Microbial Rumen proteome analysis suggests Firmicutes and Bacteroidetes as key producers of lignocellulolytic enzymes and carbohydrate-binding modules
Lignocellulosic biomass, rich in cellulose, hemicellulose, and lignin, offers a sustainable source for biofuels and and production of other materials such as polymers, paper, fabrics, bioplastics and biofertilizers. However, its complex structure hinders efficient conversion. Chemical, enzymatic, and microbial methods aim to unlock the trapped sugars and phenols. The rumen microbiome, a fascinating ecosystem within ruminant animals, holds particular promise. The Hungate 1000 project sequenced 410 microbial genomes from the rumen, enabling in silico screening for lignocellulolytic enzymes. This approach saves time and resources, supporting the development of sustainable bioconversion technologies aligned with the UN's 2030 agenda goals. Analysis of these 410 predicted proteomes revealed diverse carbohydrate-active enzymes (CAZymes) and carbohydrate-binding modules (CBMs) across various microorganisms. Notably, Firmicutes and Bacteroidetes dominated CAZyme and CBM production, suggesting collaborative efforts among different phyla during degradation. The presence of CBM50 and chitinases hints at the ability to utilize chitin from fungal cell walls. Interestingly, the absence of ligninolytic auxiliary activity enzymes reaffirms the rumen microbiome's incapability of directly degrading lignin. However, enzymes facilitating the loosening of the cell wall by cleaving lignin-hemicellulose linkages were identified. This suggests a strategy for making cellulose more accessible to hydrolytic enzymes. This study highlights the intricate relationship between rumen microbes, contributing necessary enzymes for plant cell wall deconstruction in this unique environment. Additionally, it underlines the power of in silico techniques for analyzing big data, paving the way for advancements in sustainable bioconversion.
Antifungal activity of guanidine compounds
Guanidinic compounds are a class of compounds distributed in nature but also synthesized in vitro with a wide variety of applicability. One of the potentials of those molecules is antimicrobial activity. In that sense, although mainly limited to immunocompromised people, fungi pathogens are a cause of concern, even more so after the COVID-19 pandemic. Susceptible groups and increased geographical distribution, besides drug toxicity, resistance, and high costs, made the World Health Organization (WHO) establish a guideline for research and public health politics against different fungi opportunist agents. Our present work evaluated the antifungal activity of 11 guanidine compounds (one of them synthesized for the first time) against six fungi species in the WHO Fungi Priority Pathogens List and their potential for antimicrobial selectivity. The newly synthesized compound, named LQOF-G2-S, was successfully obtained and chemically characterized as spermidine tri-substituted by guanidine moieties in benzylamine-4-bromoaniline groups, and it presented the best antifungal activity and selectivity among the others. It was the only compound active against Candida spp.; however, its activity was more promising against Cryptococcus neoformans, Cryptococcus gattii, and even more against Paracoccidioides brasiliensis and Paracoccidioides lutzii, with a selective index higher than 10. The LQOF-G2-S potential opened up the opportunity to design and evaluate other similar compounds, contributing to finding new effective, less toxic, and more affordable compounds for fungi treatment.
Do the microbiota of larval breeding site and the blood meal influence the composition and diversity of bacterial communities in the midgut of Mansonia humeralis (Diptera: Culicidae) from the western Amazon?
Mansonia humeralis is a neotropical mosquito common in floodplain ecosystems and a potential host of Mayaro virus in the Amazon region. Studies show that bacterial communities associated with the midgut of mosquito vectors can mediate insecticide detoxification and modulate vector competence. Understanding the characteristics of the intestinal microbiota, and the factors that shape them, is essential for effective mosquito control. This study investigated the influence of bacterial communities in water from the larval environment on the composition and bacterial diversity in Ma. humeralis larval intestines and characterized the midgut microbiota of adult females with and without apparent blood. Samples were obtained from the Jirau Hydroelectric Plant, Madeira River, AM, Brazil, and their bacteria characterized using the 16S rRNA molecular marker. A total of 402 bacterial Amplicon Sequencing Variants (ASVs) were identified to genus level. The sample groups (water, larvae, blood + and blood-) had distinct bacterial communities, especially the larvae, probably due to the intense feeding activity which occurs at this stage. The phylum Proteobacteria was dominant in water, blood + and blood- (52.5; 99 and 98%), respectively, while Firmicutes dominated in larvae (45%). The most abundant taxa in water were: ASV Comamonadaceae (11.7%) and hgcI_clade (9.6%), in larvae: ASV Synergistaceae (11.1%) and ASV Rhodocyclaceae (7.8%), in blood-: Serratia (46.9%) and Asaia (12.6%) and, in blood+: ASV Enterobacteriaceae (54.5%) and Serratia (21.1%). Some 19% of the taxonomic groups from water were also recorded in larvae, while 46.7% of blood- microbiota were present in blood+. Wolbachia, Acinetobacter and Enterobacter bacteria were recorded at low frequency in all samples. This result provides a powerful tool for understanding the ecology of the intestinal microbiota of Ma. humeralis and the relationships with the ambient microbiota derived from larval filter, and adult blood, feeding. The results will also be useful for future studies which focusing the development of potential tools for the biological control of this vector.
