treatment, representing a 4.33-fold increase over the control. Total flavonol levels reached their highest levels at 0.027 mg CE g−1 FW with 1 and 10 ppm harpin concentrations, resulting in a 2.25-fold increase compared to the control. The highest averages for total flavonol content were recorded at 0.024 and 0.021 mg RE g−1 FW with 1 and 10 ppm harpin concentrations, respectively, representing 1.5- and 1.3-fold increases over the control. Principal component analysis (PCA) corroborated the results obtained from the heatmap analysis, indicating that harpin applications at 1 and 10 ppm were the most effective concentration range for maximizing secondary metabolite synthesis, while very low or high concentrations diminished these effects. These findings offered valuable insights for optimizing the production of high-value bioactive compounds, which can be utilized in various fields such as medicine, pharmaceuticals, food, and cosmetics. These results are expected to serve as a valuable reference for elucidating the mechanisms by which harpin proteins, rarely used in vitro, exert their effects on grapevine calluses, contributing to the literature in this domain.

High-throughput G protein-coupled receptor-based autocrine screening for secondary metabolite production in yeast.

Biosensors are valuable tools in accelerating the test phase of the design-build-test-learn cycle of cell factory development, as well as in bioprocess monitoring and control. G protein-coupled receptor (GPCR)-based biosensors enable cells to sense a wide array of molecules and environmental conditions in a specific manner. Due to the extracellular nature of their sensing, GPCR-based biosensors require compartmentalization of distinct genotypes when screening production levels of a strain library to ensure that detected levels originate exclusively from the strain under assessment. Here, we explore the integration of production and sensing modalities into a single Saccharomyces cerevisiae strain and compartmentalization using three different methods: (1) cultivation in microtiter plates, (2) spatial separation on agar plates, and (3) encapsulation in water-in-oil-in-water double emulsion droplets, combined with analysis and sorting via a fluorescence-activated cell sorting machine. Employing tryptamine and serotonin as proof-of-concept target molecules, we optimize biosensing conditions and demonstrate the ability of the autocrine screening method to enrich for high producers, showing the enrichment of a serotonin-producing strain over a nonproducing strain. These findings illustrate a workflow that can be adapted to screening for a wide range of complex chemistry at high throughput using commercially available microfluidic systems.

Secondary metabolite profile of Streptomyces spp. changes when grown with the sub-lethal concentration of silver nanoparticles: possible implication in novel compound discovery.

The decline of new antibiotics and the emergence of multidrug resistance in pathogens necessitates a revisit of strategies used for lead compound discovery. This study proposes to induce the production of bioactive compounds with sub-lethal concentrations of silver nanoparticles (Ag-NPs). A total of Forty-two Actinobacteria isolates from four Saudi soil samples were grown with and without sub-lethal concentration of Ag-NPs (50µgml-1). The spent broth grown with Ag-NPs, or without Ag-NPs were screened for antimicrobial activity against four bacteria. Interestingly, out of 42 strains, broths of three strains grown with sub-lethal concentration of Ag-NPs exhibit antimicrobial activity against Staphylococcus aureus and Micrococcus luteus. Among these, two strains S4-4 and S4-21 identified as Streptomyces labedae and Streptomyces tirandamycinicus based on 16S rRNA gene sequence were selected for detailed study. The change in the secondary metabolites profile in the presence of Ag-NPs was evaluated using GC-MS and LC-MS analyses. Butanol extracts of spent broth grown with Ag-NPs exhibit strong antimicrobial activity against M. luteus and S. aureus. While the extracts of the controls with the same concentration of Ag-NPs do not show any activity. GC-analysis revealed a clear change in the secondary metabolite profile when grown with Ag-NPs. Similarly, the LC-MS patterns also differ significantly. Results of this study, strongly suggest that sub-lethal concentrations of Ag-NPs influence the production of secondary metabolites by Streptomyces. Besides, LC-MS results identified possible secondary metabolites, associated with oxidative stress and antimicrobial activities. This strategy can be used to possibly induce cryptic biosynthetic gene clusters for the discovery of new lead compounds.

