RESUMO
Bacterial resistance against antimicrobial drugs is a forthcoming threat to the prevention and treatment of developing bacterial infections. Hence, the development of new antimicrobial therapy or therapeutic drugs is desperately needed. A combination of antibiotics exhibits synergistic antibacterial effects. As the combination approach of antibiotics has always shown better results against pathogens compared to monotherapy with an antibiotic, we focused on creating a new combination that may reduce the chances of strains attaining resistance, consequently lowering the toxicity factor associated with the consumption of high amounts of antibiotics. Nisin, a food preservative and potential antibiotic, shows antibacterial activity against Gram-positive strains. Since the past decade, ionic liquids (ILs) have proven to be an important class of potential antibacterial agents. In our study, we studied the effect of pyrrolidinium-based ILs and arrived at a noncovalent conjugate formed by combining nisin with ILs. The conjugates were tested against a couple of clinically relevant microorganisms, namely, Escherichia coli and Staphylococcus aureus. We reached a novel discovery that the combination of sodium/iodide symporter (NIS) and IL exhibited inhibitory effects against Gram-negative bacteria, which was not observed with NIS alone. The results showed remarkable improvement in the minimum inhibitory concentration (MIC) value of NIS in the presence of ILs targeted against both microorganisms. Further, flow cytometry and confocal microscopy results revealed the membrane disruption efficiency of the best combination obtained, leading to cell death. Additionally, the complexation of nisin and ILs was studied using various techniques, such as surface tension, dynamic light scattering, absorption spectroscopy, and molecular docking.
RESUMO
Chronic lymphocytic leukemia (CLL) is an incurable neoplasm of B-lymphocytes, which accounts for about one-third of all leukemias. Ocimum sanctum, an herbaceous perennial, is considered as one of the important sources of drugs for the treatment of various diseases, including cancers and autoimmune diseases. The present study was designed to screen various phytochemicals of O. sanctum for discovering their potential to inhibit Bruton's tyrosine kinase (BTK), a well-known drug target of CLL. Various phytochemicals of O. sanctum were screened for their potential to inhibit BTK using several in silico protocols. First, the molecular docking approach was used to calculate the docking scores of the selected phytochemicals. Then, the selected top-ranked phytochemicals were screened for their physicochemical characteristics using ADME analysis. Finally, the stability of the selected compounds in their corresponding docking complexes with BTK was analysed using molecular dynamics simulations. Primarily, our observations revealed that, out of the 46 phytochemicals of O. sanctum, six compounds possessed significantly better docking scores (ranging from -9.2 kcal/mol to -10 kcal/mol). Their docking scores were comparable to those of the control inhibitors, acalabrutinib (-10.3 kcal/mol), and ibrutinib (-11.3 kcal/mol). However, after ADME analysis of these top-ranked six compounds, only three compounds (Molludistin, Rosmarinic acid, and Vitexin) possessed drug likeliness characteristics. During the MD analysis, the three compounds Molludistin, Rosmarinic acid, and Vitexin were found to remain stable in the binding pocket in their corresponding docking complexes with BTK. Therefore, among the 46 phytochemicals of O. sanctum tested in this study, the three compounds, Molludistin, Rosmarinic acid, and Vitexin are the best inhibitors of BTK. However, these findings need to be confirmed by biological experiments in the laboratory.
