Showing papers in "International Microbiology in 2004"

Biocontrol mechanisms of Trichoderma strains

Abstract: The genus Trichoderma comprises a great number of fungal strains that act as biological control agents, the antagonistic properties of which are based on the activation of multiple mechanisms. Trichoderma strains exert biocontrol against fungal phytopathogens either indirectly, by competing for nutrients and space, modifying the environmental conditions, or promoting plant growth and plant defensive mechanisms and antibiosis, or directly, by mechanisms such as mycoparasitism. These indirect and direct mechanisms may act coordinately and their importance in the biocontrol process depends on the Trichoderma strain, the antagonized fungus, the crop plant, and the environmental conditions, including nutrient availability, pH, temperature, and iron concentration. Activation of each mechanism implies the production of specific compounds and metabolites, such as plant growth factors, hydrolytic enzymes, siderophores, antibiotics, and carbon and nitrogen permeases. These metabolites can be either overproduced or combined with appropriate biocontrol strains in order to obtain new formulations for use in more efficient control of plant diseases and postharvest applications.

Bacterial degradation of aromatic pollutants: a paradigm of metabolic versatility

Abstract: Research in our laboratory is supported by grants 07M/0127/2000 and 07M/0076/2002 from the Comunidad Autonoma de Madrid, grants BIO2000-1076, BIO2003-01482, VEM2003-20075-CO2-02, and GEN2001-4698-CO5-02 from the CICYT, and by the EU contract QLRT-2001-02884.

Clostridium difficile pilot study: effects of probiotic supplementation on the incidence of C. difficile diarrhoea.

Abstract: Colonic infection with Clostridium difficile , leading to pseudomembranous colitis, is a common complication of antibiotic therapy, especially in elderly patients. It has been suggested that non-pathogenic probiotic bacteria might prevent the development and recurrence of C. difficile infection. This double-blind, placebo-controlled study examines the role of probiotic administration in the prevention of C. difficile -associated diarrhoea (CDAD) in elderly patients receiving antibiotic therapy. Consecutive patients (150) receiving antibiotic therapy were randomised to receive either a probiotic containing both Lactobacillus and Bifidobacterium or placebo for 20 days. Upon admission to hospital, bowel habit was recorded and a faecal sample taken. Trial probiotic or placebo was taken within 72 h of prescription of antibiotics, and a second stool sample was taken in the event of development of diarrhoea during hospitalisation or after discharge. Of the randomised patients, 138 completed the study, 69 with probiotics in conjunction with antibiotics and 69 with antibiotics alone. On the basis of development of diarrhoea, the incidence of samples positive for C. difficile -associated toxins was 2.9% in the probiotic group compared with 7.25% in the placebo-control group. When samples from all patients were tested (rather than just those developing diarrhoea) 46% of probiotic patients were toxin-positive compared with 78% of the placebo group. [Int Microbiol 2004; 7(1):59–62]

Cell aggregation: a mechanism of pathogenic Leptospira to survive in fresh water

Abstract: Transmission of leptospirosis is facilitated by the survival of pathogenic leptospires in moist environments outside their mammalian host. In the present study, the survival mechanisms of Leptospira interrogans serovar Canicola in aqueous conditions and lack of nutrients were investigated. In distilled water, leptospires were able to remain motile for 110 days (pH 7.2). However, when incubated in a semi-solid medium composed of distilled water and 0.5% purified agarose (pH 7.2), they survived 347 days. In this viscous environment, aggregates of live spirochetes were observed. Neither antibiotics (e.g. tetracycline and ampicillin) nor nutrients inhibited leptospiral aggregation. Immunoblot analysis suggested that cells incubated in water down-regulate the expression of LipL31, an inner-membrane protein, but retain expression of other membrane proteins. These studies provide insights into the mechanisms by which pathogenic Leptospira survives for prolonged periods of time in natural aqueous environments, a key stage in the leptospiral lifecycle.