Cuminaldehyde synergistically enhances the antimicrobial and antibiofilm potential of gentamicin: A direction towards an effective combination for the control of biofilm-linked threats of Staphylococcus aureus
Staphylococcus aureus, a Gram-positive, coccus-shaped bacterium often causes several infections on human hosts by exploiting biofilm. This current work investigates a potential strategy to manage the threats of biofilm-linked infections by embracing a combinatorial approach involving cuminaldehyde (phytochemical) and gentamicin (antibiotic). Despite showing antimicrobial properties individually, cuminaldehyde and gentamicin could exhibit enhanced antimicrobial potential when used together against S. aureus. The fractional inhibitory concentration index (FICI = 0.36) suggested that the selected compounds (cuminaldehyde and gentamicin) offered synergistic interaction while showing antimicrobial potential against the same organism. A series of experiments indicated that the selected compounds (cuminaldehyde and gentamicin) showed substantial antibiofilm potential against S. aureus when combined. The increased antibiofilm potential was linked to the accumulation of reactive oxygen species (ROS) and increased cell membrane permeability. Additionally, the combination of the selected compounds (cuminaldehyde and gentamicin) also impeded the cell surface hydrophobicity of S. aureus, aiding in the prevention of biofilm formation. The present study also showed that combining the mentioned compounds (cuminaldehyde and gentamicin) notably reduced the secretion of several virulence factors from S. aureus. Furthermore, the current research showed that these compounds (cuminaldehyde and gentamicin) could also exhibit antibiofilm potential against the clinical strains of Methicillin-Resistant S. aureus (MRSA). Taken together, this innovative approach not only enhances the potential of existing standard antibiotics but also opens up new therapeutic possibilities for combating biofilm-related infections.
Genomic and phenotypic characterization of Chryseomicrobium imtechense from canine pyometra
Chryseomicrobium imtechense is a bacterium primarily isolated in environment samples. Here we demonstrated the virulent and antimicrobial resistant profile of the C. imtechense LBV029/19 strain, which was isolated in a pyometra infection in canines, being related as causal agent of that disease. The bacterium was recovered from purulent content of a uterus with pyometra and the identity was confirmed by both, biochemical tests followed MALDI-TOF MS and 16S-rDNA gene sequencing. Antimicrobial susceptibility test, biofilm formation assessment, genomic sequencing with Illumina MiSeq platform followed by the genome characterization and phylogenetic relationships were conducted with C. imtechense LBV029/19 strain. The phylogenetic analysis revealed a close evolutionary relationship between the C. imtechense LBV029/19 and the others publicly available 16S-rDNA genes of C. imtechense. The in vitro assays shown that C. imtechense LBV029/19 has a strong ability for biofilm formation. Additionally, the antimicrobial susceptibility tests revealed a smaller inhibition zone for novobiocin, cefuroxime, and erythromycin. To the best of our knowledge the C. imtechense LBV029/19 genome is the first genome sequenced and available of C. imtechense. Regarding the genotypic profile, resistance genes to tetracyclines, fluoroquinolones, beta-lactams, and multidrug resistance were present in this genome. Additionally, genes encoded to virulence factors, including biofilm formation, motility, and sporulation were identified. The phenotypic profile associated with the genotypic description indicates the potential of C. imtechense LBV029/19 as a primary agent of animal infectious diseases. The genomic description will contribute to the understanding of the biology of the bacterium and the pathogenesis process involved in the disease.
