FEMS Microbiology Letters (FEMS MICROBIOL LETT)

Publications in this journal

• Article: Uptake and excretion of amino acids by saccharolytic clostridia

  U Szech, M Braun, D Kleiner
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  ABSTRACT: Amino acid uptake and excretion in Clostridium pasteurianum, Clostridium aceticum and Clostridium butyricum were generally inversely related: in the exponential growth phase excretion of an amino acid was observed only in strains which lacked the respective amino acid carrier. C. butyricum transports all amino acids and does not show any amino acid excretion. C. aceticum takes up all amino acids but alanine, and up to 1 mM alanine is excreted. C. pasteurianum only absorbs aspartate, glutamate, glutamine, glycine and serine, hence all other amino acids (except threonine) are found in the medium. With ammonium or N2, up to 20% or 8% of the nitrogen assimilated is lost, respectively. These data emphasize the importance of transport systems in cyclic retention of metabolites.
  FEMS Microbiology Letters 02/2013; 58:11.141.
• Article: Clostridium butyricum ammonifies nitrite, but not nitrate

  N Schirmer, U Szech, D Kleiner
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  ABSTRACT: Clostridium butyricum strains DSM 552 (ATCC 19398) and ATCC 8260 grow with nitrite and hydroxylamine, but not with nitrate as the sole nitrogen source. Nitrite is largely converted to extracellular ammonium. The nitrite reductases are neither repressed by NH4+ nor induced by NO2−, and are located in the cytoplasm. Methyl viologen and ferredoxin, but not NADH, serve as electron donors. No evidence for a nitrate reductase was found in either strain.
  FEMS Microbiology Letters 02/2013; 60:343-346.
• Article: Beyond the wall: Candida albicans secret(e)s to survive.

  Sorgo AG, Heilmann CJ, Brul S, de Koster CG, Klis FM
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  ABSTRACT: The opportunistic fungal pathogen Candida albicans occupies various niches of the human body such as the skin and the mucosal surfaces of the gastrointestinal and urogenital tracts. It can also enter the blood stream and cause deadly, systemic infections, especially in immunocompromised patients, but also in immunocompetent individuals through inserted medical devices. To survive in these diverse host environments, C. albicans has developed specialized virulence attributes and rapidly adapts itself to local growth conditions and defense mechanisms. Candida albicans secretes a considerable number of proteins that are involved in biofilm formation, tissue invasion, immune evasion, and wall maintenance, as well as acquisition of nutrients including metal ions. The secretome of C. albicans is predicted to comprise 225 proteins. On a proteomic level, however, analysis of the secretome of C. albicans is incomplete as many secreted proteins are only produced under certain conditions. Interestingly, glycosylphosphatidylinositol proteins and known cytoplasmic proteins are also consistently detected in the growth medium. Importantly, a core set of seven wall polysaccharide-processing enzymes seems to be consistently present, including the diagnostic marker Mp65. Overall, we discuss the importance of the secretome for virulence and suggest potential targets for better and faster diagnostic methods.
  FEMS Microbiology Letters 01/2013; 338(1):10-17.
• Article: Perchlorate reduction by an isolated Serratia marcescens strain under high salt and extreme pH. EMS Microbiol Lett 339 (2013) 117–121

  Anupama Vijaya Nadaraja, Prajeesh Gangadharan Puthiya Veetil, Krishnakumar Bhaskaran
  FEMS Microbiology Letters 01/2013; 339:117-121.
• Article: Nanomedicine for intracellular therapy

  Ranjan A, Pothayee N, Seleem MN, Boyle SM, Kasimanickam R, Riffle JS, Sriranganathan N
  FEMS Microbiology Letters 04/2012;
• Article: Conservation of Dcm-mediated cytosine DNA methylation inEscherichia coli

