-
Food Microbiology Dec 2018The rinds of surface-ripened cheeses have expected aesthetic properties, including distinct colors, that contribute to overall quality and consumer acceptance. Atypical...
The rinds of surface-ripened cheeses have expected aesthetic properties, including distinct colors, that contribute to overall quality and consumer acceptance. Atypical rind pigments are frequently reported in small-scale cheese production, but the causes of these color defects are largely unknown. We provide a potential microbial explanation for a striking purple rind defect in a surface-ripened cheese. A cheese producer in the United States reported to us several batches of a raw-milk washed-rind cheese with a distinctly purple rind. We isolated a Proteus species from samples with purple rind defect, but not from samples with typical rind pigments, suggesting that this strain of Proteus could be causing the defect. When provided tryptophan, a precursor in the indigo and indirubin biosynthesis pathway, the isolated strain of Proteus secreted purple-red pigments. A Psychrobacter species isolated from both purple and normal rinds also secreted purple-red pigments. Using thin-layer chromatography and liquid chromatography-mass spectrometry, we confirmed that these bacteria produced indigo and indirubin from tryptophan just as closely related bacteria make these compounds in purple urine bag syndrome in medical settings. Experimental cheese communities with or without Proteus and Psychrobacter confirmed that these Proteobacteria cause purple pigmentation of cheese rinds. Reports of purple rinds in two other cheeses from Europe and the observation of pigment production by Proteus and Psychrobacter strains isolated from other cheese rinds suggest that purple rind defect has the potential to be widespread in surface-ripened cheeses.
Topics: Animals; Cattle; Cheese; Color; Indigo Carmine; Indoles; Milk; Pigments, Biological; Proteus; Psychrobacter; Tryptophan
PubMed: 30166186
DOI: 10.1016/j.fm.2018.07.011 -
Sensors (Basel, Switzerland) Sep 2023Bacterial resistance to antibiotics is a primary global healthcare concern as it hampers the effectiveness of commonly used antibiotics used to treat infectious...
Bacterial resistance to antibiotics is a primary global healthcare concern as it hampers the effectiveness of commonly used antibiotics used to treat infectious diseases. The development of bacterial resistance continues to escalate over time. Rapid identification of the infecting bacterium and determination of its antibiotic susceptibility are crucial for optimal treatment and can save lives in many cases. Classical methods for determining bacterial susceptibility take at least 48 h, leading physicians to resort to empirical antibiotic treatment based on their experience. This random and excessive use of antibiotics is one of the most significant drivers of the development of multidrug-resistant (MDR) bacteria, posing a severe threat to global healthcare. To address these challenges, considerable efforts are underway to reduce the testing time of taxonomic classification of the infecting bacterium at the species level and its antibiotic susceptibility determination. Infrared spectroscopy is considered a rapid and reliable method for detecting minor molecular changes in cells. Thus, the main goal of this study was the use of infrared spectroscopy to shorten the identification and the susceptibility testing time of and from 48 h to approximately 40 min, directly from patients' urine samples. It was possible to identify the and species with 99% accuracy and, simultaneously, to determine their susceptibility to different antibiotics with an accuracy exceeding 80%.
Topics: Humans; Pseudomonas; Microbial Sensitivity Tests; Proteus; Bacteria; Bacterial Infections; Anti-Bacterial Agents; Spectrophotometry, Infrared; Machine Learning; Urinary Tract Infections
PubMed: 37836961
DOI: 10.3390/s23198132 -
Ecotoxicology and Environmental Safety Jun 2024Cadmium (Cd) pollution is a serious global environmental problem, which requires a global concern and practical solutions. Microbial remediation has received widespread...
Cadmium (Cd) pollution is a serious global environmental problem, which requires a global concern and practical solutions. Microbial remediation has received widespread attention owing to advantages, such as environmental friendliness and soil amelioration. However, Cd toxicity also severely deteriorates the remediation performance of functional microorganisms. Analyzing the mechanism of bacterial resistance to Cd stress will be beneficial for the application of Cd remediation. In this study, the bacteria strain, up to 1400 mg/L Cd resistance, was employed and identified as Proteus mirabilis Ch8 (Ch8) through whole genome sequence analyses. The results indicated that the multiple pathways of immobilizing and detoxifying Cd maintained the growth of Ch8 under Cd stress, which also possessed high Cd extracellular adsorption. Firstly, the changes in surface morphology and functional groups of Ch8 cells were observed under different Cd conditions through SEM-EDS and FTIR analyses. Under 100 mg/L Cd, Ch8 cells exhibited aggregation and less flagella; the Cd biosorption of Ch8 was predominately by secreting exopolysaccharides (EPS) and no significant change of functional groups. Under 500 mg/L Cd, Ch8 were present irregular polymers on the cell surface, some cells with wrapping around; the Cd biosorption capacity exhibited outstanding effects (38.80 mg/g), which was mainly immobilizing Cd by secreting and interacting with EPS. Then, Ch8 also significantly enhanced the antioxidant enzyme activity and the antioxidant substance content under different Cd conditions. The activities of SOD and CAT, GSH content of Ch8 under 500 mg/L Cd were significantly increased by 245.47%, 179.52%, and 241.81%, compared to normal condition. Additionally, Ch8 significantly induced the expression of Acr A and Tol C (the resistance-nodulation-division (RND) efflux pump), and some antioxidant genes (SodB, SodC, and Tpx) to reduce Cd damage. In particular, the markedly higher expression levels of SodB under Cd stress. The mechanism of Ch8 lays a foundation for its application in solving soil remediation.
