-
International Archives of Occupational... Aug 2022Gram-negative bacteria occur commonly in the inner tissues of stored coniferous and deciduous timber, showing a marked variation in numbers. The greatest maximal numbers... (Review)
Review
OCCURRENCE
Gram-negative bacteria occur commonly in the inner tissues of stored coniferous and deciduous timber, showing a marked variation in numbers. The greatest maximal numbers are found in the sapwood of coniferous timber. The common constituents of the Gram-negative biota are potentially pathogenic species of Enterobacteriaceae family of the genera Rahnella, Pantoea, Enterobacter, and Klebsiella. The air of wood-processing facilities is polluted with the wood-borne Gram-negative bacteria and produced by them endotoxin, as demonstrated worldwide by numerous studies.
EFFECTS
There are three potential pathways of the pathogenic impact of wood-borne Gram-negative bacteria on exposed woodworkers: allergic, immunotoxic, and infectious. Allergic impact has been underestimated for a long time with relation to Gram-negative bacteria. Hopefully, the recent demonstration of the first documented case of hypersensitivity pneumonitis (HP) in woodworkers caused by Pantoea agglomerans which developed in extremely large quantities in birch sapwood, would speed up finding of new wood-related cases of HP caused by Gram-negative bacteria. The second pathway is associated with endotoxin, exerting strong immunotoxic (excessively immunostimulative) action. It has been demonstrated that endotoxin is released into wood dust in the form of nano-sized microvesicles, by peeling off the outer membrane of bacteria. Endotoxin microvesicles are easily inhaled by humans together with dust because of small dimensions and aerodynamic shape. Afterwards, they cause a nonspecific activation of lung macrophages, which release numerous inflammatory mediators causing an inflammatory lung reaction, chest tightness, fever, gas exchange disorders, and bronchospasm, without radiographic changes. The resulting disease is known as "Organic Dust Toxic Syndrome" or "toxic pneumonitis." The potential third pathway of pathogenic impact is infection. The suspected species is Klebsiella pneumoniae that may occur commonly in wood dust; however, until now this pathway has not been confirmed.
CONCLUSION
Summarizing, Gram-negative bacteria-inhabiting timber should be considered, besides filamentous fungi and actinobacteria, as important risk factors of occupational disease in woodworkers that could be either HP with allergenic background or toxic pneumonitis elicited by endotoxin.
Topics: Bacteria; Dust; Endotoxins; Fungi; Gram-Negative Bacteria; Humans; Hypersensitivity; Occupational Exposure; Wood
PubMed: 35015109
DOI: 10.1007/s00420-021-01829-1 -
Microorganisms Apr 2022Bacterial endophytes were isolated from nodules of pea and fava bean. The strains were identified and characterized for plant beneficial activities (phosphate...
Bacterial endophytes were isolated from nodules of pea and fava bean. The strains were identified and characterized for plant beneficial activities (phosphate solubilization, synthesis of indole acetic acid and siderophores) and salt tolerance. Based on these data, four strains of and three strains of were selected. To shed light on the mechanisms underlying salt tolerance, the proteome of the two most performant strains (Ra4 and Sp2) grown in the presence or not of salt was characterized. The number of proteins expressed by the endophytes was higher in the presence of salt. The modulated proteome consisted of 302 (100 up-regulated, 202 down-regulated) and 323 (206 up-regulated, 117 down-regulated) proteins in Ra4 and Sp2, respectively. Overall, proteins involved in abiotic stress responses were up-regulated, while those involved in metabolism and flagellum structure were down-regulated. The main up-regulated proteins in Sp2 were thiol: disulfide interchange protein DsbA, required for the sulfur binding formation in periplasmic proteins, while in Ra4 corresponded to the soluble fraction of ABC transporters, having a role in compatible solute uptake. Our results demonstrated a conserved response to salt stress in the two taxonomically related species.
PubMed: 35630335
DOI: 10.3390/microorganisms10050890 -
PloS One 2023The role of bacterial microbiota in the pathogenesis of nontuberculous mycobacterial pulmonary disease (NTM-PD) is unclear. We aimed to compare the bacterial microbiome...
