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Brazilian Journal of Microbiology :... Jun 2022The genus Raoultella spp. is comprised of four species, namely, R. electrica, R. ornithinolytica, R. planticola, and R. terrigena, which are rarely reported to cause...
The genus Raoultella spp. is comprised of four species, namely, R. electrica, R. ornithinolytica, R. planticola, and R. terrigena, which are rarely reported to cause infections in humans. This study aimed to characterize six strains of Raoultella spp. isolated from stool samples from patients with diarrhea. The strains included in the study were previously identified by biochemical methods as K. pneumoniae, during a surveillance study conducted in 1987. In the present study, the strains were re-identified by MALDI TOF and 16S rRNA sequencing and subsequently subjected to virulence gene screening by PCR, hemolytic activity, biofilm formation, hypermucoviscosity phenotype, capacity to interact with Caco-2 cells, and antimicrobial susceptibility test. Our results revealed that, among the six strains, three were identified as R. ornithinolytica and three as R. planticola. The genes related to iron uptake systems (aero1, aero2, iutA, entB, and ybtS) and adhesin (mrkD) were found in all strains. Furthermore, all strains demonstrated the ability to interact in vitro with Caco-2 cells and form biofilms. In general, the strains studied were sensitive to the antimicrobials tested; however, it was possible to observe high MICs for imipenem compared to ertapenem and meropenem and high minimal inhibitory concentrations (MICs) for ceftazidime, except for one strain. Our results show the occurrence of virulent strains of Raoultella spp. with high MICs for imipenem and ceftazidime causing diarrhea. We hope that our findings can contribute to the understanding of the evolution of this species since, as far as we know, these are the oldest isolates reported so far.
Topics: Anti-Bacterial Agents; Caco-2 Cells; Ceftazidime; Diarrhea; Enterobacteriaceae; Humans; Imipenem; Klebsiella pneumoniae; Microbial Sensitivity Tests; RNA, Ribosomal, 16S
PubMed: 35138632
DOI: 10.1007/s42770-022-00699-0 -
Microorganisms Mar 2022Although (nasturtium) is an agriculturally and economically important plant, especially due to the presence of edible flowers and its medicinal properties, its...
Although (nasturtium) is an agriculturally and economically important plant, especially due to the presence of edible flowers and its medicinal properties, its microbiome is quite unexplored. Here, the structure of the total bacterial community associated with the rhizosphere, endosphere and bulk soil of was determined by 16S rRNA amplicon metagenomic sequencing. A decrease in diversity and richness from bulk soil to the rhizosphere and from the rhizosphere to the endosphere was observed in the alpha diversity analyses. The phylum Proteobacteria was the most dominant in the bacteriome of the three sites evaluated, whereas the genera and showed a significantly higher relative abundance in the rhizosphere and endosphere communities, respectively. Plant growth-promoting bacteria (236 PGPB) were also isolated from the endosphere, and 76 strains belonging to 11 different genera, mostly , and , showed positive results for at least four out of six plant growth-promoting tests performed. The selection of PGPB associated with can result in the development of a biofertilizer with activity against phytopathogens and capable of favoring the development of this important plant.
PubMed: 35336212
DOI: 10.3390/microorganisms10030638 -
Journal of Dairy Science Mar 2021Milk fan is a cheese-like fermented milk product produced in Yunnan Province, China. In this study, we characterized the microbial communities of milk fan from 6... (Review)
Review
Milk fan is a cheese-like fermented milk product produced in Yunnan Province, China. In this study, we characterized the microbial communities of milk fan from 6 distinct geographical origins and investigated their generation of volatile organic compounds (VOC). The microbial communities found in all milk fan samples were dominated by Lactococcus, Lactobacillus, and Raoultella bacteria and Rhodotorula, Torulaspora, and Candida fungi. Samples from the Kunming and Weishan regions had greater bacterial richness, and samples from Xizhou had greater fungal community richness. Sixty prominent VOC (i.e., those having odor activity values ≥1), including esters, acids, alcohols, aldehydes, ketones, and aromatic compounds, were identified by gas chromatography-mass spectrometry analysis of milk fan samples. Pearson correlation analysis revealed that Lactobacillus, Rhodotorula, Lodderomyces, and Debaryomyces had significant correlations with various VOC, revealing a total of 13 compounds that are characteristic of the odor of milk fan. These bacteria and fungi are therefore identified as functional microorganisms that collectively create the complex VOC profile of milk fan. This study provides a comprehensive overview of the microbial community of milk fan and demonstrates its contribution to the unique aroma profile of this fermented milk product.