  Kevin T. Militello, Robert D. Simon, Mehr Qureshi, Robert Maines, Michelle L. VanHorne, Stacy M. Hennick, Sangeeta K. Jayakar, Sarah Pounder
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  ABSTRACT: In Escherichia coli, cytosine DNA methylation is catalyzed by the DNA cytosine methyltransferase (Dcm) protein and occurs at the second cytosine in the sequence 5′CCWGG3′. Although the presence of cytosine DNA methylation was reported over 35 years ago, the biological role of 5-methylcytosine in E. coli remains unclear. To gain insight into the role of cytosine DNA methylation in E. coli, we (1) screened the 72 strains of the ECOR collection and 90 recently isolated environmental samples for the presence of the full-length dcm gene using the polymerase chain reaction; (2) examined the same strains for the presence of 5-methylcytosine at 5′CCWGG3′ sites using a restriction enzyme isoschizomer digestion assay; and (3) quantified the levels of 5-methyl-2′-deoxycytidine in selected strains using liquid chromatography tandem mass spectrometry. Dcm-mediated cytosine DNA methylation is conserved in all 162 strains examined, and the level of 5-methylcytosine ranges from 0.86% to 1.30% of the cytosines. We also demonstrate that Dcm reduces the expression of ribosomal protein genes during stationary phase, and this may explain the highly conserved nature of this DNA modification pathway.
  FEMS Microbiology Letters 01/2012; 328(1):78-85.
• Article: Amino acids Y229 and F603 are involved in Bacillus thuringiensis Cry1Ac delta-endotoxin stability and toxicity

  Mariam Dammak, Mamdouh Ben Ali, Samir Jaoua, Slim Tounsi
  FEMS Microbiology Letters 01/2012;
• Article: Helicobacter pylori HopQ outer membrane protein attenuates bacterial adherence to gastric epithelial cells.

  John T Loh, Victor J Torres, Holly M Scott Algood, Mark S McClain, Timothy L Cover
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  ABSTRACT: Helicobacter pylori genomes contain about 30 hop genes that encode outer membrane proteins. Helicobacter pylori hopQ alleles exhibit a high level of genetic diversity, and two families of hopQ alleles have been described. Type I hopQ alleles are found more commonly in cag-positive H. pylori strains from patients with peptic ulcer disease than in cag-negative strains from patients without ulcer disease. In this study, we mutated hopQ in four H. pylori strains that each contained a type I hopQ allele, and then analyzed interactions of the wild-type and hopQ mutant strains with AGS cells. In comparison with the wild-type strains, two of the hopQ mutant strains exhibited increased adherence to AGS cells and two hopQ mutants did not exhibit any detectable differences in adherence. Higher levels of tyrosine-phosphorylated CagA were detected when AGS cells were cocultured with a hyperadherent hopQ mutant strain than when cocultured with the corresponding wild-type strain. These data indicate that in some strains of H. pylori, the HopQ protein can attenuate bacterial adherence to gastric epithelial cells.
  FEMS Microbiology Letters 01/2009; 289(1):53-8.
• Article: Construction of a stable GFP-tagged Vibrio harveyi strain for bacterial dynamics analysis of abalone infection.

  Marie-Agnès Travers, Annaïck Barbou, Nelly Le Goïc, Sylvain Huchette, Christine Paillard, Marcel Koken
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  ABSTRACT: Vibrio harveyi is a bacterial marine pathogen that can cause fatal disease in a large range of vertebrates and invertebrates, including the commercially important marine gastropod, Haliotis tuberculata. Since 1997, strains of this bacterium have regularly been causing high mortalities in farmed and wild abalone populations. The way in which the pathogen enters into abalone and the disease transmission mechanisms are thus far unknown. Therefore, a pathogenic strain, ORM4, was green fluorescent protein-tagged and validated both for its growth characteristics and for its virulence as a genuine model for abalone disease. The strain allows V. harveyi quantification by flow cytometry in seawater and in abalone haemolymph as well as the in situ detection of the parasite inside abalone tissues.
  FEMS Microbiology Letters 01/2009; 289(1):34-40.
• Article: Characterization of two glutaminases from the filamentous cyanobacterium Anabaena sp. PCC 7120.