BACKGROUND
The role of bacterial microbiota in the pathogenesis of nontuberculous mycobacterial pulmonary disease (NTM-PD) is unclear. We aimed to compare the bacterial microbiome of disease-invaded lesions and non-invaded lung tissue from NTM-PD patients.
METHODS
We analyzed lung tissues from 23 NTM-PD patients who underwent surgical lung resection. Lung tissues were collected in pairs from each patient, with one sample from a disease-involved site and the other from a non-involved site. Lung tissue microbiome libraries were constructed using 16S rRNA gene sequences (V3-V4 regions).
RESULTS
Sixteen (70%) patients had Mycobacterium avium complex (MAC)-PD, and the remaining seven (30%) had Mycobacterium abscessus-PD. Compared to non-involved sites, involved sites showed greater species richness (ACE, Chao1, and Jackknife analyses, all p = 0.001); greater diversity on the Shannon index (p = 0.007); and genus-level differences (Jensen-Shannon, PERMANOVA p = 0.001). Analysis of taxonomic biomarkers using linear discriminant analysis (LDA) effect sizes (LEfSe) demonstrated that several genera, including Limnohabitans, Rahnella, Lachnospira, Flavobacterium, Megamonas, Gaiella, Subdoligranulum, Rheinheimera, Dorea, Collinsella, and Phascolarctobacterium, had significantly greater abundance in involved sites (LDA >3.00, p <0.05, and q <0.05). In contrast, Acinetobacter had significantly greater abundance at non-involved sites (LDA = 4.27, p<0.001, and q = 0.002). Several genera were differentially distributed between lung tissues from MAC-PD (n = 16) and M. abscessus-PD (n = 7), and between nodular bronchiectatic form (n = 12) and fibrocavitary form (n = 11) patients. However, there was no genus with a significant q-value.
CONCLUSIONS
We identified differential microbial distributions between disease-invaded and normal lung tissues from NTM-PD patients, and microbial diversity was significantly higher in disease-invaded tissues.
TRIAL REGISTRATION
Clinical Trial registration number: NCT00970801.
Topics: Humans; RNA, Ribosomal, 16S; Mycobacterium Infections, Nontuberculous; Mycobacterium avium Complex; Lung Diseases; Lung; Microbiota; Nontuberculous Mycobacteria
PubMed: 37235629
DOI: 10.1371/journal.pone.0285143 -
World Journal of Microbiology &... Jul 2017Acute oak decline (AOD) is a relatively newly described disorder affecting native oak species in Britain. Symptomatic trees are characterised by stem bleeds from... (Review)
Review
Acute oak decline (AOD) is a relatively newly described disorder affecting native oak species in Britain. Symptomatic trees are characterised by stem bleeds from vertical fissures, necrotic lesions in the live tissue beneath and larval galleries of the two spotted oak buprestid (Agrilus biguttatus). Several abiotic and biotic factors can be responsible for tree death, however the tissue necrosis and stem weeping is thought to be caused by a combination of bacterial species. Following investigations of the current episode of AOD which began in 2008, numerous strains belonging to several different bacteria in the family Enterobacteriaceae have been consistently isolated from symptomatic tissue. The majority of these enterobacteria were found to be novel species, subspecies and even genera, which have now been formally classified. The most frequently isolated species from symptomatic oak are Gibbsiella quercinecans, Brenneria goodwinii and Rahnella victoriana. Identification of these bacteria is difficult due to similarities in colony morphology, phenotypic profile and 16S rRNA gene sequences. Current identification relies heavily on gyrB gene amplification and sequencing, which is time consuming and laborious. However, newer techniques based on detection of single nucleotide polymorphisms show greater promise for rapid and reliable identification of the bacteria associated with AOD.
Topics: DNA Barcoding, Taxonomic; DNA, Bacterial; Enterobacteriaceae; Enterobacteriaceae Infections; Phylogeny; Plant Diseases; Polymorphism, Single Nucleotide; Quercus
PubMed: 28623563
DOI: 10.1007/s11274-017-2296-4 -
Foods (Basel, Switzerland) Oct 2021Fresh vegetables are an essential part of a healthy diet, but microbial contamination of fruits and vegetables is a serious concern to human health, not only for the...
