scholarly journals A Novel LysR Family Factor STM0859 is Associated with The Responses of Salmonella Typhimurium to Environmental Stress and Biofilm Formation

2021 ◽  
Vol 70 (4) ◽  
pp. 479-487
Author(s):  
ZHONGMEI MA ◽  
NA LI ◽  
CHENGCHENG NING ◽  
YUCHENG LIU ◽  
YUN GUO ◽  
...  
Keyword(s):  
Environmental Stress ◽  
Salmonella Typhimurium ◽  
Biofilm Formation ◽  
Wild Strain ◽  
Acid Stress ◽  
Environmental Stresses ◽  
Pcr Analysis ◽  
Mobility Shift ◽  
Complementation Strain ◽  
Lysr Family

Salmonella enterica subsp. enterica serovar Typhimurium (ST) is an intracellularly parasitic bacterium. This zoonotic pathogen causes food poisoning and thus imposes a severe threat to food safety. Here, to understand the regulatory roles of the novel transcription factor STM0859 on the response of ST to environmental stress and biofilm formation, the STM0859 gene-deficient strain and the complementation strain ΔSTM0859/STM0859 were generated, respectively. Then, its capacity of responding to environmental stresses and biofilm (BF) formation ability under different stresses, including acid, alkali, high salt, cholate, and oxidative stresses was tested. We further analyzed the interaction between the STM0859 protein and the promoter of the acid stress response-related gene rcsB by performing an electrophoresis mobility shift assay (EMSA). The results showed that acid resistance and BF formation capacities of ST-ΔSTM0859 strain were significantly weaker, as compared with those of Salmonella Typhimurium SL1344 (ST-SL1344) wild strain (p < 0.01). Quantitative qRT-PCR analysis showed that the expression levels of acid stress and BF formation-related genes, rcsB and rpoS, of ST-ΔSTM0859 strain were significantly reduced at the transcription levels, while the transcription levels of these genes were fully restored in complementation strain ST-ΔSTM0859/STM0859. The results of EMSA showed that STM0859 was capable of binding the promoter DNA fragments of the rcsB gene, suggesting that STM0859 can promote the transcription of the rcsB gene through interaction with its promoter, thereby exerting an indirectly regulatory role on the adaptive responses to acid stress and BF formation of ST. This study provided new insights into the regulatory mechanisms of the LysR family factors on the tolerances of ST under adverse environmental stresses.

scholarly journals Effects of 405 ± 5-nm LED Illumination on Environmental Stress Tolerance of Salmonella Typhimurium in Sliced Beef

Foods ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 136
Author(s):  
Du Guo ◽  
Yichen Bai ◽  
Shengyi Fei ◽  
Yanpeng Yang ◽  
Jiahui Li ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Environmental Stress ◽  
Salmonella Typhimurium ◽  
Bile Salts ◽  
Foodborne Pathogen ◽  
Acid Stress ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Pressure Oxidation ◽  
Light Emitting

Salmonella Typhimurium is a widely distributed foodborne pathogen and is tolerant of various environmental conditions. It can cause intestinal fever, gastroenteritis and bacteremia. The aim of this research was to explore the effect of illumination with 405 nm light-emitting diodes (LEDs) on the resistance of S. Typhimurium to environmental stress. Beef slices contaminated with S. Typhimurium were illuminated by 405 nm LEDs (18.9 ± 1.4 mW/cm2) for 8 h at 4 °C; controls were incubated in darkness at 7 °C. Then, the illuminated or non-illuminated (control) cells were exposed to thermal stress (50, 55, 60 or 65 °C); oxidative stress (0.01% H2O2 [v/v]); acid stress (simulated gastric fluid [SGF] at pH 2 or 3); or bile salts (1%, 2%, or 3% [w/v]). S. Typhimurium treated by 405 nm LED irradiation showed decreased resistance to thermal stress, osmotic pressure, oxidation, SGF and bile salts. The transcription of eight environmental tolerance-related genes were downregulated by the illumination. Our findings suggest the potential of applying 405 nm LED-illumination technology in the control of pathogens in food processing, production and storage, and in decreasing infection and disease related to S. Typhimurium.

scholarly journals Autoinducer-2 Triggers the Oxidative Stress Response in Mycobacterium avium, Leading to Biofilm Formation

2008 ◽  
Vol 74 (6) ◽  
pp. 1798-1804 ◽  
Author(s):  
Henriette Geier ◽  
Serge Mostowy ◽  
Gerard A. Cangelosi ◽  
Marcel A. Behr ◽  
Timothy E. Ford
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Quorum Sensing ◽  
Mycobacterium Avium ◽  
Biofilm Formation ◽  
Transcriptional Response ◽  
Opportunistic Pathogen ◽  
Environmental Stresses ◽  
Oxidative Stress Response ◽  
Autoinducer 2