Pathotyping and molecular serotyping of clinical isolates of Glaesserella parasuis in Taiwan
Glaesserella parasuis is a bacterial pathogen that causes severe economic losses in the swine industry worldwide. In this study, 262 G. parasuis isolates from pigs with Glässer's disease obtained between 2015 and 2022 in Taiwan were serotyped, pathotyped, and analyzed for virulence genes. The most prevalent serovars were 5 (29%), 4 (27.9%), 12 (12.2%), and non-typable strains (13%). The frequency of serositis with pulmonary lesions (55%) was significantly higher than that of pulmonary lesions alone (23.3%) and serositis lesions alone (21.7%) (p < 0.001). Serovars 4, 5, 12, 13 and non-typable strains had a significantly higher prevalence in serositis with pulmonary lesions than in pulmonary lesions alone, whereas serovar 1 had higher prevalence in pulmonary lesions. The virulence gene V4, related to virulence-associated protein D, had the highest detection rate (94.8%) in pathogenic isolates, which was significantly higher than other virulence genes in serovars 4, 5, 7, 12, 13, and non-typable strains except for serovar 1. Virulence-associated protein D may be a suitable subunit vaccine antigen candidate, and more research is required to evaluate the potential for broader application. Given the limited vaccine availability restricted to serovar 5 in Taiwan, these findings provide a basis for multivalent and subunit vaccine development providing better cross-protection.
Sequential macrophage DENV and ZIKV infection shows differential expression of CD86, IFN-β, and regulation of TNF-α and IL-1β depending on DENV serotype
Dengue virus (DENV) is an RNA virus belonging to the Flaviviridae family, comprising four antigenically distinct serotypes. Dengue is the primary arthropod-transmitted virus globally, posing a significant public health challenge, especially in Brazil, where the largest outbreak of Zika virus (ZIKV) was also recorded in 2016. ZIKV shares genomic and structural similarities with DENV, and their co-circulation in Brazil provides evidence of co-infection. The innate immune response against DENV and ZIKV is mediated by pattern recognition receptors that initiate intracellular signaling, leading to antiviral or inflammatory responses. This study aims to better understand the innate immune response to ZIKV in macrophages previously infected with DENV. To achieve this, bone marrow cells from C57BL/6 mice were differentiated into macrophages (BMDMs) and independently infected with each of the four DENV serotypes for 12 h, followed by ZIKV infection for an additional 12 h. Twenty-four hours post-infection, macrophage activation markers CD86 were assessed using flow cytometry and fluorescence microscopy. Pro-inflammatory and antiviral gene expressions were evaluated by qPCR. IFN-β was found to be down-regulated in all analyzed groups. No differences in CD86 expression were observed in ZIKV-infected BMDMs previously infected with DENV, except for serotype 4, which showed an increase in both activation markers. Conversely, TNF-α and IL-1β were down-regulated compared to non-infected or only DENV4-infected cells, correlating with increased cell viability and decreased production of the cytokine TNF-α. Bioinformatic analysis suggested that the expression of both cytokines might be regulated by miRNAs, including miR-181a-5p, which is also up-regulated in the innate immune response. Taken together, the results indicated that co-infection with DENV serotype 4 and ZIKV in mice BMDMs increases the expression of CD86, promoting macrophage activation, but reduces the expression of pro-inflammatory genes TNF-α and IL-1β, indicating enhanced cell viability what can be modulated by miRNAs.
In vivo and in vitro pathogenicity of Fusarium oxysporum and its biofilm components
Fusarium oxysporum is a widely distributed phytopathogen that affects agricultural crops and has demonstrated relevance in human and veterinary medicine. The virulence of this fungus involves factors such as mycotoxins, immunomodulatory proteins, and the ability to form biofilm. We assessed the pathogenicity of F. oxysporum in its planktonic form, as well as the influence of the extracellular matrix (ECM) from its biofilm on T. molitor larvae and cell culture. F. oxysporum inoculum was injected into larvae at different concentrations, and the survival curve was observed over 10 days. To evaluate the effects of ECM components, biofilms of 24, 72, 96, and 168 h of maturation were used. After extracting the ECM from these biofilms, it was injected into the larvae to assess the hosts response. For the cytotoxicity test of the ECM, were used on Vero cells. The increase in fungal inoculum concentrations was directly proportional to the larval mortality rate. When larvae were infected with the ECM, there was a 40% mortality rate and signs of weakness in the surviving larvae. Furthermore, biofilm metabolites showed cytotoxic effects, with reductions in cellular activity ranging from 20 to 49%. This alternative host model proved effective in investigating the fungal pathogenicity. Additionally, ECM components negatively affected cell viability, suggesting their importance in the damage caused by the fungus in host tissues. This study provides insights for the first time into F. oxysporum virulence and highlights the importance of considering the biofilm ECM in the context of fungal infections.