Fresh vegetables are an essential part of a healthy diet, but microbial contamination of fruits and vegetables is a serious concern to human health, not only for the presence of foodborne pathogens but because they can be a vehicle for the transmission of antibiotic-resistant bacteria. This work aimed to investigate the importance of fresh produce in the transmission of extended-spectrum β-lactamases (ESBL)-producing . A total of 174 samples of vegetables (117) and farm environment (57) were analysed to determine enterobacterial contamination and presence of ESBL-producing . Enterobacterial counts above the detection limit were found in 82.9% vegetable samples and 36.8% environmental samples. The average count was 4.2 log cfu/g or mL, with a maximum value of 6.2 log cfu/g in a parsley sample. Leafy vegetables showed statistically significant higher mean counts than other vegetables. A total of 15 ESBL-producing isolates were obtained from vegetables (14) and water (1) samples and were identified as (11) and (4). Five isolates of were considered multi-drug resistant. Even though their implication in human infections is rare, they can become an environmental reservoir of antibiotic-resistance genes that can be further disseminated along the food chain.
PubMed: 34828891
DOI: 10.3390/foods10112609 -
Frontiers in Microbiology 2022is an entirely heterotrophic plant, the growth of which is completely reliant on , an orchid mycorrhizal fungus. To avoid damaging ecosystems, cultivation is shifting...
is an entirely heterotrophic plant, the growth of which is completely reliant on , an orchid mycorrhizal fungus. To avoid damaging ecosystems, cultivation is shifting from woodland to farmland. However, whether the microbial community structure remains stable during this conversation is unknown. Here, we cultivated in woodland or farmland and found that woodland-cultivated produced a greater yield and larger tuber size. The relative abundance of was 22.84- and 122.25-fold higher in woodland- and farmland-cultivated soil samples, respectively, than that in uncultivated soil samples. To investigate how impacts the growth of and establishes symbiosis with , three spp. strains (HPDA25, SBD3, and SBD11) were isolated from mycorrhizosphere soil samples. It was found that these strains, especially HPDA25, promoted the growth of . Ultra-performance liquid chromatography coupled to a triple quadrupole mass spectrometry analysis detected the indole-3-acetic acid with 16.24 ng/ml in HPDA25 fermentation solution. Co-culturing with the strain HPDA25 or exogenous indole-3-acetic acid increased the branching and fresh weight of rhizomorphs and the growth rate and extracellular laccase activity of , compared with cultured alone. The results of RNA-seq and quantitative real-time polymerase chain reaction analysis showed that co-culturing with HPDA25 increased the expression level of the genes including hydrophobin, SUR7/PalI family, and pectin methylesterase, whereas decreased the expression levels of glycolysis-related genes. Furthermore, co-culturing with the strain HPDA25, promotes the growth of and enhances the tuber size of . These results provide new insights into an orchid mycorrhizal symbiosis and the cultivation of .
PubMed: 35401480
DOI: 10.3389/fmicb.2022.842893 -
BMC Genomics Mar 2024Rahnella perminowiae S11P1 and Variovorax sp. S12S4 are two plant growth-promoting rhizobacteria that were previously isolated from the rhizosphere of Crocus sativus L....
Functional analysis and comparative genomics of Rahnella perminowiae S11P1 and Variovorax sp. S12S4, two plant growth-promoting rhizobacteria isolated from Crocus sativus L. (saffron) rhizosphere.
BACKGROUND
Rahnella perminowiae S11P1 and Variovorax sp. S12S4 are two plant growth-promoting rhizobacteria that were previously isolated from the rhizosphere of Crocus sativus L. (saffron), and have demonstrated interesting PGP activities and promising results when used as inoculants in field trials. To further elucidate the molecular mechanisms underlying their beneficial effects on plant growth, comprehensive genome mining of S11P1 and S12S4 and comparative genomic analysis with closely related strains were conducted.