Shotgun metagenomic insights into secondary metabolite biosynthetic gene clusters reveal taxonomic and functional profiles of microbiomes in natural farmland soil

Antibiotic resistance is a worldwide problem that imposes a devastating effect on developing countries and requires immediate interventions. Initially, most of the antibiotic drugs were identified by culturing soil microbes. However, this method is prone to discovering the same antibiotics repeatedly. The present study employed a shotgun metagenomics approach to investigate the taxonomic diversity, functional potential, and biosynthetic capacity of microbiomes from two natural agricultural farmlands located in Bekeka and Welmera Choke Kebelle in Ethiopia for the first time. Analysis of the small subunit rRNA revealed bacterial domain accounting for 83.33% and 87.24% in the two selected natural farmlands. Additionally, the analysis showed the dominance of Proteobacteria representing 27.27% and 28.79% followed by Actinobacteria making up 12.73% and 13.64% of the phyla composition. Furthermore, the analysis revealed the presence of unassigned bacteria in the studied samples. The metagenome functional analysis showed 176,961 and 104, 636 number of protein-coding sequences (pCDS) from the two samples found a match with 172,655 and 102, 275 numbers of InterPro entries, respectively. The Genome ontology annotation suggests the presence of 5517 and 3293 pCDS assigned to the “biosynthesis process”. Numerous Kyoto Encyclopedia of Genes and Genomes modules (KEGG modules) involved in the biosynthesis of terpenoids and polyketides were identified. Furthermore, both known and novel Biosynthetic gene clusters, responsible for the production of secondary metabolites, such as polyketide synthases, non-ribosomal peptide synthetase, ribosomally synthesized and post-translationally modified peptides (Ripp), and Terpene, were discovered. Generally, from the results it can be concluded that the microbiomes in the selected sampling sites have a hidden functional potential for the biosynthesis of secondary metabolites. Overall, this study can serve as a strong preliminary step in the long journey of bringing new antibiotics to the market.

Short-Term Liquid Nitrogen Storage of Pyrostegia venusta Embryos: Effects on Germination, Phenotypic and Biochemical Characteristics, and In Vitro Secondary Metabolite Production

In this study, short-term liquid nitrogen (LN) storage was used as a strategy to conserve Pyrostegia venusta embryos, and its effects on in vitro germination, phenotypic and biochemical characteristics, and in vitro secondary metabolite production were assessed. Embryos stored in LN for 1 and 7 days presented a higher germination rate and germination speed index compared to those of the control (non-cryostored embryos). Short-term LN storage also favored the phenotypic characteristics of seedlings. LN storage significantly affected the proteins (PTN), soluble sugar (SS) and reducing sugar (RS) contents, oxidative metabolism, and phenylalanine ammonia-lyase (PAL) activity, as well as the total phenolic compound, flavonoid, phytosterol, and alkaloid levels in seedlings regenerated from embryos cryostored for 7 days. Benzoic acid derivatives and flavonoids were observed in regenerated non-acclimatized seedlings. LN storage did not affect the survival rate or phenotypic characteristics of seedlings during acclimatization. Acclimatization promoted significant changes in PTN, SS and RS contents, oxidative metabolism, and PAL activity in seedlings from embryos cryostored for 7 days. Roots from acclimatized seedlings exhibited the highest phenolic, phytosterol, and total alkaloid levels. Differences in the chromatographic profiles of the acclimatized seedlings compared with the non-acclimatized seedlings were observed. LN storage can be an effective means of ex situ conservation of P. venusta genetic resources.

Enhanced metabolite yield with compensatory biomass reduction revealed by moisture stress induction in &lt;i&gt;Centella asiatica&lt;/i&gt; (L.)

