Benzaldehyde as an insecticidal, antimicrobial, and antioxidant compound produced by Photorhabdus temperata M1021

Damage to the host cadaver, simulating the effects of scavenging, differentially affects fitness of entomopathogenic nematode species

Insect cadavers infected by entomopathogenic nematodes (EPN) are defended against scavengers by chemical mechanisms and other means. Despite these defences, the cadaver may be bitten before being rejected. In this study, we investigated the effect of damage to the cadaver cuticle on the fitness of nematodes (Heterorhabditis downesi Stock, Griffin & Burnell or Steinernema feltiae Filipjev) developing inside. We first quantified the severity of scavenger damage to EPN-infected Galleria mellonella Linnaeus cadavers in the field, and separately, with crickets (Gryllus bimaculatus De Geer) in the laboratory. In both field and laboratory, EPN-infected cadavers suffered less damage than freeze-killed controls, and damage consisted mainly of small lesions to the cuticle. In further experiments, scavenging damage was simulated shortly after death of infected cadavers by piercing the cuticle 0, 1, 3 or 5 times and incubating in moist (100% relative humidity (RH)) or dry (60-70% RH) conditions. The greater the level of damage, the greater the loss of moisture from the cadaver (estimated by weight loss), and this was exacerbated in dry conditions. The number of infective juveniles (IJs) emerging from H. downesi-infected cadavers was significantly reduced by damage, especially in dry conditions. In addition, emerging IJs were progressively smaller with increasing damage. For this species, the number of IJs was negatively correlated with moisture loss, indicating that the reduction in fitness was mediated by desiccation. For S. feltiae, damage impacted IJ number to a lesser extent and size was not affected. The reduction in numbers was not explained by moisture loss, indicating that for S. feltiae, some factor other than desiccation (perhaps competition with opportunistic microbes) impacts the nematodes when the cuticle is damaged. The greater vulnerability of H. downesi, compared to S. feltiae, to scavenger damage to the host cadaver may be due to its longer developmental time in the host resulting in longer exposure to damaging conditions. In conclusion, damage simulating biting by scavengers impacts the fitness of EPN, with the effect depending on nematode species, environmental conditions and the extent of damage. These findings have implications for the success of field application of EPN in infected cadavers.

Comparison of Growth and Metabolomic Profiles of Two Afforestation Cypress Species Cupressus chengiana and Platycladus orientalis Grown at Minjiang Valley in Southwest China

In recent years, afforestation has been conducted in China's hot and dry valleys. However, there is still a paucity of knowledge regarding the performance of tree species in these semi-arid regions, particularly with regard to interspecies differences. The present study compares the growth and metabolome characteristics of two widely used cypress species, namely Cupressus chengiana and Platycladus orientalis, grown at two sites with distinct climate conditions in the hot and dry Minjiang Valley in southwestern China. The findings indicate that C. chengiana trees exhibit superior growth rates compared to P. orientalis trees at both study sites. In comparison to P. orientalis trees, C. chengiana trees demonstrated a greater tendency to close their stomata in order to prevent water loss at the hotter and drier site, Llianghekou (LHK). Additionally, C. chengiana trees exhibited significantly lower hydrogen peroxide levels than P. orientalis trees, either due to lower production and/or higher scavenging of reactive oxygen species. C. chengiana trees accumulated soluble sugars as well as sugar derivatives, particularly those involved in sucrose and galactose metabolisms under stressful conditions. The species-specific differences were also reflected in metabolites involved in the tricarboxylic acid cycle, nitrogen, and secondary metabolisms. The metabolome profiles of the two species appeared to be influenced by the prevailing climatic conditions. It appeared that the trees at the drier and hotter site, LHK, were capable of efficient nitrogen uptake from the soil despite the low soil nitrogen concentration. This study is the first to compare the growth performance and metabolic profiles of two widely used tree species with high resistance to adverse conditions. In addition to the species-specific differences and adaptations to different sites, the present study also provides insights into potential management strategies to alleviate abiotic stress, particularly with regard to nitrogen nutrients, in the context of climate change.

Anti-foam cell activity of metabolites of a bacterium isolated from yogurt

Existing literature documents the beneficial effects of probiotics against atherosclerosis, a major cause of human death. However, it suffers from a serious limitation due to horizontal gene transfer. Therefore, currently, efforts are targeted to examine the beneficial effects of metabolites obtained from probiotics. In this context, the current study isolated a bacterium from yogurt and investigated the effect of its metabolites on foam cell formation, a key event for developing atherosclerosis. Results showed that the cell-free conditioned medium (CM) of this isolate and di-chloro methane extract of CM (CME) not only prevented the formation but also reduced the level of preformed foam cells. To understand the mechanism, the GC-MS study revealed the presence of compounds known to exert anti-atherogenic activities like anti-oxidant, anti-NF-κB, and lipolytic activities. Consistently, CME exhibited substantial anti-oxidant and anti-NF-κB activity. In conclusion, metabolites of this bacterium have anti-atherogenic activities and thus have therapeutic potential.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01515-7.

Diospyros rhodocalyx Kurz induces mitochondrial-mediated apoptosis via BAX, Bcl-2, and caspase-3 pathways in LNCaP human prostate cancer cell line

Background

Prostate cancer (PCa) is one of the causes of death in men worldwide. Although treatment strategies have been developed, the recurrence of the disease and consequential side effects remain an essential concern. Diospyros rhodocalyx Kurz, a traditional Thai medicine, exhibits diverse therapeutic properties, including anti-cancer activity. However, its anti-cancer activity against prostate cancer has not been thoroughly explored. This study aims to evaluate the anti-cancer activity and underlying mechanisms of the ethyl acetate extract of D. rhodocalyx Kurz (EADR) related to apoptosis induction in the LNCaP human prostate cancer cell line.

Methods

Ethyl acetate was employed to extract the dried bark of D. rhodocalyx Kurz. The cytotoxicity of EADR on both LNCaP and WPMY-1 cells (normal human prostatic myofibroblast cell line) was evaluated using MTS assay. The effect of EADR on the cell cycle, apoptosis induction, and alteration in mitochondrial membrane potential (MMP) was assessed by the staining with propidium iodide (PI), Annexin V-FITC/PI, and JC-1 dye, respectively. Subsequent analysis was conducted using flow cytometry. The expression of cleaved caspase-3, BAX, and Bcl-2 was examined by Western blotting. The phytochemical profiling of the EADR was performed using gas chromatography-mass spectrometry (GC-MS).

Results

EADR exhibited a dose-dependent manner cytotoxic effect on LNCaP cells, with IC50 values of 15.43 and 12.35 µg/mL after 24 and 48 h, respectively. Although it also exhibited a cytotoxic effect on WPMY-1 cells, the effect was comparatively lower, with the IC50 values of 34.61 and 19.93 µg/mL after 24 and 48 h of exposure, respectively. Cell cycle analysis demonstrated that EADR did not induce cell cycle arrest in either LNCaP or WPMY-1 cells. However, it significantly increased the sub-G1 population in LNCaP cells, indicating a potential induction of apoptosis. The Annexin V-FITC/PI staining indicated that EADR significantly induced apoptosis in LNCaP cells. Subsequent investigation into the underlying mechanism of EADR-induced apoptosis revealed a reduction in MMP as evidenced by JC-1 staining. Moreover, Western blotting demonstrated that EADR treatment resulted in the upregulation of BAX, downregulation of BCL-2, and elevation of caspase-3 cleavage in LNCaP cells. Notably, the epilupeol was a prominent compound in EADR as identified by GC-MS.

Conclusion

The EADR exhibits anti-cancer activity against the LNCaP human prostate cancer cell line by inducing cytotoxicity and apoptosis. Our findings suggest that EADR promotes apoptosis by upregulating pro-apoptotic BAX, whereas downregulation of anti-apoptotic Bcl-2 results in the reduction of MMP and the activation of caspase-3. Of particular interest is the presence of epilupeol, a major compound identified in EADR, which may hold promise as a candidate for the development of therapeutic agents for prostate cancer.

Inhibition and biocontrol potential of Ochrobactrum pseudogrignonense NC1 against four Phytophthora species

Phytophthora species are highly destructive soilborne oomycetes pathogens that spread through infested soil and water. Ochrobactrum pseudogrignonense NC1 has been shown to inhibit plant parasitic nematodes via volatile organic compounds (VOCs). In this study, we investigated the inhibitory effect of O. pseudogrignonense NC1 against four Phytophthora species on agar plates and in vivo bioassay. We found that NC1 significantly inhibited the mycelial growth and zoospore production of all four species of Phytophthora in a dose-dependent manner. The half maximal inhibitory concentration (IC50) values for inhibition of mycelial growth (or zoospore production) were 26% (14.8%), 18.9% (14.2%), 20.3% (8.3%) and 46.9% (4%) for Phytophthora capsici Leonian, Phytophthora infestans, Phytophthora parasitica var. nicotiana and Phytophthora sojae, respectively. The biocontrol efficiency of NC1 was 46.3% in pepper seedlings against P. capsici, almost 100% in potato tubers against P. infestans, 60% in tomato leave against P. parasitica and 100% in soybean leave against P. sojae, respectively. Our findings suggest that O. pseudogrignonense NC1 has great potential as a biocontrol agent for managing Phytophthora diseases.