  Jun Xia Zhou, Jie Zhou, Hao Meng Yang, Mei Chen, Fang Huang
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  ABSTRACT: The Anabaena genome contains two ORFs that appear to encode glutaminases. The genes were expressed as histidine-tagged fusion proteins in Escherichia coli. The purified proteins possessed glutaminase activity using l-glutamine as the substrate, but differed in biochemical properties. All2934 showed an optimal activity at 20 degrees C and pH 6.0, with a higher affinity for l-glutamine than All4774, which had optimal activity at 37 degrees C and pH 7.5. Remarkably, the glutaminase activity of All2934 was phosphate dependent, while All4774 was phosphate independent. The expression of all2934 and all4774 was analyzed using semi-quantitative reverse transcriptase-PCR. The expression level of all2934 was much higher than that of all4774 under normal and nitrogen-depletion conditions, indicating that All2934 may play an important role in metabolizing glutamine in Anabaena.
  FEMS Microbiology Letters 01/2009; 289(2):241-9.
• Article: ScrB (Cg2927) is a sucrose-6-phosphate hydrolase essential for sucrose utilization by Corynebacterium glutamicum.

  Verena Engels, Tobias Georgi, Volker F Wendisch
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  ABSTRACT: Corynebacterium glutamicum can grow on a variety of carbohydrates from which glucose, fructose and sucrose are taken up and phosphorylated by the phosphoenolpyruvate-dependent phosphotransferase system (PTS). Here, we show that cg2927 (scrB) encodes sucrose-6-phosphate hydrolase. The purified His-tagged protein hydrolyzed sucrose-6-phosphate and sucrose, but not sucrose-6'-phosphate. The Km value for sucrose was 190 mM while the Km for sucrose-6-phosphate was much lower, 0.04 mM. Sucrose-6-phosphate hydrolase activity was stimulated by MgSO4 and fructose-6-phosphate and was inhibited by MnCl2, CaCl2, CuSO4 and ZnSO4. A scrB deletion mutant could not grow on sucrose as the sole carbon source. In addition, growth in the absence of scrB was severely decreased when sucrose was present in addition to glucose, fructose or acetate, suggesting that higher intracellular concentrations of sucrose-6-phosphate are toxic. Transcriptional start sites in the cg2929-cg2928-scrB-ptsS locus could be revealed upstream of cg2929 and upstream of the sucrose-specific PTS gene ptsS. Of these, only ptsS showed increased expression when grown in the presence of sucrose, which was due to control by the transcriptional regulator SugR. The sucrose-6-phosphate hydrolase activity, however, was increased two- to threefold during growth in fructose- or sucrose-containing media, regardless of the presence or absence of SugR.
  FEMS Microbiology Letters 01/2009; 289(1):80-9.
• Article: Treponema zioleckii sp. nov., a novel fructan-utilizing species of rumen treponemes.

  Maria Piknova, Wanda Guczynska, Renata Miltko, Peter Javorsky, Anna Kasperowicz, Tadeusz Michalowski, Peter Pristas
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  ABSTRACT: During studies on fructan degradation in the rumen, a Treponema-like bacterium able to utilize Timothy grass fructan, commercial inulin and sucrose as the sole carbon source was recovered from sheep rumen. At least two different fructanolytic enzymes were identified in cell-free extracts of the isolated bacterium. Characterization of the strain by a polyphasic approach indicated that it can be regarded as a representative of a new bacterial species within the genus Treponema. Electron microscopy showed that the bacterium exhibited all of the features typical of spirochetes. The helical cells measured 5.4-11.5 microm x 0.42-0.51 microm and possessed up to seven regular coils. The bacterium utilized various plant mono- and disaccharides as fermentable substrates. Formate, acetate and ethanol in a molar ratio of 16 : 10 : 1 were the end products of glucose fermentation. The major cellular fatty acids were C(13:0), C(14:0), C(14:1), C(15:0), C(15:1) and C(16:0). The nearly complete 16S rRNA gene sequence was obtained, and phylogenetic analysis of the 16S rRNA gene showed the highest similarity to rumen Treponema strain CA. We propose the name Treponema zioleckii sp. nov. for this novel rumen spirochete with strain kT as the type strain.
  FEMS Microbiology Letters 01/2009; 289(2):166-72.
• Article: Adherence characteristics of endocarditis-derived Streptococcus gallolyticus ssp. gallolyticus (Streptococcus bovis biotype I) isolates to host extracellular matrix proteins.