Virulence genes and intimin types of Shiga-toxin-producing Escherichia coli isolated from cattle and beef products in Argentina

Abstract: A total of 153 Shiga-toxin-producing Escherichia coli (STEC) isolates from feces of cattle and beef products (hamburgers and ground beef) in Argentina were characterized in this study. PCR showed that 22 (14%) isolates carried stx1 genes, 113 (74%) possessed stx2 genes and 18 (12%) both stx1 and stx2. Intimin (eae), enterohemolysin (ehxA), and STEC autoagglutinating adhesin (saa) virulence genes were detected in 36 (24%), 70 (46%) and in 34 (22%) of the isolates, respectively. None of 34 saa-positive isolates carried the gene eae, and 31 were ehxA-positive. Fourteen (7 of serotype O26:H11 and 4 of serotype O5:H-) isolates had intimin b1, 16 isolates possessed intimin g1 (11 of serotype O145:H- and 5 of serotype O157:H7), 5 isolates had intimin type e1 (4 of serotypes O103:H- and O103:H2), and one isolate O111:H- showed intimin type q/g2. Although the 153 STEC isolates belonged to 63 different seropathotypes, only 12 accounted for 58% of isolates. Seropathotype ONT:H- stx2 (18 isolates) was the most common, followed by O171:H2 stx2 (12 isolates), etc. The majority (84%) of STEC isolates belonged to serotypes previously found in human STEC and 56% to serotypes associated with STEC isolated from patients with hemolytic uremic syndrome (HUS). Thus, this study confirms that cattle are a major reservoir of STEC pathogenic for humans. To our knowledge, this is the first study that described the presence of saa gene in STEC of serotypes O20:H19, O39:H49, O74:H28, O79:H19, O116:H21, O120:H19, O141:H7, O141:H8, O174:H21, and ONT:H21. The serotypes O120:H19 and O185:H7 were not previously reported in bovine STEC.

Infectious disease and environment: cholera as a paradigm for waterborne disease.

Abstract: The current international awareness of the importance of combating infectious diseases can provide the opportunity for a multidisciplinary approach that joins medicine with many other scientific and technological capabilities, with broad implications for the quality of daily life. Science and technology are major forces that have the potential to balance the world’s inequities. The scientific community and world leaders must therefore work together to use knowledge and its applications to improve the condition of the planet. The connection between cholera and the environment provides a paradigm for this perspective. A global context indisputably frames all human health issues in the twenty-first century. This context is based on several realities: the worldwide movement of people and goods, the recognition that earth processes operate on a global scale, and a dynamic international scientific enterprise. Health issues are no longer simply a personal matter between patient and physician, if they ever were. Nowadays they encompass an individual’s complex relationship with the global environment. As Gro Harlem Brundtland—former director of the World Health Organization (WHO)—said, “[i]n the modern world, bacteria and viruses travel almost as fast as money. With globalization, a single microbial sea washes all of humankind. There are no health sanctuaries.” [Brundtland GH, Lecture at the World Economic Forum, Davos, 29 Jan. 2001, available at http://www.who.int/ director-general/speeches /2001 /english/20010129_davosunequaldistr.en.html]. According to the WHO, infectious diseases account for about one quarter of all deaths worldwide (and these do not include cancer, cardiovascular and respiratory diseases, many of which we currently know to be triggered by infections). Several of them, including diarrheal diseases, tuberculosis and malaria, are classical infectious killers, whereas a new emerging infectious disease—AIDS—has become the second leading cause of death in just two decades. In children, infectious diseases are responsible for 63% of deaths, and diarrheal diseases, which until recently ranked first, are still the second most frequent cause of death for children under age five. Throughout the past half century, international travel has skyrocketed; there are now approximately 500 million international arrivals per year. The greatest increases have taken place since the mid-1990s. International arrivals increased in every region of the earth, but in Africa and the Middle East they jumped by almost half. The world has become integrated and global; consequently, the notion that it is possible to successfully eradicate a disease from the face of the planet has become simplistic. Infectious disease is a moving target, and climate shifts will affect any disease that has an environmentally sensitive stage or vector. Recognizing signals from climate models and incorporating them into health measures can thus provide new opportunities for proactive—rather than reactive—approaches to public health. Ecosystems do not respond linearly to environmental changes, nor do the pathogens that live in them. Rita R. Colwell

Hijacking of eukaryotic functions by intracellular bacterial pathogens

Abstract: Intracellular bacterial pathogens have evolved as a group of microorganisms endowed with weapons to hijack many biological processes of eukaryotic cells. This review discusses how these pathogens perturb diverse host cell functions, such as cytoskeleton dynamics and organelle vesicular trafficking. Alteration of the cytoskeleton is discussed in the context of the bacterial entry process (invasion), which occurs either by activation of membrane-located host receptors (“zipper” mechanism) or by injection of bacterial proteins into the host cell cytosol (“trigger” mechanism). In addition, the two major types of intracellular lifestyles, cytosolic versus intravacuolar (phagosomal), which are the consequence of alterations in the phagosome-lysosome maturation route, are compared. Specific examples illustrating known mechanisms of mimicry or hijacking of the host target are provided. Finally, recent advances in phagosome proteomics and genome expression in intracellular bacteria are described. These new technologies are yielding valuable clues as to how these specialized bacterial pathogens manipulate the mammalian host cell. [Int Microbiol 2004; 7(3):181–191]

Resistance to beta-lactam antibiotics in Aeromonas hydrophila isolated from rainbow trout (Oncorhynchus mykiss).