Phytochemical Composition and Antimicrobial Efficacy of Salvadora persica Root Extracts Against Carbapenem-Resistant Acinetobacter baumannii

Background Carbapenem-resistant Acinetobacter baumannii (CRAB) are difficult to eradicate from the environment and are virtually immune to all antibiotics. Consequently, CRAB may culminate in severe outbreaks and fatal infections among people attending hospitals and nursing homes. Salvadora persica has been used as an herbal remedy and chewing sticks for dental cleansing. Evaluating S. persica's efficacy against CRAB may provide an alternative approach to treating CRAB infections in healthcare environments, considering its traditional application in dental hygiene. Employing S. persica as an herbal remedy could be a part of a more sustainable approach to control CRAB infections. Aim To investigate the phytochemical composition of S. persica and evaluate its antimicrobial properties. Materials and methods The roots were extracted by Soxhlet apparatus using n-hexane, chloroform, and methanol. Each extract was analyzed using gas chromatography-mass spectrometry (GCMS) and characterized using WN908.L and National Institute of Standards and Technology (NIST) libraries. The antimicrobial activity of each extract against CRAB was evaluated using a broth microdilution assay to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results The GCMS analysis of different solvent extracts of S. persica roots showed the presence of various phytochemical compounds such as steroids, phenolic compounds, fatty acids, alcohols, terpenoids, and vitamin E. Both chloroform and hexane extracts showed the most effective antimicrobial activity with a MIC value of 3.13 mg/mL and an MBC value of 12.50 mg/mL, respectively. Benzoic acid was the major phytochemical compound identified from S. persica extract. N-hexane, chloroform, and methanol extracts exhibited maximum antimicrobial activity due to the presence of active compounds in them. Conclusion Chloroform and hexane extracts showed the most potent antibacterial activities against CRAB.

Spatial and Temporal Disparity Analyses of Glycosylated Benzaldehyde and Identification and Expression Pattern Analyses of Uridine Diphosphate Glycosyltransferase Genes in Prunus mume

The species Prunus mume consists of uniquely aromatic woody perennials with large amounts of free aromatic substances in the flower cells. Uridine diphosphate glycosyltransferase (UGT) modifies these free aromatic substances into water-soluble glycoside-bound volatiles (GBVs) which play an important role in regulating the use of volatiles by plants for information exchange, defense, and stress tolerance. To investigate the changes in the glycosidic state of aromatic substances during the flowering period of P. mume and discern the location and expression of glycoside synthesis genes, we extracted and enzymatically hydrolyzed GBVs of P. mume and then utilized gas chromatography-mass spectrometry (GC-MS) to characterize and analyze the types and contents of GBV glycosides. Further, we identified and classified the members of the UGT gene family of P. mume using the bioinformatic method and analyzed the correlation between the expression of the UGT family genes in P. mume and the changes in glycosidic content. The results showed that the benzenoids were the main aromatic substance that was glycosylated during flowering in P. mume and that glycosidic benzaldehyde was the most prevalent compound in different flower parts and at different flowering stages. The titer of glycoside benzaldehyde gradually increased during the bud stage and reached the highest level at the big bud stage (999.6 μg·g-1). Significantly, titers of glycoside benzaldehyde significantly decreased and stabilized after flowering while the level of free benzaldehyde, in contrast, significantly increased and then reached a plateau after the flowering process was completed. A total of 155 UGT family genes were identified in the P. mume genome, which were divided into 13 subfamilies (A-E, G-N); according to the classification of Arabidopsis thaliana UGT gene subfamilies, the L subfamily contains 17 genes. The transcriptome analysis showed that PmUGTL9 and PmUGTL13 were highly expressed in the bud stage and were strongly correlated with the content of the glycosidic form of benzaldehyde at all stages of flowering. This study provides a theoretical basis to elucidate the function of UGT family genes in P. mume during flower development, to explore the mechanism of the storage and transportation of aromatic compounds in flower tissues, and to exploit industrial applications of aromatic products from P. mume.

Encapsulation of Benzaldehyde Produced by the Eco-Friendly Degradation of Amygdalin in the Apricot Kernel Debitterizing Wastewater

In order to fully utilize the by-products of apricot kernel-debitterizing and address the chemical instability of benzaldehyde in the food industry, benzaldehyde was first prepared by adding the apricot kernel powder to degrade the amygdalin present in the apricot kernel-debitterizing water. Subsequently, β-cyclodextrin was employed to encapsulate the benzaldehyde, and its encapsulation efficacy was evaluated through various techniques including Fourier transform infrared spectroscopy, thermogravimetric analysis, release kinetics fitting inhibitory effect and the effect on Botrytis cinerea. Finally, the encapsulation was explored via molecular docking and molecular dynamics simulations. The results indicate that the optimal preparation conditions for the benzaldehyde were 1.8 h, 53 °C and pH 5.8, and the encapsulation of benzaldehyde with β-cyclodextrin (wall-core ratio of 5:1, mL/g) has been verified by the deceleration in the release rate, the enhanced thermal stability and the prolonged inhibition effect against Botrytis cinerea. The encapsulation proceeded spontaneously without steric hindrance in the simulation, which led to a reduction in the hydrophobic cavity of β-cyclodextrin. In conclusion, the amygdalin in the debitterizing wastewater can be degraded in an eco-friendly way to produce benzaldehyde by adding apricot kernel powder, which contains β-glucosidase; the encapsulation of benzaldehyde is stable, thus enhancing the utilization of amygdalin in the debitterizing wastewater of apricot kernels.

ZIF-8 encapsulation improves the antifungal activity of benzaldehyde and methyl anthranilate in films

In this work, two ZIF-8-based biocomposites were obtained by entrapping the biomolecules benzaldehyde and methyl anthranilate via direct impregnation with fast encapsulation kinetics and high molecule payloads were achieved. The obtained biocomposites exhibit an enhanced antifungal activity against Penicilium expansum after integration in biopolymeric zein films in comparison with the action of free molecules, making these biomaterials promising candidates for food preservation and packaging applications.

A New Benzaldehyde Derivative Exhibits Antiaflatoxigenic Activity against Aspergillus flavus

Aflatoxin B1 (AFB1) is the most potent naturally occurring carcinogen for humans and animals produced by the common fungus Aspergillus flavus (A. flavus). Aflatoxin (AF) contamination in commodities is a global concern related to the safety of food and feed, and it also impacts the agricultural economy. In this study, we investigated the AFB1-inhibiting activity of a new benzaldehyde derivative, 2-[(2-methylpyridin-3-yl)oxy]benzaldehyde (MPOBA), on A. flavus. It was found that MPOBA inhibited the production of AFB1 by A. flavus, with an IC50 value of 0.55 mM. Moreover, the inhibition of conidiation was also observed at the same concentration. The addition of MPOBA resulted in decreased transcript levels of the aflR gene, which encodes a key regulatory protein for the biosynthesis of AF, and also decreased transcript levels of the global regulator genes veA and laeA. These results suggested that MPOBA has an effect on the regulatory mechanism of the development and differentiation of conidia, leading to the inhibition of AFB1 production. In addition, the cytotoxicity study showed that MPOBA had a very low cytotoxic effect on the Madin-Darby canine kidney (MDCK) cell line. Therefore, MPOBA may be a potential compound for developing practically effective agents to control AF contamination.

Valorization of loquat seeds by hydrothermal carbonization for the production of hydrochars and aqueous phases as added-value products

In the framework of circular bio-economy, waste loquat seeds were utilized for the production of two added-value products. The seeds were hydrothermally carbonized at a temperature range of 150-250 °C and time range 2-6 h and the resultant hydrochars and aqueous phases were characterized using various methods. The optimum higher heating value of 30.64 MJ kg-1, ash content of 1.99 wt % and alkali index of 0.05 were achieved for the hydrochar prepared at 250 °C and 6 h, establishing its suitability for energy-related applications. The aqueous phase obtained at 250 °C and 6 h achieved 90% scavenging of the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and had a IC50 value of 43.71 μg mL-1. Principal component analysis showed that the production of phenols, ketones, alkenes and organic acids was favored at >200 °C, whereas furans and aldehydes were primarily formed at 150 °C. Conclusively, both added-value products were obtained at the same optimum hydrothermal carbonization conditions of 250 °C and 6 h treatment time. In a bio-refinery context, this has the practical implication that both bio-products be obtained simultaneously, without the need to switch between different temperatures and residence times.

Effect of 4-Ethylbenzaldehyde from the Volatilome of Annona muricata on Meloidogyne incognita

The demand for new soil fumigants has increased as a result of more restrictive legislation regarding the use of pesticides. In the present study, the potent nematicidal activity of volatile organic compounds released by the Annona muricata leaf macerate was demonstrated. In addition, we searched in the A. muricata volatilome for a molecule with potential to be developed as a new fumigant nematicide. In the greenhouse, even the lowest concentration of soursop leaf macerate tested (1.0%) as a biofumigant caused a significant (P < 0.05) reduction in Meloidogyne incognita infectivity and reproduction when compared with the nontreated control (0%). Forty-one compounds were identified through gas chromatography-mass spectrometry analysis, of which three (sabinene, caryophyllene oxide, and 4-ethylbenzaldehyde) were selected for studies against the nematode. Among these compounds, in in vitro trails, only 4-ethylbenzaldehyde showed nematicidal activity at 250 µg ml-1. The effective doses of 4-ethylbenzaldehyde predicted to kill 50 and 95% of the M. incognita second-stage juvenile population after 48 h of exposure were 35 and 88 µg ml-1, respectively. In in vitro tests, 4-ethylbenzaldehyde at 150 µg ml-1 reduced M. incognita egg hatching to values similar (P > 0.05) to those of the commercial nematicide fluensulfone at a concentration of 200 µg ml-1. In plant experiments, as a soil fumigant, 4-ethylbenzaldehyde at a dose of 1 ml/liter of substrate had an effect similar (P > 0.05) to that of the commercial fumigant Dazomet (250 µg ml-1). Therefore, 4-ethylbenzaldehyde shows potential for development as a new nematicide.