Topics: Animals; Cheese; China; Microbiota; Milk; Volatile Organic Compounds
PubMed: 33358802
DOI: 10.3168/jds.2020-19053 -
Molecular Microbiology Jul 2021Guanidine is sensed by at least four different classes of riboswitches that are widespread in bacteria. However, only very few insights into physiological roles of...
Guanidine is sensed by at least four different classes of riboswitches that are widespread in bacteria. However, only very few insights into physiological roles of guanidine exist. Genes predominantly regulated by guanidine riboswitches are Gdx transporters exporting the compound from the bacterial cell. In addition, urea/guanidine carboxylases and associated hydrolases and ABC transporters are often found combined in guanidine-inducible operons. We noted that the associated ABC transporters are configured to function as importers, challenging the current view that riboswitches solely control the detoxification of guanidine in bacteria. We demonstrate that the carboxylase pathway enables utilization of guanidine as sole nitrogen source. We isolated three enterobacteria (Raoultella terrigena, Klebsiella michiganensis, and Erwinia rhapontici) that utilize guanidine efficiently as N-source. Proteome analyses show that the expression of a carboxylase, associated hydrolases and transport genes is strongly induced by guanidine. Finding two urea/guanidine carboxylase enzymes in E. rhapontici, we demonstrate that the riboswitch-controlled carboxylase displays specificity toward guanidine, whereas the other enzyme prefers urea. We characterize the distribution of riboswitch-associated carboxylases and Gdx exporters in bacterial habitats by analyzing available metagenome data. The findings represent a paradigm shift from riboswitch-controlled detoxification of guanidine to the uptake and assimilation of this enigmatic nitrogen-rich compound.
Topics: Carbon-Nitrogen Ligases; Energy Metabolism; Enterobacteriaceae; Erwinia; Gene Expression Regulation, Bacterial; Guanidine; Hydrolases; Klebsiella; Membrane Transport Proteins; Riboswitch
PubMed: 33590553
DOI: 10.1111/mmi.14702 -
Archivos Espanoles de Urologia Apr 2021Emerging urinary infections by rare germs are a public health problem. The objectives of this article are to review urinary tract infections caused by an emerging... (Review)
Review
OBJECTIVES
Emerging urinary infections by rare germs are a public health problem. The objectives of this article are to review urinary tract infections caused by an emerging genus of bacteria called Raoultella and to report a case of asymptomatic urinary tract infection by Raoultella ornithinolytica.
MATERIALS AND METHODS
A review of publications on urinary tract infections caused by the genus Raoultella between 2009 and 2018 is carried out and a case of asymptomatic urinary tract infection by Raoultella ornithinolytica is reported. The search of articles in Medline/ Pubmed and Google was performed with the keywords: Raoultella, Raoultella ornithinolytica, urinary tract infection. Twelve variables were studied: year of publication, authors, specialty, type of infection, number of cases, sex, age, immunosuppression, oncological patient, urological instrumentation, urological surgery and neurogenic bladder. Results were analyzed using descriptive statistics. A new case is described.
RESULTS
24 publications were found with 120 cases of urinary infections of the genus Raoultella between 2009 and 2018, corresponding to Raoultella ornithinolytica 40.8%, Raoultella planticola 28.3%, Raoultella terrigena 30.8% and Raoultella electrica 0%. The series included 43 men (35.8%), 53 women (44.1%) and 24 patients with this data not provided (20%). The minimum age was 14 days, the maximum was 97 years and the average age was 56.6. The types of infection detected were: uncomplicated UTI 94.1%, UTI in newborn 1.6%, acute prostatitis 0.8%, chronic prostatitis 0.8%, giant kidney cyst infection 0.8%, calculous pyelonephritis 0.8% and recurrent cystitis 0.8%.
CONCLUSIONS
Urinary tract infections by species of the genus Raoultella occur in immunocompromised, oncological, instrumented or basic urological patients. The species Raoultella ornithinolytica described in 2011 is an emerging germ in urinary infections. This contribution is the second Spanish publication and twelfth worldwide of urinary infection by Raoultella ornithinolytica.