Development and characterization of active cellulose acetate films with antifungal properties of Thymus vulgaris essential oil for cheese applications : Antifungal potential film with Thymus vulgaris essential oil against cheese fungi
The aim of this study was to evaluate the antifungal activity of Thymus vulgaris essential oil (TEO) against fungal isolates from cheese and its potential as an active component in cellulose acetate films for application on cheese, and to perform the characterization of the films. The cheese rind isolates were identified as Penicillium crustosum QCP1 and Aspergillus flavus QCA2. TEO exhibited significant in vitro inhibitory activity against all isolates, with inhibition zones exceeding 40.0 mm and minimum inhibitory concentrations (MICs) of 1.0 µL mL⁻¹ and 0.8 µL mL⁻¹ for P. crustosum QCP1 and A. flavus QCA2, respectively. Incorporating TEO into cellulose acetate films altered the film's physical properties, particularly morphology and elongation. The control film, composed solely of acetate, showed the lowest values for most properties evaluated, except for tensile strength (MPa) (38.89 ± 5.29). For water permeability and water vapor permeability, no significant differences were observed between the control film and the active film containing TEO at tenfold MFC concentrations for each isolate. In in vitro tests with the active film, P. crustosum QCP1 demonstrated higher sensitivity; however, the active film effectively inhibited the growth of both fungal isolates on cheese slices for 30 days. It was concluded that TEO has antifungal potential against isolates in more than one type of methodology and, when added to cellulose acetate film, was effective in controlling fungal mycelial growth, both in vitro and in situ, extending shelf life by up to 2 times, indicating a promising application as active packaging in cheeses.
Differences in gut microbiota composition, diversity, and predicted functional activity between wild and captive zoo Carollia perspicillata in a One Health perspective
Bats play an important role in global microbial ecology, as they are the host of various microbes. Carollia perspicillata is one of the most popular bat species in zoos. The influence of the captive environment on the gut microbiota of this species is underinvestigated. In this study, we compared gut microbiota composition, diversity, and the potential functional activity of wild and captive C. perspicillata from Panama and Russia (Moscow Zoo), respectively, based on high-throughput 16S rRNA sequencing data. The abundance of 13 bacterial phyla and 35 bacterial genera significantly differed. Environment- and farm animal health-related bacteria (Mannheimia, unclassified Pasteurellaceae, Staphylococcus, and Mycoplasma) dominated wild bats, while bacteria important for public health (Bacteroides, Clostridium sensu stricto 1, and Acinetobacter) were higher in zoo bats. We also observed significantly greater alpha diversity in zoo bats, while there were no significant differences in beta diversity. These findings were accompanied by significant differences in the abundance of 32 functional pathways of gut bacteria, which are probably associated with the different diets of wild and zoo bats. This study shows that the rearing environment significantly affects the gut microbiota of C. perspicillata and highlights that the outcomes of microbiome research of captive bats need to be interpreted with care. Such differences in gut bacterial communities should be the basis for the development of new handling and veterinary care protocols, and also be the justification for further studies of the impact of microbiota of wild and zoo bats on One Health.