Effect of Rosa damascena Extract on Rat Model Alzheimer's Disease: A Histopathological, Behavioral, Enzyme Activities, and Oxidative Stress Study

The purpose of the current study is to investigate the effect of aquatic Rosa damascena extract against the oxidative damage induced by aluminum chloride intoxication in Alzheimer's model of Wister rats. Rats were divided randomly into seven groups (n = 10). Control group received no treatment, sham group received distilled water orally, aluminum group (AL) was administered AlCl3 (100 mg/kg) orally, extract 1 and 2 groups were treated with only aqueous R. damascena extract (DRE) (500 and 1000 mg/kg), and treatment 1 and 2 groups received aqueous R. damascena extract (500 and 1000 mg/kg) and AlCl3 (100 mg/kg) orally. The brain tissues were sampled for histopathological examination, and biochemical analysis was conducted for estimating the enzyme activities of acetylcholinesterase and catalase (CAT), the levels of GSH and MDA, and ferric reducing antioxidant power. According to the results of behavioral tests, AL administration showed a reduction in spatial memory and remarkably increased the time needed for reaching the invisible platform. The administration of Al-induced oxidative stress and an increase of the enzyme activity of AChE. Al administration increased AChE level from 1.176 ± 0.173 to 3.62 ± 0.348, which was a significant rise. However, treating with the extract at the dose of 1000 mg/kg downregulated it to 1.56 ± 0.303. Administration of the R. damascene extract caused an increased level of catalase and glutathione levels in treatment groups, attenuated MDA level, and regulated AChE activity. Our results illustrate that administration of R. damascene extract has a protective effect against the oxidative damage induced by AlCl3 intoxication in Alzheimer's model.

Molecular Characterization of Some Bacillus Species from Vegetables and Evaluation of Their Antimicrobial and Antibiotic Potency

Numerous natural habitats, such as soil, air, fermented foods, and human stomachs, are home to different Bacillus strains. Some Bacillus strains have a distinctive predominance and are widely recognized among other microbial communities, as a result of their varied habitation and physiologically active metabolites. The present study collected vegetable products (potato, carrot, and tomato) from local markets in Almaty, Kazakhstan. The bacterial isolates were identified using biochemical and phylogenetic analyses after culturing. Our phylogenetic analysis revealed three Gram-positive bacterial isolates BSS11, BSS17, and BSS19 showing 99% nucleotide sequence similarities with Bacillus subtilis O-3, Bacillus subtilis Md1-42, and Bacillus subtilis Khozestan2. The crude extract was prepared from bacterial isolates to assess the antibiotic resistance potency and the antimicrobial potential against various targeted multidrug-resistant strains, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus group B, Streptococcus mutans, Candida albicans, Candida krusei, Pseudomonas aeruginosa, Shigella sonnei, Klebsiella pneumoniae, Salmonella enteritidis, Klebsiella aerogenes, Enterococcus hirae, Escherichia coli, Serratia marcescens, and Proteus vulgaris. This study found that the species that were identified have the ability to produce antibiotic chemicals. Additionally, the GC-MS analysis of three bacterial extracts revealed the presence of many antibiotic substances including phenol, benzoic acid, 1,2-benzenedicarboxylic acid and bis(2-methylpropyl), methoxyphenyl-oxime, and benzaldehyde. This work sheds light on the potential of Bacillus to be employed as an antimicrobial agent to target different multidrug-resistant bacterial strains. The results indicate that market vegetables may be a useful source of strains displaying a range of advantageous characteristics that can be used in the creation of biological antibiotics.

The Symbiotic Bacteria-Xenorhabdus nematophila All and Photorhabdus luminescens H06 Strongly Affected the Phenoloxidase Activation of Nipa Palm Hispid, Octodonta nipae (Coleoptera: Chrysomelidae) Larvae

Symbiotic bacteria form a mutualistic relationship with nematodes and are pathogenic to many insect pests. They kill insects using various strategies to evade or suppress their humoral and cellular immunity. Here we evaluate the toxic effects of these bacteria and their secondary metabolites on the survival and phenoloxidase (PO) activation of Octodonta nipae larvae using biochemical and molecular methods. The results show P. luminescens H06 and X. nematophila All treatments caused significant reductions in the number of O. nipae larvae in a dose-dependent manner. Secondly, the O. nipae immune system recognizes symbiotic bacteria at early and late stages of infection via the induction of C-type lectin. Live symbiotic bacteria significantly inhibit PO activity in O. nipae whereas heat-treated bacteria strongly increase PO activity. Additionally, expression levels of four O. nipae proPhenoloxidase genes following treatment with P. luminescens H06 and X. nematophila All were compared. We found that the expression levels of all proPhenoloxidase genes were significantly down-regulated at all-time points. Similarly, treatments of O. nipae larvae with metabolites benzylideneacetone and oxindole significantly down-regulated the expression of the PPO gene and inhibited PO activity. However, the addition of arachidonic acid to metabolite-treated larvae restored the expression level of the PPO gene and increased PO activity. Our results provide new insight into the roles of symbiotic bacteria in countering the insect phenoloxidase activation system.

Oxidation of Aldehydes Used as Food Additives by Peroxynitrite

Benzaldehyde and its derivatives are used as food supplements. These substances can be used mainly as flavorings or as antioxidants. Besides, peroxynitrite, an oxidizing agent, could be formed in canned food. Both species could react between them. The present article has focused on the kinetic study of the oxidation of aldehydes by peroxynitrite. A reaction mechanism that justifies all the experimental results is proposed. This mechanism, in acidic media, passes through three competitive pathways: (a) a radical attack that produces benzoic acid. (b) peracid oxidation, and (c) a nucleophilic attack of peroxynitrous acid over aldehyde to form an intermediate, X, that produces benzoic acid, or, through a Cannizzaro-type reaction, benzoic acid and benzyl alcohol. All rate constants involved in the third pathway (c) have been calculated. These results have never been described in the literature in acid media. A pH effect was analyzed.

Phytomediated Selenium Nanoparticles Improved Physio-morphological, Antioxidant, and Oil Bioactive Compounds of Sesame under Induced Biotic Stress

Vegetable oil consumption is expected to reach almost 200 billion kilograms by 2030 in the world and almost 2.97 million tons in Pakistan. A large quantity of edible oil is imported annually from other countries to fill the gap between local production and consumption. Compared to other edible oil crops such as soybean, rapeseed, peanut and olive, sesame has innately higher (55%) oil content, which makes it an excellent candidate to be considered to meet local edible oil production. Oil seed crops, especially sesame, are affected by various pathogens, which results in decreased oil production with low quality oil. Selenium nanoparticles (SeNPs) work synergistically, as it has antifungal activity along with improving plant growth. Different concentrations of SeNPs were used, on three different varieties of sesame (TS-5, TH-6, and Till-18). Plant growth and development were accelerated by SeNPs, which ultimately led to an increase in crop yield. Morphological parameters revealed that SeNPs resulted in a growth increase of 55.7% in root length, 48% increase in leaf number/plant, and 38% in stem diameter. Out of three sesame varieties, TS-5 seedlings treated with 40 mg/L SeNPs showed 96.7% germination and 53% SVI at 40 mg/L. Sesame varieties dramatically increased antioxidant capability using SeNPs, resulting in 147% increase in SOD and 140% increase in POD enzyme units in TH-6 and 76% elevation in CAT enzymes in TS-5 (mean ± S.E). GCMS analysis revealed that bioactive compound I, sesamin, sesamol, and tocopherol contents were increased along with enhanced production of different unsaturated fatty acids. Kegg pathway analysis and MSEA revealed that these compounds were mainly involved in biosynthesis of unsaturated fatty acids, suggesting that SeNPs have elicited the biosynthesis of unsaturated fatty acids such as oleic acid, linoleic acid, and α-linoleic acid. This study concluded that SeNPs (40 mg/L) have an excellent capability to be used for crop improvement along with better oil quality.

