scholarly journals Acid resistance system CadBA is implicated in acid tolerance and biofilm formation and is identified as a new virulence factor of Edwardsiella tarda

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Chunmei Du ◽  
Xiaoping Huo ◽  
Hanjie Gu ◽  
Dongmei Wu ◽  
Yonghua Hu
Keyword(s):  
Biofilm Formation ◽  
Acid Stress ◽  
Acid Resistance ◽  
Bacterial Biofilm ◽  
Host Cells ◽  
Edwardsiella Tarda ◽  
Lysine Decarboxylase ◽  
High Homology ◽  
Intestinal Microbes ◽  
Resistance System

AbstractEdwardsiella tarda is a facultative intracellular pathogen in humans and animals. The Gram-negative bacterium is widely considered a potentially important bacterial pathogen. Adaptation to acid stress is important for the transmission of intestinal microbes, so the acid-resistance (AR) system is essential. However, the AR systems of E. tarda are totally unknown. In this study, a lysine-dependent acid resistance (LDAR) system in E. tarda, CadBA, was characterized and identified. CadB is a membrane protein and shares high homology with the lysine/cadaverine antiporter. CadA contains a PLP-binding core domain and a pyridoxal phosphate-binding motif. It shares high homology with lysine decarboxylase. cadB and cadA are co-transcribed under one operon. To study the function of the cadBA operon, isogenic cadA, cadB and cadBA deletion mutant strains TX01ΔcadA, TX01ΔcadB and TX01ΔcadBA were constructed. When cultured under normal conditions, the wild type strain and three mutants exhibited the same growth performance. However, when cultured under acid conditions, the growth of three mutants, especially TX01ΔcadA, were obviously retarded, compared to the wild strain TX01, which indicates the important involvement of the cadBA operon in acid resistance. The deletion of cadB or cadA, especially cadBA, significantly attenuated bacterial activity of lysine decarboxylase, suggesting the vital participation of cadBA operon in lysine metabolism, which is closely related to acid resistance. The mutations of cadBA operon enhanced bacterial biofilm formation, especially under acid conditions. The deletions of the cadBA operon reduced bacterial adhesion and invasion to Hela cells. Consistently, the deficiency of cadBA operon abated bacterial survival and replication in macrophages, and decreased bacterial dissemination in fish tissues. Our results also show that the expression of cadBA operon and regulator cadC were up-regulated upon acid stress, and CadC rigorously regulated the expression of cadBA operon, especially under acid conditions. These findings demonstrate that the AR CadBA system was a requisite for the resistance of E. tarda against acid stress, and played a critical role in bacterial infection of host cells and in host tissues. This is the first study about the acid resistance system of E. tarda and provides new insights into the acid-resistance mechanism and pathogenesis of E. tarda.

scholarly journals Type III Secretion System Translocon Component EseB Forms Filaments on and Mediates Autoaggregation of and Biofilm Formation by Edwardsiella tarda

2015 ◽  
Vol 81 (17) ◽  
pp. 6078-6087 ◽  
Author(s):  
Zhi Peng Gao ◽  
Pin Nie ◽  
Jin Fang Lu ◽  
Lu Yi Liu ◽  
Tiao Yi Xiao ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Edwardsiella Tarda ◽  
Dependent Manner ◽  
Content Type ◽  
Type Iii

ABSTRACTThe type III secretion system (T3SS) ofEdwardsiella tardaplays an important role in infection by translocating effector proteins into host cells. EseB, a component required for effector translocation, is reported to mediate autoaggregation ofE. tarda. In this study, we demonstrate that EseB forms filamentous appendages on the surface ofE. tardaand is required for biofilm formation byE. tardain Dulbecco's modified Eagle's medium (DMEM). Biofilm formation byE. tardain DMEM does not require FlhB, an essential component for assembling flagella. Dynamic analysis of EseB filament formation, autoaggregation, and biofilm formation shows that the formation of EseB filaments occurs prior to autoaggregation and biofilm formation. The addition of an EseB antibody toE. tardacultures before bacterial autoaggregation prevents autoaggregation and biofilm formation in a dose-dependent manner, whereas the addition of the EseB antibody toE. tardacultures in which biofilm is already formed does not destroy the biofilm. Therefore, EseB filament-mediated bacterial cell-cell interaction is a prerequisite for autoaggregation and biofilm formation.

scholarly journals HutZ is required for biofilm formation and contributes to the pathogenicity of Edwardsiella piscicida