The exposure to any kind of stress tends to accelerate the secondary metabolism in medicinal plants increasing the production of secondary metabolites. The present investigation was undertaken to study the effect of moisture stress (100, 75, 50, 25 and 10% pot capacity) and control (as without plant) on growth, yield and metabolite content of Centella asiatica var. ‘Arka Prabhavi’, for two growing seasons under polyhouse conditions. Results revealed that moisture stress treatments had a significant effect on all observed growth and yield traits. Plants maintained at 100% PC exhibited luxurious vegetative growth with maximum leaf length (6.28 cm), leaf breadth (8.14 cm), petiole length (22.32 cm) and fresh biomass yield (164 g/pot). Cumulative water transpired and water use efficiency of the plants was also observed to be maximum at 100% PC. In contrary to biomass yield, increased asiaticoside (1.864%, 1.892%), madecassoside (2.856%, 3.382%) and total triterpenoid content (5.356%, 5.578%) at higher moisture stress levels of 75% and 50% PC, respectively, was observed. Hence, it is appropriate to grow Centella either at 100% or 75% PC to get optimum biomass and metabolite yield on a commercial scale.

Elicitors directed in vitro growth and production of stevioside and other secondary metabolites in Stevia rebaudiana (Bertoni) Bertoni

Stevia rebaudiana (stevia) is a plant in the Asteraceae that contains several biologically active compounds including the antidiabetic diterpene glycosides (e.g. stevioside, rebaudioside and dulcoside) that can serve as zero-calorie sugar alternatives. In this study, an elicitation strategy was applied using 5% polyethylene glycol (PEG), sodium chloride (NaCl; 50 and 100 mM) and gibberellic acid (2.0 and 4.0 mg/L GA3) to investigate their effect on shoot morphogenesis, and the production of phenolics, flavonoids, total soluble sugars, proline and stevioside, as well as antioxidant activity, in shoot cultures of S. rebaudiana. Herewith, the media supplemented with 2 mg/L and 4 mg/L GA3 exhibited the highest shooting response (87% and 80%). The augmentation of lower concentrations of GA3 (2 mg/L) in combination with 6-benzylaminopurine (BAP) resulted in the maximum mean shoot length (11.1 cm). The addition of 100 mM NaCl salts to the media led to the highest observed total phenolics content (TPC; 4.11 mg/g-DW compared to the control 0.52 mg/g-DW), total flavonoids content (TFC; 1.26 mg/g-DW) and polyphenolics concentration (5.39 mg/g-DW) in shoots cultured. However, the maximum antioxidant activity (81.8%) was observed in shoots raised in media treated with 50 mM NaCl. The application of 2 mg/L of GA3 resulted in the highest accumulation of proline (0.99 μg/mL) as compared to controls (0.37 μg/mL). Maximum stevioside content (71 µL/mL) was observed in cultures supplemented with 100 mM NaCl and 5% PEG, followed by the 4 mg/L GA3 treatment (70 µL/mL) as compared to control (60 µL/mL). Positive correlation was observed between GA3 and stevioside content. Notably, these two compounds are derived from a shared biochemical pathway. These results suggest that elicitation is an effective option to enhance the accumulation of steviosides and other metabolites and provides the groundwork for future industrial scale production using bioreactors.

Filamentous morphology: a new frontier for genetic modification of filamentous fungal cell factories

Filamentous fungi are a group of eukaryotic microorganisms widely found in nature. Some filamentous fungi have been developed as "cell factories" and extensively used for the production of recombinant proteins, organic acids, and secondary metabolites due to their strong protein secretion capabilities or effective synthesis of many natural products. The growth morphology of filamentous fungi significantly influences the quality and quantity of fermented products. Previous research conducted by the authors' group revealed that an increase in hyphal branches leads to enhanced protein secretion during liquid fermentation. With the development of morphological engineering of filamentous fungi, an increasing number of studies have focused on modifying fungal mycelium morphology to improve the yield of target metabolites during fermentation. While there have been a few reviews on the relationship between fungal fermentation morphology and productivity, research in this area is rapidly developing and requires updates. The paper presents a comprehensive review of domestic and international research reports, along with the authors' own research findings, to systematically review the morphological patterns of filamentous fungi, the impact of fungal morphology on industrial fermentation, as well as methods and strategies for regulating mycelial morphology. The aim of this review is to enhance the understanding of relevant domestic scholars regarding the morphological development of filamentous fungi and provide ideas for the rational engineering of fungal strains suitable for industrial fermentation.

