The aeroponic rhizosphere microbiome: community dynamics in early succession suggest strong selectional forces.

In the last decade there has been increased interest in the manipulation of rhizosphere microbial communities in soilless systems (hydroponics) through the addition of plant growth promoting microbes (PGPMs) to increase plant nutrition, lower plant stress response, and control pathogens. This method of crop management requires documenting patterns in communities living in plant roots throughout the growing season to inform decisions on timing of application and composition of the supplemental PGPM consortium. As a contribution to this effort, we measured changes in the bacterial community through early succession (first 26 days) in plant root biofilms growing in an indoor commercial aeroponic system where roots were sprayed with a mist of nutrient-amended water. By 12 days following seed germination, a root-associated community had established that was distinct from the source communities found circulating in the system. Successional patterns in the community over the following 2 weeks (12-26 days) included changes in abundance of bacterial groups that have been documented in published literature as able to utilize plant root exudates, release plant hormones, or augment nutrient availability. Six bacterial families/genera (Hydrogenophilaceae, Rhizobium, Legionellaceae, Methylophilus, Massilia, or Herbaspirillum) were the most abundant in each root sample, comprising 8-37% of the microbiome. Given the absence of soil-associated microbial communities in hydroponic systems, they provide an ideal design for isolating plant-microbial interactions and identifying key components possibly contributing to plant health.

Taking a Closer Look at the Valid Publication and Authorship of Legionella bozemanae Brenner et al. 1980, Fluoribacter bozemanae Garrity et al. 1980, Legionella pittsburghensis Pasculle et al. 1980, Legionella micdadei Hébert et al. 1980 and Tatlockia micdadei (Hébert et al. 1980) Garrity et al. 1980.

The names Legionella bozemanae Brenner et al. 1980, Fluoribacter bozemanae Garrity et al. 1980, Legionella pittsburghensis Pasculle et al. 1980, Legionella micdadei Hébert et al. 1980 and Tatlockia micdadei (Hébert et al. 1980) Garrity et al. 1980, all appeared in the same issue of the International Journal of Systematic Bacteriology. Fluoribacter bozemanae Garrity et al. 1980 appeared as the name of new taxon at the rank of species and Tatlockia micdadei (Hébert et al. 1980) Garrity et al. 1980 as a new combination, both in the same original article in the International Journal of Systematic Bacteriology. The names Legionella bozemanae Brenner et al. 1980 (originally published as Legionella bozemanii) Legionella pittsburghensis Pasculle et al. 1980 (originally published as Legionella pittsburgensis) and Legionella micdadei Hébert et al. 1980, all appeared initially in effective publications outside of the International Journal of Systematic Bacteriology and were validly published by inclusion in Validation List no 5. While it is evident from the inclusion of the names Legionella bozemanae Brenner et al. 1980, Legionella pittsburghensis Pasculle et al. 1980 and Legionella micdadei Hébert et al. 1980 on Validation List no. 5 that the authors were following the 1975 revision of the International Code of Nomenclature of Bacteria, the wording of Garrity et al. 1980 indicates that they were following the interpretation found in the 1966 revision of the International Code of Nomenclature of Bacteria. Changes to the International Code of Nomenclature of Bacteria between the 1966 and 1975 revisions introduced new criteria for the valid publication of names. In particular, there was a change from all effective publications being accepted as the publication in which valid publication of a name could occur to only one journal being accepted as the publication in which valid publication could occur (the International Journal of Systematic Bacteriology, now the International Journal of Systematic and Evolutionary Microbiology). This change has a direct effect on the order of valid publication of the names Legionella bozemanae Brenner et al. 1980, Fluoribacter bozemanae Garrity et al. 1980, Legionella pittsburghensis Pasculle et al. 1980, Legionella micdadei Hébert et al. 1980 and Tatlockia micdadei (Hébert et al. 1980) Garrity et al. 1980, their authorships, as well as determining which names should be treated as names of new taxa at the rank of species (sp. nov.) vs new combinations (comb. nov.) based on the names of existing taxa. Given the fact that Legionella pittsburghensis Pasculle et al. 1980, Legionella micdadei Hébert et al. 1980 and Tatlockia micdadei (Hébert et al. 1980) Garrity et al. 1980 share the same nomenclatural type, this also has an influence on which epithet has priority and which epithet is illegitimate.

Detection of novel Chlamydiae and Legionellales from human nasal samples of healthy volunteers.

Chlamydiae are intracellular bacterial parasites of eukaryotes, ranging from amoebae to humans. They comprise many novel members and are investigated as emerging pathogens. Environmental studies highlighted similarities between the ecologies of chlamydiae and legionellae, both groups being important agents of respiratory infections. Herein, we analyzed nasal samples from healthy persons, searching for the presence of amoebae, chlamydiae and legionellae. From a total of 25 samples, we recovered by PCR eight samples positive to chlamydiae and six samples positive to legionellae. Among these samples, four were positive to both organisms. The sequencing of 16S rDNAs allowed to identify (i) among Chlamydiae: Parachlamydia acanthamoebae, Chlamydophila psittaci, Chlamydophila felis, and members of Rhabdochlamydiaceae, Simkaniaceae and E6 lineage and (ii) among Legionellaceae: Legionella longbeachae, Legionella bozemanii and Legionella impletisoli. Unexpectedly, we also recovered Diplorickettsia sp. Amoebae collected from nasal mucosae, Acanthamoeba and Vermamoeba, were endosymbiont-free, and chlamydiae revealed refractory to amoeba coculture. This study shows common exposure to chlamydiae and legionellae and suggests open air activities like gardening as a probable additional source of infection.