Optimization of endospore production by solid and liquid fermentation for the development of effective formulations of Bacillus velezensis-based products
The objective of this study was to optimize the culture medium for enhanced production of Bacillus velezensis AP-3 endospores using both liquid and solid-state fermentation techniques. Additionally, the study aimed to assess the stability of endospores in powder formulations containing talc and potato starch, and to evaluate the growth-promoting effects of these formulations on bean plants. Further, we evaluated the inhibition of mycelial growth of Sclerotinia sclerotiorum and Fusarium oxysporum f. sp. lycopercisi by metabolites produced by this bacterial strain. The plant growth promotion assay evaluated these formulations across various application methods: seed treatment, sowing furrow application, and a combination of both. Adjustments to culture medium significantly influenced the endospore yield of B. velezensis. Solid-state fermentation in rice flour and potato starch yielded up to 2.06 × 10 and 1.82 × 10 CFU g after 7 days in a 60% moisture medium, respectively. Conversely, submerged fermentation in molasses + cottonseed flour medium produced 1.7 × 10 CFU mL (viable endospores) in 3 days. The powder formulations showed high stability, maintaining viability for up to 226 days at room temperature. This bacterial strain effectively inhibited the mycelial growth of target fungal pathogens and promoted bean plant growth, particularly by enhancing root development. These findings highlight the versatility of B. velezensis AP-3 in producing endospores through two fermentation methods, its extended shelf-life as a wettable powder formulation, and its efficacy both as biocontrol agent and plant growth promoter, contributing to a sustainable agriculture.
New records of molecular detection of hemotropic Mycoplasma spp. in road-killed wild mammals at Southern Brazil
Hemotropic Mycoplasma spp., also known as Hemoplasmas, infect several species of domestic and wild animals, including humans. Although infections in wild animals are mostly asymptomatic and chronic, there is a risk of spreading the patogen to other susceptible animals. They can cause death in immunosuppressed mammals, and have implications for the conservation of already threatened wild mammals. The objective of this study was to report on the molecular detection of Mycoplasma spp. hemotropic. in wild mammals run over in the Southern Brazil, describing new findings of hemoplasmas in this region. Carcasses of 24 road-killed wild animals were collected on the highways of cities belonging to the Pelotas microregion, in the south of RS, Brazil, and were necropsied. Ectoparasites were removed and classified according to morphological taxonomic keys. Blood samples from all animals were collected and genomic DNA was extracted. Polymerase chain reaction (PCR) amplification targeting the 16S rDNA and 23S rRNA genes revealed the presence of Mycoplasma spp. DNA in blood samples from 87.5% of animals. This study reports the first molecular finding of hemotropic mycoplasma in Brazilian guinea pig (Cavia aperea) and pampas fox (Lycalopex gymnocercus). The detection of hemoplasma in different host species demonstrates the spread of the agent among wild mammals in southern Brazil.
Anti-virulence effects of Diclofenac sodium in combination with gentamicin on Pseudomonas aeruginosa: attenuation of quorum sensing related traits and efflux pump systems
Antibiotic resistance is a major clinical and public health problem. Non-steroidal anti-inflammatory drugs (NSAIDs) could increase the susceptibility of bacteria to antibiotics and have shown broad antimicrobial activity. In this work, the effect of Diclofenac sodium alone and in combination with Gentamicin on the expression of efflux pump genes and some virulence traits in clinical isolates of P. aeruginosa was investigated. The checkerboard titration assay was used to evaluate the synergistic effect of Diclofenac sodium and Gentamicin. The relative expression of MexAB-OprM and MexXY-OprM efflux pump genes was determined using qPCR. The impact of drugs on the activity of the efflux pump and some virulence traits, including biofilm formation, swarming, swimming and twitching, and bacterial proteolytic and hemolytic activities were assessed. The minimum inhibitory concentration (MIC) of Diclofenac sodium and Gentamicin for clinical P. aeruginosa strains was 5120 and 128 µg/mL and the drugs showed synergic antibacterial activity. Diclofenac sodium reduced the expression of the mexB, mexX, and mexY genes, and increased the expression of the mexA and oprM genes. In addition, Diclofenac sodium alone and in combination with Gentamicin inhibited the activity of the bacterial efflux pump and the simultaneous treatment of P. aeruginosa with Diclofenac sodium and Gentamicin significantly reduced biofilm formation, bacterial motility, proteolytic (40.78%) and hemolytic (85%) activities compared with untreated group. This study addresses clinically relevant questions about the efficacy and potential synergistic effects of diclofenac sodium and gentamicin in treating P. aeruginosa infections that can be applicable to clinical practice.