Assuntos
Leucemia Linfocítica Crônica de Células B , Humanos , Leucemia Linfocítica Crônica de Células B/tratamento farmacológico , Leucemia Linfocítica Crônica de Células B/metabolismo , Tirosina Quinase da Agamaglobulinemia/metabolismo , Simulação de Acoplamento Molecular , Ocimum sanctum/metabolismo , Inibidores de Proteínas Quinases/química , Ácido RosmarínicoRESUMO
Candida albicans and Staphylococcus aureus, representing two different kingdoms, are the most frequently isolated pathogens from invasive infections. Their pathogenic attributes, combined with drug resistance, make them a major threat and a challenge to successful treatments, mainly when involved in polymicrobial biofilm-associated infections. In the present study, we investigated the antimicrobial potential of Lactobacillus metabolite extracts (LMEs) purified from cell-free supernatant of four Lactobacillus strains (KAU007, KAU0010, KAU0021, and Pro-65). Furthermore, LME obtained from the strain KAU0021 (LMEKAU0021), being the most effective, was analyzed for its anti-biofilm property against mono- and polymicrobial biofilms formed by C. albicans and S. aureus. The impact of LMEKAU0021 on membrane integrity in single and mixed culture conditions was also evaluated using propidium iodide. The MIC values recorded for LMEKAU0021 was 406 µg/mL, 203 µg/mL, and 406 µg/mL against planktonic cells of C. albicans SC5314, S. aureus and polymicrobial culture, respectively. The LMEKAU0021 at sub-MIC values potentially abrogates both biofilm formation as well as 24 h mature mono- and polymicrobial biofilms. These results were further validated using different microscopy and viability assays. For insight mechanism, LMEKAU0021 displayed a strong impact on cell membrane integrity of both pathogens in single and mixed conditions. A hemolytic assay using horse blood cells at different concentrations of LMEKAU0021 confirmed the safety of this extract. The results from this study correlate the antimicrobial and anti-biofilm properties of lactobacilli against bacterial and fungal pathogens in different conditions. Further in vitro and in vivo studies determining these effects will support the aim of discovering an alternative strategy for combating serious polymicrobial infections caused by C. albicans and S. aureus.
RESUMO
Pattern recognition receptors (PRRs) recognize distinct features on the surface of pathogens or damaged cells and play key roles in the innate immune system. PRRs are divided into various families, including Toll-like receptors, retinoic acid-inducible gene-I-like receptors, nucleotide oligomerization domain-like receptors, and C-type lectin receptors. As these are implicated in host health and several diseases, their accurate identification is indispensable for their functional characterization and targeted therapeutic approaches. Here, we construct PRR-HyPred, a novel two-layer hybrid framework in which the first layer predicts whether a given sequence is PRR or non-PRR using a support vector machine, and in the second, the predicted PRR sequence is assigned to a specific family using a random forest-based classifier. Based on a 10-fold cross-validation test, PRR-HyPred achieved 83.4 % accuracy in the first layer and 95 % in the second, with Matthew's correlation coefficient values of 0.639 and 0.816, respectively. This is the first study that can simultaneously predict and classify PRRs into specific families. PRR-HyPred is available as a web portal at https://procarb.org/PRRHyPred/. We hope that it could be a valuable tool for the large-scale prediction and classification of PRRs and subsequently facilitate future studies.
Assuntos
Imunidade Inata , Receptores de Reconhecimento de Padrão , Humanos , Receptores de Reconhecimento de Padrão/genética , Receptores Toll-Like , Lectinas Tipo CRESUMO
Marine species are known as rich sources of metabolites largely involved in the pharmaceutical industry. This study aimed to evaluate in silico the effect of natural compounds identified in algae on the SARS-CoV-2 Main protease, RNA-dependent-RNA polymerase activity (RdRp), endoribonuclease (NSP15) as well as on their interaction with viral spike protein. A total of 45 natural compounds were screened for their possible interaction on SARS-CoV-2 target proteins using Maestro interface for molecular docking, molecular dynamic (MD) simulation to estimate compounds binding affinities. Among the algal compounds screened in this study, three (Laminarin, Astaxanthin and 4'-chlorostypotriol triacetate) exhibited the lowest docking energy and best interaction with SARS-CoV-2 viral proteins (Main protease, RdRp, Nsp15, and spike protein). The complex of the main protease with laminarin shows the most stable RMSD during a 150 ns MD simulation time. Which indicates their possible inhibitory activity on SARS-CoV-2.Communicated by Ramaswamy H. Sarma.
