Defensive Role of Plant-Derived Secondary Metabolites: Indole and Its’ Derivatives

The diversity of indole concerning its production and functional role has increased in both prokaryotic and eukaryotic systems. The bacterial species produce indole and use it as a signaling molecule at interspecies, intraspecies, and even at an interkingdom level for controlling the capability of drug resistance, level of virulence, and biofilm formation. Numerous indole derivatives have been found to play an important role in the different systems and are reported to occur in various bacteria, plants, human, and plant pathogens. Indole and its derivatives have been recognized for a defensive role against pests and insects in the plant kingdom. These indole derivatives are produced as a result of the breakdown of glucosinolate products at the time of insect attack or physical damages. Apart from the defensive role of these products, in plants, they also exhibit several other secondary responses that may contribute directly or indirectly to the growth and development. The present review summarized recent signs of progress on the functional properties of indole and its derivatives in different plant systems. The molecular mechanism involved in the defensive role played by indole as well as its’ derivative in the plants has also been explained. Furthermore, the perspectives of indole and its derivatives (natural or synthetic) in understanding the involvement of these compounds in diverse plants have also been discussed.

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Essential Functional Role of the Polysaccharide Intercellular Adhesin of Staphylococcus epidermidis in Hemagglutination

Infection and Immunity ◽

10.1128/iai.67.2.1004-1008.1999 ◽

1999 ◽

Vol 67 (2) ◽

pp. 1004-1008 ◽

Cited By ~ 76

Author(s):

Dietrich Mack ◽

Joachim Riedewald ◽

Holger Rohde ◽

Tim Magnus ◽

Hubert H. Feucht ◽

...

Keyword(s):

Immunoglobulin G ◽

Staphylococcus Epidermidis ◽

Biofilm Formation ◽

Functional Role ◽

Common Property ◽

Polysaccharide Intercellular Adhesin ◽

Functional Component ◽

Negative Phenotype

ABSTRACT Hemagglutination of erythrocytes is a common property ofStaphylococcus epidermidis strains, which is related to adherence and biofilm formation and may be essential for the pathogenesis of biomaterial-associated infections caused byS. epidermidis. In three independent biofilm-producing, hemagglutination-positive S. epidermidis isolates, interruption of the icaADBC operon essential for polysaccharide intercellular adhesin (PIA) synthesis by Tn917 insertions led to a hemagglutination-negative phenotype. An immunoglobulin G fraction of antiserum to PIA greatly reduced hemagglutination. Purified PIA led to a 64-fold decrease of hemagglutination titers of these strains; however, it did not mediate hemagglutination by itself. These observations define PIA as the hemagglutinin of S. epidermidis or at least as its major functional component.

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Matrix inhibition by Salmonella excludes uropathogenic E. coli from biofilm

FEMS Microbiology Ecology ◽

10.1093/femsec/fiaa214 ◽

2020 ◽

Vol 97 (1) ◽

Author(s):

Sandeep Miryala ◽

Veena G Nair ◽

S Chandramohan ◽

C S Srinandan

Keyword(s):

Biofilm Formation ◽

Bacterial Species ◽

Interference Competition ◽

Physicochemical Analysis ◽

Upec Strain ◽

E Coli ◽

The Matrix ◽

Agar Media ◽

Matrix Production

ABSTRACT Biofilm is a predominant lifestyle of bacteria that comprises of cells as collectives enmeshed in a polymeric matrix. Biofilm formation is vital for bacterial species as it provides access to nutrients and protects the cells from environmental stresses. Here we show that interference in biofilm matrix production is a strategy by the competing bacterial species to reduce the ability of the other species to colonize a surface. Escherichia coli colonies that differ in matrix production display different morphologies on Congo red agar media, which we exploited for screening bacterial isolates capable of inhibiting the matrix. The cell-free supernatants from growth culture of the screened isolates impaired uropathogenic E. coli (UPEC) UTI89 strain's biofilm. A physicochemical analysis suggested that the compound could be a glycopeptide or a polysaccharide. Isolates that inhibited matrix production belonged to species of the family Enterobacteriaceae such as Shigella, Escherichia, Enterobacter and Salmonella. Competition experiments between the isolates and the UPEC strain resulted in mutual inhibition, particularly during biofilm formation causing significant reduction in productivity and fitness. Furthermore, we show that Salmonella strains competitively excluded the UPEC strain in the biofilm by inhibiting its matrix production, highlighting the role of interference competition.

