International Journal of Microbiology

Publications in this journal

• Article: Isolation of cellulose-degrading bacteria and determination of their cellulolytic potential.

  Pratima Gupta, Kalpana Samant, Avinash Sahu
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  ABSTRACT: Eight isolates of cellulose-degrading bacteria (CDB) were isolated from four different invertebrates (termite, snail, caterpillar, and bookworm) by enriching the basal culture medium with filter paper as substrate for cellulose degradation. To indicate the cellulase activity of the organisms, diameter of clear zone around the colony and hydrolytic value on cellulose Congo Red agar media were measured. CDB 8 and CDB 10 exhibited the maximum zone of clearance around the colony with diameter of 45 and 50 mm and with the hydrolytic value of 9 and 9.8, respectively. The enzyme assays for two enzymes, filter paper cellulase (FPC), and cellulase (endoglucanase), were examined by methods recommended by the International Union of Pure and Applied Chemistry (IUPAC). The extracellular cellulase activities ranged from 0.012 to 0.196 IU/mL for FPC and 0.162 to 0.400 IU/mL for endoglucanase assay. All the cultures were also further tested for their capacity to degrade filter paper by gravimetric method. The maximum filter paper degradation percentage was estimated to be 65.7 for CDB 8. Selected bacterial isolates CDB 2, 7, 8, and 10 were co-cultured with Saccharomyces cerevisiae for simultaneous saccharification and fermentation. Ethanol production was positively tested after five days of incubation with acidified potassium dichromate.
  International Journal of Microbiology 01/2012; 2012:578925.
• Article: Isolation, purification, and characterization of xylanase produced by a new species of bacillus in solid state fermentation.

  Rajashri D Kamble, Anandrao R Jadhav
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  ABSTRACT: A thermoalkalophilic new species of Bacillus, similar to Bacillus arseniciselenatis DSM 15340, produced extracellular xylanase under solid state fermentation when wheat bran is used as carbon source. The extracellular xylanase was isolated by ammonium sulfate (80%) precipitation and purified using ion exchange chromatography. The molecular weight of xylanase was ~29.8 kDa. The optimum temperature and pH for the enzyme activity were 50°C and pH 8.0. The enzyme was active on birchwood xylan and little active on p-nitrophenyl xylopyranoside but not on Avicel, CMC, cellobiose, and starch, showing its absolute substrate specificity. For birchwood xylan, the enzyme gave a Km 5.26 mg/mL and Vmax 277.7 μmol/min/mg, respectively. In addition, the xylanase was also capable of producing high-quality xylo-oligosaccharides, which indicated its application potential not only in pulp biobleaching processes but also in the nutraceutical industry.
  International Journal of Microbiology 01/2012; 2012:683193.
• Article: Antimicrobial Activity of Xoconostle Pears (Opuntia matudae) against Escherichia coli O157:H7 in Laboratory Medium.

  Saeed A Hayek, Salam A Ibrahim
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  ABSTRACT: The objective of this study was to investigate the antimicrobial activity of xoconostle pears (Opuntia matudae) against Escherichia coli O157:H7. Xoconostle pears were sliced, blended, and centrifuged. The supernatant was then filtered using a 0.45 μm filter to obtain direct extract. Direct extract of xoconostle pears was tested against four strains of E. coli O157:H7 in brain heart infusion (BHI) laboratory medium using growth over time and agar well diffusion assays. Our results showed that direct extract of xoconostle pears had a significant (P < 0.05) inhibitory effect at 4, 6, and 8% (v/v) concentrations and complete inhibitory effect at 10% (v/v) during 8 h of incubation at 37°C. Minimum inhibitory volume (MIV) was 400 μL mL(-1) (v/v) and minimum lethal volume (MLV) was 650 μL mL(-1) (v/v). The inhibitory effect of xoconostle pears found to be concentration dependent and not strain dependent. Thus, xoconostle pears extract has the potential to inhibit the growth of E. coli O157:H7 and could provide a natural means of controlling pathogenic contamination, thereby mitigating food safety risks.
  International Journal of Microbiology 01/2012; 2012:368472.
• Article: Comparison of Disk Diffusion and Etest Methods to Determine the Susceptibility of Staphylococcus aureus Circulating in Riyadh, Saudi Arabia to Fusidic Acid.

