Letters in Applied Microbiology

Cover image for Vol. 58 Issue 4

April 2014

Volume 58, Issue 4

Pages 299–400

  1. Editor's Choice

    1. Top of page
    2. Editor's Choice
    3. Original Articles
    1. You have full text access to this OnlineOpen article
      Conjugative transfer frequencies of mef(A)-containing Tn1207.3 to macrolide-susceptible Streptococcus pyogenes belonging to different emm types (pages 299–302)

      N.F. Hadjirin, E.M. Harrison, M.A. Holmes and G.K. Paterson

      Article first published online: 24 JAN 2014 | DOI: 10.1111/lam.12213

      Significance and Impact of the Study: The spread of antimicrobial resistance among pathogenic bacteria is an important problem, but the mechanisms of horizontal transfer between strains and species are often poorly understood. For instance, little is known on how macrolide resistance spreads between strains of the human pathogen Strep. pyogenes and why certain strains more commonly display resistance than others. Here, we show that Streppyogenes strains vary greatly in their ability to acquire a transposon encoding macrolide resistance by horizontal gene transfer in vitro. These data provide a novel insight into the transfer of antibiotic resistance between bacterial strains and offer an explanation for the differences in the frequency of resistance determinates and resistance seen among clinical isolates.

  2. Original Articles

    1. Top of page
    2. Editor's Choice
    3. Original Articles
    1. Identification of a symbiotic fungus from blue–green alga and its extracellular polysaccharide (pages 303–310)

      Q.L. Dong, T.Y. Lin, X.Y. Xing, B. Chen and Y. Han

      Article first published online: 22 NOV 2013 | DOI: 10.1111/lam.12192

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      Significance and Impact of the Study: A novel fungus (Simplicillium) symbiotic with a single-celled blue–green alga Chroococcus sp. and its major primary metabolite have been isolated and identified. These findings broaden the scope of symbiotic fungi and provide a unique extracellular polysaccharide with potential applications in food industry.

    2. Rapid identification of Salmonella using Hektoen enteric agar and 16s ribosomal DNA probe-gold nanoparticle immunochromatography assay in clinical faecal specimens (pages 311–317)

      C.-Y. Yeung, C.-C. Liu, Y.-T. Tseng, K.-C. Tsai, M.-A. Hsieh, W.-T. Chan, H.-L. Liu, H.-C. Lee and S.-Y. Hou

      Article first published online: 29 NOV 2013 | DOI: 10.1111/lam.12191

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      Significance and Impact of the Study: This is the first application of using 16s ribosomal DNA probe–gold nanoparticles and immunochromatography method on clinical samples with sensitivity 100% and specificity 94·93%. The assay time is about 30 min after the DNA purification. We find this assay a rapid, convenient, sensitive and inexpensive tool for Salmonella identification of clinical faecal samples, which is worth further promotion and clinical use and can replace the traditional time-consuming and labour-intense biochemical tests. The potential benefit of this approach is to develop a rapid point-of-care test that provides results while the patient is still at the doctors' office.

    3. Effects of culture conditions on spore types of Clonostachys rosea 67-1 in submerged fermentation (pages 318–324)

      M.H. Sun, Y.M. Chen, J.F. Liu, S.D. Li and G.Z. Ma

      Article first published online: 29 NOV 2013 | DOI: 10.1111/lam.12193

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      Significance and Impact of the study: Clonostachys rosea is one of the most promising biocontrol agents in countering many plant fungal diseases. However, large-scale production and commercialization are hampered by the lack of understanding of the impacts of culture conditions on performance and types of C. rosea sporulation and subsequently inadequate research on the techniques for chlamydospore production. In addressing these concerns, this study provides a unique insight into the manipulation of C. rosea sporulation and chlamydospore fermentation of the biocontrol fungus.

    4. MALDI-TOF MS, a useful instrument for differentiating metallo-β-lactamases in Enterobacteriaceae and Pseudomonas spp. (pages 325–329)

      Y. Hoyos-Mallecot, J.J. Cabrera-Alvargonzalez, C. Miranda-Casas, M.D. Rojo-Martín, C. Liebana-Martos and J.M. Navarro-Marí

      Article first published online: 18 DEC 2013 | DOI: 10.1111/lam.12203

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      Significance and Impact of the Study: MALDI-TOF mass spectrometry is increasingly present in microbiology laboratories due to its increasing use for bacterial identification. This study describes a method for detection of carbapenemase activity using MALDI-TOF, which is similar to the reference method: the detection of imipenem hydrolysis using UV spectrometry.