Abstract: Bacterial infections caused by members of the genus Aeromonas, with a relatively high antibiotic resistance, are among the most common and troublesome diseases of fish raised in ponds with recirculation systems. In this study, carried out at an experimental aquaculture station in northern Portugal, 51 strains identified as belonging to the genus Aeromonas were isolated from 20 rainbow trout (Oncorhynchus mykiss) skin and kidney samples, as well as from raceway water samples. Macro- and microscopic examination of the fish tissues revealed lesions or cellular alterations in skin and kidney that seemed to correlate with the presence of those isolates. The sensitivity of all isolated strains to different groups of beta-lactam antibiotics (penicillins, cephalosporins, monobactams and carbapenems) was evaluated using the disc diffusion method. The highest rates of resistance were to amoxicillin, carbenicillin and ticarcillin. Unexpected resistance to imipenem, an antibiotic of clinical usage, was also detected, which suggests that resistance may have been transferred to the Aeromonas population from the environment.

The Fusarium oxysporum f. sp. ciceris/Cicer arietinum pathosystem: a case study of the evolution of plant-pathogenic fungi into races and pathotypes

Abstract: The use of resistant cultivars is one of the most practical and cost-efficient strategies for managing plant diseases. However, the efficiency of resistant cultivars in disease management is limited by pathogenic variability in pathogen populations. Knowledge of the evolutionary history and potential of the pathogen population may help to optimize the management of disease-resistance genes, irrespective of the breeding strategy used for their development. In this review, we examine the diversity in virulence phenotypes of Fusarium oxysporum f. sp. ciceris, the causal agent of Fusarium wilt of chickpeas, analyze the genetic variability existing within and among those phenotypes, and infer a phylogenetic relationship among the eight known pathogenic races of this fungus. The inferred intraspecific phylogeny shows that each of those races forms a monophyletic lineage. Moreover, virulence of races to resistant chickpea cultivars has been acquired in a simple stepwise pattern, with few parallel gains or losses. Although chickpea cultivars resistant to Fusarium wilt are available, they have not yet been extensively deployed, so that the stepwise acquisition of virulence is still clearly evident.

Signature sequences in diverse proteins provide evidence for the late divergence of the Order Aquificales.

Abstract: The Aquificales species are presently believed to be the earliest branching lineage within Bacteria. However, the branching order of this group in different phylogenetic trees is highly variable and not resolved. In the present work, the phylogenetic placement of Aquificales was examined by means of a cladistic approach based on the shared presence or absence of definite signature sequences (consisting of conserved inserts or deletions) in many highly conserved and important proteins, e.g. RNA polymerase beta (RpoB), RNA polymerase beta (RpoC), alanyl-tRNA synthetase (AlaRS), CTP synthase, inorganic pyrophosphatase (PPase), Hsp70 and Hsp60. For this purpose, fragments of the above genes that contained the signature regions were cloned from different Aquificales species (Calderobacterium hydrogenophilum, Hydrogenobacter marinus, and Thermocrinis ruber) and the sequence data were compared with those available from all other species. The presence in Aquificales species of distinctive inserts in Hsp70 and Hsp60 that are not found in any Firmicutes, Actinobacteria, or Thermotoga-Clostridium species excluded them from these groups of Bacteria. The shared presence of prominent indels in the RpoB (>100 amino acids), RpoC (>100 amino acids) and AlaRS (4 amino acids) proteins, which are only found in the various Aquificales species, the Chlamydiae, the CFBG (Cytophaga-Flavobacteria-Bacteroides-green sulfur bacteria) group, and Proteobacteria, strongly suggests their placement within these groups of Bacteria. A specific relationship between Proteobacteria and Aquificales is suggested by the presence in inorganic pyrophosphatase of a 2-amino-acid insert that is uniquely found in these phyla. However, the Aquificales species lacked a number of other protein signatures (e.g. indels in CTP synthase and Hsp70) that are characteristic of Proteobacteria, indicating that they constitute a distinct phylum related to Proteobacteria. These results provide strong and consistent evidence that the Aquificales diverged after the branching of Firmicutes, Actinobacteria, Thermotoga, Deinococcus-Thermus, green nonsulfur bacteria, Cyanobacteria, Spirochetes, Chlamydiae, and CFBG group, but before the emergence of the Proteobacteria.