2019 ◽  
Vol 50 (1) ◽  
Author(s):  
Yan-Jie Shi ◽  
Qing-Jian Fang ◽  
Hui-Qin Huang ◽  
Chun-Guang Gong ◽  
Yong-Hua Hu
Keyword(s):  
Biofilm Formation ◽  
Functional Characterization ◽  
Bacterial Biofilm ◽  
Host Cells ◽  
Fish Pathogen ◽  
Protein Activity ◽  
Biofilm Growth ◽  
Normal Medium ◽  
Iron Deficient ◽  
Edwardsiella Piscicida

Abstract Edwardsiella piscicida is a severe fish pathogen. Haem utilization systems play an important role in bacterial adversity adaptation and pathogenicity. In this study, a speculative haem utilization protein, HutZEp, was characterized in E. piscicida. hutZEp is encoded with two other genes, hutW and hutX, in an operon that is similar to the haem utilization operon hutWXZ identified in V. cholerae. However, protein activity analysis showed that HutZEp is probably not related to hemin utilization. To explore the biological role of HutZEp, a markerless hutZEp in-frame mutant strain, TX01ΔhutZ, was constructed. Deletion of hutZEp did not significantly affect bacterial growth in normal medium, in iron-deficient conditions, or in the presence of haem but significantly retarded bacterial biofilm growth. The expression of known genes related to biofilm growth was not affected by hutZEp deletion, which indicated that HutZEp was probably a novel factor promoting biofilm formation in E. piscicida. Compared to the wild-type TX01, TX01ΔhutZ exhibited markedly compromised tolerance to acid stress and host serum stress. Pathogenicity analysis showed that inactivation of hutZEp significantly impaired the ability of E. piscicida to invade and reproduce in host cells and to infect host tissue. In contrast to TX01, TX01ΔhutZ was defective in blocking host macrophage activation. The expression of hutZEp was directly regulated by the ferric uptake regulator Fur. This study is the first functional characterization of HutZ in a fish pathogen, and these findings suggested that HutZEp is essential for E. piscicida biofilm formation and contributes to host infection.

scholarly journals Escherichia coli Glutamate- and Arginine-Dependent Acid Resistance Systems Increase Internal pH and Reverse Transmembrane Potential

2004 ◽  
Vol 186 (18) ◽  
pp. 6032-6041 ◽  
Author(s):  
Hope Richard ◽  
John W. Foster
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Transmembrane Potential ◽  
Acid Stress ◽  
Acid Resistance ◽  
Physiological Parameter ◽  
Resistance System ◽  
Internal Ph ◽  
System 2 ◽  
Acidic Nature

ABSTRACT Due to the acidic nature of the stomach, enteric organisms must withstand extreme acid stress for colonization and pathogenesis. Escherichia coli contains several acid resistance systems that protect cells to pH 2. One acid resistance system, acid resistance system 2 (AR2), requires extracellular glutamate, while another (AR3) requires extracellular arginine. Little is known about how these systems protect cells from acid stress. AR2 and AR3 are thought to consume intracellular protons through amino acid decarboxylation. Antiport mechanisms then exchange decarboxylation products for new amino acid substrates. This form of proton consumption could maintain an internal pH (pHi) conducive to cell survival. The model was tested by estimating the pHi and transmembrane potential (ΔΨ) of cells acid stressed at pH 2.5. During acid challenge, glutamate- and arginine-dependent systems elevated pHi from 3.6 to 4.2 and 4.7, respectively. However, when pHi was manipulated to 4.0 in the presence or absence of glutamate, only cultures challenged in the presence of glutamate survived, indicating that a physiological parameter aside from pHi was also important. Measurements of ΔΨ indicated that amino acid-dependent acid resistance systems help convert membrane potential from an inside negative to inside positive charge, an established acidophile strategy used to survive extreme acidic environments. Thus, reversing ΔΨ may be a more important acid resistance strategy than maintaining a specific pHi value.

scholarly journals CRISPR-cas3 of Salmonella Upregulates Bacterial Biofilm Formation and Virulence to Host Cells by Targeting Quorum-Sensing Systems

Pathogens ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 53 ◽  
Author(s):  
Luqing Cui ◽  
Xiangru Wang ◽  
Deyu Huang ◽  
Yue Zhao ◽  
Jiawei Feng ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Bacterial Biofilm ◽  
Host Cells ◽  
Microbial Pathogens ◽  
Bacterial Invasion ◽  
Type I ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Sensing Systems ◽  
Type Three Secretion System