  Ali M Somily, David R Peaper, Elijah Paintsil, Thomas S Murray
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  ABSTRACT: Fusidic acid is a common therapy for staphylococcal infections in Saudi Arabia, but reports have suggested high rates of resistance among clinical isolates. Susceptibility testing of S. aureus to fusidic acid is further complicated by the lack of consensus on mean inhibitory concentrations (MIC) and disk diffusion cutoffs to determine resistance. The purpose of this study was to determine the correlation between disk diffusion and Etest determined MIC susceptibility results in clinical isolates of S. aureus from a large academic hospital in Riyadh, Saudi Arabia. Our data demonstrate excellent correlation between Etest determined MIC and disk diffusion susceptibility data, using either previously proposed zone sizes of ≥21 mm as susceptible and ≤18 mm as resistant or the EUCAST recommended zone size of ≤24 mm for resistance, in an area with relatively high rates of fusidic acid resistance.
  International Journal of Microbiology 01/2012; 2012:391251.
• Article: Polymorphic Amplified Typing Sequences and Pulsed-Field Gel Electrophoresis Yield Comparable Results in the Strain Typing of a Diverse Set of Bovine Escherichia coli O157:H7 Isolates.

  Indira T Kudva, Margaret A Davis, Robert W Griffin, Jeonifer Garren, Megan Murray, Manohar John, Carolyn J Hovde, Stephen B Calderwood
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  ABSTRACT: Polymorphic amplified typing sequences (PATS), a PCR-based Escherichia coli O157:H7 (O157) strain typing system, targets insertions-deletions and single nucleotide polymorphisms at XbaI and AvrII restriction enzyme sites, respectively, and the virulence genes (stx1, stx2, eae, hlyA) in the O157 genome. In this study, the ability of PATS to discriminate O157 isolates associated with cattle was evaluated. An in-depth comparison of 25 bovine O157 isolates, from different geographic locations across Northwest United States, showed that about 85% of these isolates shared the same dendogram clade by PATS and pulsed-field gel electrophoresis (PFGE), irrespective of the restriction enzyme sites targeted. The Pearson's correlation coefficient, r, calculated at about 0.4, 0.3, and 0.4 for XbaI-based, AvrII-based and combined-enzymes PATS and PFGE similarities, respectively, indicating that these profiles shared a good but not high correlation, an expected inference given that the two techniques discriminate differently. Isolates that grouped differently were better matched to their locations using PATS. Overall, PATS discriminated the bovine O157 isolates without interpretive biases or sophisticated analytical software, and effectively complemented while not duplicating PFGE. With its quick turnaround time, PATS has excellent potential as a convenient tool for early epidemiological or food safety investigations, enabling rapid notification/implementation of quarantine measures.
  International Journal of Microbiology 01/2012; 2012:140105.
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  Available from: PubMed Central

  Article: Invasive mold infections: virulence and pathogenesis of mucorales.

  Giulia Morace, Elisa Borghi
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  ABSTRACT: Mucorales have been increasingly reported as cause of invasive fungal infections in immunocompromised subjects, particularly in patients with haematological malignancies or uncontrolled diabetes mellitus and in those under deferoxamine treatment or undergoing dialysis. The disease often leads to a fatal outcome, but the pathogenesis of the infection is still poorly understood as well as the role of specific virulence determinants and the interaction with the host immune system. Members of the order Mucorales are responsible of almost all cases of invasive mucormycoses, the majority of the etiological agents belonging to the Mucoraceae family. Mucorales are able to produce various proteins and metabolic products toxic to animals and humans, but the pathogenic role of these potential virulence factors is unknown. The availability of free iron in plasma and tissues is believed to be crucial for the pathogenesis of these mycoses. Vascular invasion and neurotropism are considered common pathogenic features of invasive mucormycoses.
  International Journal of Microbiology 01/2012; 2012:349278.
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  Available from: PubMed Central

  Article: Application of bioluminescence imaging for in vivo monitoring of fungal infections.