Impact of climate change on the yield of medicinal plants in recent years

Climate change significantly impacts the yield and quality of medicinal plants due to alterations in temperature, precipitation patterns, and increased frequency of extreme weather events. These changes affect the growth, secondary metabolite production, and geographical distribution of medicinal plants, leading to reduced yields and compromised medicinal properties. Adaptive strategies such as developing climate-resilient plant varieties, sustainable agricultural practices, and enhanced conservation efforts are essential to mitigate these effects. Increased research and collaborative efforts are necessary to safeguard these vital resources for future generations.

Volatile communication in Actinobacteria: a language for secondary metabolism regulation

BackgroundVolatile compounds are key elements in the interaction and communication between organisms at both interspecific and intraspecific levels. In complex bacterial communities, the emission of these fast-acting chemical messengers allows an exchange of information even at a certain distance that can cause different types of responses in the receiving organisms. The changes in secondary metabolism as a consequence of this interaction arouse great interest in the field of searching for bioactive compounds since they can be used as a tool to activate silenced metabolic pathways. Regarding the great metabolic potential that the Actinobacteria group presents in the production of compounds with attractive properties, we evaluated the reply the emitted volatile compounds can generate in other individuals of the same group.ResultsWe recently reported that volatile compounds released by different streptomycete species trigger the modulation of biosynthetic gene clusters in Streptomyces spp. which finally leads to the activation/repression of the production of secondary metabolites in the recipient strains. Here we present the application of this rationale in a broader bacterial community to evaluate volatiles as signaling effectors that drive the activation of biosynthesis of bioactive compounds in other members of the Actinobacteria group. Using cocultures of different actinobacteria (where only the volatile compounds reach the recipient strain) we were able to modify the bacterial secondary metabolism that drives overproduction (e.g., granaticins, actiphenol, chromomycins) and/or de novo production (e.g., collismycins, skyllamycins, cosmomycins) of compounds belonging to different chemical species that present important biological activities.ConclusionsThis work shows how the secondary metabolism of different Actinobacteria species can vary significantly when exposed in co-culture to the volatile compounds of other phylum-shared bacteria, these effects being variable depending on strains and culture media. This approach can be applied to the field of new drug discovery to increase the battery of bioactive compounds produced by bacteria that can potentially be used in treatments for humans and animals.

Rethinking Aspergillosis in the Era of Microbiota and Mycobiota.

Aspergillosis encompasses a wide range of clinical conditions based on the interaction between Aspergillus and the host. It ranges from colonization to invasive aspergillosis. The human lung provides an entry door for Aspergillus. Aspergillus has virulence characteristics such as conidia, rapid growth at body temperature, and the production of specific proteins, carbohydrates, and secondary metabolites that allow A. fumigatus to infiltrate the lung's alveoli and cause invasive aspergillosis. Alveolar epithelial cells play an important role in both fungus clearance and immune cell recruitment via cytokine release. Although the innate immune system quickly clears conidia in immunocompetent hosts, A. fumigatus has evolved multiple virulence factors in order to escape immune response such as ROS detoxifying enzymes, the rodlet layer, DHN-melanin and toxins. Bacterial co-infections or interactions can alter the immune response, impact Aspergillus growth and virulence, enhance biofilm formation, confound diagnosis, and reduce treatment efficacy. The gut microbiome's makeup influences pulmonary immune responses generated by A. fumigatus infection and vice versa. The real-time PCR for Aspergillus DNA detection might be a particularly useful tool to diagnose pulmonary aspergillosis. Metagenomics analyses allow quick and easy detection and identification of a great variety of fungi in different clinical samples, although optimization is still required particularly for the use of NGS techniques. This review will analyze the current state of aspergillosis in light of recent discoveries in the microbiota and mycobiota.