  Jouko Sillanpää, Sreedhar R Nallapareddy, Kavindra V Singh, Mary J Ferraro, Barbara E Murray
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  ABSTRACT: Members of the Streptococcus bovis group are frequent colonizers of the intestinal tract, which can also cause endocarditis. However, their ability to adhere to and colonize host tissues and the factors associated with pathogenicity are largely unknown. Here, we assessed 17 endocarditis-derived human isolates [identified here as 15 Streptococcus gallolyticus ssp. gallolyticus (S. bovis biotype I), one S. gallolyticus ssp. pasteurianus (biotype II/2) and one Streptococcus infantarius ssp. coli (biotype II/1)] for their in vitro adherence to components of the extracellular matrix (ECM). Adherence to collagen type I was found to be the most common phenotype exhibited by 76% of isolates, followed by collagen type IV (53%), fibrinogen (47%), collagen type V (35%) and fibronectin (35%). Pulsed-field gel electrophoresis analyses showed that >50% of endocarditis-derived S. gallolyticus ssp. gallolyticus isolates are genetically diverse, although two clusters of two and four isolates were observed. The diversity of strains and differences observed in adherence characteristics to distinct host ECM proteins suggest that isolates of S. gallolyticus ssp. gallolyticus produce different surface components, similar to other gram-positive pathogens, to colonize the host and cause infection.
  FEMS Microbiology Letters 01/2009; 289(1):104-9.
• Article: Cross-utilization and expression of outer membrane receptor proteins for siderophore uptake by Diamondback moth Plutella xylostella (Lepidoptera: Plutellidae) gut bacteria.

  Pandiyan Indiragandhi, Rangasamy Anandham, Munusamy Madhaiyan, Gil-Hah Kim, Tongmin Sa
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  ABSTRACT: Siderophore production by entomo- and phytopathogens, plus the cross-utilization of these siderophores and expression of outer membrane receptor proteins (OMRPs) by Diamondback moth (DBM) gut bacterial strains, were all examined. All the tested strains grew in the presence of 2, 2'-dipyridyl, and the Brachybacterium sp. PSGB10, Pseudomonas sp. PRGB06, and Serratia marcescens FLGB16 strains were found to cross-utilize the siderophores of various entomopathogens, including Bacillus thuringiensis. A sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis also showed the presence of the OMRPs responsible for the siderophore cross-utilization. In contrast, Stenotrophomonas sp. PRGB08 was unable to cross-utilize siderophores and did not express OMRPs. Thus, siderophore cross-utilization and OMRP expression by the DBM gut bacterial strains would seem to support the potential for microbial populations in the insect gut to evolve efficient mechanisms to overcome any iron limitation imposed by the host insect and eventually contribute to the defense mechanism of the host insect. Furthermore, it is important to consider that other biologically active metabolites produced by insect gut microorganisms may also confer a protective effect on a host insect species.
  FEMS Microbiology Letters 01/2009; 289(1):27-33.
• Article: Characterization and transcriptional analysis of an ECF sigma factor from Xanthomonas campestris pv. campestris.

  Ching-Yuan Cheng, Sheau-Yann Shieh, Chao-Chin Hsu, Ming-Te Yang
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  ABSTRACT: The genomic DNA segment encoding the rpoE gene and its flanking region was cloned from Xanthomonas campestris pv. campestris strain 11 (Xc11). The transcriptional start site of rpoE was located at nucleotide G, which is 33 nucleotides preceding the putative translation initiation codon of rpoE, and a extracytoplasmic function sigma factors (sigma(E))-dependent promoter was identified with -35 (5'-GAACTT-3') and -10 (5'-TCTCA-3') consensus sequences. The protein encoded by rpoE gene acted as a sigma (sigma) factor and was sufficient to direct core RNA polymerase to the rpoE promoter and to stimulate initiation of transcription in vitro. The specific binding of the reconstituted Esigma(E) holoenzyme with the Xc11 rpoE promoter was demonstrated by gel retardation assay and DNAse I footprint analysis. This study clearly demonstrated that the rpoE-rseA-mucD genomic organization of X. campestris is similar to that found in Xylella fastidiosa; however, expression of rpoE in X. campestris is autoregulated by its own sigma(E)-dependent promoter.
  FEMS Microbiology Letters 01/2009; 289(2):250-7.
• Article: RAPD: a database of recombinantly-produced antimicrobial peptides.