Topics: Proteus mirabilis; Cadmium; Soil Pollutants; Biodegradation, Environmental
PubMed: 38728947
DOI: 10.1016/j.ecoenv.2024.116432 -
Methods in Molecular Biology (Clifton,... 2019This chapter outlines a method for making unmarked, in-frame deletion mutations in Proteus mirabilis by allelic replacement. This method utilizes an R6K-based suicide...
This chapter outlines a method for making unmarked, in-frame deletion mutations in Proteus mirabilis by allelic replacement. This method utilizes an R6K-based suicide plasmid allowing for integration of the plasmid by homologous recombination via a cloned insert. The plasmid also contains the sacB gene to select for plasmid loss (excision) in the presence of sucrose to create a mutant allele. This method has been applied to the P. mirabilis strains PM7002 and BB2000 and should be generally applicable to other P. mirabilis strains. The same methods described in this chapter can be used to introduce marked or point mutations in a given gene.
Topics: Alleles; Bacterial Proteins; Bacteriological Techniques; Genes, Transgenic, Suicide; Homologous Recombination; Mutagenesis; Plasmids; Proteus mirabilis
PubMed: 31309497
DOI: 10.1007/978-1-4939-9601-8_8 -
Journal of Orthopaedic Research :... Apr 2020While Gram-positive organisms are the most common causative agent of initial bone infections, the percentage of Gram-negative species increases in reoccurring bone...
While Gram-positive organisms are the most common causative agent of initial bone infections, the percentage of Gram-negative species increases in reoccurring bone infections. As bacterial internalization has been suggested as one cause of reoccurring bone infection, we tested the hypothesis that Gram-negative species of bacteria can be internalized into bone cells. Using the MLO-A5 and the MLO-Y4 cell lines as our cell models, we demonstrated that the Gram-negative species, Proteus mirabilis and Serratia marcescens, can be internalized in these cells using an internalization assay. This rate at which these two species were internalized was both time- and initial concentration-dependent. Confocal analysis demonstrated the presence of internalized bacteria within both cell types. Inhibition of the cellular uptake with methyl-β-cyclodextrin and chloroquine both reduced internalized bacteria, indicating that this process is, at least in part, cell mediated. Finally, we demonstrated that the presence of internalized P. mirabilis did not impact cell viability, measured either by lactate dehydrogenase (LDH) release or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) activity, while the presence of S. marcescens, on the other hand, both increased LDH release and reduced MTT activity, indicating a loss of cell viability in response to the organism. These results indicated that both species of Gram-negative bacteria can be internalized by bone cells and that these internalized bacteria could potentially result in reoccurring bone infections. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:861-870, 2020.
Topics: Animals; Cell Line; Endocytosis; Host-Pathogen Interactions; Mice; Microscopy, Confocal; Osteocytes; Proteus mirabilis; Serratia marcescens
PubMed: 31692074
DOI: 10.1002/jor.24510 -
Biotechnology Advances Nov 2017Enantiomerically pure amino acids are of increasing interest for the fine chemical, agrochemicals and pharmaceutical industries. During past years l-amino acids have... (Review)
Review
Enantiomerically pure amino acids are of increasing interest for the fine chemical, agrochemicals and pharmaceutical industries. During past years l-amino acids have been produced from deracemization of dl-solution employing the stereoselective flavoenzyme d-amino acid oxidase. On the other hand, the isolation of corresponding d-isomer was hampered by the scarce availability of a suitable l-amino acid oxidase activity. On this side, l-amino acid deaminase (LAAD), only present in the Proteus bacteria, represents a suitable alternative. This FAD-containing enzyme catalyzes the deamination of l-amino acids to the corresponding α-keto acids and ammonia, with no hydrogen peroxide production (a potentially dangerous oxidizing species) since the electrons of the reduced cofactor are transferred to a membrane-bound cytochrome. Very recently the structure of LAAD has been solved: in addition to a FAD-binding domain and to a substrate-binding domain, it also possesses an N-terminal putative transmembrane α-helix (residues 8-27, not present in the crystallized protein variant) and a small α+β subdomain (50-67 amino acids long, named "insertion module") strictly interconnected to the substrate binding domain. Structural comparison showed that LAAD resembles the structure of several soluble amino acid oxidases, such as l-proline dehydrogenase, glycine oxidase or sarcosine oxidase, while only a limited structural similarity with d- or l-amino acid oxidase is apparent. In this review, we present an overview of the structural and biochemical properties of known LAADs and describe the advances that have been made in their biotechnological application also taking advantage from improved variants generated by protein engineering studies.