Commercial wine yeast nitrogen requirement influences the production of secondary metabolites (aroma, hydroxytyrosol, melatonin and other bioactives) during alcoholic fermentation

During alcoholic fermentation, Saccharomyces cerevisiae synthesizes different compounds, which are crucial for product quality: volatile compounds with sensory impact, and bioactive compounds such as melatonin (MEL) and hydroxytyrosol (HT), linked to health benefits. As many of these compounds are related with yeast's nitrogen metabolism, their production have been studied in four different commercial strains with different nitrogen requirement (Red Fruit, Uvaferm VRB, Lalvin Rhone 2323 and Lalvin QA23) being, Uvaferm UVR the higher nitrogen demander strain. All strains produced the secondary metabolites, notably Uvaferm UVR produced the highest HT concentration, despite its low growth. Uvaferm UVR emerged also as a significant producer of MEL, indicating a potential role in fermentation related stress. Moreover, Uvaferm UVR shows the highest total concentrations of volatile compounds. Multivariate analysis revealed distinct clustering based on nitrogen requirements of the strains, highlighting the strain-dependent metabolic responses.

Sirtuin E deacetylase is required for full virulence of Aspergillus fumigatus

Aspergillus fumigatus represents a public health problem due to the high mortality rate in immunosuppressed patients and the emergence of antifungal-resistant isolates. Protein acetylation is a crucial post-translational modification that controls gene expression and biological processes. The strategic manipulation of enzymes involved in protein acetylation has emerged as a promising therapeutic approach for addressing fungal infections. Sirtuins, NAD+-dependent lysine deacetylases, regulate protein acetylation and gene expression in eukaryotes. However, their role in the human pathogenic fungus A. fumigatus remains unclear. This study constructs six single knockout strains of A. fumigatus and a strain lacking all predicted sirtuins (SIRTKO). The mutant strains are viable under laboratory conditions, indicating that sirtuins are not essential genes. Phenotypic assays suggest sirtuins’ involvement in cell wall integrity, secondary metabolite production, thermotolerance, and virulence. Deletion of sirE attenuates virulence in murine and Galleria mellonella infection models. The absence of SirE alters the acetylation status of proteins, including histones and non-histones, and triggers significant changes in the expression of genes associated with secondary metabolism, cell wall biosynthesis, and virulence factors. These findings encourage testing sirtuin inhibitors as potential therapeutic strategies to combat A. fumigatus infections or in combination therapy with available antifungals.

Screening and evaluation of antibacterial active strains of Actinomycetes isolated from Northern Indian soil for biofilm inhibition against selected ESKAPE pathogens

AbstractThe growing problem of antimicrobial resistance (AMR) globally has warranted the search for new and alternate anti-infective strategies. This study aimed to isolate and screen soil Actinomycetes from three different locations in Northern India for their broad-spectrum antibacterial and antibiofilm activity against certain drug-resistant bacteria from ESKAPE group. A total of 110 isolates of Actinomycetes were screened for antibacterial activity using overlay and agar-well diffusion assay against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Ninety-five isolates showed antibacterial activity against one or more test bacteria. These isolates were tentatively identified as members of genus Streptomyces. Five isolates (IMA13, IMA25, IMA43, IMA46, and IMA47) demonstrated broad-spectrum activity against test pathogens and were subjected to production of secondary metabolites in liquid medium. Ethyl acetate fraction of culture filtrate showed MIC in the range of 64–512 µg/ml against test bacteria. The most active isolate, IMA-46, was identified by 16srRNA gene sequence analysis as Streptomyces rameus. Further, ethyl acetate fraction from S. rameus-IMA46 was used to inhibit biofilm formation at sub-MIC values. A significant level (50% to 92%) of biofilm inhibition was recorded against test pathogens. Light microscopy and SEM analysis revealed the biofilm structural changes, reduction in cell aggregation and EPS production. LC/MS analysis of the active extract of S. rameus IMA46 showed the presence of many biologically active compounds, including tetracycline and doxycycline. The present study highlights the potential of soil Actinomycetes in production of broad-spectrum anti-infective compounds in combating growing problem of AMR.