Assuntos
COVID-19 , Humanos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus , RNA Polimerase Dependente de RNARESUMO
Streptococcus pyogenes is one of the most common bacteria causing sinusitis in children and adult patients. Probiotics are known to cause antagonistic effects on S. pyogenes growth and biofilm formation. In the present study, we demonstrated the anti-biofilm and anti-virulence properties of Lactiplantibacillus plantarum KAU007 against S. pyogenes ATCC 8668. The antibacterial potential of L. plantarum KAU007 metabolite extract (LME) purified from the cell-free supernatant of L. plantarum KAU007 was evaluated in terms of minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC). LME was further analyzed for its anti-biofilm potential using crystal violet assay and microscopic examination. Furthermore, the effect of LME was tested on the important virulence attributes of S. pyogenes, such as secreted protease production, hemolysis, extracellular polymeric substance production, and cell surface hydrophobicity. Additionally, the impact of LME on the expression of genes associated with biofilm formation and virulence attributes was analyzed using qPCR. The results revealed that LME significantly inhibited the growth and survival of S. pyogenes at a low concentration (MIC, 9.76 µg/mL; MBC, 39.06 µg/mL). Furthermore, LME inhibited biofilm formation and mitigated the production of extracellular polymeric substance at a concentration of 4.88 µg/mL in S. pyogenes. The results obtained from qPCR and biochemical assays advocated that LME suppresses the expression of various critical virulence-associated genes, which correspondingly affect various pathogenicity markers and were responsible for the impairment of virulence and biofilm formation in S. pyogenes. The non-hemolytic nature of LME and its anti-biofilm and anti-virulence properties against S. pyogenes invoke further investigation to study the role of LME as an antibacterial agent to combat streptococcal infections.
RESUMO
Many eukaryotic and prokaryotic organisms employ RNA editing (insertion, deletion, or conversion) as a post-transcriptional modification mechanism. RNA editing events are common in these organelles of plants and have gained particular attention due to their role in the development and growth of plants, as well as their ability to cope with abiotic stress. Owing to rapid developments in sequencing technologies and data analysis methods, such editing sites are being accurately predicted, and many factors that influence RNA editing are being discovered. The mechanism and role of the pentatricopeptide repeat protein family of proteins in RNA editing are being uncovered with the growing realization of accessory proteins that might help these proteins. This review will discuss the role and type of RNA editing events in plants with an emphasis on chloroplast RNA editing, involved factors, gaps in knowledge, and future outlooks.
RESUMO
Microorganisms have dynamic and complex interactions with their hosts. Diverse microbial communities residing near, on, and within the plants, called phytobiome, are an essential part of plant health and productivity. Exploiting citrus-associated microbiomes represents a scientific approach toward sustained and environment-friendly module of citrus production, though periodically exposed to several threats, with Huanglongbing (HLB) predominantly being most influential. Exploring the composition and function of the citrus microbiome, and possible microbial redesigning under HLB disease pressure has sparked renewed interest in recent times. A concise account of various achievements in understanding the citrus-associated microbiome, in various niche environments viz., rhizosphere, phyllosphere, endosphere, and core microbiota alongside their functional attributes has been thoroughly reviewed and presented. Efforts were also made to analyze the actual role of the citrus microbiome in soil fertility and resilience, interaction with and suppression of invading pathogens along with native microbial communities and their consequences thereupon. Despite the desired potential of the citrus microbiota to counter different pathogenic diseases, utilizing the citrus microbiome for beneficial applications at the field level is yet to be translated as a commercial product. We anticipate that advancement in multiomics technologies, high-throughput sequencing and culturing, genome editing tools, artificial intelligence, and microbial consortia will provide some exciting avenues for citrus microbiome research and microbial manipulation to improve the health and productivity of citrus plants.