Aetiology, source and prevention of waterborne healthcare-associated infections: a review.

The purpose of this review is to discuss the scientific literature on waterborne healthcare-associated infections (HCAIs) published from 1990 to 2012. The review focuses on aquatic bacteria and describes both outbreaks and single cases in relation to patient characteristics, the settings and contaminated sources. An overview of diagnostic methods and environmental investigations is summarized in order to provide guidance for future case investigations. Lastly, on the basis of the prevention and control measures adopted, information and recommendations are given. A total of 125 reports were included, 41 describing hospitalized children. All cases were sustained by opportunistic pathogens, mainly Legionellaceae, Pseudomonadaceae and Burkholderiaceae. Hot-water distribution systems were the primary source of legionnaires' disease, bottled water was mainly colonized by Pseudomonaceae, and Burkholderiaceae were the leading cause of distilled and sterile water contamination. The intensive care unit was the most frequently involved setting, but patient characteristics were the main risk factor, independent of the ward. As it is difficult to avoid water contamination by microbes and disinfection treatments may be insufficient to control the risk of infection, a proactive preventive plan should be put in place. Nursing staff should pay special attention to children and immunosuppressed patients in terms of tap-water exposure and also their personal hygiene, and should regularly use sterile water for rinsing/cleaning devices.

Occurrence and diversity of Legionellaceae in polar lakes of the Antarctic peninsula.

Legionellaceae is a family of gram-negative, mesophilic, and facultative intracellular parasitic bacteria that inhabits freshwater environments. In this article, the Legionella population of water samples from the North and South Lake, located close to the Brazilian Scientific Station on King George Island, Keller Peninsula, Antarctica has been characterized. Culture onto selective medium and a independent-culture method were applied to the samples. In our attempt to isolate Legionella species from Antarctic lakes, we were able to obtain one L. pneumophila colony by an amoebic coculture procedure followed by plate culture onto a selective medium. In addition, results obtained from phylogenetic inference showed the presence of noncharacterized specimens of Legionella spp. These findings indicated the presence of legionellae in Antarctica and suggest that these bacteria can adapt to extreme conditions and open new possibilities for understanding the survival strategies of mesophilic Legionellaceae living in Antarctic environments. Furthermore, the isolation of these symbiotic bacteria in Antarctic lakes will allow future studies on cold-resistant mechanisms of legionellae in polar environments.

Characterization of members of the Legionellaceae family by automated ribotyping.

In order to implement a new and reliable method for characterizing different species of Legionella, a genetic fingerprinting study with an automated ribotyping system (RiboPrinter) was completed with members of this genus which were deposited at the American Type Culture Collection. The RiboPrinter examined the different patterns of EcoRI digestion fragments from the rRNA operons of 110 strains, representing 48 of the 49 described Legionella species as well as 70 serogroups of those species. Distinctive and consistent patterns were obtained for the type strains of the 48 species investigated. Legionella pneumophila subsp. fraseri and L. pneumophila subsp. pascullei each generated a specific pattern, whereas L. pneumophila subsp. pneumophila produced six different fingerprint patterns. No correlation seemed to exist between the ribotypes obtained and the 15 serotypes of L. pneumophila. For the other species, those with two known serogroups presented two distinctive patterns with the RiboPrinter with the exception of L. hackeliae and L. quinlivanii, which yielded only one pattern. We also encountered ribotypes for strains which were not identified to the species level. The ribotypes generated for these strains with the RiboPrinter did not match those generated for known type strains, suggesting the putative description of new serogroups or species. Although the automated system did not have sufficient discriminatory ability to serve as an epidemiological tool in a clinical setting, it appeared to be a powerful tool for general genomic analysis of the Legionella isolates (e.g., determination of new species) and assessment of the interrelationship among Legionella strains through the RiboPrinter database connection.

Presence of Legionellaceae in warm water supplies and typing of strains by polymerase chain reaction.

Outbreaks of Legionnaire's disease present a public health challenge especially because fatal outcomes still remain frequent. The aim of this study was to describe the abundance and epidemiology of Legionellaceae in the human-made environment. Water was sampled from hot-water taps in private and public buildings across the area of Göttingen, Germany, including distant suburbs. Following isolation, we used polymerase chain reaction in order to generate strain specific banding profiles of legionella isolates. In total, 70 buildings were examined. Of these 18 (26%) had the bacterium in at least one water sample. Legionella pneumophila serogroups 1, 4, 5 and 6 could be identified in the water samples. Most of the buildings were colonized solely by one distinct strain, as proven by PCR. In three cases equal patterns were found in separate buildings. There were two buildings in this study where isolates with different serogroups were found at the same time.

