Microbiological Research (MICROBIOL RES )

Publisher: Elsevier


Microbiological Research is an international journal devoted to publishing original research papers, reviews and short communications on prokaryotic and eukaryotic microorganisms, Bacteria, Archaea, Mycota and uni-cellular organisms. Microbiological Research covers articles from many facets of microbiology: antimicrobial drugs - biochemistry - biotechnology - environmental microbiology - genetics - molecular biology - molecular diagnosis - phylogeny - physiology - phytopatholgy - systematics and taxonomy.

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  • Other titles
    Microbiological research (Online)
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    Document, Periodical, Internet resource
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    Internet Resource, Computer File, Journal / Magazine / Newspaper

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    • Articles in some journals can be made Open Access on payment of additional charge
    • NIH Authors articles will be submitted to PubMed Central after 12 months
    • Publisher last contacted on 18/10/2013
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Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Regulation of gene expression is one of the mechanisms of virulence in pathogenic organisms. In this context, we would like to understand the gene regulation of acetamidase enzyme of Mycobacterium smegmatis, which is the first reported inducible enzyme in mycobacteria. The acetamidase is highly inducible and the expression of this enzyme is increased 100-fold when the substrate acetamide is added. The acetamidase structural gene (amiE) is found immediately downstream of three predicted open reading frames (ORFs). Three of these genes along with a divergently expressed ORF are predicted to form an operon and involved in the regulation of acetamidase enzyme. Here we report expression, purification and functional characterization of AmiA which is one of these predicted ORFs. Electrophoretic mobility shift assays showed that AmiA binds to the region between the amiA and amiD near the predicted promoter (P2). Over-expression of AmiA significantly lowered the expression of acetamidase compared to the wild type as demonstrated by qRT-PCR and SDS-PAGE. We conclude that AmiA binds near P2 promoter and acts as a repressor in the regulation of acetamidase operon. The described work is a further step forward toward broadening the knowledge on understanding of the complex gene regulatory mechanism of Mycobacterium sp.
    Microbiological Research 11/2014;
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    ABSTRACT: In filamentous fungi, the pathogenic mitogen-activated protein kinase (PMK) pathway performs an important function in plant infection. STE12-like genes found in higher eukaryotes encode transcription factors and are regulated by the PMK pathway. However, the functions of STE12-like genes in foliar pathogens remain poorly understood. In this study, we cloned StSTE12 from Setosphaeria turcica and investigated its functions by RNA interference. Transformants ste12-3, ste12-2 and, ste12-1, in which the StSTE12 silencing efficiency increased in order, were confirmed by real time PCR. Compared with the wild-type (WT) strain, the transformants showed reduced growth rate, lighter colony color, and obviously decreased conidium production. More importantly, different to WT strain and ste12-3 with lower StSTE12silencing efficiency, ste12-1 and ste12-2 with higher StSTE12 silencing efficiency were nonpathogenic on intact leaves, but pathogenic on wounded leaves. However, the biological activity of HT-toxin from all transformants showed no difference on corn leaves. Furthermore, ste12-1 and ste12-2 did not penetrate artificial cellophane membrane and showed abnormal and delayed development appressoria. Although it could penetrate the cellophane membranes, ste12-3 formed appressoria after 48 h of inoculation more than WT. Therefore, StSTE12 was involved in vegetative growth, conidiation, appressorial development, penetration as well as the pathogenicity, but it was not related to HT-toxin biosynthesis. More interestingly, all the results suggested that StSTE12 was crucial for pathogenicity due to involvement in regulating appressoria development and penetration.