  Matthias Brock
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  ABSTRACT: Fungi can cause severe invasive infections especially in the immunocompromised host. Patient populations at risk are increasing due to ongoing developments in cancer treatment and transplantation medicine. Only limited diagnostic tools and few antifungals are available, rendering a significant number of invasive fungal infections life threatening. To reduce mortality rates, a better understanding of the infection processes is urgently required. Bioluminescence imaging (BLI) is a powerful tool for such purposes, since it allows visualisation of temporal and spatial progression of infections in real time. BLI has been successfully used to monitor infections caused by various microorganisms, in particular bacteria. However, first studies have also been performed on the fungi Candida albicans and Aspergillus fumigatus. Although BLI was, in principle, suitable to study the infection process, some limitations remained. Here, different luciferase systems are introduced, and current approaches are summarised. Finally, suggestions for further improvements of BLI to monitor fungal infections are provided.
  International Journal of Microbiology 01/2012; 2012:956794.
• Article: Use of Self-Organizing Map to Analyze Images of Fungi Colonies Grown from Triticum aestivum Seeds Disinfected by Ozone Treatment.

  Thierry Marique, Olivier Allard, Martin Spanoghe
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  ABSTRACT: We submitted to ozone treatment Triticum aestivum (common wheat) seeds severely contaminated by fungi. Fungi colonies developed when seeds were placed over malt agar medium in Petri dishes; Fusarium sp. and Alternaria sp. were identified. However, conventional colonies counting did not allow a clear assessment of the effect of ozone disinfection. We thus used self-organizing maps (SOMs) to perform an image analysis of colonies surface area that clearly showed a significant disinfection effect on Fusarium sp.
  International Journal of Microbiology 01/2012; 2012:865175.
• Article: Diversity across Seasons of Culturable Pseudomonas from a Desiccation Lagoon in Cuatro Cienegas, Mexico.

  Alejandra Rodríguez-Verdugo, Valeria Souza, Luis E Eguiarte, Ana E Escalante
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  ABSTRACT: Cuatro Cienegas basin (CCB) is a biodiversity reservoir within the Chihuahuan desert that includes several water systems subject to marked seasonality. While several studies have focused on biodiversity inventories, this is the first study that describes seasonal changes in diversity within the basin. We sampled Pseudomonas populations from a seasonally variable water system at four different sampling dates (August 2003, January 2004, January 2005, and August 2005). A total of 70 Pseudomonas isolates across seasons were obtained, genotyped by fingerprinting (BOX-PCR), and taxonomically characterized by 16S rDNA sequencing. We found 35 unique genotypes, and two numerically dominant lineages (16S rDNA sequences) that made up 64% of the sample: P. cuatrocienegasensis and P. otitidis. We did not recover genotypes across seasons, but lineages reoccurred across seasons; P. cuatrocienegasensis was isolated exclusively in winter, while P. otitidis was only recovered in summer. We statistically show that taxonomic identity of isolates is not independent of the sampling season, and that winter and summer populations are different. In addition to the genetic description of populations, we show exploratory measures of growth rates at different temperatures, suggesting physiological differences between populations. Altogether, the results indicate seasonal changes in diversity of free-living aquatic Pseudomonas populations from CCB.
  International Journal of Microbiology 01/2012; 2012:201389.
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  Available from: PubMed Central

  Article: Communication in fungi.

  Fabien Cottier, Fritz A Mühlschlegel
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  ABSTRACT: We will discuss fungal communication in the context of fundamental biological functions including mating, growth, morphogenesis, and the regulation of fungal virulence determinants. We will address intraspecies but also interkingdom signaling by systematically discussing the sender of the message, the molecular message, and receiver. Analyzing communication shows the close coevolution of fungi with organisms present in their environment giving insights into multispecies communication. A better understanding of the molecular mechanisms underlying microbial communication will promote our understanding of the "fungal communicome."
  International Journal of Microbiology 01/2012; 2012:351832.
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  Available from: PubMed Central

  Article: Impact of HMGB1/TLR Ligand Complexes on HIV-1 Replication: Possible Role for Flagellin during HIV-1 Infection.