Disease caused by Neofusicoccum parvum in pruning wounds of grapevine shoots and its control by Trichoderma spp. and Xenorhabdus szentirmaii

Neofusicoccum parvum, is a fungal pathogen and one of the etiological agents of dieback disease in grapevines. The fungus causes deterioration of vines due to vascular colonization and/or production of toxins. We report herein the inhibitory effects of Trichoderma spp. isolates and the antifungal effects of cell-free supernatants (CFS) from Xenorhabdus and Photorhabdus bacteria against N. parvum in agar plates. We also evaluated the effects of the most effective fungi and bacteria against the pathogen in pruning wounds of vine shoots. All isolates of Trichoderma exhibited antifungal activity ranging between 82 and 97.5% at 14 days of post-treatment. All Xenorhabdus and Photorhabdus CFS at 10 and 33% concentrations inhibited mycelial growth with X. szentirmaii PAM 11 and PAM 25 causing the highest inhibition (>74%). In the shoot experiments, T. asperellum IB 01/13 and T. asperellum Quality®, X. szentirmaii PAM 11 (undiluted growth culture and CFS) suppressed the fungus by ≥ 93%. Our study highlights the potential of Trichoderma and X. szentirmaii PAM 11 for use as biofungicides in the management of N. parvum in grapevines. Further studies should be conducted to develop formulations of Trichoderma and Xenorhabdus that enhance stability in shelf-life and increase the efficacy of N. parvum control in grapevines under field conditions.

Genome analysis of secondary metabolite‑biosynthetic gene clusters of Photorhabdus akhurstii subsp. akhurstii and its antibacterial activity against antibiotic-resistant bacteria

Xenorhabdus and Photorhabdus can produce a variety of secondary metabolites with broad spectrum bioactivity against microorganisms. We investigated the antibacterial activity of Xenorhabdus and Photorhabdus against 15 antibiotic-resistant bacteria strains. Photorhabdus extracts had strong inhibitory the growth of Methicillin-resistant Staphylococcus aureus (MRSA) by disk diffusion. The P. akhurstii s subsp. akhurstii (bNN168.5_TH) extract showed lower minimum inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC). The interaction between either P. akhurstii subsp. akhurstii (bNN141.3_TH) or P. akhurstii subsp. akhurstii (bNN168.5_TH) or P. hainanensis (bNN163.3_TH) extract in combination with oxacillin determined by checkerboard assay exhibited partially synergistic interaction with fractional inhibitory concentration index (FICI) of 0.53. Time-killing assay for P. akhurstii subsp. akhurstii (bNN168.5_TH) extract against S. aureus strain PB36 significantly decreased cell viability from 105 CFU/ml to 103 CFU/ml within 30 min (P < 0.001, t-test). Transmission electron microscopic investigation elucidated that the bNN168.5_TH extract caused treated S. aureus strain PB36 (MRSA) cell membrane damage. The biosynthetic gene clusters of the bNN168.5_TH contained non-ribosomal peptide synthetase cluster (NRPS), hybrid NRPS-type l polyketide synthase (PKS) and siderophore, which identified potentially interesting bioactive products: xenematide, luminmide, xenortide A-D, luminmycin A, putrebactin/avaroferrin and rhizomide A-C. This study demonstrates that bNN168.5_TH showed antibacterial activity by disrupting bacterial cytoplasmic membrane and the draft genome provided insights into the classes of bioactive products. This also provides a potential approach in developing a novel antibacterial agent.

Efficacy of pectin-based caproic acid, caprylic acid, linalool, and cuminaldehyde coatings in reducing Salmonella Heidelberg on chicken eggs

Among the animal derived food products, contamination of poultry eggs, and egg shell surface is one of the major causes for foodborne salmonellosis in the United States. As a means of reducing the pathogen transfer to the internal egg contents, polysaccharide-based coatings containing antimicrobial phytochemicals could potentially serve as a biocontrol strategy for shelled egg products. The current study investigated the efficacy of four GRAS (Generally Recognized as Safe)-status plant-derived compounds, namely, caproic acid (CAO), caprylic acid (CAY), linalool (LIN) and cuminaldehyde (CUM), as pectin-based coating treatments, individually or in combination, for reducing Salmonella Heidelberg (SH) on shell eggs. A three-strain mixture of SH (~8.0 log CFU in 50 μL inoculum) was spot-inoculated on surface sterilized white-shelled eggs. Eggs were evenly coated with either pectin-based treatments of CAO (1%), CAY (1%), LIN (1%) and CUM (1%), individually, or a combination of 4 phytochemicals (COMB- each phytochemical at 0.5% v/v level of inclusion). The treated eggs were stored at 4°C and SH counts were enumerated on days 0, 1, 3, 5, 7, 14, and 21 of storage. The study was replicated thrice, 3 eggs/treatment/day time point, and the data were analyzed using two-way ANOVA with significance tested at p &lt; 0.05. On day 0, pectin-coated control eggs had ~7.6 log CFU of SH/egg. At the end of refrigerated storage (day 21), pectin-based coating of CAO and CAY at 1% level reduced SH by 2.0–2.5 log CFU/egg (P &lt; 0.05) when compared to controls. In addition, the CUM and LIN based coatings produced 3.0 log and 3.9 log reduction, respectively, in SH counts on eggs by day 21 of storage. Among the treatments with phytochemical combinations, COMB1 [pectin (2%) + Caprylic acid, caproic acid and cuminaldehyde (each at 0.5% level)] was found to be most effective, reducing SH counts to 2.5–3.3 log CFU/egg from day 0 through day 14, and by the end of storage period (day 21), a 3.5 log CFU reduction/egg (p &lt; 0.05) compared to untreated controls. Morphological studies of treated eggs using atomic force microscopy (AFM) have shown that the roughness of eggs can be influenced by a combination of various compounds. Results indicate the potential efficacy of the aforesaid phytochemicals in reducing SH on shell eggs; however, further studies investigating their industrial feasibility and effects on sensory attributes of eggs are warranted.

Antibacterial activity of essential oils for combating colistin-resistant bacteria

OBJECTIVES

Colistin (polymyxin E) is a bactericidal antibiotic used to treat severe infections caused by multidrug-resistant Gram-negative bacteria. The product of the mcr1 gene generates transferrable plasmid-mediated colistin resistance, which has arisen as a worldwide healthcare problem. This study aimed to isolate, and identify colistin-resistant bacteria, and evaluate the ability of essential oils its fights.

METHODS

: Twenty-seven bacterial isolates were collected from patients who were admitted to National Cancer Institute, Cairo, Egypt, and processed by standard microbiological methods. Essential oils were purchased from AB chem company, Egypt, screened for antibacterial, cytotoxic activity, and (GC-MS) analysis.

RESULTS

A total of 5 bacterial isolates were resistant to colistin with minimum inhibitory concentration (MIC) ranging from 6.25->200µg/ml. Cinnamon oil exhibited the highest activity against colistin-resistant strains followed by thyme and eucalyptus oil. The (MIC) of cinnamon oils against resistant strains ranged from 4.88 to 312.5 µg/ml. Moreover, mcr-1 gene expression was extremely down-regulated after treatment of bacterial strains with cinnamon oil and decreased to 20-35-fold. Examination of treated bacterial cells with sub-inhibitory concentrations under transmission electron microscopy showed various abnormalities occurred in most of these cells.

CONCLUSIONS

cinnamon oil exhibits antibacterial activity against colistin-resistant strains, showing as a promising natural alternative in clinical therapy.

The Entomopathogenic Nematodes H. bacteriophora and S. carpocapsae Inhibit the Activation of proPO System of the Nipa Palm Hispid Octodonta nipae (Coleoptera: Chrysomelidae)

Entomopathogenic nematodes are biocontrol agents of invasive insect pests in soil and cryptic habitats. Nipa palm hispid, Octodonta nipae, is a pest of palm trees in Sothern China. To address its increasing damage, environmentally friendly control methods are required. This study aimed to test efficacy of Heterorhabditis bacteriophora and Steinernema carpocapsae on O. nipae and investigated the influence of secondary metabolites, nematodes, and their isolated cuticles on the activation of O. nipae’s prophenoloxidase system using qPCR analysis. Our data revealed that O. nipae were less susceptible to H. bacteriophora than S. carpocapsae and penetrations of infective juveniles were higher with S. carpocapsae treatment than H. bacteriophora. Moreover, expression levels of the serine protease P56, prophenoloxidase activation factor 1, PPO and serine protease inhibitor 28 upon S. carpocapsae and H. bacteriophora infections were generally downregulated at all times. However, upon heating, the cuticles lost their inhibitory effects and resulted in upregulation of the PPO gene. Similarly, the addition of arachidonic acid reversed the process and resulted in the upregulation of the PPO gene compared to the control. Further work is needed to identify toxic substances secreted by these EPNs to evade O. nipae’s immune system.

Natural products from Photorhabdus and Xenorhabdus: mechanisms and impacts

Insects and fungal pathogens pose constant problems to public health and agriculture, especially in resource-limited parts of the world; and the use of chemical pesticides continues to be the main methods for the control of these organisms. Photorhabdus spp. and Xenorhabdus spp., (Fam; Morganellaceae), enteric symbionts of Steinernema, and Heterorhabditis nematodes are naturally found in soil on all continents, except Antarctic, and on many islands throughout the world. These bacteria produce diverse secondary metabolites that have important biological and ecological functions. Secondary metabolites include non-ribosomal peptides, polyketides, and/or hybrid natural products that are synthesized using polyketide synthetase (PRS), non-ribosomal peptide synthetase (NRPS), or similar enzymes and are sources of new pesticide/drug compounds and/or can serve as lead molecules for the design and synthesize of new alternatives that could replace current ones. This review addresses the effects of these bacterial symbionts on insect pests, fungal phytopathogens, and animal pathogens and discusses the substances, mechanisms, and impacts on agriculture and public health. KEY POINTS: • Insects and fungi are a constant menace to agricultural and public health. • Chemical-based control results in resistance development. • Photorhabdus and Xenorhabdus are compelling sources of biopesticides.