Recombinant viruses as tools to induce protective cellular immunity against infectious diseases

Abstract: Infections by intracellular pathogens such as viruses, some bacteria and many parasites, are cleared in most cases after activation of specific T cellular immune responses that recognize foreign antigens and eliminate infected cells. Vaccines against those infectious organisms have been traditionally developed by administration of whole live attenuated or inactivated microorganisms. Nowadays, research is focused on the development of subunit vaccines, containing the most immunogenic antigens from the particular pathogen. However, when purified subunit vaccines are administered using traditional immunization protocols, the levels of cellular immunity induced are mostly low and not capable of eliciting complete protection against diseases caused by intracellular microbes. In this review, we present a promising alternative to those traditional protocols, which is the use of recombinant viruses encoding subunit vaccines as immunization tools. Recombinant viruses have several interesting features that make them extremely efficient at inducing immune responses mediated by T-lymphocytes. This cellular immunity has recently been demonstrated to be of key importance for protection against malaria and AIDS, both of which are major targets of the World Health Organization for vaccine development. Thus, this review will focus in particular on the development of new vaccination protocols against these diseases.

A new set of DNA macrochips for the yeast Saccharomyces cerevisiae: features and uses

Abstract: The yeast Saccharomyces cerevisiae has been widely used for the implementation of DNA chip technologies. For this reason and due to the extensive use of this organism for basic and applied studies, yeast DNA chips are being used by many laboratories for expression or genomic analyses. While membrane arrays (macroarrays) offer several advantages, for many laboratories they are not affordable. Here we report that a cluster of four Spanish molecular-biology yeast laboratories, with relatively small budgets, have developed a complete set of probes for the genome of S. cerevisiae. These have been used to produce a new type of macroarray on a nylon surface. The macroarrays have been evaluated and protocols for their use have been optimized. [Int Microbiol 2004; 7(3):199-206]

How are gene sequence analyses modifying bacterial taxonomy? The case of Klebsiella.

Abstract: Bacterial names are continually being changed in order to more adequately describe natural groups (the units of microbial diversity) and their relationships. The problems in Klebsiella taxonomy are illustrative and common to other bacterial genera. Like other bacteria, Klebsiella spp. were isolated long ago, when methods to identify and classify bacteria were limited. However, recently developed molecular approaches have led to taxonomical revisions in several cases or to sound proposals of novel species. [Int Microbiol 2004; 7(4):261-268]

Simultaneous PCR detection of ica cluster and methicillin and mupirocin resistance genes in catheter-isolated Staphylococcus

Abstract: Recent data show that more than 50% of catheter-associated bloodstream infections are caused by staphylococci. Staphylococcal infections produced by intercellular-adhesion cluster (ica) carriers can be even more problematic due to the presence of methicillin and mupirocin resistance genes. In the present study, a multiplex PCR protocol that allows the simultaneous identification of staphylococci and detection of both the ica and methicillin and/or mupirocin resistance genes was developed. Furthermore, the method allows differential detection of the ica locus from Staphylococcus aureus and Staphylococcus epidermidis. [Int Microbiol 2004; 7(1):63–66]

Laboratory diagnosis of brucellosis in a rural endemic area in northeastern Spain.

Abstract: Sera obtained from 62 patients from four mountain counties in Catalonia (Northeastern Spain), in whom brucellosis had been diagnosed on the basis of clinical evidence and/or personal history, were analyzed using the rose Bengal test, standard serum agglutination test (SAT), Coombs' test, ELISA, and complement fixation. The diagnosis was further confirmed through blood cultures. Clinical evidence, epidemiology, and the results from serologic tests were used to assign patients to one of two groups: group 1 (n = 38) patients had primary infections, whereas group 2 (n = 24) patients had been previously exposed to the microorganism, i.e. re-infection of group 2 individuals occurred after long periods of time during which no active infection by Brucella had been detected. Receiving-operating charts (ROC) were used to determine the diagnostic value of the different tests and to establish discriminant values. Blood culture was a valuable diagnostic tool in group 1 (0.92 sensitivity) but was inappropriate in group 2 (0.08). The combination of positive rose Bengal test and agglutination >/=1/160 was valid for diagnosis in group 1. In group 2, agglutination /=1/320 was the best diagnostic criterion (0.8 specificity; 1 sensitivity). ELISA (for IgG, IgM, or both) did not improve diagnostic accuracy.