    5. Silver nanoparticle inhibition of polycyclic aromatic hydrocarbons degradation by Mycobacterium species RJGII-135 (pages 330–337)

      S.R. Mueller-Spitz and K.D. Crawford

      Article first published online: 18 DEC 2013 | DOI: 10.1111/lam.12205

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      Significance and Impact of the Study: Silver nanoparticle (AgNP) pollution threatens bacterial-mediated processes due to their antibacterial properties. With the widespread commercial use of AgNP, continued environmental release is inevitable and we are just beginning to understand the potential environmental ramifications of nanoparticle pollution. This study examined AgNP inhibition of carbon metabolism through the polycyclic aromatic hydrocarbon degradation by Mycobacterium species RJGII-135. Sublethal doses altered PAH metabolism, which is dependent upon cell membrane properties and intracellular proteins. The changed carbon metabolism when exposed to sublethal doses of AgNP suggests broad impacts of this pollution on bacterial carbon cycling in diverse environments.

    6. Characterization of a Campylobacter fetus-like strain isolated from the faeces of a sick leopard tortoise (Stigmochelys pardalis) using matrix-assisted laser desorption/ionization time of flight as an alternative to bacterial 16S rDNA phylogeny (pages 338–343)

      L. Benejat, A. Gravet, E. Sifré, S. Ben Amor, B. Quintard, F. Mégraud and P. Lehours

      Article first published online: 9 DEC 2013 | DOI: 10.1111/lam.12194

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      Significance and Impact of Study: The major impact of this work is the demonstration that proteomics and especially MALDI-TOF typing can be used as an alternative method to 16S rDNA sequencing for phylogeny and can lead to the discovery of new Campylobacters.

    7. In vitro activity of isoimperatorin, alone and in combination, against Mycobacterium tuberculosis (pages 344–349)

      N. Guo, J. Wu, J. Fan, P. Yuan, Q. Shi, K. Jin, W. Cheng, X. Zhao, Y. Zhang, W. Li, X. Tang and L. Yu

      Article first published online: 12 DEC 2013 | DOI: 10.1111/lam.12195

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      Significance and Impact of the Study: This is the first report on the in vitro synergistic antimycobacterial effects of isoimperatorin (IO) in combination with three first-line drugs: rifampin (RMP), isoniazid (INH) and ethambutol (EMB). The results indicated that the antimycobacterial activity of IO was modest; however, IO was a useful and effective agent against Myco. tuberculosis when it was combined with first-line antimycobacterial drugs and is worthy of further development as a lead compound for the development of novel antimycobacterial therapeutic agents.

    8. A method of direct PCR without DNA extraction for rapid detection of begomoviruses infecting jute and mesta (pages 350–355)

      C. Biswas, P. Dey and S. Satpathy

      Article first published online: 9 DEC 2013 | DOI: 10.1111/lam.12196

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      Significance and Impact of the Study: Identification of begomoviruses by serology is not suitable due to difficulty in preparing high titre and specific antisera. Begomoviruses are routinely detected by PCR-based techniques using universal or specific primers. However, it is a prerequisite to isolate pure DNA from the samples before PCR. DNA extraction from some plants such as jute, mesta is very difficult due to the presence of mucilage and other impurities. Therefore, we have developed a method of direct PCR without DNA extraction for detection of begomoviruses from these crops. It is the first report of a direct PCR method in jute and mesta.

    9. Mutational analysis of positively charged residues in the N-terminal region of the class IIa bacteriocin pediocin PA-1 (pages 356–361)

      D.F. Song, X. Li, Y.H. Zhang, M.Y. Zhu and Q. Gu

      Article first published online: 19 DEC 2013 | DOI: 10.1111/lam.12197

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      Significance and Impact of the Study: No previous work has systematically examined the N-terminal cationic residues of the pediocin PA-1 for their functional importance or redundancy. In this study, we examined the structure–function relationships of pediocin PA-1 by site-directed mutagenesis. Mutated peptides in which the positively charged residues were substituted and increased in number exhibited a twofold increase in the bacteriostatic activity. This study demonstrated the importance of the cationic patch in the N-terminal half of pediocin PA-1. The cationic residues influenced the electrostatic binding of the bacteriocin to the target cells and had a greater effect on the potency of the peptide towards Micrococcus luteus and Staphylococcus aureus.