Root-Associated Bacteria Are Biocontrol Agents for Multiple Plant Pests

Biological control is an important process for sustainable plant production, and this trait is found in many plant-associated microbes. This study reviews microbes that could be formulated into pesticides active against various microbial plant pathogens as well as damaging insects or nematodes. The focus is on the beneficial microbes that colonize the rhizosphere where, through various mechanisms, they promote healthy plant growth. Although these microbes have adapted to cohabit root tissues without causing disease, they are pathogenic to plant pathogens, including microbes, insects, and nematodes. The cocktail of metabolites released from the beneficial strains inhibits the growth of certain bacterial and fungal plant pathogens and participates in insect and nematode toxicity. There is a reinforcement of plant health through the systemic induction of defenses against pathogen attack and abiotic stress in the plant; metabolites in the beneficial microbial cocktail function in triggering the plant defenses. The review discusses a wide range of metabolites involved in plant protection through biocontrol in the rhizosphere. The focus is on the beneficial firmicutes and pseudomonads, because of the extensive studies with these isolates. The review evaluates how culture conditions can be optimized to provide formulations containing the preformed active metabolites for rapid control, with or without viable microbial cells as plant inocula, to boost plant productivity in field situations.

Process Development for Benzyl Alcohol Production by Whole-Cell Biocatalysis in Stirred and Packed Bed Reactors

The ocean is an excellent source for new biocatalysts due to the tremendous genetic diversity of marine microorganisms, and it may contribute to the development of sustainable industrial processes. A marine bacterium was isolated and selected for the conversion of benzaldehyde to benzyl alcohol, which is an important chemical employed as a precursor for producing esters for cosmetics and other industries. Enzymatic production routes are of interest for sustainable processes. To overcome benzaldehyde low water solubility, DMSO was used as a biocompatible cosolvent up to a concentration of 10% (v/v). A two-phase system with n-hexane, n-heptane, or n-hexadecane as organic phase allowed at least a 44% higher relative conversion of benzaldehyde than the aqueous system, and allowed higher initial substrate concentrations. Cell performance decreased with increasing product concentration but immobilization of cells in alginate improved four-fold the robustness of the biocatalyst: free and immobilized cells were inhibited at concentrations of benzyl alcohol of 5 and 20 mM, respectively. Scaling up to a 100 mL stirred reactor, using a fed-batch approach, enabled a 1.5-fold increase in benzyl alcohol productivity when compared with batch mode. However, product accumulation in the reactor hindered the conversion. The use of a continuous flow reactor packed with immobilized cells enabled a 9.5-fold increase in productivity when compared with the fed-batch stirred reactor system.

Bacterial Volatile-Mediated Suppression of Root-Knot Nematode (Meloidogyne incognita)

Root-knot nematodes (Meloidogyne spp.) are obligate plant parasites that cause severe economic losses to agricultural crops worldwide. Because of serious health and environmental concerns related to the use of chemical nematicides, the development of efficient alternatives is of great importance. Biological control through exploiting the potential of rhizosphere microorganisms is currently accepted as an important approach for pest management in sustainable agriculture. In our research, during screening of rhizosphere bacteria against the root-knot nematodes Meloidogyne incognita, Ochrobactrum pseudogrignonense strain NC1 from the rhizosphere of healthy tomatoes showed strong nematode inhibition. A volatile nematicidal assay showed that the cell-free fermentation filtrate in the first-row wells of 12-well tissue culture plates caused M. incognita juvenile mortality in the second-row wells. Gas chromatography-mass spectrometry analysis revealed that dimethyl disulfide (DMDS) and benzaldehyde were the main volatile compounds produced by strain NC1. The nematicidal activity of these compounds indicated that the lethal concentration 50 against the M. incognita juveniles in the second-row wells and the fourth-row wells were 23.4 μmol/ml and 30.7 μmol/ml for DMDS and 4.7 μmol/ml and 15.2 μmol/ml for benzaldehyde, respectively. A greenhouse trial using O. pseudogrignonense strain NC1 provided management efficiencies of root-knot nematodes of 88 to 100% compared with the untreated control. This study demonstrated that nematode-induced root-gall suppression mediated by the bacterial volatiles DMDS and benzaldehyde presents a new opportunity for root-knot nematode management.

Solanum linnaeanum Leaves: Chemical Profiling of VOCs and Effects on Seed Germination and Early Growth of Monocots and Dicots

Some Solanaceae plants are a rich source of sesquiterpenoid phytoalexins with allelopathic potential. Powder and aqueous extract obtained from the leaves of Solanum linnaeanum Hepper & P.M.L. Jaeger were used to treat the seeds of three target species (Lolium multiflorum Lam., Sinapis alba L. and Trifolium incarnatum L.). Both matrices were evaluated along with untreated controls to determine their toxicity on germination and seedling growth. The results revealed that the pre-emergence treatments were able to be very effective against all three species in the filter paper test by inhibiting the germination up to 100 %. The effectiveness was reduced by the interaction with soil. Despite this, significant data were obtained, albeit different according to the applied matrix. In general, L. multiflorum was the most sensitive to both the action of the leaf powder and aqueous extract while S. alba was found to be the most resistant to powder activity and T. incarnatum had the strongest response to the extract. For the first time, SPME-GC/MS technique was used to characterize the volatile chemical profile of S. linnaeanum leaves. The analyses highlighted the presence of different classes of compounds including terpenoids and sesquiterpenoids potentially useful in the fight against noxious plants both in natural and cultivated ecosystems.

Heterorhabditis and Photorhabdus Symbiosis: A Natural Mine of Bioactive Compounds

Phylum Nematoda is of great economic importance. It has been a focused area for various research activities in distinct domains across the globe. Among nematodes, there is a group called entomopathogenic nematodes, which has two families that live in symbiotic association with bacteria of genus Xenorhabdus and Photorhabdus, respectively. With the passing years, researchers have isolated a wide array of bioactive compounds from these symbiotically associated nematodes. In this article, we are encapsulating bioactive compounds isolated from members of the family Heterorhabditidae inhabiting Photorhabdus in its gut. Isolated bioactive compounds have shown a wide range of biological activity against deadly pathogens to both plants as well as animals. Some compounds exhibit lethal effects against fungi, bacteria, protozoan, insects, cancerous cell lines, neuroinflammation, etc., with great potency. The main aim of this article is to collect and analyze the importance of nematode and its associated bacteria, isolated secondary metabolites, and their biomedical potential, which can serve as potential leads for further drug discovery.

Recent trends in microbial flavour Compounds: A review on Chemistry, synthesis mechanism and their application in food

Aroma and flavour represent the key components of food that improves the organoleptic characteristics of food and enhances the acceptability of food to consumers. Commercial manufacturing of aromatic and flavouring compounds is from the industry's microbial source, but since time immemorial, its concept has been behind human practices. The interest in microbial flavour compounds has developed in the past several decades because of its sustainable way to supply natural additives for the food processing sector. There are also numerous health benefits from microbial bioprocess products, ranging from antibiotics to fermented functional foods. This review discusses recent developments and advancements in many microbial aromatic and flavouring compounds, their biosynthesis and production by diverse types of microorganisms, their use in the food industry, and a brief overview of their health benefits for customers.

Selective Toxicity of Secondary Metabolites from the Entomopathogenic Bacterium Photorhabdus luminescens sonorensis against Selected Plant Parasitic Nematodes of the Tylenchina Suborder

Entomopathogenic Photorhabdus bacteria (Enterobacteriaceae: Gamma-proteobacteria), the natural symbionts of Heterorhabditis nematodes, are a rich source for the discovery of biologically active secondary metabolites (SMs). This study describes the isolation of three nematicidal SMs from in vitro culture supernatants of the Arizona-native Photorhabdus luminescenssonorensis strain Caborca by bioactivity-guided fractionation. Nuclear magnetic resonance spectroscopy and comparison to authentic synthetic standards identified these bioactive metabolites as trans-cinnamic acid (t-CA), (4E)-5-phenylpent-4-enoic acid (PPA), and indole. PPA and t-CA displayed potent, concentration-dependent nematicidal activities against the root-knot nematode (Meloidogyne incognita) and the citrus nematode (Tylenchulus semipenetrans), two economically and globally important plant parasitic nematodes (PPNs) that are ubiquitous in the United States. Southwest. Indole showed potent, concentration-dependent nematistatic activity by inducing the temporary rigid paralysis of the same targeted nematodes. While paralysis was persistent in the presence of indole, the nematodes recovered upon removal of the compound. All three SMs were found to be selective against the tested PPNs, exerting little effects on non-target species such as the bacteria-feeding nematode Caenorhabditis elegans or the entomopathogenic nematodes Steinernema carpocapsae, Heterorhabditis bacteriophora, and Hymenocallis sonorensis. Moreover, none of these SMs showed cytotoxicity against normal or neoplastic human cells. The combination of t-CA + PPA + indole had a synergistic nematicidal effect on both targeted PPNs. Two-component mixtures prepared from these SMs revealed complex, compound-, and nematode species-dependent interactions. These results justify further investigations into the chemical ecology of Photorhabdus SMs, and recommend t-CA, PPA and indole, alone or in combinations, as lead compounds for the development of selective and environmentally benign nematicides against the tested PPNs.