Differential circadian expression of genes fcp2 and fcp6 in Cyclotella cryptica.

Abstract: The steady-state mRNA concentrations of two fcp genes encoding fucoxanthin chlorophyll a/c light-harvesting polypeptides of the centric diatom Cyclotella cryptica were investigated over a 4-day period by RNA dot-blotting experiments. Before and during the first day of the experiment, the cultures were grown under a 12-h light/12-h dark regime. On the following 3 days, the algae were kept in darkness. On the first day, the steady-state mRNA concentration of fcp2 followed a diurnal pattern, with a maximum occurring around noon, approximately 6 h after the onset of light. The gene fcp6 also had a diurnal pattern on the first day. Its maximum, however, occurred immediately after the onset of light. During the subsequent incubation period in darkness, the diurnal pattern of expression of both fcp genes continued, thus demonstrating that their steady-state mRNA concentrations oscillated in a circadian manner. [Int Microbiol 2004; 7(2):127–131]

IS200: an old and still bacterial transposon

Abstract: IS200 is a mobile element found in a variety of eubacterial genera, such as Salmonella, Escherichia, Shigella, Vibrio, Enterococcus, Clostridium, Helicobacter, and Actinobacillus. In addition, IS200-like elements are found in archaea. IS200 elements are very small (707-711 bp) and contain a single gene. Cladograms constructed with IS200 DNA sequences suggest that IS200 has not spread among eubacteria by horizontal transfer; thus it may be an ancestral component of the bacterial genome. Self-restraint may have favored this evolutionary endurance; in fact, unlike typical mobile elements, IS200 transposes rarely. Tight repression of transposase synthesis is achieved by a combination of mechanisms: inefficient transcription, protection from impinging transcription by a transcriptional terminator, and repression of translation by a stem-loop mRNA structure. A consequence of IS200 self-restraint is that the number and distribution of IS200 elements remain fairly constant in natural populations of bacteria. This stability makes IS200 a suitable molecular marker for epidemiological and ecological studies, especially when the number of IS200 copies is high. In Salmonella enterica, IS200 fingerprinting is extensively used for strain discrimination.

An in vitro study of the susceptibility of mobile and cystic forms of Borrelia burgdorferi to tinidazole.

Abstract: The susceptibility of mobile and cystic forms of Borrelia burgdorferi to tinidazole (TZ) was examined. The minimal bactericidal concentration (MBC) of TZ against the mobile spirochetes was >128 μg/ml at 37°C in micro-oxic atmosphere when incubated for 14 days. TZ significantly reduced the conversion of mobile spirochetes to cystic forms during incubation. The MBC for older (10- months-old) cysts at 37°C in a micro-oxic atmosphere was >0.5 μg/ml, but >0.125 μg/ml for young (1-day-old) cysts. Acridine orange staining, dark-field microscopy and transmission electron microscopy revealed that, when the concentration of TZ was ≥ MBC, the contents of the cysts were partly degraded, core structures did not develop inside the young cysts, and the amount of RNA in these cysts decreased significantly. When cysts were exposed to TZ, both the spirochetal structures and core structures inside the cysts dissolved, and the production of blebs was significantly reduced. These observations may be valuable in the treatment of resistant infections caused by B. burgdorferi, and suggest that a combination of TZ and a macrolide antibiotic could eradicate both cystic and mobile forms of B. burgdorferi. [Int Microbiol 2004; 7(2):139–142]

Distribution of phototrophic populations and primary production in a microbial mat from the Ebro Delta, Spain.

Abstract: Microbial mats arising in the sand flats of the Ebro Delta (Tarragona, Spain) were investigated during the summer season, when the community was highly developed. These mats are composed of three pigmented layers of phototrophic organisms, an upper brown layer mainly composed of Lyngbya aestuarii and diatoms, an intermediate green layer of the cyanobacterium Microcoleus chthonoplastes, and an underlying pink layer of a so-far unidentified purple sulfur bacterium. In the photic zone, oxygenic phototrophs constitute about 58% of total photosynthetic biomass, measured as biovolume, and anoxygenic phototrophs represent 42%. Diatoms constitute 11.8% of the oxygenic biomass, M. chthonoplastes 61.2%, and L. aestuarii and coccoid cyanobacteria 20.6 and 6.4%, respectively. In this laminated community, organic matter has an autochthonous origin, and photosynthesis is the most important source of organic carbon. Oxygen production reaches up to 27.2 mmol O(2) m(-2) h(-1), measured at 1000 microE m(-2) s(-1) light intensity, whereas oxidation of sulfide in the light has been calculated to be 18.6 mmol S m(-2) h(-1). This amount represents 26% of the total photosynthetic production in terms of photoassimilated carbon, demonstrating the important role of anoxygenic phototrophs as primary producers in the pink layer of Ebro Delta microbial mats.