Topics: Aged, 80 and over; Anti-Bacterial Agents; Enterobacteriaceae; Enterobacteriaceae Infections; Female; Humans; Infant, Newborn; Male; Middle Aged; Urinary Tract Infections
PubMed: 33818423
DOI: No ID Found -
International Journal of Food... Jun 2023Interaction between Listeria monocytogenes and resident background microbiota may occur in food processing environments and may influence the survival of this pathogen...
Interaction between Listeria monocytogenes and resident background microbiota may occur in food processing environments and may influence the survival of this pathogen in a factory environment. Therefore the aim of this study was to characterize the growth performance of microbiota isolated from the processing environments of frozen sliced mushrooms, and to investigate the competitive performance of L. monocytogenes when co-cultured with accompanying environmental microbiota. Acinetobacter, Enterobacteriaceae, Lactococcus and Pseudomonas were the most prominent background microbiota isolated from the processing environment of frozen sliced mushrooms. All individual microbiota strains were able to grow and form biofilm in filter-sterilized mushroom medium, with the mannitol-consumers Raoultella and Ewingella as top performers, reaching up to 9.6 and 9.8 log CFU/mL after 48 h incubation at room temperature. When L. monocytogenes mushroom isolates were co-cultured with the microbiota strains, L. monocytogenes counts ranged from 7.6 to 8.9 log CFU/mL after 24 h of incubation, while counts of the microbiota strains ranged from 5.5 to 9.0 log CFU/mL. Prolonged incubation up to 48 h resulted in further increase of L. monocytogenes counts when co-cultured with non-acidifying species Pseudomonas and Acinetobacter reaching 9.1 to 9.2 log CFU/mL, while a decrease of L. monocytogenes counts reaching 5.8 to 7.7 log CFU/mL was observed in co-culture with Enterobacteriaceae and acidifying Lactococcus representatives. In addition, L. monocytogenes grew also in spent mushroom media of the microbiota strains, except in acidified spent media of Lactococcus strains. These results highlight the competitive ability of L. monocytogenes during co-incubation with microbiota in fresh and in spent mushroom medium, indicative of its invasion and persistence capacity in food processing factory environments.
Topics: Listeria monocytogenes; Agaricales; Food Microbiology; Food Handling; Pseudomonas; Enterobacteriaceae; Lactococcus; Microbiota; Colony Count, Microbial
PubMed: 37001480
DOI: 10.1016/j.ijfoodmicro.2023.110183 -
Biofilm Dec 2023Many companies in the food industry apply reverse osmosis (RO) membranes to ensure high-quality reuse of water. Biofouling is however, a common, recalcitrant and...
Many companies in the food industry apply reverse osmosis (RO) membranes to ensure high-quality reuse of water. Biofouling is however, a common, recalcitrant and recurring problem that blocks transport over membranes and decreases the water recovery. Microorganisms adhering to membranes may form biofilm and produce an extracellular matrix, which protects against external stress and ensures continuous attachment. Thus, various agents are tested for their ability to degrade and disperse biofilms. Here, we identified industrially relevant bacterial model communities that form biofilms on RO membranes used for treating process water before reuse. There was a marked difference in the biofilm forming capabilities of bacteria isolated from contaminated RO membranes. One species, , was particularly capable of forming biofilm and was included in most communities. The potential of different enzymes (Trypsin-EDTA, Proteinase K, α-Amylase, β-Mannosidase and Alginate lyase) as biofouling dispersing agents was evaluated at different concentrations (0.05 U/ml and 1.28 U/ml). Among the tested enzymes, β-Mannosidase was the only enzyme able to reduce biofilm formation significantly within 4 h of exposure at 25 °C (0.284 log reduction), and only at the high concentration. Longer exposure duration, however, resulted in significant biofilm reduction by all enzymes tested (0.459-0.717 log reduction) at both low and high concentrations. Using confocal laser scanning microscopy, we quantified the biovolume on RO membranes after treatment with two different enzyme mixtures. The application of proteinase K and β-Mannosidase significantly reduced the amount of attached biomass (43% reduction), and the combination of all five enzymes showed even stronger reducing effect (71% reduction). Overall, this study demonstrates a potential treatment strategy, using matrix-degrading enzymes for biofouled RO membranes in food processing water treatment streams. Future studies on optimization of buffer systems, temperature and other factors could facilitate cleaning operations based on enzymatic treatment extending the lifespan of membranes with a continuous flux.