High frequency of chromosomal polymyxin resistance in Escherichia coli isolated from dairy farm animals and genomic analysis of mcr-1-positive strain
Escherichia coli strains are naturally susceptible to polymyxins. The frequency of polymyxin resistance in E. coli associated with chromosomal mutations is usually low (0.2-0.6%). Here, we report polymyxin-resistant E. coli strains isolated from flies (Diptera: Muscomorpha) and animals (bovine, equine, canine, and sheep) cohabitants on two dairy farms, A and B (Botucatu, State of Sao Paulo, Brazil), in 2015. We isolated 877 E. coli from the external surface of flies and healthy animal feces. The screening of polymyxin-resistant E. coli was performed using MacConkey agar with polymyxin B (2 µg/mL). We detected a high percentage of polymyxin-resistant isolates from flies (33.33%; 66/198) and farm animals (46.09%; 313/679). Fisher's exact test revealed no associations between polymyxin resistant and multidrug resistant strains. We investigated mcr genes (mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5) using PCR, and five E. coli from calves (farm B) present the mcr-1 gene. Sanger sequencing and conjugation assays were performed for gene confirmation. All five mcr-1-positive E. coli showed fingerprints more than 80% similar assayed by pulsed-field gel electrophoresis. The minimum inhibitory concentrations (MICs) for polymyxin B against mcr-1-positive E. coli were 4 µg/mL (two strains), and 8 µg/mL (three strains). Whole-genome sequencing showed mcr-1.1 gene in the IncX4 plasmid and a class 1 integron unusual harboring sul3 and qacL as a non-variable structure. In Brazil, the therapeutic use of polymyxin is allowed, but stewardship in dairy cattle is uncommon; thus, our data indicate a probable selection of polymyxin-resistant strains related to environmental pressure.
Diversity and biological activities of endophytic fungi: insights from in-silico docking studies
A study was conducted to understand the diversity of endophytic fungi from various natural hosts and their antimicrobial and alkali-tolerance activity with bioactive metabolite profiling and in-silico docking. A total of 176 endophytic fungi were isolated from nine hosts from India, and classified into 31 genera based on their morphology and molecular analysis of the ITS rDNA gene region. The endophytic community was dominated by fungi belonging to the genus Colletotrichum (20.5%), followed by Nigrospora (14.03%), Pestalotiopsis (9.35%), Lasiodiplodia (8.2%) and lastly by Hypoxylon (7.01%). The diversity of endophytic fungal species was highest in Catharanthus roseus, whereas it was lowest in Piper longum. Representative endophytic fungi were screened for their antimicrobial activity against seven clinical pathogens. Nearly 77% of the isolates showed potential antimicrobial activity against one or more test pathogens. Interestingly, Xylaria sp. and Nigrospora sphaerica showed robust antimicrobial activity compared to the standard antibiotics. Further, the alkali tolerance demonstrated that nearly 30% of the isolates grew well at high pH. Two of the isolates (Fusarium equiseti CR-10 and Colletotrichum fructicola GS-10) showed remarkable growth in alkaline media compared to standard media. Further, Xylaria sp. metabolites were characterized by Liquid Chromatography-Mass Spectrometer (LC-MS). In-silico docking analysis revealed compounds like substance P, geldanamycin, 1- palmitoyl- 2 -linoleoyl-sn-glycero- 3 -phosphate, 7,7- dimethyl-(5Z,8Z)- eicosadienoic acid, 6-3-(1-Adamantyl)- 4-hydroxyphenyl- 2-naphthalenecarboxylic acid and 15-ketoiloprost was found to exhibit potent antibacterial activity with higher binding energy with selected bacterial proteins compared to standards. This suggests that this endophytic fungal metabolite can be a potential source for producing promising natural antimicrobial drugs.
Chitosan nanoparticles encapsulating farnesol show potent antifungal activity against Candida albicans biofilms
Candida albicans biofilms are characterized as the main virulence factor responsible for therapeutic failure with antifungals and the development of resistant strains. Chitosan nanoparticles with farnesol (NF) may be able to penetrate biofilms due to their small size and enable the delivery of molecules to specific locations. The objective of the study was to assess the in vitro effectiveness of NF on C. albicans biofilms, as an additional study of the previously presented in vivo data. In the antifungal tests with C. albicans ATCC 10231, NF showed an IC of 73.25 µg/mL and inhibited biofilm formation at concentrations of up to 146.5 µg/mL. Images obtained by scanning electron microscopy demonstrated the ability of NF to inhibit the development of biofilms in vitro. In addition to their in vivo effectiveness against C. albicans infections, the produced nanoparticles could serve as a promising alternative to inhibit the formation of C. albicans biofilms on surfaces.