Open access: A turning point in scientific publication

Abstract: The birth of Open Access \" Open access \" is the term used to describe literature that is available to any reader at no cost on the Internet. The copyright owner—usually the author—allows the user to freely read, download, copy, print, distribute, search, link to the full text of the article, crawl it for indexing, convert the reported data to software, or use the article for any other lawful purpose. In open-access journals, authors either retain copyright or are asked to transfer the copyright to the publisher. In both cases, the copyright holder must consent to open access to the articles. The only role of copyright in open-access literature is to give authors control of the integrity of their work and the right to be properly acknowledged and cited [8]. Although open access is a concept that is most often applied to online publication, it is nonetheless compatible with print for those journals that also have a printed version. Open access is free of charge for readers of the online version, but does not exclude priced access to print versions of the same work. It all started in Budapest, on December 1–2, 2001, when leading proponents of a new initiative in scientific and scholarly publication and archiving gathered under the auspices of the Open Society Institute (OSI). The OSI was founded in 1993 by the investor and philanthropist George Soros to serve his foundations, which currently have expanded to more than fifty countries. OSI and the Soros foundations aim \" to promote open societies by shaping government policy and supporting education, media, public health and human and women's rights, as well as social, legal, and economic reform. \" The participants at the Budapest meeting, who had previous experience with the various initiatives discussed by the open-access movement, represented many organizations, scientific disciplines and countries. The objective of that meeting was to join efforts and unite the strategies of the separate initiatives into a plan of action aimed at achieving broader, deeper and more rapid success, and to determine how the resources of the OSI could be used to aid the cause of open access [1]. The primary outcome of the meeting was the Budapest Open Access Initiative (BOAI), which is a statement of principle, strategy and commitment. Since the BOAI was released, on February 14, 2002, around 270 organizations and 3400 individuals have added their names in support of the …

Fecal pollution in water from storm sewers and adjacent seashores in Natal, Rio Grande do Norte, Brazil.

Abstract: Summary. A study on the distribution patterns of enteropathogenic bacteria polluting the shoreline in Natal, Rio Grande do Norte, Brazil, was carried out based on 72 samples obtained from three storm sewers and adjoining beach locations, Praia do Meio (PM), Areia Preta (AP) and Ponta Negra (PN). From each location, 12 water samples were taken and analyzed for fecal coliforms (FC) and Escherichia coli. In AP, two (16.7%) of the seawater samples and five (41.7%) of the storm sewer samples yielded values above 1.1 × 10 7 FC/100 ml, whereas only one (8.3%) of the samples from PM reached this level. There was no correlation (p > 0.05) between rainfall indeces and FC values. A total of 64 E. coli isolates were obtained: 37 from the storm sewer samples and 27 from the seawater samples. Of these isolates, four (O143, two O112ac, and O124) were enteroinvasive and two (O111 and O125) were enteropathogenic. Resistance to antibiotics and to heavy metals was also analyzed. Almost 36% of the E. coli strains isolated were resistant to more than one antibiotic. All strains were resistant to zinc and copper at the highest concentration tested (250 µg/ml), and several (23.4%) were resistant to mercury at 50 µg/ml. Our results agreed with previous reports that antibiotic resistance is commonly associated with heavy-metal resistance in pathogens. [Int Microbiol 2004; 7(3):213–218]

Organic matter in meteorites

Abstract: Some primitive meteorites are carbon-rich objects containing a variety of organic molecules that constitute a valuable record of organic chemical evolution in the universe prior to the appearance of microorganisms. Families of compounds include hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, amino acids, amines, amides, heterocycles, phosphonic acids, sulfonic acids, sugar-related compounds and poorly defined high-molecular weight macromolecules. A variety of environments are required in order to explain this organic inventory, including interstellar processes, gas-grain reactions operating in the solar nebula, and hydrothermal alteration of parent bodies. Most likely, substantial amounts of such organic materials were delivered to the Earth via a late accretion, thereby providing organic compounds important for the emergence of life itself, or that served as a feedstock for further chemical evolution. This review discusses the organic content of primitive meteorites and their relevance to the build up of biomolecules. [Int Microbiol 2004; 7(4):239-248]