PubMed: 37131492
DOI: 10.1016/j.bioflm.2023.100119 -
Journal of Food Protection Apr 2023In Mexico, bullfrogs (Lithobates catesbeianus) are produced as gourmet food. However, bullfrogs can be carriers of pathogens because the frogs' preferred living...
In Mexico, bullfrogs (Lithobates catesbeianus) are produced as gourmet food. However, bullfrogs can be carriers of pathogens because the frogs' preferred living conditions occur in stagnant water. The present study aimed to identify bacteria that cause foodborne diseases or are associated with human diseases. For molecular identification, based on the sequential analysis by 16S rRNA or rpoD was conducted on all isolates obtained from bullfrog. A total of 91 bacterial isolates were obtained from bullfrogs; 14 genera and 23 species were identified, including Acinetobacter johnsonii 16.5%; Aeromonas media 14.3%; Aeromonas veronii 13.2%; Providencia rettgeri 7.7%; Citrobacter freundii 6.6%; Aeromonas caviae 4.4%; Aeromonas hydrophila and Elizabethkingia ursingii 3.3%; Pseudomonas stutzeri, Raoultella ornithinolytica, and Shewanella putrefaciens 2.2%; Acinetobacter guillouiae, Acinetobacter pseudolwoffii, Citrobacter portucalensis, Citrobacter werkmanii, Edwardsiella anguillarum, Klebsiella michiganensis, Kluyvera intermedia, Kocuria rosea, Myroides odoratimimus, Myroides odoratus, Proteus sp., and Proteus hauseri 1.1%. In this study, 49.4% of the isolates obtained cause foodborne disease, 19.8% are bacteria that play an important role in the spoilage of food, 5.5% of isolates have nosocomial significance, 13.2% of bacteria are considered to be pollutants of the ecosystem, and in the case of A. salmonicida and Edwardsiella anguillarum (12.1%) to have a negative impact on aquaculture. Acinetobacter pseudolwoffii and Citrobacter portucalensis have not been reported to cause disease. Lastly of these isolates, 97.8% (89/91) can cause disease by food consumption or by direct contact for immunocompromised persons. The presence of these bacteria in bullfrogs represents a significant problem for human health. There is evidence that these microorganisms are pathogenic and frogs may also be reservoirs.
Topics: Animals; Humans; Rana catesbeiana; Ecosystem; RNA, Ribosomal, 16S; Foodborne Diseases
PubMed: 36948016
DOI: 10.1016/j.jfp.2023.100067 -
Microorganisms Jun 2022Histamine is a toxic biogenic amine commonly found in seafood products or their derivatives. This metabolite is produced by histamine-producing bacteria (HPB) such as ,... (Review)
Review
Histamine is a toxic biogenic amine commonly found in seafood products or their derivatives. This metabolite is produced by histamine-producing bacteria (HPB) such as , , , , , , , , spp., , , , , , , , , , spp., , , , , , and In this review, the role of these bacteria in histamine production in fish and seafood products with consequences for human food poisoning following consumption are discussed. In addition, methods to control their activity in countering histamine production are proposed.
PubMed: 35744715
DOI: 10.3390/microorganisms10061197 -
JPRAS Open Sep 2022is a rare encapsulated Gram-negative aerobic and facultative anaerobic rod belonging to the Enterobacteriaceae family. It tends to inhabit water and soil environments...
is a rare encapsulated Gram-negative aerobic and facultative anaerobic rod belonging to the Enterobacteriaceae family. It tends to inhabit water and soil environments and can be found on insects, fish, ticks, and termites, but can also found in the hospital environment. has been documented in respiratory, urinary, gastrointestinal, and biliary tract infections as well as bacteraemia and systemic infections but has rarely been documented in soft tissue infections. This case study describes a recurrent paronychia infection secondary to in a young woman not responding to antibiotics and successfully treated with surgical management.
PubMed: 35633992
DOI: 10.1016/j.jpra.2022.04.004