scholarly journals Application of sonicated extracts of cyanobacteria and microalgae for the mitigation of bacterial canker in tomato seedlings

2021 ◽  
Author(s):  
A. J. Toribio ◽  
M. M. Jurado ◽  
F. Suárez-Estrella ◽  
J. A. López-González ◽  
M. R. Martínez-Gallardo ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Crop Protection ◽  
Resistance Mechanisms ◽  
Bacterial Canker ◽  
Clavibacter Michiganensis ◽  
Bioactive Substances ◽  
Tomato Seedlings ◽  
Promote Plant Growth

AbstractMicroalgae and cyanobacteria could play an important role in crop protection, since they produce bioactive substances that promote plant growth and/or trigger the plant resistance mechanisms. The present study focuses on the control of bacterial canker caused by Clavibacter michiganensis subsp. michiganensis on tomato plants by using sonicated extracts from cyanobacteria and microalgae of the genera Leptolyngbya, Nostoc, Chlorella, and Scenedesmus. For the development of this study, 8 strains were firstly tested for their capacity to inhibit the growth of C. michiganensis subsp. michiganensis in vitro, as well as to produce cytokinins and salicylic acid. In order to discard those more phytotoxic strains, the germination index was also estimated in watercress seeds. Scenedesmus-677 and Leptolyngbya-1267 strains were selected in this first phase based on their pesticide and phytostimulant capacity in vitro. Subsequent bioassays on tomato seedlings showed that root application of Scenedesmus-677 could be more aimed at controlling the disease caused by C. michiganensis subsp. michiganensis, while foliar and root application of Leptolyngbya-1267 seems to be more related to the strengthening of the plant through the salicylic acid route. These preliminary results could serve as the basis for a deeper characterization of the biopesticidal and biostimulant effect of both strains, as well as to reveal the benefits derived from the combination of both capacities.

scholarly journals Molecular characterization of Mycobacterium ulcerans DNA gyrase and identification of mutations reduced susceptibility against quinolones in vitro

2021 ◽  
Author(s):  
Hyun Kim ◽  
Shigtarou Mori ◽  
Tsuyoshi Kenri ◽  
Yasuhiko Suzuki
Keyword(s):  
Buruli Ulcer ◽  
Dna Gyrase ◽  
Resistance Mechanisms ◽  
Docking Studies ◽  
Mycobacterium Ulcerans ◽  
Amino Acid Residues ◽  
Wild Type Enzyme ◽  
Ulcer Disease

ABSTRACTBuruli ulcer disease is a neglected necrotizing and disabling cutaneous tropical illness caused by Mycobacterium ulcerans (Mul). Fluoroquinolone (FQ), used in the treatment of this disease, has been known to act by inhibiting the enzymatic activities of DNA gyrase; however, the detailed molecular basis of these characteristics and the FQ resistance mechanisms in Mul remains unknown. This study investigated the detailed molecular mechanism of Mul DNA gyrase and the contribution of FQ resistance in vitro using recombinant proteins from the Mul subsp. shinshuense and Agy99 strains with reduced sensitivity to FQs. The IC50 of FQs against Ala91Vla and Asp95Gly mutants of Mul shinshuense and Agy99 GyrA subunits were 3.7- to 42.0-fold higher than those against wild-type enzyme. Similarly, the CC25 was 10- to 210-fold higher than those for the WT enzyme. Furthermore, the interaction between the amino acid residues of WT/mutant Mul DNA gyrase and FQ side chains was assessed via molecular docking studies. This is the first detailed study showing the contribution of Mul DNA GyrA subunit mutations to reduce the susceptibility against FQs.

scholarly journals Structural Characterization of an Alternative Mode of Tigecycline Binding to the Bacterial Ribosome