RESULTS
Functional annotation of the two strains predicted a large number of genes involved in auxin and siderophore production, nitrogen fixation, sulfur metabolism, organic acid biosynthesis, pyrroloquinoline quinone production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, volatile organic compounds production, and polyamine biosynthesis. In addition, numerous genes implicated in plant-bacteria interactions, such as those involved in chemotaxis and quorum sensing, were predicted. Moreover, the two strains carried genes involved in bacterial fitness under abiotic stress conditions. Comparative genomic analysis revealed an open pan-genomic structure for the two strains. COG annotation showed that higher fractions of core and accessory genes were involved in the metabolism and transport of carbohydrates and amino acids, suggesting the metabolic versatility of the two strains as effective rhizosphere colonizers. Furthermore, this study reports the first comparison of Multilocus sequence analysis (MLSA) and core-based phylogenies of the Rahnella and Variovorax genera.
CONCLUSIONS
The present study unveils the molecular mechanisms underlying plant growth promotion and biocontrol activity of S11P1 and S12S4, and provides a basis for their further biotechnological application in agriculture.
Topics: Crocus; Rahnella; Rhizosphere; Plant Development; Bacteria; Genomics; Alphaproteobacteria; Plant Roots; Soil Microbiology
PubMed: 38500021
DOI: 10.1186/s12864-024-10088-6 -
Scientific Reports Jul 2023Persian walnut (Juglans regia) has a considerable economic importance worldwide. However, the vigor and vitality of walnut trees were heavily affected by bark canker...
Persian walnut (Juglans regia) has a considerable economic importance worldwide. However, the vigor and vitality of walnut trees were heavily affected by bark canker during the last few years. Irregular longitudinal cankers in the outer bark, stem tissue necrosis, and bleeding with black-colored exudates walnut trees were observed in Kermanshah, Hamedan, Markazi, Alborz, Isfahan, Qom, Semnan, and Razavi Khorasan provinces in western, central and eastern Iran during 2018 and 2019. A total of 150 symptomatic samples were collected from affected walnut trees in order to identify bacteria associated with walnut decline. Two-hundred sixty strains with a metallic green sheen were isolated on EMB-agar medium. The pathogenicity of all strains was proved by inoculating a suspension of the bacterial strains under the bark of immature walnut fruits cv. 'Hartley'. Ninety-five strains caused necrosis and a dark-colored region in the mesocarp around the inoculation site 14 days post-inoculation. Moreover, 12 representative strains induced necrotic and black-colored tissues in the bark of young green twigs of two-year old walnut seedling cv. 'Chandler'. The strains were classified into four categories based on conventional phenotypic characters confirmed with the 16S rRNA gene sequences. A phylogenetic tree based on the concatenated sequences of two housekeeping gene fragments, gyrB and infB, indicated that strains including I1, Q6, and S6 were grouped in a cluster with Gibbsiella quercinecans FBR97 as well as strains I2, I5, and KE6 were clustered with Rahnella victoriana FRB 225. Moreover, strains MR1, MR3, and MR5 were grouped with the Enterobacter hormaechei subsp. hoffmannii DSM 14563. The phylogenetic analyses based on the partial sequencing of housekeeping genes including fusA, pyrG, and leuS revealed that strains KH1, KH3, and KH7 belong to Citrobacter braakii species. To the best of our knowledge, this is the first report of C. braakii and E. hormaechei as plant pathogens and R. victoriana associated with walnut decline.
Topics: Juglans; Phylogeny; RNA, Ribosomal, 16S; Necrosis
PubMed: 37438442
DOI: 10.1038/s41598-023-38427-9 -
The American Journal of Case Reports Apr 2021BACKGROUND Rahnella aquatilis is a facultatively anaerobic, gram-negative rod bacterium commonly found in freshwater. There are few cases of bacteremia caused by...