RESUMO
Cancer is among the highly complex disease and renal cell carcinoma is the sixth-leading cause of cancer death. In order to understand complex diseases such as cancer, diabetes and kidney diseases, high-throughput data are generated at large scale and it has helped in the research and diagnostic advancement. However, to unravel the meaningful information from such large datasets for comprehensive and minute understanding of cell phenotypes and disease pathophysiology remains a trivial challenge and also the molecular events leading to disease onset and progression are not well understood. With this goal, we have collected gene expression datasets from publicly available dataset which are for two different stages (I and II) for renal cell carcinoma and furthermore, the TCGA and cBioPortal database have been utilized for clinical relevance understanding. In this work, we have applied computational approach to unravel the differentially expressed genes, their networks for the enriched pathways. Based on our results, we conclude that among the most dominantly altered pathways for renal cell carcinoma, are PI3K-Akt, Foxo, endocytosis, MAPK, Tight junction, cytokine-cytokine receptor interaction pathways and the major source of alteration for these pathways are MAP3K13, CHAF1A, FDX1, ARHGAP26, ITGBL1, C10orf118, MTO1, LAMP2, STAMBP, DLC1, NSMAF, YY1, TPGS2, SCARB2, PRSS23, SYNJ1, CNPPD1, PPP2R5E. In terms of clinical significance, there are large number of differentially expressed genes which appears to be playing critical roles in survival.
Assuntos
Carcinoma de Células Renais , Neoplasias Renais , Biomarcadores Tumorais/genética , Carcinoma de Células Renais/genética , Carcinoma de Células Renais/patologia , Biologia Computacional , Procedimentos Clínicos , Feminino , Proteínas Ativadoras de GTPase/metabolismo , Perfilação da Expressão Gênica/métodos , Regulação Neoplásica da Expressão Gênica , Redes Reguladoras de Genes , Humanos , Integrina beta1 , Neoplasias Renais/genética , Neoplasias Renais/patologia , Masculino , Fosfatidilinositol 3-Quinases/metabolismo , Proteína Fosfatase 2/metabolismo , Proteínas Supressoras de Tumor/genéticaRESUMO
Gastric cancer (GC) is a significant health concern worldwide, with a GLOBOCAN estimate of 1.08 million novel cases in 2020. It is the leading cause of disability-adjusted life years lost to cancer, with the fourth most common cancer in males and the fifth most common cancer in females. Strategies are pursued across the globe to prevent gastric cancer progression as a significant fraction of gastric cancers have been linked to various pathogenic (bacterial and viral) infections. Early diagnosis (in Asian countries), and non-invasive and surgical treatments have helped manage this disease with 5-year survival for stage IA and IB tumors ranging between 60% and 80%. However, the most prevalent aggressive stage III gastric tumors undergoing surgery have a lower 5-year survival rate between 18% and 50%. These figures point to a need for more efficient diagnostic and treatment strategies, for which the oncolytic viruses (OVs) appear to have some promise. OVs form a new therapeutic agent class that induces anti-tumor immune responses by selectively killing tumor cells and inducing systemic anti-tumor immunity. On the contrary, several oncogenic viruses have been shown to play significant roles in malignancy progression in the case of gastric cancer. Therefore, this review evaluates the current state of research and advances in understanding the dual role of viruses in gastric cancer.