ABSTRACT Mycobacterium avium is an environmental organism and opportunistic pathogen with inherent resistance to drugs, environmental stresses, and the host immune response. To adapt to these disparate conditions, M. avium must control its transcriptional response to environmental cues. M. avium forms biofilms in various environmental settings, including drinking water pipes and potable water reservoirs. In this study, we investigated the role of the universal signaling molecule autoinducer-2 (AI-2) in biofilm formation by M. avium. The addition of the compound to planktonic M. avium cultures resulted in increased biofilm formation. Microarray and reverse transcriptase PCR studies revealed an upregulation of the oxidative stress response upon addition of AI-2. This suggests that the response to AI-2 might be related to oxidative stress, rather than quorum sensing. Consistent with this model, addition of hydrogen peroxide, a known stimulus of the oxidative stress response, to M. avium cultures resulted in elevated biofilm formation. These results suggest that AI-2 does not act as a quorum-sensing signal in M. avium. Instead, biofilm formation is triggered by environmental stresses of biotic and abiotic origins and AI-2 may exert effects on that level.

scholarly journals Effect of a Berry Polyphenolic Fraction on Biofilm Formation, Adherence Properties and Gene Expression of Streptococcus mutans and Its Biocompatibility with Oral Epithelial Cells

Antibiotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 46
Author(s):  
Mariem Souissi ◽  
Amel Ben Lagha ◽  
Kamel Chaieb ◽  
Daniel Grenier
Keyword(s):  
Epithelial Cells ◽  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Cell Model ◽  
Pcr Analysis ◽  
Adhesion Properties ◽  
Oral Epithelial Cells ◽  
Polymerase Chain ◽  
Oral Epithelial ◽  
Wild Blueberry

The ability of Streptococcus mutans to adhere to oral surfaces and form biofilm is a key step in the tooth decay process. The aim of this study was to investigate a berry (wild blueberry, cranberry, and strawberry) polyphenolic fraction, commercialized as Orophenol®, for its antibacterial, anti-biofilm, and anti-adhesion properties on S. mutans. Moreover, the biocompatibility of the fraction with human oral epithelial cells was assessed. Phenolic acids, flavonoids (flavonols, anthocyanins, flavan-3-ols), and procyanidins made up 10.71%, 19.76%, and 5.29% of the berry polyphenolic fraction, respectively, as determined by chromatography and mass spectrometry. The berry polyphenolic preparation dose-dependently inhibited S. mutans biofilm formation while not reducing bacterial growth. At concentrations ranging from 250 to 1000 µg/mL, the fraction inhibited the adhesion of S. mutans to both saliva-coated hydroxyapatite and saliva-coated nickel–chrome alloy. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that incubating S. mutans with the berry polyphenolic fraction was associated with a reduced expression of luxS gene, which regulates quorum sensing in S. mutans. The berry fraction did not show any significant cytotoxicity in an oral epithelial cell model. In conclusion, Orophenol®, which is a mixture of polyphenols from wild blueberry, cranberry and strawberry, possesses interesting anti-caries properties while being compatible with oral epithelial cells.

Effect of lactic acid stress on biofilm formation of Escherichia coli O26 at different temperatures

2020 ◽  
Author(s):  
Xiaoyu Mi ◽  
Jie Hu ◽  
Su Zhang ◽  
Siqi Wang ◽  
Wangchen Zhao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Biofilm Formation ◽  
Acid Stress ◽  
Different Temperatures

scholarly journals Cyclic Di-GMP Regulates Multiple Cellular Functions in the Symbiotic Alphaproteobacterium Sinorhizobium meliloti

2015 ◽  
Vol 198 (3) ◽  
pp. 521-535 ◽  
Author(s):  
Simon Schäper ◽  
Elizaveta Krol ◽  
Dorota Skotnicka ◽  
Volkhard Kaever ◽  
Rolf Hilker ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Sinorhizobium Meliloti ◽  
Acid Stress ◽  
Second Messenger ◽  
Lifestyle Changes ◽  
Single Domain ◽  
Receptor Protein ◽  
Leguminous Plant ◽  
Content Type