Producing a scientific journal in a small scientific community: an author-helpful policy

Abstract: Most scientific information is published in a small number of prestigious journals that address mainstream science [4]. At the same time, developing countries encompass almost a quarter of the world’s scientists but only less than 6% of research spending [4]. Journals from this “scientific periphery” [10] are poorly visible in the scientific community: the Science Citation Index (SCI), one of the most prestigious bibliographic databases, included less than 2% of journals in developing countries in 1995 [4]. We have previously described the vicious cycle of inadequacy for small journals from small scientific communities [4]: due to the small number and poor quality of manuscripts submitted, inadequate review process, and imperfect English, these journals cannot reach sufficient high visibility to attract better-quality reports and a broader readership, to become indexed, and thus to eventually escape from the shadow of anonymity [10]. We have also described our experience at the Croatian Medical Journal (CMJ) with breaking out of this vicious cycle [8,11,15,17]. During our work with Croatian authors during the war years from 1991 to 1995 [9,12,14], we developed an author-helpful editorial policya procedure with which most of the articles received were pre-reviewed intramurally and improved before being sent out for extramural review [11,14,17]. This scheme of work evolved naturally from our everyday practice, because our authors were mostly inexperienced scientists and writers, unaware of the importance of publishing and lacking the knowledge and technology for research planning. Thus, we had to embark on teaching not only scientific writing but also research planning, as well as data analysis and interpretation [13]. By taking on the role of educators, teaching both authors and undergraduate and postgraduate students how to write a scientific paper, we have helped them to produce and publish articles not only in the CMJ but also in many other international journals [8,14]. Such a policy has resulted in an enormous burden to the journal’s personnel, but also in a significant formal successthe inclusion of the CMJ in the most selective international indexing databases (MEDLINE in 1998, and Current

Functional characteristics of culturable bacterioplankton from marine and estuarine environments

Abstract: Information on the structure of bacterioplankton communities is continuously increasing, while knowledge of their metabolic capabilities remains limited. In this study, the metabolic capacity of bacterioplankton was investigated, as such information is necessary to fully understand carbon cycling and other biogeochemical processes. The diversity of dominant culturable chemoorganotrophic bacteria from one estuarine and three marine environments was analyzed by random isolation of colony-forming units on solid media, taxonomical identification by partial 16S rRNA gene sequence analysis, and functional characterization of the isolates. A total of 76 16S rRNA gene sequences, representing 19 different genotypes, were obtained from the four sampling localities, including Bacillus , Pseudomonas , Pseudoalteromonas , Vibrio , and Erythrobacter as the most frequently isolated genera. The range of metabolic functions possessed by the cultured bacterial assemblages differed significantly between sites. Similarly, the percentage at each sampling station of bacteria capable of performing a specific function was significantly different for 18 of the 25 investigated metabolic functions. At two localities, the bacterial assemblages were dominated by a single genus ( Pseudoalteromonas or Erythrobacter ) and appeared to be functionally specialized. More than 95% of the isolates were capable of utilizing dissolved free amino acids and protein as their sole nitrogen sources, and all isolates of the specialized assemblages expressed β-glucosidase. Furthermore, only some of the isolates were able to utilize NH4 + , while up to two thirds of the isolates of the two marine sites were able to grow on NO 3 – . [Int Microbiol 2004; 7(3):219–227]

G and P genotypes of rotavirus circulating among children with diarrhea in the Colombian northern coast.

Abstract: A study on the prevalence of rotavirus G and P genotypes was carried out based on 253 stool specimens obtained from children living in the Colombia northern coast region who were less than 3-years-old and who suffered from acute diarrhea. A previous study had detected the presence of rotavirus A in 90 (36.5%) of the 246 samples tested by enzyme immunoassay (EIA), and these strains were investigated in the present study. Of these, 50 strains yielded an RNA electropherotype, most of which (80.0%) had long profiles and 20.0% of which had short profiles. Genotyping of 84 positive samples indicated that 67.9% of the strains could be typed. G1 (57.9%), was the most predominant VP7 genotype, followed by G3 (21.1%), G9 (15.8%) and G2 (5.3%). Among the VP4 genotypes, P[4] (49.1%) was the most prevalent, followed by P[6] 36.4% and P[8] (14.5%). Neither G4 nor G8 nor P[9] types were detected. The most common G-P combinations were G3 P[4] (8.8%) and G9 P[6] (7.0%), followed by G1 P[4] and G1 P[8] (5.3% each). All G1 P[8] strains showed long RNA profiles, whereas G3 P[4] and G9 P[6] displayed both long and short patterns. Mixed infections involved 21.0% of strains. There was a marked diversity among strains collected, and novel strains, including G9, as well as other atypical combinations of G and P genotypes, such as G9 P[6] and G3 P[4], were found. [Int Microbiol 2004; 7(2):113-120]

Nucleotide sequence and expression of the ncr nickel and cobalt resistance in Hafnia alvei 5-5.