Distribution of mip-related sequences in 39 species (48 serogroups) of Legionellaceae.

The macrophage infectivity potentiator gene (mip) from Legionella pneumophila is a major virulence factor of the species. Thus, mip-detection by amplification has been proposed to assess the presence of L. pneumophila in clinical and environmental samples. The distribution of mip-related sequences within the Legionellaceae was studied by DNA amplification using mip-specific primers followed by Southern blot hybridization with an internal probe. Thirty-nine species (48 serogroups) of Legionellaceae were screened in this attempt. Using this approach, sequences related to mip were observed in 89% of the tested species including the most recently described L. fairfieldensis, L. lansingensis and L. shakespearei. In several cases, cloning and sequencing of the amplified products confirmed the high levels of similarity between the sequence found in non-pneumophila species with that of the L. pneumophila mip gene. This confirms previous reports that mip related genes are widespread among Legionellaceae and therefore specific detection of the species L. pneumophila cannot be based on mip-targeted amplification.

Intergenic 16S rRNA gene (rDNA)-23S rDNA sequence length polymorphisms in members of the family Legionellaceae.

A method based on PCR amplification of the 16S rRNA gene (rDNA)-23S rDNA intergenic regions was developed for the identification of species within the family Legionellaceae. The sizes of the PCR products varied from 1,353 to 350 bp. Strains of Legionella pneumophila were characterized as having products of approximately 900 and 530 bp, and L. birminghamensis had products of 1,390, 960, and 380 bp. Of the 38 species of legionellae examined, only 7 were indistinguishable (L. erythra from L. rubrilucens, L. anisa or L. cherrii from L. tucsonensis, and L. quateirensis from L. shakespearei). Two environmental isolates were identified as L. pneumophila. Strain LLAP-3, which was a symbiont of amoebae, could not be associated with any Legionella sp. studied.

Restriction fragment length polymorphism of rRNA genes for molecular typing of members of the family Legionellaceae.

Typing of Legionella pneumophila remains important in the investigation of outbreaks of Legionnaires' disease and in the control of organisms contaminating hospital water. We found that the discriminatory power of a nonradioactive ribotyping method could be improved by combining results obtained with four restriction enzymes (HindIII, NciI, ClaI, and PstI). Fifty-eight clinical and environmental L. pneumophila strains including geographically unrelated as well as epidemiologically connected isolates were investigated. Epidemiologically related strains had the same ribotypes independent of the combinations of enzymes used. Some strains belonging to the same serogroup were assigned to different ribotypes, and some ribotypes contained members of different serogroups, indicating, as others have found, that serogroup and genotype are not always related. The discriminatory power of the method was estimated by calculating an index of discrimination (ID) for individual enzymes and combinations thereof. The combined result with all four enzymes was highly discriminatory (ID = 0.97), but results for three enzymes also yielded ID values acceptable for epidemiological purposes. In addition, the testing of 27 type strains and 6 clinical isolates representing Legionella species other than L. pneumophila indicated that ribotyping might be of value for species identification within this genus, as previously suggested.

Properties of the genus Tatlockia. Differentiation of Tatlockia (Legionella) maceachernii and micdadei from each other and from other legionellae.

The biochemical reactions, carbohydrate content, and 16S-rRNA sequences of Tatlockia (Legionella) maceachernii and Tatlockia micdadei strains were studied. Except for catalase activity, Tatlockia strains were relatively inert in the biochemical tests commonly used in clinical laboratories. Phenotypically, the two Tatlockia species could be distinguished from other legionellae by the presence of yersiniose A, by their inability to hydrolyze hippurate or starch, by the absence of colony or media fluorescence, and by the absence of distinct browning of tyrosine-containing medium. These two species differed from one another by the production of acetoin by T. micdadei but not by T. maceachernii. Gelatinase activity, which had been reported in T. maceachernii, was observed in only one of the four strains studied. The 16S-rRNA sequences and carbohydrate profiles of T. maceachernii and T. micdadei were essentially identical. In preparing the RNA for study, it was noted that the 23S rRNA was fragmented in all T. maceachernii strains tested, while the 23S rRNA of T. micdadei strains was intact. Among the legionellae studied, T. maceachernii was most closely related to T. micdadei.

[The epidemiological, clinical, diagnostic and treatment aspects of Legionella infection]. / Epidemiologicheskie, klinicheskie, diagnosticheskie i lechebnye aspekty legionelleznoi infektsii.

The article studies the modern problems of legionellosis infection and gives data concerning epidemiological aspects of this disease, especially clinical course of its types (pneumonia, acute respiratory viral infection syndrome, alveolitis, pleuritis), as well as methods of bacteriological and serological diagnostics, and etiotropic treatment. The authors use their own materials to describe the restricted outbreak of legionellosis infection and sporadic cases of this disease. The article makes clinic classification of legionellosis taking into account various publications and the proper experience of the authors.