IMPORTANCE Two phenylpropanoid and one alkaloid secondary metabolites were isolated and identified from culture filtrates of Photorhabdus l. sonorensis strain Caborca. The three identified metabolites showed selective nematicidal and/or nematistatic activities against two important plant parasitic nematodes, the root-knot nematode (Meloidogyne incognita) and the citrus nematode (Tylenchulus semipenetrans). The mixture of all three metabolites had a synergistic nematicidal effect on both targeted nematodes, while other combinations showed compound- and nematode-dependent interactions.

Heavy metal ATPase genes (HMAs) expression induced by endophytic bacteria, "AI001, and AI002" mediate cadmium translocation and phytoremediation

Contamination of heavy metals is a serious threat, which causes threats to the environment. Our study aimed to determine the role of endophytic bacteria in Cd phytoremediation and heavy metal ATPase gene expression. Cadmium (Cd) resistant endophytic bacteria were isolated from Solanum nigrum on LB agar plates, contaminated with 0-30 mg/L Cd. The phosphate solubilization and indole-3-acetic acid (IAA) production of endophytes were estimated by growing them on Pikovskaya agar medium and GC-MS analysis, respectively. An experiment in a pot was performed to evaluate the effects of bacteria on rice plants contaminated with 5-25 mg/L of Cd. Expression of Cd response genes was quantified through qRT-PCR and Cd translocation from one part to another part of the plant was measured through the ICP. BLAST alignment of 16 S-rDNA gene sequences confirmed the bacterial isolates as Serratia sp. AI001 and Klebsiella sp. Strain AI002. Both strains tolerated Cd up to 25 mg/L and produced 27-30 μg/mL of IAA. Inoculation of AI001 and AI002 improved plant growth dynamics (i.e., plant length, biomass, chlorophyll contents), relieved electrolyte leakage, and improved reduced glutathione significantly (P < 0.05). The inoculation of AI001 and AI002 significantly (P < 0.05) induced the expression of heavy metal ATPase genes ie., "HMA2, HMA3, and HMA4" and Cd translocation compared to uninoculated plants. Both AI001 and AI002 exhibited very prominent plant-growth-promoting and Cd phytoremediation properties. The results revealed that isolates also contributed a lot to the expression of rice plant heavy metal ATPase genes and in the Cd translocation in the plant.

Analysis of the chemical composition of root essential oil from Indian sarsaparilla (Hemidesmus indicus) and its application as an ecofriendly insecticide and pharmacological agent

The Indian sarsaparilla (Hemidesmus indicus) is a commonly used plant in Indian traditional medicine of Ayurveda for the preparation of various non-alcoholic beverages. However, limited studies are available on the essential oil of H. indicus roots (HRO); therefore, the study evaluated the antioxidant, anti-inflammatory and antidiabetic activities of H. indicus root essential oil as well as insecticide potential against the common pests of stored food materials (Sitophilus oryzae, Callosobruchus maculatus and Tribolium castaneum). The repellant efficacy of HRO was found to be high against S. oryzae (8.21 ± 0.55 μg/mL). Likewise, the fumigant potential was also observed for HRO against these pests; the higher activities were observed against S. oryzae and C. maculatus (32.46 ± 1.42 and 35.18 ± 1.62 μg/L). Besides, the essential oil was also found to be active as a contact poison, however, against all the three pests, the toxicity was above 100 μg/mm³, being the highest against C. maculatus (122.8 ± 3.57 μg/mm³). To analyze the possible effect of the essential oil on grains, the different grains were allowed to germinate and compared to that of normal; thus, the non-toxic nature of HRO against the stored products is also confirmed. The essential oil shown to have DPPH hydrogen peroxide and ABTS radical scavenging, nitric oxide scavenging potential, and inhibition of lipoxgenase, alpha-amylase and alpha-glucosidase. Overall, the present study concludes that the H. indicus may be a suitable repellant and fumigant agent against different pests of stored products and a possible antioxidant, anti-inflammatory, and anti-diabetic agent.

Volatilome and Essential Oil of Ulomoides dermestoides: A Broad-Spectrum Medical Insect

Ulomoides dermestoides are used as a broad-spectrum medical insect in the alternative treatment of various diseases. Preliminary volatilome studies carried out to date have shown, as the main components, methyl-1,4-benzoquinone, ethyl-1,4-benzoquinone, 1-tridecene, 1-pentadecene, and limonene. This work focused on the production of metabolites and their metabolic variations in U. dermestoides under stress conditions to provide additional valuable information to help better understand the broad-spectrum medical uses. To this end, VOCs were characterized by HS-SPME with PEG and CAR/PDMS fibers, and the first reported insect essential oils were obtained. In HS-SMPE, we found 17 terpenes, six quinones, five alkenes, and four aromatic compounds; in the essential oils, 53 terpenes, 54 carboxylic acids and derivatives, three alkynes, 12 alkenes (1-Pentadecene, EOT1: 77.6% and EOT2: 57.9%), 28 alkanes, nine alkyl disulfides, three aromatic compounds, 19 alcohols, three quinones, and 12 aldehydes were identified. Between both study approaches, a total of 171 secondary metabolites were identified with no previous report for U. dermestoides. A considerable number of the identified metabolites showed previous studies of the activity of pharmacological interest. Therefore, considering the wide variety of activities reported for these metabolites, this work allows a broader vision of the therapeutic potential of U. dermestoides in traditional medicine.

Volatile Organic Compounds in the Azteca/Cecropia Ant-Plant Symbiosis and the Role of Black Fungi

Black fungi of the order Chaetothyriales are grown by many tropical plant-mutualistic ants as small so-called “patches” in their nests, which are located inside hollow structures provided by the host plant (“domatia”). These fungi are introduced and fostered by the ants, indicating that they are important for the colony. As several species of Chaetothyriales tolerate, adsorb, and metabolize toxic volatiles, we investigated the composition of volatile organic compounds (VOCs) of selected domatia in the Azteca/Cecropia ant-plant mutualism. Concentrations of VOCs in ant-inhabited domatia, empty domatia, and background air were compared. In total, 211 compounds belonging to 19 chemical families were identified. Ant-inhabited domatia were dominated by ketones with 2-heptanone, a well-known ant alarm semiochemical, as the most abundant volatile. Empty domatia were characterized by relatively high concentrations of the monoterpenes d-limonene, p-cymene and β-phellandrene, as well as the heterocyclic sulphur-containing compound, benzothiazole. These compounds have biocidal properties and are primarily biosynthesized by plants as a defense mechanism. Interestingly, most of the latter compounds were present at lower concentrations in ant inhabited domatia than in non-colonized ones. We suggest that Chaetothyriales may play a role in reducing the VOCs, underlining that the mutualistic nature of these fungi as VOCs accumulation might be detrimental for the ants, especially the larvae.

Can Symbiotic Bacteria (Xenorhabdus and Photorhabdus) Be More Efficient than Their Entomopathogenic Nematodes against Pieris rapae and Pentodon algerinus Larvae?

Simple Summary

Food security is the people’s main concern, and agricultural crops play a significant role in ensuring it. Agricultural pests, on the other hand, are regarded one of the most serious threats to cause a significant problem for food security. Entomopathogenic nematodes of the genera Herterorhabditids and Sterinernematids fulfil the fundamental requirements of perfect bio-control agents; however, their efficacy mostly dependent on their symbiotic bacteria. As a result, this study aimed to investigate the ability of the isolated symbiotic bacteria (Photorhabdus and Xenorhabdus) to control Pieris rapae and Pentodon algerinus larvae in comparison with their own nematodes, Heterorhabditis bacteriophora and Steinernema riobravis, respectively. The results showed that both nematode species and their symbiotic bacteria were able to suppress both insect species. However, both bacterial genera were more efficient than the investigated nematode species against P. rapae, although nematodes were superior against P. algerinus. Gas chromatography–mass spectrophotometry of Xenorhabdus sp. and Photorhabdus sp. identified the key components with the insecticidal properties. The two bacteria genera were proven to be safe and had no significant effect on normal WI-38 human cells. In conclusion, the symbiotic bacteria can be employed safely and effectively against the tested insects independently on their own entomopathogenic nematodes.

Abstract

Pieris rapae and Pentodon algerinus are considered a global threat to agricultural crops and food security; hence, their control is a critical issue. Heterorhabditid and Steinernematid nematodes, along with their symbiotic bacteria, can achieve the optimal biocontrol agent criterion. Therefore, this study aimed to evaluate the efficacy of Heterorhabditis bacteriophora, Steinernema riobravis, and their symbiotic bacteria (Xenorhabdus and Photorhabdus) against P. rapae and P. algerinus larvae. The virulence of entomopathogenic nematodes (EPNs) was determined at different infective juvenile concentrations and exposure times, while the symbiotic bacteria were applied at the concentration of 3 × 10⁷ colony-forming units (CFU)/mL at different exposure times. Gas chromatography–mass spectrophotometry (GC-MS) analysis and the cytotoxic effect of Photorhabdus sp. and Xenorhabdus sp. were determined. The results indicated that H. bacteriophora, S. riobravis, and their symbiotic bacteria significantly (p ≤ 0.001) induced mortality in both insect species. However, H. bacteriophora and its symbiont, Photorhabdus sp., were more virulent. Moreover, the data clarified that both symbiotic bacteria outperformed EPNs against P. rapae but the opposite was true for P. algerinus. GC-MS analysis revealed the main active compounds that have insecticidal activity. However, the results revealed that there was no significant cytotoxic effect. In conclusion, H. bacteriophora, S. riobravis, and their symbiotic bacteria can be an optimal option for bio-controlling both insect species. Furthermore, both symbiotic bacteria can be utilized independently on EPNs for the management of both pests, and, hence, they can be safely incorporated into biocontrol programs and tested against other insect pests.