2015 ◽  
Vol 59 (5) ◽  
pp. 2849-2854 ◽  
Author(s):  
Andreas Schedlbauer ◽  
Tatsuya Kaminishi ◽  
Borja Ochoa-Lizarralde ◽  
Neha Dhimole ◽  
Shu Zhou ◽  
...  
Keyword(s):  
Ribosomal Subunit ◽  
Resistance Mechanisms ◽  
Side Chain ◽  
Alternative Mode ◽  
X Ray Crystallography ◽  
Bacterial Ribosome ◽  
A Site

ABSTRACTAlthough both tetracycline and tigecycline inhibit protein synthesis by sterically hindering the binding of tRNA to the ribosomal A site, tigecycline shows increased efficacy in bothin vitroandin vivoactivity assays and escapes the most common resistance mechanisms associated with the tetracycline class of antibiotics. These differences in activities are attributed to thetert-butyl-glycylamido side chain found in tigecycline. Our structural analysis by X-ray crystallography shows that tigecycline binds the bacterial 30S ribosomal subunit with its tail in an extended conformation and makes extensive interactions with the 16S rRNA nucleotide C1054. These interactions restrict the mobility of C1054 and contribute to the antimicrobial activity of tigecycline, including its resistance to the ribosomal protection proteins.

Formulation and in vitro characterization of tea tree oil anti-dandruff shampoo

2021 ◽  
Vol 01 ◽  
Author(s):  
Humra Umar ◽  
Tariq Mahmood ◽  
Talib Hussain ◽  
Rabia Aslam ◽  
Yasser Shahzad ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Antifungal Activity ◽  
Synergistic Effects ◽  
Quality Attributes ◽  
Tea Tree Oil ◽  
Tea Tree ◽  
In Vitro Characterization ◽  
Selenium Sulfide

Background: Dandruff is the common scalp condition affecting half of the population of the world. Objective: The current study was aimed at developing anti-dandruff shampoos containing tea tree oil, which is believed to have effects against Malassezia furfur, a fungus involved in dandruff production. Methodology: Various shampoos containing tea tree oil in 0.5 to 3% concentration were prepared after careful selection of various shampoo ingredients. The formulated shampoos were subjected to various quality tests such as pH, viscosity, foam production, dirt dispersion, wetting time, surface tension, solid contents and antimicrobial activity against a model fungal strain, namely Candida albicans. The formulated shampoos were also compared with the marketed shampoos for quality attributes. Results: The results revealed that tea tree oil shampoos had pH values in the range of 5 – 6, which is close to the slightly acidic skin’s pH and considered as good for hair. All other quality attributes were comparable to the marketed products. The marketed shampoos had superior antifungal activity due to presence of zinc pyrithione or higher concentration of salicylic acid or selenium sulfide. Notwithstanding, the tea tree oil shampoos demonstrated an appreciable antifungal activity due to synergistic effects of tea tree oil, sodium lauryl sulphate and salicylic acid. Furthermore, the tea tree oil shampoos were stable during two months long stability testing. Conclusion: Thus, tea tree oil anti-dandruff shampoos have the potential to address the dandruff problem.

scholarly journals Functional Profiling and Crystal Structures of Isothiocyanate Hydrolases Found in Gut-Associated and Plant-Pathogenic Bacteria

2018 ◽  
Vol 84 (14) ◽  
Author(s):  
Tijs J. M. van den Bosch ◽  
Kemin Tan ◽  
Andrzej Joachimiak ◽  
Cornelia U. Welte
Keyword(s):  
Active Site ◽  
Pathogenic Bacteria ◽  
Tertiary Structure ◽  
Crop Protection ◽  
X Ray Crystallography ◽  
Beneficial Effects ◽  
Functional Profiling ◽  
Cruciferous Plants