RESUMO
The dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) is a novel, promising and emerging biological target for therapeutic intervention in neurodegenerative diseases, especially in Alzheimer's disease (AD). The molMall database, comprising rare, diverse and unique compounds, was explored for molecular docking-based virtual screening against the DYRK1A protein, in order to find out potential inhibitors. Ligands exhibiting hydrogen bond interactions with key amino acid residues such as Ile165, Lys188 (catalytic), Glu239 (gk+1), Leu241 (gk+3), Ser242, Asn244, and Asp307, of the target protein, were considered potential ligands. Hydrogen bond interactions with Leu241 (gk+3) were considered key determinants for the selection. High scoring structures were also docked by Glide XP docking in the active sites of twelve DYRK1A related protein kinases, viz. DYRK1B, DYRK2, CDK5/p25, CK1, CLK1, CLK3, GSK3ß, MAPK2, MAPK10, PIM1, PKA, and PKCα, in order to find selective DYRK1A inhibitors. MM/GBSA binding free energies of selected ligand-protein complexes were also calculated in order to remove false positive hits. Physicochemical and pharmacokinetic properties of the selected six hit ligands were also computed and related with the proposed limits for orally active CNS drugs. The computational toxicity webserver ProTox-II was used to predict the toxicity profile of selected six hits (molmall IDs 9539, 11352, 15938, 19037, 21830 and 21878). The selected six docked ligand-protein systems were exposed to 100 ns molecular dynamics (MD) simulations to validate their mechanism of interactions and stability in the ATP pocket of human DYRK1A kinase. All six ligands were found to be stable in the ATP binding pocket of DYRK1A kinase.
Assuntos
Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Inibidores de Proteínas Quinases , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/química , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/química , Domínio Catalítico , Humanos , Estrutura Molecular , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Quinases DyrkRESUMO
Marine species are known as rich sources of metabolites involved mainly in the pharmaceutical industry. This study aimed to evaluate the effect of biologically active compounds in the marine sponge on the SARS-CoV-2 RNA-dependent-RNA polymerase protein (RdRp) using the in-silico method. A total of 51 marine compounds were checked for their possible interaction with SARS-CoV-2 RdRp using Maestro interface for molecular docking, molecular dynamic (MD) simulation, and MM/GBSA method to estimate compounds binding affinities. Among the 51 compounds screened in this study, two (mycalamide A, and nakinadine B) exhibited the lowest docking energy and best interaction. Among these compounds, mycalamide A was identified as a potent inhibitor of SARS-CoV-2 RdRp that showed the best and stable interaction during molecular dynamic simulation, with residues (Asp760 and Asp761) found in the catalytic domain of RdRp. The analysis through MM/GBSA for molecular dynamic simulation results revealed binding energy -59.7 ± 7.18 for Mycalamide A and -56 ± 10.55 for Nakinadine B. These results elucidate the possible use of mycalamide A for treating coronavirus disease.Communicated by Ramaswamy H. Sarma.
Assuntos
COVID-19 , Poríferos , Animais , Simulação de Dinâmica Molecular , Simulação de Acoplamento Molecular , RNA Viral , SARS-CoV-2 , Nucleotidiltransferases , Antivirais/farmacologiaRESUMO
The coronavirus disease 2019 (COVID-19), which emerged in December 2019, continues to be a serious health concern worldwide. There is an urgent need to develop effective drugs and vaccines to control the spread of this disease. In the current study, the main phytochemical compounds of Nigella sativa were screened for their binding affinity for the active site of the RNA-dependent RNA polymerase (RdRp) enzyme of the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The binding affinity was investigated using molecular docking methods, and the interaction of phytochemicals with the RdRp active site was analyzed and visualized using suitable software. Out of the nine phytochemicals of N. sativa screened in this study, a significant docking score was observed for four compounds, namely α-hederin, dithymoquinone, nigellicine, and nigellidine. Based on the findings of our study, we report that α-hederin, which was found to possess the lowest binding energy (-8.6 kcal/mol) and hence the best binding affinity, is the best inhibitor of RdRp of SARS-CoV-2, among all the compounds screened here. Our results prove that the top four potential phytochemical molecules of N. sativa, especially α-hederin, could be considered for ongoing drug development strategies against SARS-CoV-2. However, further in vitro and in vivo testing are required to confirm the findings of this study.