  Yifeng Li, Zhengxin Chen
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  ABSTRACT: We have developed the Recombinantly-produced Antimicrobial Peptides Database (RAPD) to house relevant information on recombinant approaches to generate antimicrobial peptides. Key information stored in the database, which is extracted from published experiments, includes expression host, fusion strategy, release method and yield for individual peptides. Bibliographic data directly related to each particular case are also available. RAPD allows easy comparison of the relative popularity and efficiency of different strategies, and can thus be used as a guideline for future production of similar peptides. The database is freely available at http://faculty.ist.unomaha.edu/chen/rapd/index.php.
  FEMS Microbiology Letters 01/2009; 289(2):126-9.
• Article: The involvement of the pyruvate dehydrogenase E1alpha subunit, in Streptococcus mutans acid tolerance.

  Bryan Korithoski, Céline M Lévesque, Dennis G Cvitkovitch
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  ABSTRACT: Streptococcus mutans, an etiological agent of dental caries, is a normal inhabitant of dental plaque. Two main virulence factors of S. mutans are acidogenicity and aciduricity - the ability to produce acid and survive at low pH, respectively. Metabolic processes, including the catabolism of pyruvate, are finely regulated following acid exposure in S. mutans. Proteome analysis of the S. mutans acid response has shown pyruvate dehydrogenase A (PdhA) is upregulated. PdhA is the E1alphasubunit of the four-enzyme pyruvate dehydrogenase complex, responsible for the heterofermentative catalysis of pyruvate into acetyl-CoA. Acetyl-CoA is subsequently catalyzed into ethanol and acetate yielding additional ATP. This investigation examined the relationships between PdhA, aciduricity, and metabolism in S. mutans. An S. mutans pdhA knockout (PDHAKO) revealed an acid sensitive phenotype, displayed by increased doubling times, and decreased competitiveness in a biofermentor. Quantitative real-time PCR showed pdhA expression increased dramatically during acidic growth and under acid adaptation. Additionally, pdhA expression responded to conditions favoring heterofermentative growth; decreased in the presence of excess glucose, and increased during stationary phase compared with mid-log phase growth. This study demonstrated that in S. mutans, pdhA expression responds to conditions conducive to heterofermentation and deletion of pdhA resulted in decreased aciduricity.
  FEMS Microbiology Letters 01/2009; 289(1):13-9.
• Article: Expression of the PitA phosphate/metal transporter of Escherichia coli is responsive to zinc and inorganic phosphate levels.

  Rachel J Jackson, Marie R B Binet, Lucy J Lee, Renli Ma, Alison I Graham, Cameron W McLeod, Robert K Poole
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  ABSTRACT: Escherichia coli possesses two major systems for inorganic phosphate (P(i)) uptake. The Pst system (pstSCAB) is inducible by low phosphate concentrations whereas the low-affinity transporter (pitA) has been described as constitutively expressed. PitA catalyses transport of metal [Mg(II), Ca(II)]-phosphate complexes, and mutations in pitA confer Zn(II) resistance. Here we report that pitA transcription is not constitutive; activity of a single-copy pitA-lacZ transcriptional fusion (monolysogen) was maximal at high extracellular Zn(II) (150 microM), in the absence of added P(i), and in a well-defined pitA mutant strain. Intracellular zinc levels were unaffected by adding Zn(II) to the medium for both the wild-type and mutant strains. However, in the wild-type strain, Mg levels (per gram of dry biomass) fell by eightfold in cells grown with added Zn(II) and by 20-fold when Zn(II) and P(i) were added to cultures. Mutation of pitA reduced the effects of external Zn(II) and phosphate levels on Mg pools, consistent with competition or inhibition by Zn(II) of PitA. The mechanism of pitA regulation by extracellular Zn(II) and P(i) is unknown but appears not to involve Fur or other well-characterized regulators.
  FEMS Microbiology Letters 01/2009; 289(2):219-24.