ABSTRACT Isothiocyanates (ITCs) are produced by cruciferous plants to protect them against herbivores and infection by microbes. These compounds are of particular interest due to their antimicrobial and anticarcinogenic properties. The breakdown of ITCs in nature is catalyzed by isothiocyanate hydrolases (ITCases), a novel family within the metallo-β-lactamase (MBL)-fold superfamily of proteins. saxA genes that code for ITCases are particularly widespread in insect- and plant-associated bacteria. Enzymatic characterization of seven phylogenetically related but distinct ITCases revealed similar activities on six selected ITCs, suggesting that phylogenetic diversity does not determine the substrate specificity of ITCases. X-ray crystallography studies of two ITCases sharing 42% amino acid sequence identity revealed a highly conserved tertiary structure. Notable features of ITCases include a hydrophobic active site with two Zn 2+ ions coordinating water/hydroxide and a flexible cap that is implicated in substrate recognition and covers the active site. This report reveals the function and structure of the previously uncharacterized family of isothiocyanate hydrolases within the otherwise relatively well-studied superfamily of metallo-β-lactamases. IMPORTANCE This study explores a newly discovered protein in the β-lactamase superfamily, namely, SaxA, or isothiocyanate hydrolase. Isothiocyanates are defensive compounds found in many cabbage-related crop plants and are currently being investigated for their antimicrobial and anticarcinogenic properties. We show that isothiocyanate hydrolases are responsible for the breakdown of several of these plant defensive chemicals in vitro and suggest their potential for mitigating the beneficial effects of isothiocyanates in crop protection and cancer prevention.

scholarly journals The Resistant-Population Cutoff (RCOFF): a New Concept for Improved Characterization of Antimicrobial Susceptibility Patterns of Non-Wild-Type Bacterial Populations

2015 ◽  
Vol 53 (6) ◽  
pp. 1806-1811 ◽  
Author(s):  
Giorgia Valsesia ◽  
Michael Hombach ◽  
Florian P. Maurer ◽  
Patrice Courvalin ◽  
Malgorzata Roos ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Resistance Mechanisms ◽  
Clinical Strain ◽  
Wild Type ◽  
Bacterial Populations ◽  
Content Type ◽  
Resistant Population ◽  
Susceptibility Patterns

This study aimed to determine resistant-population cutoffs (RCOFFs) to allow for improved characterization of antimicrobial susceptibility patterns in bacterial populations. RCOFFs can complement epidemiological cutoff (ECOFF)-based settings of clinical breakpoints (CBPs) by systematically describing the correlation between non-wild-type and wild-type populations. We illustrate this concept by describing three paradigmatic examples of wild-type and non-wild-typeEscherichia colipopulations from our clinical strain database of disk diffusion diameters. The statistical determination of RCOFFs and ECOFFs and their standardized applications in antimicrobial susceptibility testing (AST) facilitates the assignment of isolates to wild-type or non-wild-type populations. This should improve the correlation ofin vitroAST data and distinct antibiotic resistance mechanisms with clinical outcome facilitating the setting and validation of CBPs.

scholarly journals Targeted Activation Tagging of the Arabidopsis NBS-LRR gene, ADR1, Conveys Resistance to Virulent Pathogens

2003 ◽  
Vol 16 (8) ◽  
pp. 669-680 ◽  
Author(s):  
John J. Grant ◽  
Andrea Chini ◽  
Debrabata Basu ◽  
Gary J. Loake
Keyword(s):  
Salicylic Acid ◽  
Disease Resistance ◽  
Crop Protection ◽  
Constitutive Expression ◽  
Marker Genes ◽  
Erysiphe Cichoracearum ◽  
Biotrophic Pathogens ◽  
Luc Reporter Gene ◽  
Leucine Rich Repeats