Evaluation of Benzaldehyde as an Antibiotic Modulator and Its Toxic Effect against Drosophila melanogaster

Products of natural origin remain important in the discovery of new bioactive molecules and are less damaging to the environment. Benzaldehyde is a product of the metabolism of plants, and similarly to oxygenated terpenes, it can have antibacterial activity against Staphylococcus aureus and toxic action against Drosophila melanogaster; we aimed to verify these activities. The broth microdilution tests determined the minimum inhibitory concentration (MIC) of benzaldehyde alone and in association with antibiotics and ethidium bromide (EtBr). Toxicity against Drosophila melanogaster was determined by fumigation tests that measured lethality and damage to the locomotor system. The results indicated that there was an association of norfloxacin and ciprofloxacin with benzaldehyde, from 64 μg/mL to 32 μg/mL of ciprofloxacin in the strain K6028 and from 256 μg/mL to 128 μg/mL of norfloxacin in the strain 1199B; however, the associations were not able to interfere with the functioning of the tested efflux pumps. In addition, benzaldehyde had a toxic effect on flies. Thus, the results proved the ability of benzaldehyde to modulate quinolone antibiotics and its toxic effects on fruit flies, thus enabling further studies in this area.

Hermetia illucens (L.) (Diptera: Stratiomyidae) Odorant Binding Proteins and Their Interactions with Selected Volatile Organic Compounds: An In Silico Approach

The black soldier fly (BSF), Hermetia illucens (Diptera: Stratiomyidae), has considerable global interest due to its outstanding capacity in bioconverting organic waste to insect biomass, which can be used for livestock, poultry, and aquaculture feed. Mass production of this insect in colonies requires the development of methods concentrating oviposition in specific collection devices, while the mass production of larvae and disposing of waste may require substrates that are more palatable and more attractive to the insects. In insects, chemoreception plays an essential role throughout their life cycle, responding to an array of chemical, biological and environmental signals to locate and select food, mates, oviposition sites and avoid predators. To interpret these signals, insects use an arsenal of molecular components, including small proteins called odorant binding proteins (OBPs). Next generation sequencing was used to identify genes involved in chemoreception during the larval and adult stage of BSF, with particular attention to OBPs. The analysis of the de novo adult and larval transcriptome led to the identification of 27 and 31 OBPs for adults and larvae, respectively. Among these OBPs, 15 were common in larval and adult transcriptomes and the tertiary structures of 8 selected OBPs were modelled. In silico docking of ligands confirms the potential interaction with VOCs of interest. Starting from the information about the growth performance of H. illucens on different organic substrates from the agri-food sector, the present work demonstrates a possible correlation between a pool of selected VOCs, emitted by those substrates that are attractive for H. illucens females when searching for oviposition sites, as well as phagostimulants for larvae. The binding affinities between OBPs and selected ligands calculated by in silico modelling may indicate a correlation among OBPs, VOCs and behavioural preferences that will be the basis for further analysis.

Toxicity of Five Plant Volatiles to Adult and Egg Stages of Drosophila suzukii Matsumura (Diptera: Drosophilidae), the Spotted-Wing Drosophila

The environmental impact of methyl bromide (MB) has resulted in its phase out as an insecticidal fumigant except for critical use exempted categories. Consequently, there is an urgent need to develop an environmentally sustainable MB alternative fumigant. trans-Cinnamaldehyde (TC), benzaldehyde, allyl isothiocyanate (AITC), hexanal, and ethyl formate (EF) are naturally occurring plant volatiles with insecticidal properties. This study assessed the toxicity of these plant volatiles to adult and egg stages of the spotted-wing drosophila (SWD) (Drosophila suzukii Matsumura). The plant volatile treatments had a significant effect on adult SWD mortality. The descending order of toxicity to adult SWD was benzaldehyde > AITC > TC > hexanal > EF at a headspace concentration of 0.50 μL/L air for 24 h. All the volatiles, at a concentration of 4.00 μL/L air, significantly inhibited larval emergence from SWD eggs in artificial diet compared to the control. At a 0.50 μL/L air level, among the volatiles tested, only AITC exhibited 100% inhibition against larval emergence from SWD eggs in blueberry fruits after 24 h exposure. In summary, this study shows that all volatiles tested elicited varying degrees of toxicity toward SWD adults and eggs. However, AITC was the most efficacious volatile and the one with the greatest promise as a post-harvest fumigant for both adult and egg stages of SWD.

Endophytic Colonization by the Entomopathogenic Fungus Beauveria Bassiana Affects Plant Volatile Emissions in the Presence or Absence of Chewing and Sap-Sucking Insects

Entomopathogenic fungi are gaining acceptance in Integrated Pest Management (IPM) systems as effective and environmental safety biological control agents to protect a great variety of crops against pest insects. Many of these insect-pathogenic fungi can establish themselves as endophytes and thereby may induce the plant immune system. The activation of plant defenses by the fungal endophytic colonization can have a direct impact on herbivores and plant pathogens. An integral component of many plant defense responses is also the release of volatile organic compounds, which may serve as an indirect defense by attracting the natural enemies of herbivores. Here we investigated the effect of endophytic colonization by the entomopathogenic fungus Beauveria bassiana on the volatile emission by melon and cotton plants, either unharmed or after being damaged by sap-sucking aphids or leaf chewing caterpillars. We found that when the plants are colonized by B. bassiana they emit a different blend of volatile compounds compared to uncolonized control plants. Some of the emitted compounds have been reported previously to be released in response to herbivory and have been implicated in natural enemy attraction. Several of the compounds are also known to have antimicrobial properties. Therefore, endophytic colonization by B. bassiana might help to not only direct control insect pests but also increase the resistance of plants against agronomically important pests and phytopathogens.

Antimicrobial Peptides: Novel Source and Biological Function With a Special Focus on Entomopathogenic Nematode/Bacterium Symbiotic Complex

The rapid emergence of multidrug resistant microorganisms has become one of the most critical threats to public health. A decrease in the effectiveness of available antibiotics has led to the failure of infection control, resulting in a high risk of death. Among several alternatives, antimicrobial peptides (AMPs) serve as potential alternatives to antibiotics to resolve the emergence and spread of multidrug-resistant pathogens. These small proteins exhibit potent antimicrobial activity and are also an essential component of the immune system. Although several AMPs have been reported and characterized, studies associated with their potential medical applications are limited. This review highlights the novel sources of AMPs with high antimicrobial activities, including the entomopathogenic nematode/bacterium (EPN/EPB) symbiotic complex. Additionally, the AMPs derived from insects, nematodes, and marine organisms and the design of peptidomimetic antimicrobial agents that can complement the defects of therapeutic peptides have been used as a template.

Antifungal activity of different Xenorhabdus and Photorhabdus species against various fungal phytopathogens and identification of the antifungal compounds from X. szentirmaii

Xenorhabdus and Photorhabdus spp. are enteric bacterial symbionts of Steinernema and Heterorhabditis nematodes, respectively. These bacteria produce an extensive set of natural products (NPs) with antibacterial, antifungal, antiprotozoal, insecticidal, or other bioactivities when vectored into insect hemocoel by nematodes. We assessed the in vitro activity of different Xenorhabdus and Photorhabdus cell-free supernatants against important fungal phytopathogens, viz., Cryphonectria parasitica, Fusarium oxysporum, Rhizoctonia solani, and Sclerotinia sclerotiorum and identified the bioactive antifungal compound/s present in the most effective bacterial supernatant using the easyPACId (easy promoter-activated compound identification) approach against chestnut blight C. parasitica. Our data showed that supernatants from Xenorhabdus species were comparatively more effective than extracts from Photorhabdus in suppressing the fungal pathogens; among the bacteria assessed, Xenorhabdus szentirmaii was the most effective species against all tested phytopathogens especially against C. parasitica. Subsequent analysis revealed fabclavines as antifungal bioactive compounds in X. szentirmaii, generated by a polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) hybrid system. Fabclavines are broad-spectrum, heat-stable NPs that have great potential as biological control compounds against fungal plant pathogens. More studies are needed to assess the potential phytotoxicity of these compounds and their effects on non-target organisms before commercialization. KEY POINTS: • Chemical fungicides have toxic effects on humans and other non-target organisms. • Alternatives with novel modes of action to supplant current fungicide are needed. • A novel bioactive antifungal compound from Xenorhabdus szentirmaii was identified.