    Microbiological Research 11/2014;
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    ABSTRACT: To determine whether the composition and structure of skin microbiota differ with age, cutaneous bacteria were isolated from the axillary fossa of 37 healthy human adults in two age groups (old people and young adults). Bacterial genomic DNA was extracted and characterized by nested PCR-denaturing gradient gel electrophoresis (PCR-DGGE) with primers specifically targeting V3 region of the 16S rRNA gene. The excised gel bands were sequenced to identify bacterial categories. The total bacteria, Staphylococcus spp., Staphylococcus epidermidis and Corynebacterium spp. were further enumerated by quantitative PCR. There were no significant differences in the species diversity profiles between age groups. The similarity index was lower across age groups than that it was intra-group. This indicates that the composition of skin flora is more similar to others of the same age than across age groups. While Staphylococcus spp. and Corynebacterium spp. were the dominant bacteria in both groups, sequencing and quantitative PCR revealed that skin bacterial composition differed by age. The copy number of total bacteria and Corynebacterium spp. were significantly lower in younger subjects, whereas there were no statistical differences in the quantity of Staphylococcus spp. and Staphylococcus epidermidis. These results suggest that the skin flora undergo both quantitative and qualitative changes related to aging.
    Microbiological Research 09/2014;
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    ABSTRACT: Iron–sulfur ([Fe–S]) cluster is an essential cofactor of proteins involved in various physiological processes including cellular defense against oxidative stress. In Xanthomonas campestris pv. campestris (Xcc), IscR plays a negative role in regulation of the transcription of [Fe–S] assembly genes, iscR-sufBCDS. The expression level of sufBCDS was up-regulated in an Xcc iscR mutant. In addition, the iscR promoter activity in an Xcc iscR mutant was also higher than the wild-type strain, indicating an autoregulatory circuit. Purified IscR was shown to bind at the iscR promoter region and three putative IscR binding sites were identified. The expression of iscR-suf operon was highly induced by oxidant treatments and iron limited conditions. The iscR mutant showed increased sensitivity toward hydrogen peroxide phenotype but, surprisingly, had hyper-resistant phenotype toward plumbagin compared to the wild-type strain. Most importantly, the iscR mutant was impaired in its ability to cause lesion on leaves of a compatible host plant, Chinese radish (Raphanus sativus). These results demonstrate that a transcription regulator gene, iscR, negatively regulates genes involved in [Fe–S] biosynthesis and plays a role in oxidative stress response and pathogenesis of Xcc.
    Microbiological Research 08/2014;
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    ABSTRACT: Tobacco bacterial wilt caused by Ralstonia solanacearum is one of the most serious diseases of tobacco in the area of tobacco cultivation. As there is no effective control method for tobacco bacterial wilt diseases, developing new antibacterial agents in tobacco will make great practical sense. The antibacterial activity against R. solanacearum of Lansiumamide B which isolated from the seeds of Clausena lansium is reported in this paper for the first time. The bioassay results indicates that Lansiumamide B could completely inhibits the growth of R. solanacearum at the concentration of 125 mg/L in vitro, the EC50 and EC90 are 48.82 mg/L and 86.26 mg/L, respectively. The result of pot experiments indicates that the control efficiency of the Lansiumamide B on tobacco bacterial wilt are 95.84%, 91.67% and 86.38% at 7d, 14d and 21d after treatment at the concentration of 100 mg/kg, respectively, nearly 40 times higher than Streptomycin, a special fungicide to the disease, at 21 d after treatment with root irrigation method. These results suggest that Lansiumamide B has the potential of developing as a new type of plant-type fungicide on controlling the diseases of tobacco bacterial wilt.
    Microbiological Research 07/2014;
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    ABSTRACT: The opportunistic pathogen Pseudomonas aeruginosa produces a variety of virulence factors, and biofilms of this bacterium are much more resistant to antibiotics than planktonic cells. Thirty-six metal ions have been investigated to identify antivirulence and antibiofilm metal ions. Zinc ions and ZnO nanoparticles were found to markedly inhibit biofilm formation and the production of pyocyanin, Pseudomonas quinolone signal (PQS), pyochelin, and hemolytic activity of P. aeruginosa without affecting the growth of planktonic cells. Transcriptome analyses showed that ZnO nanoparticles induce the zinc cation efflux pump czc operon and several important transcriptional regulators (porin gene opdT and type III repressor ptrA), but repress the pyocyanin-related phz operon, which explains observed phenotypic changes. A mutant study showed that the effects of ZnO nanoparticles on the control of pyocyanin production and biofilm formation require the czc regulator CzcR. In addition, ZnO nanoparticles markedly increased the cellular hydrophilicity of P. aeruginosa cells. Our results support that ZnO nanoparticles are potential antivirulence materials against recalcitrant P. aeruginosa infections and possibly other important pathogens.