No synergy between P and AMF inoculation to improve Sun Protection Factor production in Anadenanthera colubrina (Vell.) Brenan leaves

Secondary metabolite production in medicinal plants and other plants is improved by arbuscular mycorrhizae, plant stress, as well as nutritional factors. The compounds responsible for Sun Protection Factor from Anadenanthera colubrina (Vell.) such as flavonoids and proanthocyanidins may also increase by manipulation of plant stress or nutrient status, and inoculation with arbuscular mycorrhizal fungi (AMF). However, specific gaps regarding the viability of this agricultural tool need clarification, especially regarding the role of Phosphorus (P), one of the mycorrhizal symbiosis regulators and widely employed in plant cultivation. Therefore, this study aimed to understand the role of P in regulating SPF in Anadenanthera colubrina when cultivated in association with arbuscular mycorrhizal fungi (AMF). To this end, two concentrations of P2O5 (8 mg dm−3 and 50 mg dm−3) were evaluated, and two inoculation treatments were tested: control and seedlings inoculated with AMF inoculant. After 150 days in a greenhouse, the leaves were collected to obtain the ethanolic extracts and used to assess the SPF, production of flavonols, proanthocyanidins, saponins, pigments, and in vitro antioxidant activity. The presence of higher P levels in the soil (50 mg dm−3) renders mycorrhizal inoculation dispensable for the enhancement of SPF, production of photoprotective compounds, and antioxidant activity as plants grown under this condition showed a six-fold increase compared to non-inoculated seedlings kept in soil with a lower P level. On the other hand, leaves of A. colubrina seedlings inoculated with AMF and cultivated in soil supplemented with 8 mg P dm−3 displayed a SPF with a 4.9-fold increase and the biosynthesis of photoprotective and antioxidant compounds enhanced by more than five-fold compared to those not inoculated. Despite these benefits, these cultivation practices did not increase the accumulation of carotenoids and chlorophylls. Mycorrhizal inoculation and phosphate fertilization are agricultural practices that, independently, contribute to the increased SPF, biosynthesis of secondary metabolites, and antioxidant activity in A. colubrina leaves.

Callus induction of red ginger (Zingiber officinale var. rubrum) with 2,4-D and Kinetin combination to enhance total phenolic and flavonoid content

Abstract Plant tissue culture perform as in vitro technique which use any parts of plants under environmental and nutritional control. Tissue culture provides a competitive systems for effective secondary metabolites production, including in red ginger which has many functional properties with high demand in health and pharmaceutical sectors. This study aims to develop an appropriate procedure to cultivate red ginger with in vitro technique to enhance its phenolic and flavonoid content. The rhizome buds were use as explants for callus induction by MS medium with some combination of 2,4-D and kinetin (1:0; 1:1; 1:5; and 5:1). The 70% ethanol, 5,25% sodium hypochlorite, and 10% povidone iodine were used for surface sterilization of bud explants. The result reveals that in 1:0 combination of 2,4-D and Kinetin, the compact callus were initiated on day-16. The other three combinations showed shorter callus forming time in day-14 and they were friable. The 1:1 combination showed the highest percentage (70%) of callus formation compared to other three combinations. In this combination also indicated no contamination occurs. From this in vitro tissue culture, the methanolic extract of callus obtained highest total phenolic content (204,793 µg/mL) than rhizome (130.77 µg/mL). Though, the total flavonoid content of callus extract (0,289 µg/mL) was lower than rhizome extract (6.74 µg/mL). This study showed that the in vitro tissue culture was quite appropriate to enhance total phenolic content in red ginger, although not at the flavonoid content.