Essential oils from Lamiaceae plants effectively control Colletotrichum gloeosporioides, Elsinoë ampelina and Phytophthora infestans
The aim of this paper was to evaluate the effect of essential oils from the Lamiaceae family on the control of Colletotrichum gloeosporioides, Elsinoë ampelina and Phytophthora infestans, as well as to investigate mode of action of the most effective essential oils. Capitalize oils of Lavender (LEO), Basil (BEO), Mint (MEO), Oregano (OEO) and Thyme (TEO) were used at doses of 0, 250, 500, 750 and 1000 µL L. Effects on mycelial growth and spore germination were evaluated to identify the most potent essential oils. Additionally, the action of volatile compounds and the effects of the oils effect on ergosterol content, membrane permeability, and transfer test assessed. OEO and TEO were the most promising, completely inhibiting the development of phytopathogens at nearly all tested doses. Consequently, these two essential oils were selected for further analysis, except 250 µL Ldose, which did not completely inhibit the phytopathogens. Regarding ergosterol content, OEO significantly reduced ergosterol levels in C. gloeosporioides and E. ampelina, while TEO decreased only the ergosterol content of C. gloeosporioides, and did not interfere with the other microorganism. The membrane permeability was also affected by the two essential oils. Only OEO showed no effect on the membrane permeability of E. ampelina. The study also revealed that OEO and TEO exhibited fungicidal effects against C. gloeosporioides and E. ampelina, while showing fungistatic effects against P. infestans. In conclusion, OEO and TEO were found to be the most effective oils in the management of C. gloeosporioides, E. ampelina, and P. infestans. Their distinct mechanisms of action further indicate their potential as potent agents for directly controlling plant diseases.
Assessing dry inoculation carriers and Salmonella transfer in low moisture foods: a peanut-based model investigation
Salmonella has been responsible for several foodborne outbreaks associated to low moisture foods (LMFs) worldwide, including peanut based products. In this study the performance of calcium carbonate (a 0.331), non-fat milk powder (a 0.226), soil (a 0.388), crushed peanut skin (a 0.357) and crushed peanut shell (a 0.341) as dry carriers for Salmonella was evaluated. In addition, Salmonella dry transfer from soil and crushed peanut skin to peanut kernels was assessed. Immediately after the dry inoculation, the highest Salmonella count was obtained in calcium carbonate, ca. 7 log CFU/g, followed by soil and peanut shells, both with 6.4 log CFU/g, powdered milk, with 6.2 log CFU/g and peanut skin, with 6.0 log CFU/g. However, there was no significant difference (p > 0.05) among the carriers. The stability of Salmonella on the carriers was also evaluated for 7 days at 37 ºC. At the end of the storage time, only peanut skin showed a significant decline in the inoculum load (p < 0.05), with reduction of 2.7 log CFU/g. For the other carriers the Salmonella counts varied by up to 1.2 log CFU/g. Moreover, the Salmonella transfer rate from soil and crushed peanut skin to peanut kernels was 0.14% and 0.10%, corresponding to ca. 4 log CFU/g. After 30 days at 25 ºC, reductions of 2 log CFU/g in the peanut samples were observed. Neither the carriers nor the culture media used to recover the inoculum from peanuts had significant effect on the results (p > 0.05). In conclusion, four out of the five carriers displayed good performance. The indirect inoculation method optimized in this study reduced the inoculum preparation time. In addition, soil and crushed peanut skin showed potential for dry transfer of Salmonella to peanuts, illustrating a representative scenario of cross-contamination of peanuts.
