Alteration of O-specific polysaccharide structure of symbiotically defective Mesorhizobium loti mutant 2213.1 derived from strain NZP2213.

2008 ◽  
Vol 55 (1) ◽  
pp. 191-200 ◽  
Author(s):  
Anna Turska-Szewczuk ◽  
Hubert Pietras ◽  
Wojciech Borucki ◽  
Ryszard Russa
Keyword(s):  
Wild Type Strain ◽  
2D Nmr ◽  
Chain Structure ◽  
Wild Type ◽  
Immunoblot Assay ◽  
Mesorhizobium Loti ◽  
Nmr Data ◽  
Specific Polysaccharide ◽  
C Nmr

Mesorhizobium loti mutant 2213.1 derived from the wild-type strain NZP2213 by Tn5 mutagenesis showed impaired effectiveness of symbiosis with the host plant Lotus corniculatus (Turska-Szewczuk et al., 2007 Microbiol Res, in press). The inability of lipopolysaccharide (LPS) isolated from the mutant 2213.1 strain or de-O-acetylated LPS of the parental cells to inactivate phage A1 particles implicated alterations in the LPS structure. The O-specific polysaccharide of the mutant was studied by chemical analyses along with (1)H and (13)C NMR spectroscopy, which clearly confirmed alterations in the O-chain structure. 2D NMR data showed that the mutant O-polysaccharide consists of a tetrasaccharide repeating unit containing non-substituted as well as O-acetylated or O-methylated 6-deoxytalopyranose residues. Additionally, an immunogold assay revealed a reduced number of gold particles on the mutant bacteroid cell surface, which could result from both a diminished amount of an O-antigenic determinant in mutant LPS and modifications of structural epitopes caused by alterations in O-acetylation or O-methylation of sugar residues. Western immunoblot assay of alkaline de-O-acetylated lipophilic M. loti NZP2213 LPS showed no reactivity with homologous serum indicating a role of O-acetyl groups in its O-specificity.

scholarly journals Enhanced production of Clavulanic acid by improving glycerol utilization using reporter-guided mutagenesis of an industrial Streptomyces clavuligerus strain

2021 ◽  
Author(s):  
Chang-Hun Shin ◽  
Hang Soo Cho ◽  
Hyung-Jin Won ◽  
Ho Jeong Kwon ◽  
Chan-Wha Kim ◽  
...  
Keyword(s):  
Clavulanic Acid ◽  
Wild Type Strain ◽  
Random Mutagenesis ◽  
Streptomyces Clavuligerus ◽  
Wild Type ◽  
Mutant Selection ◽  
Enhanced Production ◽  
Industrial Strains ◽  
Glycerol Utilization

Abstract Clavulanic acid (CA) produced by Streptomyces clavuligerus is a clinically important β-lactamase inhibitor. It is known that glycerol utilization can significantly improve cell growth and CA production of S. clavuligerus. We found that the industrial CA-producing S. clavuligerus strain OR generated by random mutagenesis consumes less glycerol than the wild-type strain; we then developed a mutant strain in which the glycerol utilization operon is overexpressed, as compared to the parent OR strain, through iterative random mutagenesis and reporter-guided selection. The CA production of the resulting S. clavuligerus ORUN strain was increased by approximately 31.3 per cent (5.21 ± 0.26 g/L) in a flask culture and 17.4 per cent (6.11 ± 0.36 g/L) in a fermenter culture, as compared to that of the starting OR strain. These results confirmed the important role of glycerol utilization in CA production and demonstrated that reporter-guided mutant selection is an efficient method for further improvement of randomly mutagenized industrial strains.

scholarly journals Role Of Selected Fimbrial Adheins In Pathogenesis Of Acid-Induced Eneterohemorrhagic Escherichia Coli 0157:H7

2021 ◽  
Author(s):  
Shahnaz Haque
Keyword(s):  
Fatty Acid ◽  
Type Strain ◽  
Wild Type Strain ◽  
Short Chain Fatty Acid ◽  
Acid Stress ◽  
Chain Fatty Acid ◽  
Short Chain ◽  
Wild Type ◽  
Food Borne