    Microbiological Research 06/2014;
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    ABSTRACT: Natural product drug discovery has regained interest due to low production costs, structural diversity, and multiple uses of active compounds to treat various diseases. Attention has been directed towards medicinal plants as these plants have been traditionally used for generations to treat symptoms of numerous diseases. It is established that plants harbour microorganisms, collectively known as endophytes. Exploring the as-yet untapped natural products from the endophytes increases the chances of finding novel compounds. The concept of natural products targeting microbial pathogens has been applied to isolate novel antimycobacterial compounds, and the rapid development of drug-resistant Mycobacterium tuberculosis has significantly increased the need for new treatments against this pathogen. It remains important to continuously screen for novel compounds from natural sources, particularly from rarely encountered microorganisms, such as the endophytes. This review focuses on bioprospecting for polyketides and small peptides exhibiting antituberculosis activity, although current treatments against tuberculosis are described. It is established that natural products from these structure classes are often biosynthesised by microorganisms. Therefore it is hypothesised that some bioactive polyketides and peptides originally isolated from plants are in fact produced by their endophytes. This is of interest for further endophyte natural product investigations (Figure 1).
    Microbiological Research 01/2014;
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    ABSTRACT: Ethanol is one of the good sources of liquid energy for automobiles and industries. Ethanol is used as universal solvent. It is also used as fuel. In future, ethanol is going to blend with petrol in high proportion. Among the liquid fuels, ethanol is used as an alternative to petroleum (gasohol) by blending with petrol at the rate of 20%. To reach the future demand of ethanol, it should be produced in high quantity from the agricultural raw material. Although, there are enormous saccharine and starchy materials, their use as raw material for ethanol production is prohibitive because of their use as a food material for feeding the billions of our population. The present investigation was undertaken to optimize various pretreatment methods for maximum reducing sugar, selection of suitable efficient yeast and bacterial cultures, optimization of fermentation parameters and finally to study the ethanol production from the hydrolysate of deseeded sunflower head waste. Among the different pretreatments, combination of acid + steam pretreatment was found to give more reducing sugar than the other pretreatment for both micro organisms. The maximum ethanol production (18.59 g/L) was obtained at a substrate concentration of 5% (v/v) at pH 6.5 for Zymomonas mobilis and (16.46 g/L) was obtained at 3% (v/v) of substrate concentration at pH 5.5 for Saccharomyces cerevisiae.
    Microbiological Research 01/2014; 5(3):208-216.
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    ABSTRACT: Streptococcus suis (SS) is an important zoonotic pathogen causing a variety of life-threatening infections in pigs and humans. Tran, a novel transcriptional regulator which was identified to be an infection-related factor in S. suis serotype 2 using suppression subtractive hybridization (SSH), has been reported by our group. In this study, a tran deletion mutant was constructed to compare with the wild-type ZY05719 in some biological characteristics. It is suggested that longer chains and relatively slower growth could be observed in tran deletion mutants. In order to identify gene transcription profiles, microarray analysis was performed. It indicated that the inactivation of Tran led to 130 differentially expressed genes spread throughout the genome. Among these, 21 genes were upregulated, and 109 genes were downregulated. Most of the differentially expressed genes were involved in bacterial metabolism, such as the phosphotransferase system (PTS), and heat shock proteins. In the case of glucose scarcity, the growth characteristics of tran deletion mutants was impacted significantly, meanwhile Δtran mutant was highly sensitive to environmental stresses. Moreover, cell adherence decreased by 22.2%, and virulence in zebrafish declined to more than 5 times in Δtran mutants. These data demonstrate the role of Tran in regulation in S. suis serotype 2, that is affect bacterial virulence by influencing bacterial metabolism and stress tolerance of external environment.