Abstract: Summary. The structural genes for the nickel and cobalt resistance of the conjugative plasmid pEJH 501 of Hafnia alvei 5-5, contained on a SalI-EcoRI fragment of 4.8 kb, were cloned and sequenced. The DNA sequence included five genes in the following order: ncrA, ncrB, ncrC, ncrY, and ncrX. The predicted amino acid sequences of ncrA were homologous to the amino acid sequences of nreB of Achromobacter xylosoxidans 31A. Expression of ncr with the T7 RNA polymerase-promoter system allowed Escherichia coli BL21 (DE3) to overexpress NcrA, NcrB, and NcrC but not NcrY, and NcrX. The apparent molecular masses of NcrA, NcrB, and NcrC were 30, 33, and 17 kDa, respectively. Primer-extension analysis showed that ncr mRNA started at nucleotide position 23 upstream from ncrA. The promoter region of the ncr operon possessed a strong, putative –35 element of σ 32 -type promoter sequence, and transcriptional 'lacZ fusion studies indicated that the –35 element influenced σ 32 -specific transcription. [Int Microbiol

Streptococcus pneumoniae and its bacteriophages: one long argument

Abstract: Infectious diseases currently kill more than 15 million people annually, and the WHO estimates that every year 1.6 million people die from pneumococcal diseases. Streptococcus pneumoniae (pneumococcus), a bacterium with a long biological pedigree, best illustrates the rapid evolution of antibiotic resistance, which has led to major public health concern. This article discusses the molecular basis of the two main virulence factors of pneumococcus, the capsule and cell-wall hydrolases, as well as new approaches to developing medicinal weapons for preventing pneumococcal infections. In addition, current knowledge regarding pneumococcal phages as potential contributors to virulence and the use of lytic enzymes encoded by these phages as therapeutic tools is reviewed.

Fe-Si biominerals in the Vilyuchinskie hot springs, Kamchatka Peninsula, Russia.

Abstract: The micromorphological structure of microbial mats (biomats) from the hot springs of the Vilyuchinskaya hydrothermal system, Kamchatka Peninsula, Russia, were investigated. The Vilyuchinskie hot springs had a discharge temperature of 55–56°C and Na-Ca-HCO 3 -type waters rich in silicic and boric acids. Water and biomats had high concentrations of Fe, Mn, Sr, and As. Enumeration of total bacterial abundance (TBA) demonstrated a low density of bacterial populations. However, the fractions of metabolically active bacteria and respiring iron-oxidizing bacteria in the hot-spring water were high, comprising 68 and 21% of TBA, respectively. Scanning electron microscopy equipped with an energy dispersive X-ray spectrometer (SEM-EDX) showed that unicellular rod-shaped bacteria about 5-μm long predominated in the brown biomats. The mineral capsules of these bacteria contained large amounts of Fe and Si. Extracellular and intracellular particles were observed by transmission electron microscopy. Fe-oxidizing bacteria were isolated from the biomats on agar plates with selective medium. Therefore, it can be concluded that microorganisms inhabiting the biomats of the Vilyuchinskie hot springs are essential for the deposition of Fe-minerals at neutral pH. [Int Microbiol 2004; 7(3):193–198]

Dynamics of CaCdc10, a septin of Candida albicans, in living cells and during infection.

Abstract: The morphogenetic program in the pathogenic fungus Candida albicans , including the dimorphic transition, is an interesting field of study, not only because it is absent in the commonly used model yeast Saccharomyces cerevisiae, but because of the close relationship between hyphal development and virulence of C. albicans. We studied one of the most important aspects of fungal morphogenesis-the septin ring–in C. albicans. By using a fusion construct to green fluorescent protein (GFP), the subcellular localization and dynamics of C. albicans Cdc10 in the different morphologies that this fungus is able to adopt was identified. The localization features reached were contrasted and compared with the results obtained from Candida cells directly extracted from an animal infection model under environmental conditions as similar as possible to the physiological conditions encountered by C. albicans during host infection. [Int Microbiol 2004; 7(2):105–112]