Infection by Histoplasma capsulatum and Candida tropicalis in a Coendou longicaudatus boliviensis (neotropical porcupine)
Fungal diseases associated with wild animals have been described, showing increased frequency and mortality or change in populations at risk. The new animal host in fungal infection is an important epidemiologic issue to understand the transmission and spread of fungus in the environment and the threat to public health. Histoplasmosis is a mycosis widely distributed throughout the world with a respiratory and systemic presentation reported in domestic and wild mammals, and is potentially fatal in immunosuppressed and immunocompetent individuals humans and not humans. Candidiasis is an opportunistic fungal disease reported in numerous species of birds and wild mammals, such as parakeets, dolphins, beavers, guanacos, and porcupines. To our knowledge, the first case of simultaneous co-infection of Histoplasma capsulatum and Candidia tropicalis in Coendou longicaudatus boliviensis (neotropical porcupine) is described through clinical, microbiological, and pathological diagnosis and confirmation with DNA sequencing. Both these fungi pose risks to public health associated with environment dissemination and antifungal resistance, and it is important to develop preventive diagnostics to adopt risk reduction measures.
Exploration of endophytic and rhizospheric bacteria of invasive plant Xanthium strumarium L. reveals their potential in plant growth promotion and bacterial wilt suppression
Plant-associated microbiome plays important role in maintaining overall health of the host plant. Xanthium strumarium displaying resilience to various environmental fluctuations may harbor some bacterial isolates which can help this plant to grow worldwide. The present study aims to isolate endophytic and rhizospheric bacteria from X. strumarium and assess their plant growth-promoting and Ralstonia solanacearum antagonism activity. From a total of 148 isolated bacteria, 7 endophytic and 2 rhizospheric bacterial isolates were found to endow with significant in vitro plant growth promotion activities. The 16S rRNA gene sequence similarity of the 7 endophytic isolates has revealed these bacteria belonging to 5 genera viz. Curtobacterium, Pantoea, Pseudomonas, Microbacterium and Paracoccus whereas, the two rhizospheric isolates were identified as species of Ralstonia pickettii and Priestia megaterium. Maximum growth promotion was observed using the strains Pseudomonas fluorescens XSS6 and Microbacterium hydrothermale XSS20 in the assay conducted on tomato plants. In the in planta inhibition assay of R. solanacearum carried out in tomato seedlings using root bacterization method, Pseudomonas fluorescens XSS6 and Panotea vagans XSS3 showed antagonistic activity with biocontrol efficacy of 94.83% and 83.96%, respectively. GC-MS analysis detected several known antimicrobial compounds in the extract of the culture supernatant of Pseudomonas fluorescens XSS6 and Panotea vagans XSS3 strains, which may contribute to the inhibition of R. solanacearum by these strains. The results of our study indicated that the bacteria associated with X. strumarium exhibit multiple plant-beneficial effects. These bacteria have the potential to be developed as effective biofertilizers and biological control agents, promoting sustainable agriculture practices.
Chemical composition, antibacterial and antioxidant activities of Piper betle and Anethum graveolens essential oils against Methicillin-resistant Staphylococcus aureus clinical isolates
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of infection worldwide due to its antimicrobial resistance. Plant-derived essential oils (EOs) have undergone extensive observational and clinical research to explore their antimicrobial properties. The present study aimed to check mec A positive MRSA isolates using sequencing analysis, determination of chemical composition using gas chromatography-mass spectroscopy (GC-MS), antioxidant, and antimicrobial activity of Anethum graveolens and Piper betle EOs against the infectious agent MRSA. The result demonstrates a significant antibacterial activity of both essential oils against MRSA clinical isolates. GC-MS analysis of Piper betle showed (41.06%) 3-Allyl-6-methoxyphenol (Eugenol) as the major compound, whereas Anethum graveolens exhibited o-cymene (14.01%) abundantly. Piper betle essential oil retained appreciable levels of total phenolic (39.5 ± 10.9 mg/g of gallic acid equivalents) and flavonoid content (216 ± 145 mg quercetin equivalent/g), when compared to Anethum graveolens essential oil. A strong correlation was observed between antioxidant activity (DPPH, FRAP, and ABTS), total phenolic, and total flavonoid content in the Piper betle and displayed using principal component analysis (PCA) and a scatter matrix plot. Parallelly, clear morphological bacterial alterations were visualized by scanning electron microscopy after treating it with essential oils. MRSA showed malformed cell surfaces or broken cells with pore formation and septae. These findings imply that both essential oils are potential natural sources of antimicrobials against the MRSA superbug. They can also be used in combination therapies with other plant EOs or with traditional antibiotics to combat the rise of bacteria resistance.