    Microbiological Research 01/2014;
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    ABSTRACT: Calpains are intracellular, cysteine proteases found in plants, animals and fungi functioning as signal transduction components in different cellular pathways including sporulation and alkaline adaptation in fungi. Calpains-related MoCAPN1 (MGG_14872), MoCAPN3 (MGG_15810) and MoCAPN4 (MGG_04818) genes from M. oryzae genome which are 2604, 3513 and 771-bp in length and encoding identical proteins of 867, 1170 and 256 amino acids were functionally characterized for different phenotypes through gene disruption method. All the mutants except those for MoCAPN1 showed normal phenotypes. In pathogenicity test, the mutants did not lead to any visible changes in phenotypes causing similar blast lesions on blast susceptible rice and barley leaves as those of the Guy-11 strain suggesting no major role in pathogenicity. Germ tubes formation, appressorium formation, mycelium radial growth and mating with 2539 strain were indistinguishable among the mutants and Guy-11 strains. Cell wall integrity (congo red) test, stress response under chemical pressure (ZnSO4, CuSO4 and CdCl2), osmotic and oxidative (NaCl and H2O2) stress response, growth response on glucose and nitrogen deficient media resulted in similar results in the mutants and Guy-11 strains. However, mutants for ΔMoCAPN1 gene produced reduced (0.57 ± 0.15B and 0.54 ± 0.05B) conidia compared to that (1.69 ± 0.13A) of the Guy-11 strain showing its involvement in conidiation.
    Microbiological Research 01/2014;
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    ABSTRACT: The oomycete pathogen, Phytophthora meadii, causes various diseases in Hevea brasiliensis at different stages of its life cycle. The study reports the structural characterization of the active principle from the culture filtrate of Alcaligenes sp. EIL-2 (GenBank ID: HQ641257) offering antagonistic activity against P. meadii. Gas Chromatography Mass Spectroscopy (GC-MS) analysis showed the similarity of the compound with phenazine derivatives. The specific representations of FT-IR spectrum such as 3200cm(-1) (OH stretching, NH stretching and presence of aromatic ring), 1737cm(-1) (carboxylic acid), 2200-2400cm(-1) (conjugated dienes) and 1467cm(-1), and 1422cm(-1) (CN bonds) were an indicative of phenazine-1-carboxylic acid (PCA). The structure of the compound was further confirmed by (1)H NMR/(13)C NMR spectroscopy, DEPT experiments, and two-dimensional NMR spectral studies, including (1)H-(1)H COSY and (1)H-(13)C HSQC as PCA with the molecular formula of C13H8N2O2. P. meadii was sensitive to purified PCA extract from the endophyte and a concentration of 5μg/ml completely inhibited the mycelia growth. PCA also showed zoosporicidal activity against P. meadii zoospores. This is the first study of this kind where PCA from an endophyte of H. brasiliensis is being confirmed to carry antagonistic activity against P. meadii.
    Microbiological Research 01/2014;
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    ABSTRACT: Seventy nine isolates of B. cinerea were collected from different host plants and different locations of India and Nepal. All the isolates were identified as B. cinerea based on morphological features and were confirmed using B. cinerea specific primers. Differentiation among the isolates was assessed using morphological, genetic and biochemical approaches. To analyze morphological variability, differences in conidial size, presence or absence of sclerotia and their arrangement were observed. Genetic variability was characterized using RAPD analysis, presence or absence of transposons and mating type genes. Cluster analysis based on RAPD markers was used for defining groups on the basis of geographical region and host. The biochemical approach included determining differences in concentration of oxalic acid and activity of lytic enzymes. All the isolates were categorized into different pathogenic groups on the basis their variable reaction towards chickpea plants. Isolates with higher concentration of oxalic acid and greater activity of lytic enzymes were generally more pathogenic. Pathogenicity was also correlated to transposons. Isolates containing transposa group showed some degree of correlation with pathogenic behavior. However, isolates could not be grouped on the basis of a single approach which provides evidence of their wide diversity and high evolution potential. Sensitivity of sampled isolates was also tested against five botryticides. Most of the isolates from same region were inhibited by a particular fungicide. This feature provided interesting cues and would assist in devising novel and more effective measures for managing the disease.
    Microbiological Research 01/2014;