RESUMO
The facile bio-fabrication of zinc oxide (ZnO) nanoparticles (NPs) is described in this study using an aqueous leaf extract of Salvia officinalis L. as an efficient stabilizing/capping agent. Biosynthesis of nanomaterials using phytochemicals present in the plants has received great attention and is gaining significant importance as a possible alternative to the conventional chemical methods. The properties of the bio-fabricated ZnONPs were examined by different techniques, such as UV-visible spectroscopy, X-ray diffraction spectroscopy (XRD), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric/differential scanning calorimetry analysis (TGA/DTG). The photocatalytic activity of ZnONPs was investigated against methyl orange (MO) under UV light irradiation. Under optimum experimental conditions, ZnONPs exhibited 92.47% degradation of MO. Furthermore, the antifungal activity of bio-fabricated ZnONPs was determined against different clinical Candida albicans isolates following standard protocols of broth microdilution and disc diffusion assay. The susceptibility assay revealed that ZnONPs inhibit the growth of all the tested fungal isolates at varying levels with MIC values ranging from 7.81 to 1.95 µg/mL. Insight mechanisms of antifungal action appeared to be originated via inhibition of ergosterol biosynthesis and the disruption of membrane integrity. Thus, it was postulated that bio-fabricated ZnONPs have sustainable applications in developing novel antifungal agents with multiple drug targets. In addition, ZnONPs show efficient photocatalytic efficiency without any significant catalytic loss after the catalyst was recycled and reused multiple times.
RESUMO
Infectious diseases are the disorders caused by organisms such as bacteria, viruses, fungi, or parasites. Although many of them are permentantly hazardous, a number of them live in and on our bodies and they are normally harmless or even helpful. Under certain circumstances, some organisms may cause diseases and these infectious diseases may be passed directly from person to person or via intermediate vectors including insects and other animals. Dengue virus and Streptococcus pneumoniae are the critical and common sources of infectious diseases. So, it is critical to understand the gene expression profiling and their inferred functions in comparison to the normal and virus infected conditions. Here, we have analyzed the gene expression profiling for dengue hemorrhagic fever, dengue fever, and normal human dataset. Similar to it, streptococcus pneumoniae infectious data were analyzed and both the outcomes were compared. Our study leads to the conclusion that the dengue hemorrhagic fever arises in result to potential change in the gene expression pattern, and the inferred functions obviously belong to the immune system, but also there are some additional potential pathways which are critical signaling pathways. In the case of pneumoniae infection, 19 pathways were enriched, almost all these pathways are associated with the immune system and 17 of the enriched pathways were common with dengue infection except platelet activation and antigen processing and presentation. In terms of the comparative study between dengue virus and Streptococcus pneumoniae infection, we conclude that cell adhesion molecules (CAMs), MAPK signaling pathway, natural killer cell mediated cytotoxicity, regulation of actin cytoskeleton, and cytokine-cytokine receptor interaction are commonly enriched in all the three cases of dengue infection and Streptococcus pneumoniae infection, focal adhesion was enriched between classical dengue fever - dengue hemorrhagic fever, dengue hemorrhagic fever-normal samples, and SP, and antigen processing and presentation and Leukocyte transendothelial migration were enriched in classical dengue fever -normal samples, dengue hemorrhagic fever-normal samples, and Streptococcus pneumoniae infection.
Assuntos
Dengue , Infecções Pneumocócicas , Animais , Perfilação da Expressão Gênica , Humanos , Células Matadoras Naturais , Análise em MicrossériesRESUMO
BACKGROUND: Dengue virus is a potential source of propagating dengue hemorrhagic fever. This virus leads to dengue hemorrhagic fever/dengue shock syndrome, benign syndrome, and severe syndrome and due to its infection, there occurs alterations at multiple levels such as gene expression and pathway levels. So, it is critical to understand the pathogenesis of dengue infection in terms of gene expression and the associated functions. METHODS: For this purpose, here, we have analyzed the temporal gene expression profiling for the dengue hemorrhagic fever dataset at 12, 24, and 48 hours. RESULTS: The outcome appears that the dengue hemorrhagic fever evolves differently at different time periods or stages. CONCLUSION: The change in the gene expression pattern increases exponentially from 12 hours to 48 hours and the number of altered functions (pathways) also increases. Wnt, apoptosis, and transcription signaling are among the critical pathways which are dominantly altered. In the initial phase (first 12 hours), only two pathways are altered due to dengue infection, while in the next 12 hours, eight pathways are altered, and finally, in the next 24 hours, 11 pathways are altered and most of these 11 pathways are very critical in terms of biological pathways and functions.