ABSTRACTSinorhizobium melilotiundergoes major lifestyle changes between planktonic states, biofilm formation, and symbiosis with leguminous plant hosts. In many bacteria, the second messenger 3′,5′-cyclic di-GMP (c-di-GMP, or cdG) promotes a sessile lifestyle by regulating a plethora of processes involved in biofilm formation, including motility and biosynthesis of exopolysaccharides (EPS). Here, we systematically investigated the role of cdG inS. melilotiRm2011 encoding 22 proteins putatively associated with cdG synthesis, degradation, or binding. Single mutations in 21 of these genes did not cause evident changes in biofilm formation, motility, or EPS biosynthesis. In contrast, manipulation of cdG levels by overproducing endogenous or heterologous diguanylate cyclases (DGCs) or phosphodiesterases (PDEs) affected these processes and accumulation ofN-Acyl-homoserine lactones in the culture supernatant. Specifically, individual overexpression of theS. melilotigenespleD,SMb20523,SMb20447,SMc01464, andSMc03178encoding putative DGCs and ofSMb21517encoding a single-domain PDE protein had an impact and resulted in increased levels of cdG. Compared to the wild type, anS. melilotistrain that did not produce detectable levels of cdG (cdG0) was more sensitive to acid stress. However, it was symbiotically potent, unaffected in motility, and only slightly reduced in biofilm formation. TheSMc01790-SMc01796locus, homologous to theAgrobacterium tumefaciensuppABCDEFcluster governing biosynthesis of a unipolarly localized polysaccharide, was found to be required for cdG-stimulated biofilm formation, while the single-domain PilZ protein McrA was identified as a cdG receptor protein involved in regulation of motility.IMPORTANCEWe present the first systematic genome-wide investigation of the role of 3′,5′-cyclic di-GMP (c-di-GMP, or cdG) in regulation of motility, biosynthesis of exopolysaccharides, biofilm formation, quorum sensing, and symbiosis in a symbiotic alpha-rhizobial species. Phenotypes of anS. melilotistrain unable to produce cdG (cdG0) demonstrated that this second messenger is not essential for root nodule symbiosis but may contribute to acid tolerance. Our data further suggest that enhanced levels of cdG promote sessility ofS. melilotiand uncovered a single-domain PilZ protein as regulator of motility.

scholarly journals Inhibition of Quorum Sensing and Biofilm Formation of Esculetin on Aeromonas Hydrophila

2021 ◽  
Vol 12 ◽  
Author(s):  
Bing Sun ◽  
Huaizhi Luo ◽  
Huan Jiang ◽  
Zhennan Wang ◽  
Aiqun Jia
Keyword(s):  
Quorum Sensing ◽  
Aeromonas Hydrophila ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Pcr Analysis ◽  
Swarming Motility ◽  
Gene Expression Levels ◽  
Good Agreement

Quorum sensing (QS) and biofilm formation inhibition activity of esculetin on Aeromonas hydrophila SHAe 115 were evaluated. Exposure to esculetin at 25, 50, and 100μg/ml significantly inhibited the production of protease and hemolysin, the formation of biofilms and attenuated the swarming motility of A. hydrophila SHAe 115. Biofilm forming inhibition was also observed through confocal laser scanning microscopy and scanning electron microscope. Quantitative real-time PCR analysis indicated that genes positively related to QS and biofilm formation were downregulated to varying degrees, while gene (litR) negatively related to biofilm formation was significantly upregulated. The phenotypic results were in good agreement with gene expression levels. These results indicated that esculetin would be a potential QS inhibitor for A. hydrophila.

scholarly journals Effects ofibeADeletion on Virulence and Biofilm Formation of Avian PathogenicEscherichia coli

2010 ◽  
Vol 79 (1) ◽  
pp. 279-287 ◽  
Author(s):  
Shaohui Wang ◽  
Chunling Niu ◽  
Zhenyu Shi ◽  
Yongjie Xia ◽  
Muhammad Yaqoob ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Wild Type Strain ◽  
Chicken Embryo Fibroblast ◽  
Neonatal Meningitis ◽  
Pcr Analysis ◽  
E Coli ◽  
Reverse Transcription Pcr ◽  
Animal System ◽  
The Brain

ABSTRACTTheibeAgene is located on a genomic island, GimA, which is involved in the pathogenesis of neonatal meningitisEscherichia coli(NMEC) and avian pathogenicE. coli(APEC). The prevalence ofibeAin the APEC collection in China was investigated, and 20 of 467 strains (4.3%) were positive. In addition, analysis of the association of theE. colireference (ECOR) groups with positive strains revealed thatibeAwas linked to group B2. TheibeAgene in DE205B was analyzed and compared to those of APEC and NMEC, which indicated that the specificity ofibeAwas not consistent along pathotypes. The invasion of chicken embryo fibroblast DF-1 cells by APEC DE205B and RS218 was observed, which suggested that DF-1 cells could be a model to study the mechanism of APEC invasion. The inactivation ofibeAin APEC DE205B led to the reduced capacity to invade DF-1 cells, defective virulencein vivo, and decreased biofilm formation compared to the wild-type strain. In addition, strain AAEC189 expressingibeAexhibited enhanced invasion capacity and biofilm formation. The results of the quantitative real-time reverse transcription-PCR (qRT-PCR) analysis and animal system infection experiments indicated that the loss ofibeAdecreased the colonization and proliferation capacities of APEC in the brain during system infection.