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Response of Escherichia coli minimal ter operon to UVC and auto-aggregation: pilot study

PeerJ ◽

10.7717/peerj.11197 ◽

2021 ◽

Vol 9 ◽

pp. e11197

Author(s):

Lenka Jánošíková ◽

Lenka Pálková ◽

Dušan Šalát ◽

Andrej Klepanec ◽

Katarina Soltys

Keyword(s):

Escherichia Coli ◽

Environmental Stress ◽

Biofilm Formation ◽

Large Fraction ◽

Bacterial Species ◽

Whole Genome Sequence ◽

Lower Sensitivity ◽

Aggregation Assay ◽

E Coli

Aim The study of minimal ter operon as a determinant of tellurium resistance (TeR) is important for the purpose of confirming the relationship of these genes to the pathogenicity of microorganisms. The ter operon is widespread among bacterial species and pathogens, implicated also in phage inhibition, oxidative stress and colicin resistance. So far, there is no experimental evidence for the role of the Escherichia coli (E. coli) minimal ter operon in ultraviolet C (UVC) resistance, biofilm formation and auto-aggregation. To identify connection with UVC resistance of the minimal ter operon, matched pairs of Ter-positive and -negative E. coli cells were stressed and differences in survival and whole genome sequence analysis were performed. This study was aimed also to identify differences in phenotype of cells induced by environmental stress. Methods In the current study, a minimal ter operon(terBCDEΔF) originating from the uropathogenic strain E. coli KL53 was used. Clonogenic assay was the method of choice to determine cell reproductive death after treatment with UVC irradiation at certain time intervals. Bacterial suspensions were irradiated with 254 nm UVC-light (germicidal lamp in biological safety cabinet) in vitro. UVC irradiance output was 2.5 mW/cm2 (calculated at the UVC device aperture) and plate-lamp distance of 60 cm. DNA damage analysis was performed using shotgun sequencing on Illumina MiSeq platform. Biofilm formation was measured by a crystal violet retention assay. Auto-aggregation assay was performed according to the Ghane, Babaeekhou & Ketabi (2020). Results A large fraction of Ter-positive E. coli cells survived treatment with 120-s UVC light (300 mJ/cm2) compared to matched Ter-negative cells; ∼5-fold higher resistance of Ter-positive cells to UVC dose (p = 0.0007). Moreover, UVC surviving Ter-positive cells showed smaller mutation rate as Ter-negative cells. The study demonstrated that a 1200-s exposure to UVC (3,000 mJ/cm2) was sufficient for 100% inhibition of growth for all the Ter-positive and -negative E. coli cells. The Ter-positive strain exhibited of 26% higher auto-aggregation activities and was able to inhibit biofilm formation over than Ter- negative strain (**** P < 0.0001). Conclusion Our study shows that Ter-positive cells display lower sensitivity to UVC radiation, corresponding to a presence in minimal ter operon. In addition, our study suggests that also auto-aggregation ability is related to minimal ter operon. The role of the minimal ter operon (terBCDEΔF) in resistance behavior of E. coli under environmental stress is evident.

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SdiA, a Quorum-Sensing Regulator, Suppresses Fimbriae Expression, Biofilm Formation, and Quorum-Sensing Signaling Molecules Production in Klebsiella pneumoniae

Frontiers in Microbiology ◽

10.3389/fmicb.2021.597735 ◽

2021 ◽

Vol 12 ◽

Author(s):

Thaisy Pacheco ◽

Ana Érika Inácio Gomes ◽

Nathália Maria Gonçalves Siqueira ◽

Lucas Assoni ◽

Michelle Darrieux ◽

...

Keyword(s):

Cell Division ◽

Quorum Sensing ◽

Klebsiella Pneumoniae ◽

Mutant Strain ◽

Virulence Factors ◽

Biofilm Formation ◽

Bacterial Species ◽

Bacterial Cells ◽

Gram Negative

Klebsiella pneumoniae is a Gram-negative pathogen that has become a worldwide concern due to the emergence of multidrug-resistant isolates responsible for various invasive infectious diseases. Biofilm formation constitutes a major virulence factor for K. pneumoniae and relies on the expression of fimbrial adhesins and aggregation of bacterial cells on biotic or abiotic surfaces in a coordinated manner. During biofilm aggregation, bacterial cells communicate with each other through inter- or intra-species interactions mediated by signallng molecules, called autoinducers, in a mechanism known as quorum sensing (QS). In most Gram-negative bacteria, intra-species communication typically involves the LuxI/LuxR system: LuxI synthase produces N-acyl homoserine lactones (AHLs) as autoinducers and the LuxR transcription factor is their cognate receptor. However, K. pneumoniae does not produce AHL but encodes SdiA, an orphan LuxR-type receptor that responds to exogenous AHL molecules produced by other bacterial species. While SdiA regulates several cellular processes and the expression of virulence factors in many pathogens, the role of this regulator in K. pneumoniae remains unknown. In this study, we describe the characterization of sdiA mutant strain of K. pneumoniae. The sdiA mutant strain has increased biofilm formation, which correlates with the increased expression of type 1 fimbriae, thus revealing a repressive role of SdiA in fimbriae expression and bacterial cell adherence and aggregation. On the other hand, SdiA acts as a transcriptional activator of cell division machinery assembly in the septum, since cells lacking SdiA regulator exhibited a filamentary shape rather than the typical rod shape. We also show that K. pneumoniae cells lacking SdiA regulator present constant production of QS autoinducers at maximum levels, suggesting a putative role for SdiA in the regulation of AI-2 production. Taken together, our results demonstrate that SdiA regulates cell division and the expression of virulence factors such as fimbriae expression, biofilm formation, and production of QS autoinducers in K. pneumoniae.

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