Enterohemorrhagic Escherichia coli (EHEC) 0157:H7 is a food-borne pathogen that causes hemolytic uremic syndrome and hemorrhagic colitis. The mechanisms underlying the adhesion of EHEC 0157:H7 to intestinal epithelial cells are not well understood. Like other food-borne pathogens, ECEC 0157:H7 must survive the acid stress of the gastric juice in the stomach and short chain fatty acid in the intestine in order to colonize the large intestine. We have found that acid stress and short chain fatty acid stress significantly enhance host-adhesion of EHEC 0157:H7 and also upregulates expression of EHEC fimbrial genes, lpfA1, lpfA2 and yagZ, as demonstrated by our DNA microarray. We now report that disruption of the yagZ (also known as the E. coli common pilus A) gene results in loss of the acid-induced and short chain fatty acid-induced adhesion increase seen for the wild type strain. When the yagZ mutant is complemented with yagZ, the sress-induced and short chain fatty acid-induced adhesion increase seen for the wild type strain. When the yagZ mutant is complemented with yagZ, the stress-induced adhesion pehnotype is restored, confirming the role of yagZ in the acid as well as short chain fatty acid induced adhesion to HEp-2 cells. On the other hand, neither disruption in the long polar fimbria genes lpfA1 or lpfA2 in the wild type showed any effect in adherence to HEp-2 cells; rather displaying a hyperadherant phenotype to HEp-2 cells after acid-induced or short chain fatty acid-induced stress. The results also indicate that acid or short chain fatty acid stress, which is a part of the host's natural defense mechanism against pathogens, may regulate virulence factors resulting in enhanced bacteria-host attachment during colonization in the human or bovine host.

Identification of Crp as a novel regulator of the Std fimbrial expression in Salmonella

Microbiology ◽  
2021 ◽  
Author(s):  
Karine Dufresne ◽  
France Daigle
Keyword(s):  
Wild Type Strain ◽  
Distal Region ◽  
Transcriptional Factor ◽  
Major Influence ◽  
Wild Type ◽  
Content Type ◽  
Link Type ◽  
Serovar Typhimurium ◽  
Metabolic Regulators

The Salmonella enterica serovar Typhi genome contains 14 putative fimbrial systems. The Std fimbriae belong to the chaperone-usher family and its regulation has not been investigated in S. Typhi. Several regulators of Std were previously identified in the closely related serovar Typhimurium. We hypothesize that regulators of S. Typhimurium may be shared with S. Typhi, but that several other regulators remain to be discovered. Here, we describe the role of more than 50 different candidate regulators on std expression. Three types of regulators were investigated: known regulators in S. Typhimurium, in silico predicted regulators and virulence/metabolic regulators. Expression of std was determined in the regulator mutants and compared with the wild-type strain. Overall, 21 regulator mutations affect std promoter expression. The role of Crp, a newly identified factor for std expression, was further investigated. Crp acted as an activator of std expression on a distal region of the std promoter region. Together, our results demonstrate the major influence of Crp as a novel transcriptional factor on std promoter expression and later production of Std fimbriae in Salmonella .

scholarly journals Flavonoids from Curcuma longa Leaves and their NMR Assignments

2015 ◽  
Vol 10 (1) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Chia-Ling Jiang ◽  
Sheng-Fa Tsai ◽  
Shoei-Sheng Lee
Keyword(s):  
Nmr Assignments ◽  
Soluble Fraction ◽  
Curcuma Longa ◽  
2D Nmr ◽  
Etoh Extract ◽  
Spectroscopic Analyses ◽  
Nmr Data ◽  
The Common ◽  
Reported Data ◽  
C Nmr

Chemical investigation of the n-BuOH-soluble fraction of the EtOH extract of the aerial part of Curcuma longa led to the isolation of 11 flavonol glycosides and one dihydroflavonol glucoside (1) via chromatography over Sephadex LH-20 and Lobar RP-18 columns. Although they are known, the 1H and 13C NMR data recorded in CD3OD rather than the common DMSO- d6 are doubly checked via extensive 2D NMR spectroscopic analyses, leading to some revisions of the reported data, especially for the glycon part.

scholarly journals Role of CpALS4790 and CpALS0660 in Candida parapsilosis Virulence: Evidence from a Murine Model of Vaginal Candidiasis

2020 ◽  
Vol 6 (2) ◽  
pp. 86
Author(s):  
Marina Zoppo ◽  
Fabrizio Fiorentini ◽  
Cosmeri Rizzato ◽  
Mariagrazia Di Luca ◽  
Antonella Lupetti ◽  
...  
Keyword(s):  
Cell Wall ◽  
Murine Model ◽  
Type Strain ◽  
Wild Type Strain ◽  
Candida Parapsilosis ◽  
Vaginal Candidiasis ◽  
Phenotypic Characterization ◽  
Wild Type ◽  
Mutant Strains