Salmonella is recognized as one of the most common microbial pathogens worldwide. The bacterium contains the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems, providing adaptive immunity against invading foreign nucleic acids. Previous studies suggested that certain bacteria employ the Cas proteins of CRISPR-Cas systems to target their own genes, which also alters the virulence during invasion of mammals. However, whether CRISPR-Cas systems in Salmonella have similar functions during bacterial invasion of host cells remains unknown. Here, we systematically analyzed the genes that are regulated by Cas3 in a type I-E CRISPR-Cas system and the virulence changes due to the deletion of cas3 in Salmonella enterica serovar Enteritidis. Compared to the cas3 gene wild-type (cas3 WT) Salmonella strain, cas3 deletion upregulated the lsrFGBE genes in lsr (luxS regulated) operon related to quorum sensing (QS) and downregulated biofilm-forming-related genes and Salmonella pathogenicity island 1 (SPI-1) genes related to the type three secretion system (T3SS). Consistently, the biofilm formation ability was downregulated in the cas3 deletion mutant (Δcas3). The bacterial invasive and intracellular capacity of Δcas3 to host cells was also reduced, thereby increasing the survival of infected host cells and live chickens. By the transcriptome-wide screen (RNA-Seq), we found that the cas3 gene impacts a series of genes related to QS, the flagellum, and SPI-1-T3SS system, thereby altering the virulence phenotypes. As QS SPI-1-T3SS and CRISPR-Cas systems are widely distributed in the bacteria kingdom, our findings extend our understanding of virulence regulation and pathogenicity in mammalian hosts for Salmonella and potentially other bacteria.

Bacterial biofilm behavior in water-supply lines of dental units

1992 ◽  
Vol 50 (1) ◽  
pp. 882-883
Author(s):  
B.D. Tall ◽  
K.S. George ◽  
R. T. Gray ◽  
H.N. Williams
Keyword(s):  
Water Supply ◽  
Medical Devices ◽  
Biofilm Formation ◽  
Bacterial Biofilm

Studies of bacterial behavior in many environments have shown that most organisms attach to surfaces, forming communities of microcolonies called biofilms. In contaminated medical devices, biofilms may serve both as reservoirs and as inocula for the initiation of infections. Recently, there has been much concern about the potential of dental units to transmit infections. Because the mechanisms of biofilm formation are ill-defined, we investigated the behavior and formation of a biofilm associated with tubing leading to the water syringe of a dental unit over a period of 1 month.

Inhibition of Bacterial Biofilm Formation by Phytotherapeutics with Focus on Overcoming Antimicrobial Resistance

2020 ◽  
Vol 26 (24) ◽  
pp. 2807-2816 ◽  
Author(s):  
Yun Su Jang ◽  
Tímea Mosolygó
Keyword(s):  
Antimicrobial Resistance ◽  
Biofilm Formation ◽  
Antimicrobial Agents ◽  
Bacterial Biofilm ◽  
Experimental Investigations ◽  
Resistant Bacteria ◽  
Salmonella Spp ◽  
Food Borne ◽  
High Prevalence ◽  
Scientific Attention

: Bacteria within biofilms are more resistant to antibiotics and chemical agents than planktonic bacteria in suspension. Treatment of biofilm-associated infections inevitably involves high dosages and prolonged courses of antimicrobial agents; therefore, there is a potential risk of the development of antimicrobial resistance (AMR). Due to the high prevalence of AMR and its association with biofilm formation, investigation of more effective anti-biofilm agents is required. : From ancient times, herbs and spices have been used to preserve foods, and their antimicrobial, anti-biofilm and anti-quorum sensing properties are well known. Moreover, phytochemicals exert their anti-biofilm properties at sub-inhibitory concentrations without providing the opportunity for the emergence of resistant bacteria or harming the host microbiota. : With increasing scientific attention to natural phytotherapeutic agents, numerous experimental investigations have been conducted in recent years. The present paper aims to review the articles published in the last decade in order to summarize a) our current understanding of AMR in correlation with biofilm formation and b) the evidence of phytotherapeutic agents against bacterial biofilms and their mechanisms of action. The main focus has been put on herbal anti-biofilm compounds tested to date in association with Staphylococcus aureus, Pseudomonas aeruginosa and food-borne pathogens (Salmonella spp., Campylobacter spp., Listeria monocytogenes and Escherichia coli).