Assuntos
Vírus da Dengue , Dengue , Causalidade , Dengue/genética , Perfilação da Expressão Gênica , HumanosRESUMO
Foodborne pathogens are one of the major cause of food-related diseases and food poisoning. Bacterial biofilms and quorum sensing (QS) mechanism of cell-cell communication have also been found to be associated with several outbreaks of foodborne diseases and are great threat to food safety. Therefore, In the present study, we investigated the activity of three tetrahedrally coordinated copper(I) complexes against quorum sensing and biofilms of foodborne bacteria. All the three complexes demonstrated similar antimicrobial properties against the selected pathogens. Concentration below the MIC i.e. at sub-MICs all the three complexes interfered significantly with the quorum sensing regulated functions in C. violaceum (violacein), P. aeruginosa (elastase, pyocyanin and alginate production) and S. marcescens (prodigiosin). The complexes demonstrated potent broad-spectrum biofilm inhibition in Pseudomonas aeruginosa, E. coli, Chromobacterium violaceum, Serratia marcescens, Klebsiella pneumoniae and Listeria monocytogenes. Biofilm inhibition was visualized using SEM and CLSM images. Action of the copper(I) complexes on two key QS regulated functions contributing to biofilm formation i.e. EPS production and swarming motility was also studied and statistically significant reduction was recorded. These results could form the basis for development of safe anti-QS and anti-biofilm agents that can be utilized in the food industry as well as healthcare sector to prevent food-associated diseases.
RESUMO
Abiotic stresses such as salinity, drought and excessive heat are associated with significant loss of crop productivity globally, and require effective strategies for their reduction or tolerance. Biofilm-forming rhizobacteria, which harbor multifarious plant growth promoting traits and tolerance to abiotic stress, are believed to benefit plant health and production even under environmental stresses. The primary objective of this study was to investigate indigenous biofilm-forming rhizobacteria (Pseudomonas spp., Bacillus sp., Pantoea sp., Brevibacterium sp. and Acinetobacter sp.) for their functional diversity relevant to plant growth promoting activities, biofilm development and tolerance to abiotic stress conditions. The most promising isolates among FAP1, FAP2, FAP3, FAP4, FAP5, FAP10, FAB1, FAB3 and FAA1 were selected. Rhizobacteria exhibited high tolerance to salinity (1.5 M NaCl) and drought stress (up to 55% PEG-6000) conditions in vitro. The isolates demonstrated varying levels of PGP activities (IAA production and phosphate solubilization), biofilm development, and production of alginate and exopolysaccharides in the presence of salinity, drought stress and elevated temperature. Further efficacy of the isolates was demonstrated by inoculating to wheat (Triticum aestivum L.) plants in greenhouse conditions under both normal and drought stress for up to 30 days inoculation. The plant growth potential of the isolates was in the order of FAP3 > FAB3 > FAB1 > FAP10 > FAP5 > FAP4 > FAA1 > FAP2 > FAP1. The present study resulted in successful selection of promising PGPR as identified by 16S rRNA gene sequence analysis. Field study is needed to evaluate their relative performance in both 'normal' and stressed environments in order to be exploited for plant stress management.