The Candida parapsilosis genome encodes for five agglutinin-like sequence (Als) cell-wall glycoproteins involved in adhesion to biotic and abiotic surfaces. The work presented here is aimed at analyzing the role of the two still uncharacterized ALS genes in C. parapsilosis, CpALS4790 and CpALS0660, by the generation and characterization of CpALS4790 and CpALS066 single mutant strains. Phenotypic characterization showed that both mutant strains behaved as the parental wild type strain regarding growth rate in liquid/solid media supplemented with cell-wall perturbing agents, and in the ability to produce pseudohyphae. Interestingly, the ability of the CpALS0660 null mutant to adhere to human buccal epithelial cells (HBECs) was not altered when compared with the wild-type strain, whereas deletion of CpALS4790 led to a significant loss of the adhesion capability. RT-qPCR analysis performed on the mutant strains in co-incubation with HBECs did not highlight significant changes in the expression levels of others ALS genes. In vivo experiments in a murine model of vaginal candidiasis indicated a significant reduction in CFUs recovered from BALB/C mice infected with each mutant strain in comparison to those infected with the wild type strain, confirming the involvement of CpAls4790 and CpAls5600 proteins in C. parapsilosis vaginal candidiasis in mice.

Dammarane and Ceanothane Triterpenes from Zizyphus glabrata

2006 ◽  
Vol 61 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Seru Ganapaty ◽  
Pannakal S. Thomas ◽  
Kancharalapalli V. Ramana ◽  
Gloria Karagianis ◽  
Peter G. Waterman
Keyword(s):  
Bactericidal Activity ◽  
Chemical Constituents ◽  
2D Nmr ◽  
First Report ◽  
Nmr Data ◽  
C Nmr ◽  
Dammarane Glycoside

From the leaves of Zizyphus glabrata, a new dammarane-type triterpene, pseudojujubogenin -3-O- β -D-glucopyranoside, along with the known ceanothane triterpenes, granulosic acid, ceanothic acid and daucosterol were isolated. The structures of the compounds were fully characterized by detailed NMR investigations including 1H and 13C NMR, HSQC, COSY, HMBC and NOESY experiments. In addition, the dammarane glycoside was tested for its potential to inhibit various bacteria and was found to possess significant bactericidal activity. The 1H, 13C and full 2D-NMR data on granulosic acid has also been presented. This is the first report on the chemical constituents of the leaves of Z. glabrata.

scholarly journals The Role of a Host-Induced Arginase of Xanthomonas oryzae pv. oryzae in Promoting Virulence on Rice

2019 ◽  
Vol 109 (11) ◽  
pp. 1869-1877
Author(s):  
Yuqiang Zhang ◽  
Guichun Wu ◽  
Ian Palmer ◽  
Bo Wang ◽  
Guoliang Qian ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Bacterial Blight ◽  
Wild Type Strain ◽  
Bacterial Pathogen ◽  
Extracellular Polysaccharide ◽  
Rice Cultivar ◽  
Xanthomonas Oryzae ◽  
Wild Type ◽  
Bacterial Blight Of Rice

The plant bacterial pathogen Xanthomonas oryzae pv. oryzae causes bacterial blight of rice, which is one of the most destructive rice diseases prevalent in Asia and parts of Africa. Despite many years of research, how X. oryzae pv. oryzae causes bacterial blight of rice is still not completely understood. Here, we show that the loss of the rocF gene caused a significant decrease in the virulence of X. oryzae pv. oryzae in the susceptible rice cultivar IR24. Bioinformatics analysis demonstrated that rocF encodes arginase. Quantitative real-time PCR and Western blot assays revealed that rocF expression was significantly induced by rice and arginine. The rocF deletion mutant strain showed elevated sensitivity to hydrogen peroxide, reduced extracellular polysaccharide (EPS) production, and reduced biofilm formation, all of which are important determinants for the full virulence of X. oryzae pv. oryzae, compared with the wild-type strain. Taken together, the results of this study revealed a mechanism by which a bacterial arginase is required for the full virulence of X. oryzae pv. oryzae on rice because of its contribution to tolerance to reactive oxygen species, EPS production, and biofilm formation.

scholarly journals The RcsCB His-Asp Phosphorelay System Is Essential To Overcome Chlorpromazine-Induced Stress in Escherichia coli

2002 ◽  
Vol 184 (10) ◽  
pp. 2850-2853 ◽  
Author(s):  
Annie Conter ◽  
Rachel Sturny ◽  
Claude Gutierrez ◽  
Kaymeuang Cam
Keyword(s):  
Escherichia Coli ◽  
Type Strain ◽  
Wild Type Strain ◽  
Cell Envelope ◽  
Wild Type ◽  
E Coli ◽  
Induced Stress ◽  
Mutant Strains ◽  
Molecular Nature