BACKGROUND Rahnella aquatilis is a facultatively anaerobic, gram-negative rod bacterium commonly found in freshwater. There are few cases of bacteremia caused by Rahnella aquatilis in the literature and even fewer cases reported of it causing sepsis in immunocompetent individuals. In this case report, we present a rare case of an immunocompetent individual who developed sepsis secondary to bacteremia caused by Rahnella aquatilis. CASE REPORT A 37-year-old immunocompetent man with cerebral palsy and chronic enterocutaneous fistulas, with an indwelling peripherally inserted central catheter (PICC) line for total parenteral nutrition (TPN), presented to the emergency department with complaints of increased enteric drainage from his fistula, rigors, and subjective fevers following a mechanical fall, which occurred approximately 1 week before. The day following admission, the patient developed septic shock and was transferred to the intensive care unit for vasopressor support. He was given intravenous cefepime and metronidazole for empiric therapy. Blood cultures grew Rahnella aquatilis, and antibiotic therapy was de-escalated to monotherapy with intravenous ceftriaxone. The patient's condition stabilized, his PICC line was replaced, and he was successfully discharged, and continued on outpatient antibiotic therapy with ceftriaxone. CONCLUSIONS This case report represents a novel presentation of septic shock secondary to bacteremia caused by a gram-negative rod bacterium, Rahnella aquatilis, in an immunocompetent host dependent on TPN via a PICC line. This case also demonstrates that Rahnella aquatilis can be susceptible to and treated successfully with intravenous ceftriaxone. Bacteremia caused by Rahnella aquatilis can cause a swift, aggressive decompensation and should be treated with antibiotics immediately.
Topics: Adult; Anti-Bacterial Agents; Bacteremia; Cerebral Palsy; Gram-Negative Bacterial Infections; Humans; Immunocompetence; Male; Rahnella; Shock, Septic
PubMed: 33861730
DOI: 10.12659/AJCR.930888 -
BMC Microbiology Feb 2010Rahnella is a widely distributed genus belonging to the Enterobacteriaceae and frequently present on vegetables. Although Rahnella has interesting agro-economical and...
BACKGROUND
Rahnella is a widely distributed genus belonging to the Enterobacteriaceae and frequently present on vegetables. Although Rahnella has interesting agro-economical and industrial properties and several strains possess antibiotic resistances and toxin genes which might spread within microbial communities, little is known about plasmids of this genus. Thus, we isolated a number of Rahnella strains and investigated their complements of small plasmids.
RESULTS
In total 53 strains were investigated and 11 plasmids observed. Seven belonged to the ColE1 family; one was ColE2-like and three shared homology to rolling circle plasmids. One of them belonged to the pC194/pUB110 family and two showed similarity to poorly characterised plasmid groups. The G+C content of two rolling circle plasmids deviated considerably from that of Rahnella, indicating that their usual hosts might belong to other genera. Most ColE1-like plasmids formed a subgroup within the ColE1 family that seems to be fairly specific for Rahnella. Intriguingly, the multimer resolution sites of all ColE1-like plasmids had the same orientation with respect to the origin of replication. This arrangement might be necessary to prevent inappropriate synthesis of a small regulatory RNA that regulates cell division. Although the ColE1-like plasmids did not possess any mobilisation system, they shared large parts with high sequence identity in coding and non-coding regions. In addition, highly homologous regions of plasmids isolated from Rahnella and the chromosomes of Erwinia tasmaniensis and Photorhabdus luminescens could be identified.
CONCLUSIONS
For the genus Rahnella we observed plasmid-containing isolates at a frequency of 19%, which is in the average range for Enterobacteriaceae. These plasmids belonged to different groups with members of the ColE1-family most frequently found. Regions of striking sequence homology of plasmids and bacterial chromosomes highlight the importance of plasmids for lateral gene transfer (including chromosomal sequences) to distinct genera.
Topics: Bacterial Proteins; Base Sequence; Cloning, Molecular; Gene Transfer, Horizontal; Models, Genetic; Molecular Sequence Data; Multigene Family; Phylogeny; Plasmids; Rahnella; Sequence Alignment; Vegetables
PubMed: 20170524
DOI: 10.1186/1471-2180-10-56