Assuntos
Bacillus/fisiologia , Biofilmes/crescimento & desenvolvimento , Brevibacterium/fisiologia , Gammaproteobacteria/fisiologia , Reguladores de Crescimento de Plantas/metabolismo , Microbiologia do Solo , Estresse FisiológicoRESUMO
Cadmium (Cd) is a toxic heavy metal and an abiotic stressor to plants; however, inoculation of endophytic bacteria can raise resistance in plants against Cd, as well as improve plant growth. In the present study, two endophytic bacterial strains were isolated from Solanum nigrum, identified as Serratia sp. IU01 and Enterobacter sp. IU02 by 16S DNA sequencing. Both IU01 and IU02 were tolerant up to 9.0â¯mM of Cd in culture broth and successive increase in Cd concentration from 0â¯mM to 9.0â¯mM, led to an increase in the SOD enzyme activity of the isolates. Both strains were capable of indole-3-acetic acid (IAA) synthesis and phosphate solubilization, detected through gas spectrometry-mass chromatography (GC-MS) and Pikovskaya agar medium respectively. Brassica juncea plants stressed with 0-25â¯mg/kg Cd showed retardation in all growth attributes, however, inoculation of strain IU01 and IU02 significantly promoted the plant growth attributes as compared to control. Moreover, antioxidant enzymes and metabolites against reactive oxygen species (ROS) including polyphenol oxidase (PPO), peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), alcohol dehydrogenase (ADH), reduced glutathione (GSH), malondialdehyde (MDA), flavonoid and polyphenolic contents were also significantly relieved by inoculation of IU01 and IU02 in plant exposed to different concentration of Cd stress as compared to control plants. Phytohormone production, phosphate solubilization, and/or antioxidative support of IU01 and IU02 might be responsible for growth promotion and Cd resistance in the plant.
Assuntos
Antioxidantes/metabolismo , Cádmio/toxicidade , Endófitos/isolamento & purificação , Enterobacter/isolamento & purificação , Serratia/isolamento & purificação , Poluentes do Solo/toxicidade , Solanum nigrum/microbiologia , Biodegradação Ambiental , Enterobacter/efeitos dos fármacos , Mostardeira/efeitos dos fármacos , Mostardeira/microbiologia , Espécies Reativas de Oxigênio , Serratia/efeitos dos fármacosRESUMO
Compatible interaction between commonly used plant growth promoting rhizobacteria (PGPR) in biofilm mode in vitro and in the rhizosphere is expected to provide better understanding for the development of effective consortium. With the above hypothesis, the present study evaluated two characterized PGPR (Pseudomonas fluorescens FAP2 and Bacillus licheniformis B642) for their biofilm-related functions using standard protocols. The interaction between the FAP2 and B642 in planktonic mode was studied by plate spot/overlay method and competitive growth assessment. Biofilm development on a microtitre plate and a glass surface was studied by standard methods. Biofilm formation was characterized by SEM. Rhizosphere and rhizoplane colonization of wheat seedlings by both isolates individually and by co-inoculation was studied by determining CFU/g of soil/root samples. Biofilm development on the root surface was further analyzed by SEM. Both isolates demonstrated multiple plant growth promoting (PGP) traits (production of IAA, siderophore, and ammonia; phosphate solubilization) and biofilm-related functions such as production of EPS, alginate, cell surface hydrophobicity and swarming motility. Both strains formed strong biofilms on a glass cover slip in vitro. Interaction between the two strains under the planktonic mode revealed no antagonism in terms of growth inhibition and competitive growth kinetics. Similarly, FAP2 and B642 strains formed a mixed biofilm on a glass cover slip as well as on seedling roots. Wheat rhizosphere and rhizoplane were colonized by both isolates as evidenced from their viable counts in single and co-inoculation. The effect of single and co inoculation revealed the significant enhancement of vegetative growth and photosynthetic parameters such as chlorophyll content, transpiration rate (E), internal CO2 concentration (Ci), stomatal conductance (gs), and net photosynthetic rate (PN) and leaf water potential (LWP) as compared to uninoculated control. Indigenous Pseudomonas fluorescens FAP2 strain and Bacillus licheniformis B642 are compatible PGPR in both planktonic and biofilm modes of growth and threfore could be developed effective consortium of PGPR. Further indepth investigation is required to understand molecular mechanism of the interaction in biofilm mode of growth under natural condition.