    10. Development of a loop-mediated isothermal amplification assay for rapid and simple detection of Erysipelothrix rhusiopathiae (pages 362–369)

      Y. Yamazaki, E. Oba, N. Kashiwagi, K. Sugita, K. Shiiba, Y. Baba, Y. Shimoji and W. Yamazaki

      Article first published online: 11 DEC 2013 | DOI: 10.1111/lam.12198

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      Significance and Impact of the Study: This is the first report of a loop-mediated isothermal amplification (LAMP) assay for simple and cost-effective detection of E. rhusiopathiae from swine samples. The LAMP assay provided more rapid detection of the bacterium than conventional PCR and biochemical-based assays, and it may potentially facilitate surveillance and early diagnosis of swine erysipelas in the field.

    11. Variation in detection limits between bacterial growth phases and precision of an ATP bioluminescence system (pages 370–375)

      S.J. Vogel, M. Tank and N. Goodyear

      Article first published online: 16 DEC 2013 | DOI: 10.1111/lam.12199

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      Significance and Impact of the Study Surface hygiene is a critical component of food safety and infection control; increasingly, ATP detection by bioluminescence is used to evaluate surface hygiene and effective cleaning. This is the first study to show that the number of living and potentially infectious bacteria remaining when the device reads zero varies between the different bacterial life cycle phases: lag, log, stationary and death. ATP device users need to be aware of this information to use the devices appropriately.

    12. Effective application of multiple locus variable number of tandem repeats analysis to tracing Staphylococcus aureus in food-processing environment (pages 376–383)

      Z. Rešková, J. Koreňová and T. Kuchta

      Article first published online: 11 DEC 2013 | DOI: 10.1111/lam.12200

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      Significance and Impact of the Study: Subspecies genotyping of microbial contaminants in food-processing factories may facilitate identification of spatial and temporal aspects of the contamination. This may help to properly manage the process hygiene. With S. aureus, multiple locus variable number of tandem repeats analysis (MLVA) proved to be an effective method for the purpose, being sufficiently discriminative, yet comparatively fast and inexpensive. The application of automated flow-through gel electrophoresis to separation of DNA fragments produced by multiplex PCR helped to improve the accuracy and speed of the method.

    13. Intestinal dysbacteriosis contributes to decreased intestinal mucosal barrier function and increased bacterial translocation (pages 384–392)

      H. Wang, W. Zhang, L. Zuo, J. Dong, W. Zhu, Y. Li, L. Gu, J. Gong, Q. Li, N. Li and J. Li

      Article first published online: 19 DEC 2013 | DOI: 10.1111/lam.12201

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      Significance and Impact of the Study: Colistin has been reported to be effective in selective digestive decontamination (SDD), which is an infection prevention measure used in the treatment of certain patients in intensive care. We are the first to report that colistin-induced intestinal dysbacteriosis can injure intestinal mucosal barrier function and increase bacterial translocation, whereas a high dose of colistin does not damage the intestinal mucosal barrier in germ-free (GF) mice raised in a GF environment. These results may indicate that prolonged use of a high dose of a SDD medication should be carefully considered.

    14. Production and characterization of recombinant glucose oxidase from Aspergillus niger expressed in Pichia pastoris (pages 393–400)

      Y. Meng, M. Zhao, M. Yang, Q. Zhang, J. Hao and Y. Meng

      Article first published online: 2 JAN 2014 | DOI: 10.1111/lam.12202

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      Significance and Impact of Study: Glucose oxidase is a very important enzyme produced by several species. However, large-scale applications have always been postponed by its complexity in fermentation and purification. Our research focused on developing new purification strategy of recombinant GOD from A. niger expressed in P. pastoris. Here, we described this novel one-step purification method and subsequent research in the characteristics of rGOD which showed different results from previous work. These can open new opportunities to increase its application.

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