A transgenic Arabidopsis line containing a chimeric PR-1∷luciferase (LUC) reporter gene was subjected to mutagenesis with activation tags. Screening of lines via high-throughput LUC imaging identified a number of dominant Arabidopsis mutants that exhibited enhanced PR-1 gene expression. Here, we report the characterization of one of these mutants, designated activated disease resistance (adr) 1. This line showed constitutive expression of a number of key defense marker genes and accumulated salicylic acid but not ethylene or jasmonic acid. Furthermore, adr1 plants exhibited resistance against the biotrophic pathogens Peronospora parasitica and Erysiphe cichoracearum but not the necrotrophic fungus Botrytis cinerea. Analysis of a series of adr1 double mutants suggested that adr1-mediated resistance against P. parasitica was salicylic acid (SA)-dependent, while resistance against E. cichoracearum was both SA-dependent and partially NPR1-dependent. The ADR1 gene encoded a protein possessing a number of key features, including homology to subdomains of protein kinases, a nucleotide binding domain, and leucine-rich repeats. The controlled, transient expression of ADR1 conveyed striking disease resistance in the absence of yield penalty, highlighting the potential utility of this gene in crop protection.

Isolation and characterization of cassava root endophytic bacteria with the ability to promote plant growth and control the in vitro and in vivo growth of Phytopythium sp.

2021 ◽  
pp. 101709
Author(s):  
Solange da Cunha Ferreira ◽  
Alessandra Keiko Nakasone ◽  
Silvia Mara Coelho do Nascimento ◽  
Danyllo Amaral de Oliveira ◽  
Andrei Santos Siqueira ◽  
...  
Keyword(s):  
Plant Growth ◽  
Endophytic Bacteria ◽  
Isolation And Characterization ◽  
Cassava Root ◽  
Promote Plant Growth ◽  
In Vivo Growth ◽  
And Control

scholarly journals Limiting Populations and Spread of Clavibacter michiganensis subsp. michiganensis on Seedling Tomatoes in the Greenhouse

Plant Disease ◽  
2002 ◽  
Vol 86 (5) ◽  
pp. 535-542 ◽  
Author(s):  
N. A. Werner ◽  
D. W. Fulbright ◽  
R. Podolsky ◽  
J. Bell ◽  
M. K. Hausbeck
Keyword(s):  
Bacterial Canker ◽  
Susceptible Cultivar ◽  
Copper Hydroxide ◽  
Clavibacter Michiganensis ◽  
Canker Disease ◽  
Resistant Cultivars ◽  
Tomato Seedlings ◽  
Greenhouse Tomato ◽  
Clavibacter Michiganensis Subsp ◽  
Pathogen Populations

Symptomless greenhouse tomato transplants may harbor high populations of Clavibacter michiganensis subsp. michiganensis, the causal agent of bacterial canker, leading to yield loss in the field. The objective of this study was to determine whether resistant cultivars, acibenzolar-S-methyl, avirulent strains of C. michiganensis subsp. michiganensis, or standard bactericides reduce pathogen populations and spread among greenhouse tomato seedlings. All treatments limited pathogen populations compared with the untreated inoculated susceptible cultivar in 1996 and 1998, but not in 1997. In 1996, copper hydroxide alone or mixed with mancozeb or streptomycin limited pathogen populations relative to acibenzolar-S-methyl, acibenzolar-S-methyl mixed with copper hydroxide, and avirulent strains. Copper hydroxide mixed with streptomycin limited pathogen populations compared with copper hydroxide mixed with mancozeb. Adding copper hydroxide to acibenzolar-S-methyl limited pathogen populations compared with acibenzolar-S-methyl alone. In 1998, treatments did not differ significantly from each other in limiting pathogen populations. The treatments limited spread of the bacterium only in 1997. Copper hydroxide mixed with mancozeb limited spread compared with copper hydroxide mixed with streptomycin. Pathogen spread was also reduced among resistant cultivars compared with the susceptible cultivar treated with streptomycin. In the field, the untreated inoculated susceptible cultivar produced yields that were 61% (1996) and 93% (1997) of those produced by the uninoculated susceptible cultivar. Fruit spotting occurred regardless of treatment. To prevent severe bacterial canker disease in the field, growers should initiate and sustain bactericide applications to tomato transplants while in the greenhouse to suppress pathogen populations. Cultivar resistance and acibenzolar-S-methyl may be helpful in disease management of bacterial canker on tomato.

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