Heat stress decreases the diversity, abundance and functional potential of coral gas emissions

Terrestrial ecosystems emit large quantities of biogenic volatile organic compounds (BVOCs), many of which play important roles in abiotic stress responses, pathogen and grazing defences, inter- and intra-species communications, and climate regulation. Conversely, comparatively little is known about the diversity and functional potential of BVOCs produced in the marine environment, especially in highly productive coral reefs. Here we describe the first 'volatilomes' of two common reef-building corals, Acropora intermedia and Pocillopora damicornis, and how the functional potential of their gaseous emissions is altered by heat stress events that are driving rapid deterioration of coral reef ecosystems worldwide. A total of 87 BVOCs were detected from the two species and the chemical richness of both coral volatilomes-particularly the chemical classes of alkanes and carboxylic acids-decreased during heat stress by 41% and 62% in A. intermedia and P. damicornis, respectively. Across both coral species, the abundance of individual compounds changed significantly during heat stress, with the majority (>86%) significantly decreasing compared to control conditions. Additionally, almost 60% of the coral volatilome (or 52 BVOCs) could be assigned to four key functional groups based on their activities in other species or systems, including stress response, chemical signalling, climate regulation and antimicrobial activity. The total number of compounds assigned to these functions decreased significantly under heat stress for both A. intermedia (by 35%) and P. damicornis (by 64%), with most dramatic losses found for climatically active BVOCs in P. damicornis and antimicrobial BVOCs in A. intermedia. Together, our observations suggest that future heat stress events predicted for coral reefs will reduce the diversity, quantity and functional potential of BVOCs emitted by reef-building corals, potentially further compromising the healthy functioning of these ecosystems.

High-Throughput Volatilome Fingerprint Using PTR-ToF-MS Shows Species-Specific Patterns in Mortierella and Closely Related Genera

In ecology, Volatile Organic Compounds (VOCs) have a high bioactive and signaling potential. VOCs are not only metabolic products, but are also relevant in microbial cross talk and plant interaction. Here, we report the first large-scale VOC study of 13 different species of Mortierella sensu lato (s. l.) isolated from a range of different alpine environments. Proton Transfer Reaction-Time-of-Flight Mass Spectrometry (PTR-ToF-MS) was applied for a rapid, high-throughput and non-invasive VOC fingerprinting of 72 Mortierella s. l. isolates growing under standardized conditions. Overall, we detected 139 mass peaks in the headspaces of all 13 Mortierella s. l. species studied here. Thus, Mortierella s. l. species generally produce a high number of different VOCs. Mortierella species could clearly be discriminated based on their volatilomes, even if only high-concentration mass peaks were considered. The volatilomes were partially phylogenetically conserved. There were no VOCs produced by only one species, but the relative concentrations of VOCs differed between species. From a univariate perspective, we detected mass peaks with distinctively high concentrations in single species. Here, we provide initial evidence that VOCs may provide a competitive advantage and modulate Mortierella s. l. species distribution on a global scale.

Chemical Composition and Antimicrobial Activities of the Essential Oil From the Leaves of Pterocephalus hookeri

Detailed chemical constituents of essential oil from the Pterocephalus hookeri leaves and its antimicrobial activities were investigated in this study. The essential oil, obtained by hydrodistillation, was characterized by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry analyses. Among the 90 identified compounds, hexadecanoic acid (21.27%), phytol (8.03%), furfural (7.08%), oleic acid (5.25%), and phytone (4.56%) were the major components. In the antimicrobial assay, the essential oil showed strong inhibitory activities against Escherichia coli, Candida albicans, and Staphylococcus aureus with minimum inhibitory concentration values of 31.3, 62.5, and 125 µg/mL, respectively. To our knowledge, this is the first report concerning chemical composition and antimicrobial activities of the essential oil from Pterocephalus hookeri.

Role of Carbon Monoxide in Host-Gut Microbiome Communication

Nature is full of examples of symbiotic relationships. The critical symbiotic relation between host and mutualistic bacteria is attracting increasing attention to the degree that the gut microbiome is proposed by some as a new organ system. The microbiome exerts its systemic effect through a diverse range of metabolites, which include gaseous molecules such as H₂, CO₂, NH₃, CH₄, NO, H₂S, and CO. In turn, the human host can influence the microbiome through these gaseous molecules as well in a reciprocal manner. Among these gaseous molecules, NO, H₂S, and CO occupy a special place because of their widely known physiological functions in the host and their overlap and similarity in both targets and functions. The roles that NO and H₂S play have been extensively examined by others. Herein, the roles of CO in host-gut microbiome communication are examined through a discussion of (1) host production and function of CO, (2) available CO donors as research tools, (3) CO production from diet and bacterial sources, (4) effect of CO on bacteria including CO sensing, and (5) gut microbiome production of CO. There is a large amount of literature suggesting the "messenger" role of CO in host-gut microbiome communication. However, much more work is needed to begin achieving a systematic understanding of this issue.

Fungal benzene carbaldehydes: occurrence, structural diversity, activities and biosynthesis

Covering: up to April 2020Fungal benzene carbaldehydes with salicylaldehydes as predominant representatives carry usually hydroxyl groups, prenyl moieties and alkyl side chains. They are found in both basidiomycetes and ascomycetes as key intermediates or end products of various biosynthetic pathways and exhibit diverse biological and pharmacological activities. The skeletons of the benzene carbaldehydes are usually derived from polyketide pathways catalysed by iterative fungal polyketide synthases. The aldehyde groups are formed by direct PKS releasing, reduction of benzoic acids or oxidation of benzyl alcohols.

Antibacterial activity of Xenorhabdus and Photorhabdus isolated from entomopathogenic nematodes against antibiotic-resistant bacteria

Xenorhabdus and Photorhabdus, symbiotically associated with entomopathogenic nematodes (EPNs), produce a range of antimicrobial compounds. The objective of this study is to identify Xenorhabdus and Photorhabdus and their EPNs hosts, which were isolated from soil samples from Saraburi province, and study their antibacterial activity against 15 strains of drug-resistant bacteria. Fourteen isolates (6.1%), consisting of six Xenorhabdus isolates and eight Photorhabdus isolates, were obtained from 230 soil samples. Based on the BLASTN search incorporating the phylogenetic analysis of a partial recA gene, all six isolates of Xenorhabdus were found to be identical and closely related to X. stockiae. Five isolates of Photorhabdus were found to be identical and closely related to P. luminescens subsp. akhurstii. Two isolates of Photorhabdus were found to be identical and closely related to P. luminescens subsp. hainanensis. The remaining isolate of Photorhabdus was found to be identical to P. asymbiotica subsp. australis. The bacterial extracts from P. luminescens subsp. akhurstii showed strong inhibition the growth of S. aureus strain PB36 (MSRA) by disk diffusion, minimal inhibitory concentration, and minimal bactericidal concentration assay. The combination between each extract from Xenorhabdus/Photorhabdus and oxacillin or vancomycin against S. aureus strain PB36 (MRSA) exhibited no interaction on checkerboard assay. Moreover, killing curve assay of P. luminescens subsp. akhurstii extracts against S. aureus strain PB36 exhibited a steady reduction of 10⁵ CFU/ml to 10³ CFU/ml within 30 min. This study demonstrates that Xenorhabdus and Photorhabdus, showed antibacterial activity. This finding may be useful for further research on antibiotic production.

The impact of certain flavourings and preservatives on the survivability of eggs of Ascaris suum and Trichuris suis

The article describes a laboratory study of nematocidal properties of flavourings with antibacterial effect against Ascaris suum (Goeze, 1782) and Trichuris suis Schrank, 1788. In the experiments, eight concentrations of food additives with antibacterial properties were used: cinnamaldehyde, benzoic acid, formic acid, linalool, citral, β-ionone. Minimum LC50 value for eggs of A. suum was observed while using cinnamaldehyde and benzoic acid – 1.62 ± 0.37% and 1.69 ± 0.14%, and for eggs of T. suis – 0.57 ± 0.03% and 1.80 ± 0.11% respectively. The lowest influence on the development of eggs of nematodes of pigs’ A. suum and T. suis was exerted by formic acid, linalool, citral and β-ionone. In eggs of A. suum and T. suis, larvae formed in 21 and 50 days even during exposure to 3% emulsions of these substances. The strongest negative impact on the eggs of parasitic nematodes was displayed by cinnamaldehyde flavouring. Further study on nematocidal properties of flavourings, as well as their mixtures, would contribute to the development of preparations which would have a strong effect on eggs and larvae of nematodes of animals and humans.

Isoniazid-phytochemical conjugation: A new approach for potent and less toxic anti-TB drug development

Mycobacterium tuberculosis (Mtb) causes one of the most grievous pandemic infectious diseases, tuberculosis (TB), with long-term morbidity and high mortality. The emergence of drug-resistant Mtb strains, and the co-infection with human immunodeficiency virus, challenges the current WHO-TB stewardship programs. The first-line anti-TB drugs, isoniazid (INH) and rifampicin (RIF), have become extensively obsolete in TB control from chromosomal mutations during the last decades. However, based on clinical trial statistics, the production of well-tolerated anti-TB drug(s) is miserably low. Alternately, semi-synthesis or structural modifications of first-line obsolete antitubercular drugs remain as the versatile approach for getting some potential medicines. The use of any suitable phytochemicals with INH in a hybrid formulation could be an ideal approach for the development of potent anti-TB drug(s). The primary objective of this review was to highlight and analyze available INH-phytochemical hybrid research works. The utilization of phytochemicals through chemical conjugation is a new trend toward the development of safer/non-toxic anti-TB drugs.