scholarly journals Identification of the Regulon of AphB and Its Essential Roles in LuxR and Exotoxin Asp Expression in the Pathogen Vibrio alginolyticus

2017 ◽  
Vol 199 (20) ◽  
Author(s):  
Xiating Gao ◽  
Yang Liu ◽  
Huan Liu ◽  
Zhen Yang ◽  
Qin Liu ◽  
...  
Keyword(s):  
Binding Sites ◽  
Specific Binding ◽  
Vibrio Alginolyticus ◽  
Physiological Adaptation ◽  
Pcr Analysis ◽  
Growth Stages ◽  
Mobility Shift ◽  
Marine Animals ◽  
Content Type ◽  
Virulence Gene Expression

ABSTRACT In Vibrio species, AphB is essential to activate virulence cascades by sensing low-pH and anaerobiosis signals; however, its regulon remains largely unknown. Here, AphB is found to be a key virulence regulator in Vibrio alginolyticus, a pathogen for marine animals and humans. Chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq) enabled the detection of 20 loci in the V. alginolyticus genome that contained AphB-binding peaks. An AphB-specific binding consensus was confirmed by electrophoretic mobility shift assays (EMSAs), and the regulation of genes flanking such binding sites was demonstrated using quantitative real-time PCR analysis. AphB binds directly to its own promoter and positively controls its own expression in later growth stages. AphB also activates the expression of the exotoxin Asp by binding directly to the promoter regions of asp and the master quorum-sensing (QS) regulator luxR. DNase I footprinting analysis uncovered distinct AphB-binding sites (BBS) in these promoters. Furthermore, a BBS in the luxR promoter region overlaps that of LuxR-binding site I, which mediates the positive control of luxR promoter activity by AphB. This study provides new insights into the AphB regulon and reveals the mechanisms underlying AphB regulation of physiological adaptation and QS-controlled virulence in V. alginolyticus. IMPORTANCE In this work, AphB is determined to play essential roles in the expression of genes associated with QS, physiology, and virulence in V. alginolyticus, a pathogen for marine animals and humans. AphB was found to bind directly to 20 genes and control their expression by a 17-bp consensus binding sequence. Among the 20 genes, the aphB gene itself was identified to be positively autoregulated, and AphB also positively controlled asp and luxR expression. Taken together, these findings improve our understanding of the roles of AphB in controlling physiological adaptation and QS-controlled virulence gene expression.

The extrachromosomal replication of Dictyostelium plasmid Ddp2 requires a cis-acting element and a plasmid-encoded trans-acting factor

1990 ◽  
Vol 10 (7) ◽  
pp. 3727-3736
Author(s):  
B Leiting ◽  
I J Lindner ◽  
A A Noegel
Keyword(s):  
Escherichia Coli ◽  
Copy Number ◽  
Wild Strain ◽  
Open Reading Frame ◽  
Mobility Shift ◽  
Reading Frame ◽  
Cis Acting ◽  
Transformation Vector ◽  
Cis And Trans ◽  
Electrophoretic Mobility Shift Assays

Dictyostelium discoideum plasmid Ddp2 from the wild strain WS380B is a 5.8-kilobase (kb) supercoiled circle with a copy number of 300 per haploid genome. We previously described the construction of an extrachromosomally replicating transformation vector pnDeI carrying 4.7 kb of Ddp2 sequences (B. Leiting, and A. Noegel, Plasmid 20:241-248, 1988). In order to reduce the sequences required for extrachromosomal maintenance in D. discoideum, we characterized Ddp2 by sequence analysis, by deletion experiments, by transcription mapping, by electrophoretic mobility shift assays, and by expression of its single open reading frame in Escherichia coli. Two elements were involved in replication of Ddp2: a cis-acting sequence located on a 592-base-pair (bp) fragment that consisted of 220 bp of essential and 372 bp of auxiliary sequences, and a 2.7-kb open reading frame which most likely encodes a trans-acting factor. The cis- and trans-acting elements did not overlap and were shown to act independently from the location of the sequences encoding the trans-acting factor.

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