  Piotr Nowak, Samir Abdurahman, Annica Lindkvist, Marius Troseid, Anders Sönnerborg
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  ABSTRACT: Objective. We hypothesized that HMGB1 in complex with bacterial components, such as flagellin, CpG-ODN, and LPS, promotes HIV-1 replication. Furthermore, we studied the levels of antiflagellin antibodies during HIV-1-infection. Methods. Chronically HIV-1-infected U1 cells were stimulated with necrotic extract/recombinant HMGB1 in complex with TLR ligands or alone. HIV-1 replication was estimated by p24 antigen in culture supernatants 48-72 hours after stimulation. The presence of systemic anti-flagellin IgG was determined in 51 HIV-1-infected patients and 19 controls by immunoblotting or in-house ELISA. Results. Flagellin, LPS, and CpG-ODN induced stronger HIV-1 replication when incubated together with necrotic extract or recombinant HMGB1 than activation by any of the compounds alone. Moreover, the stimulatory effect of necrotic extract was inhibited by depletion of HMGB1. Elevated levels of anti-flagellin antibodies were present in plasma from HIV-1-infected patients and significantly decreased during 2 years of antiretroviral therapy. Conclusions. Our findings implicate a possible role of HGMB1-bacterial complexes, as a consequence of microbial translocation and cell necrosis, for immune activation in HIV-1 pathogenesis. We propose that flagellin is an important microbial product, that modulates viral replication and induces adaptive immune responses in vivo.
  International Journal of Microbiology 01/2012; 2012:263836.
• Article: Molecular analysis of the bacterial communities in crude oil samples from two brazilian offshore petroleum platforms.

  Elisa Korenblum, Diogo Bastos Souza, Monica Penna, Lucy Seldin
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  ABSTRACT: Crude oil samples with high- and low-water content from two offshore platforms (PA and PB) in Campos Basin, Brazil, were assessed for bacterial communities by 16S rRNA gene-based clone libraries. RDP Classifier was used to analyze a total of 156 clones within four libraries obtained from two platforms. The clone sequences were mainly affiliated with Gammaproteobacteria (78.2% of the total clones); however, clones associated with Betaproteobacteria (10.9%), Alphaproteobacteria (9%), and Firmicutes (1.9%) were also identified. Pseudomonadaceae was the most common family affiliated with these clone sequences. The sequences were further analyzed by MOTHUR, yielding 81 operational taxonomic units (OTUs) grouped at 97% stringency. Richness estimators also calculated by MOTHUR indicated that oil samples with high-water content were the most diverse. Comparison of bacterial communities present in these four samples using LIBSHUFF and Principal Component Analysis (PCA) indicated that the water content significantly influenced the community structure only of crude oil obtained from PA. Differences between PA and PB libraries were observed, suggesting the importance of the oil field as a driver of community composition in this habitat.
  International Journal of Microbiology 01/2012; 2012:156537.
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  Available from: PubMed Central

  Article: Plant Growth Promoting of Endophytic Sporosarcina aquimarina SjAM16103 Isolated from the Pneumatophores of Avicennia marina L.

  S Rylo Sona Janarthine, P Eganathan
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  ABSTRACT: Endophytic Sporosarcina aquimarina SjAM16103 was isolated from the inner tissues of pneumatophores of mangrove plant Avicennia marina along with Bacillus sp. and Enterobacter sp. Endophytic S. aquimarina SjAM16103 was Gram variable, and motile bacterium measured 0.6-0.9 μm wide by 1.7-2.0 μm long and light orange-brown coloured in 3-day cultures on tryptone broth at 26°C. Nucleotide sequence of this strain has been deposited in the GenBank under accession number GU930359. This endophytic bacterium produced 2.37 μMol/mL of indole acetic acid and siderophore as it metabolites. This strain could solubilize phosphate molecules and fixes atmospheric nitrogen. Endophytic S. aquimarina SjAM16103 was inoculated into four different plants under in vitro method to analyse its growth-promoting activity and role inside the host plants. The growth of endophytic S. aquimarina SjAM16103 inoculated explants were highly significant than the uninoculated control explants. Root hairs and early root development were observed in the endophytic S. aquimarina SjAM16103 inoculated explants.
  International Journal of Microbiology 01/2012; 2012:532060.