ABSTRACT The RcsCB His-Asp phosphorelay system regulates the expression of several genes of Escherichia coli, but the molecular nature of the inducing signal is still unknown. We show here that treatment of an exponentially growing culture of E. coli with the cationic amphipathic compound chlorpromazine (CPZ) stimulates expression of a set of genes positively regulated by the RcsCB system. This induction is abolished in rcsB or rcsC mutant strains. In addition, treatment with CPZ inhibits growth. The wild-type strain is able to recover from this inhibition and resume growth after a period of adaptation. In contrast, strains deficient in the RcsCB His-Asp phosphorelay system are hypersensitive to CPZ. These results suggest that cells must express specific RcsCB-regulated genes in order to cope with the CPZ-induced stress. This is the first report of the essential role of the RcsCB system in a stress situation. These results also strengthen the notion that alterations of the cell envelope induce a signal recognized by the RcsC sensor.

scholarly journals Evaluation of the Role of the Bvg Intermediate Phase in Bordetella pertussis during Experimental Respiratory Infection

2005 ◽  
Vol 73 (2) ◽  
pp. 748-760 ◽  
Author(s):  
Nuria Vergara-Irigaray ◽  
Alberto Chávarri-Martínez ◽  
Juan Rodríguez-Cuesta ◽  
Jeff F. Miller ◽  
Peggy A. Cotter ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Bordetella Pertussis ◽  
Wild Type Strain ◽  
Intermediate Phase ◽  
Transcriptional Level ◽  
Wild Type ◽  
Environmental Signals ◽  
Time Point

ABSTRACT The BvgAS system of Bordetella pertussis was traditionally considered to mediate a transition between two phenotypic phases (Bvg+ and Bvg−) in response to environmental signals. We characterized a third state, the intermediate (Bvgi) phase, which can be induced by introducing a 1-bp substitution into bvgS (the bvgS-I1 mutation) or by growing B. pertussis under conditions intermediate between those leading to the Bvg+ and Bvg− phases. Like B. bronchiseptica, B. pertussis displays in its Bvgi phase a characteristic colony morphology and hemolytic activity and expresses a Bvgi-phase-specific polypeptide called BipA, whose synthesis is regulated by bvgAS at the transcriptional level. Based on our results, we hypothesize that the Bvgi phase of B. pertussis may be involved in facilitating transmission between hosts. Thus, a B. pertussis mutant carrying the bvgS-I1 mutation (GMT1i) persisted at wild-type levels only in the upper murine respiratory tract. Interestingly, a bipA deletion derivative of GMT1i displayed a reduced ability to colonize the nasal cavity of mice compared with GMT1i. However, in experimental mixed infections GMT1i expressing the Bvgi phase could establish an initial colonization in the nose and trachea of mice as efficiently as GMT1, but the wild-type strain outcompeted GMT1i at a later time point at all sites of the respiratory tract, suggesting that the Bvgi phase does not serve as a phenotypic phase specialized in colonization. Finally, even though B. pertussis expresses in vitro the Bvgi phase at the human nasal temperature, anti-BipA antibodies were undetectable in a large collection of sera from pertussis patients.

scholarly journals Role of Calcineurin in Stress Resistance, Morphogenesis, and Virulence of a Candida albicans Wild-Type Strain

2006 ◽  
Vol 74 (7) ◽  
pp. 4366-4369 ◽  
Author(s):  
Teresa Bader ◽  
Klaus Schröppel ◽  
Stefan Bentink ◽  
Nina Agabian ◽  
Gerwald Köhler ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Type Strain ◽  
Pulmonary Infection ◽  
Wild Type Strain ◽  
Selection Marker ◽  
Wild Type ◽  
Environmental Signals ◽  
Successful Infection ◽  
Strain Sc5314

ABSTRACT By generating a calcineurin mutant of the Candida albicans wild-type strain SC5314 with the help of a new recyclable dominant selection marker, we confirmed that calcineurin mediates tolerance to a variety of stress conditions but is not required for the ability of C. albicans to switch to filamentous growth in response to hypha-inducing environmental signals. While calcineurin was essential for virulence of C. albicans in a mouse model of disseminated candidiasis, deletion of CMP1 did not significantly affect virulence during vaginal or pulmonary infection, demonstrating that the requirement for calcineurin for a successful infection depends on the host niche.

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