Antibiotics Application Strategies to Control Biofilm Formation in Pathogenic Bacteria

2020 ◽  
Vol 21 (4) ◽  
pp. 270-286 ◽  
Author(s):  
Fazlurrahman Khan ◽  
Dung T.N. Pham ◽  
Sandra F. Oloketuyi ◽  
Young-Mog Kim
Keyword(s):  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Extracellular Polymeric Substances ◽  
Quorum Quenching ◽  
Resistance Mechanisms ◽  
Bacterial Biofilm ◽  
Bacterial Cells ◽  
High Concentration ◽  
Biofilm Inhibition ◽  
Abiotic Surfaces

Background: The establishment of a biofilm by most pathogenic bacteria has been known as one of the resistance mechanisms against antibiotics. A biofilm is a structural component where the bacterial community adheres to the biotic or abiotic surfaces by the help of Extracellular Polymeric Substances (EPS) produced by bacterial cells. The biofilm matrix possesses the ability to resist several adverse environmental factors, including the effect of antibiotics. Therefore, the resistance of bacterial biofilm-forming cells could be increased up to 1000 times than the planktonic cells, hence requiring a significantly high concentration of antibiotics for treatment. Methods: Up to the present, several methodologies employing antibiotics as an anti-biofilm, antivirulence or quorum quenching agent have been developed for biofilm inhibition and eradication of a pre-formed mature biofilm. Results: Among the anti-biofilm strategies being tested, the sub-minimal inhibitory concentration of several antibiotics either alone or in combination has been shown to inhibit biofilm formation and down-regulate the production of virulence factors. The combinatorial strategies include (1) combination of multiple antibiotics, (2) combination of antibiotics with non-antibiotic agents and (3) loading of antibiotics onto a carrier. Conclusion: The present review paper describes the role of several antibiotics as biofilm inhibitors and also the alternative strategies adopted for applications in eradicating and inhibiting the formation of biofilm by pathogenic bacteria.

scholarly journals Surface Immobilization of Nano-Silver on Polymeric Medical Devices to Prevent Bacterial Biofilm Formation

Pathogens ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 93 ◽  
Author(s):  
Riau ◽  
Aung ◽  
Setiawan ◽  
Yang ◽  
Yam ◽  
...  
Keyword(s):  
Medical Devices ◽  
Biofilm Formation ◽  
Culture Media ◽  
Silver Ions ◽  
Bacterial Biofilm ◽  
Surface Immobilization ◽  
Nano Silver ◽  
Gram Positive Bacteria ◽  
Tissue Microenvironment

: Bacterial biofilm on medical devices is difficult to eradicate. Many have capitalized the anti-infective capability of silver ions (Ag+) by incorporating nano-silver (nAg) in a biodegradable coating, which is then laid on polymeric medical devices. However, such coating can be subjected to premature dissolution, particularly in harsh diseased tissue microenvironment, leading to rapid nAg clearance. It stands to reason that impregnating nAg directly onto the device, at the surface, is a more ideal solution. We tested this concept for a corneal prosthesis by immobilizing nAg and nano-hydroxyapatite (nHAp) on poly(methyl methacrylate), and tested its biocompatibility with human stromal cells and antimicrobial performance against biofilm-forming pathogens, Pseudomonas aeruginosa and Staphylococcus aureus. Three different dual-functionalized substrates—high Ag (referred to as 75:25 HAp:Ag); intermediate Ag (95:5 HAp:Ag); and low Ag (99:1 HAp:Ag) were studied. The 75:25 HAp:Ag was effective in inhibiting biofilm formation, but was cytotoxic. The 95:5 HAp:Ag showed the best selectivity among the three substrates; it prevented biofilm formation of both pathogens and had excellent biocompatibility. The coating was also effective in eliminating non-adherent bacteria in the culture media. However, a 28-day incubation in artificial tear fluid revealed a ~40% reduction in Ag+ release, compared to freshly-coated substrates. The reduction affected the inhibition of S. aureus growth, but not the P. aeruginosa. Our findings suggest that Ag+ released from surface-immobilized nAg diminishes over time and becomes less effective in suppressing biofilm formation of Gram-positive bacteria, such as S. aureus. This advocates the coating, more as a protection against perioperative and early postoperative infections, and less as a long-term preventive solution.

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