Topics: Amino Acids; Aminohydrolases; Biotechnology; D-Amino-Acid Oxidase; Enzymes; Protein Engineering; Proteus
PubMed: 28782586
DOI: 10.1016/j.biotechadv.2017.07.011 -
Archives of Virology Aug 2018Four lytic Proteus bacteriophages, PM75, PM85, PM93, and PM116, which are active against multi-drug-resistant strains of P. mirabilis, were isolated from cattle and...
Four lytic Proteus bacteriophages, PM75, PM85, PM93, and PM116, which are active against multi-drug-resistant strains of P. mirabilis, were isolated from cattle and poultry samples. According to electron microscopy data, all of the investigated phages belonged to the family Podoviridae. They all demonstrated lytic activity against sensitive strains of P. mirabilis, and three of the phages, PM85, PM93, and PM116, are potential candidates for use in antibacterial treatment. The genomes and putative proteins of bacteriophages PM85, PM93, and PM116 were similar to those of Proteus phage vB_PmiP_Pm5460 [KP890822], and the investigated phages formed a distinct clade within the genus Sp6virus, subfamily Autographivirinae. The genome sequence of phage PM75 was similar to that of a previously described Proteus phage, PM16 [KF319020], and both of them demonstrated low nucleotide sequence identity to the genomes of the other most similar phages, namely, Vibrio phage VP93, Pantoea phage LIMElight, and KP34-like bacteriophages. According to cluster analysis of the complete genome sequences and phylogenetic analysis of the proteins essential for their life cycle, phages PM75 and PM16 are distinct from other similar phages from the phiKMV supergroup and should be recognized as constituting a new genus, "Pm16virus", within the subfamily Autographivirinae.
Topics: Animals; Bacteriophages; Cattle; Cattle Diseases; Chickens; Genome, Viral; Phylogeny; Podoviridae; Poultry Diseases; Proteus Infections; Proteus mirabilis; Viral Proteins
PubMed: 29721709
DOI: 10.1007/s00705-018-3853-3 -
BMC Microbiology Jun 2020Members of the genus Proteus are mostly opportunistic pathogens that cause a variety of infections in humans. The molecular evolutionary characteristics and genetic...
Multilocus sequence analysis for the taxonomic updating and identification of the genus Proteus and reclassification of Proteus genospecies 5 O'Hara et al. 2000, Proteus cibarius Hyun et al. 2016 as later heterotypic synonyms of Proteus terrae Behrendt et al. 2015.
BACKGROUND
Members of the genus Proteus are mostly opportunistic pathogens that cause a variety of infections in humans. The molecular evolutionary characteristics and genetic relationships among Proteus species have not been elucidated to date. In this study, we developed a multilocus sequence analysis (MLSA) approach based on five housekeeping genes (HKGs) to delineate phylogenetic relationships of species within the genus Proteus.
RESULTS
Of all 223 Proteus strains collected in the current study, the phylogenetic tree of five concatenated HKGs (dnaJ, mdh, pyrC, recA and rpoD) divided 223 strains into eleven clusters, which were representative of 11 species of Proteus. Meanwhile, the phylogenetic trees of the five individual HKGs also corresponded to that of the concatenated tree, except for recA, which clustered four strains at an independent cluster. The evaluation of inter- and intraspecies distances of HKG concatenation indicated that all interspecies distances were significantly different from intraspecies distances, which revealed that these HKG concatenations can be used as gene markers to distinguish different Proteus species. Further web-based DNA-DNA hybridization estimated by genome of type strains confirmed the validity of the MLSA, and each of eleven clusters was congruent with the most abundant Proteus species. In addition, we used the established MLSA method to identify the randomly collected Proteus and found that P. mirabilis is the most abundant species. However, the second most abundant species is P. terrae but not P. vulgaris. Combined with the genetic, genomic and phenotypic characteristics, these findings indicate that three species, P. terrae, P. cibarius and Proteus genospecies 5, should be regarded as heterotypic synonyms, and the species should be renamed P. terrae, while Proteus genospecies 5 has not been named to date.
CONCLUSIONS
This study suggested that MLSA is a powerful method for the discrimination and classification of Proteus at the species level. The MLSA scheme provides a rapid and inexpensive means of identifying Proteus strains. The identification of Proteus species determined by the MLSA approach plays an important role in the clinical diagnosis and treatment of Proteus infection.
Topics: Bacterial Proteins; Bacterial Typing Techniques; Cross Infection; Genes, Essential; Humans; Multilocus Sequence Typing; Phylogeny; Proteus
PubMed: 32522175
DOI: 10.1186/s12866-020-01844-1 -
Emerging Microbes & Infections Dec 2020The incidence and transmission of carbapenemase (KPC) producing plasmids have been well documented. However, the evolutionary dynamics of KPC plasmids and their fitness...
The incidence and transmission of carbapenemase (KPC) producing plasmids have been well documented. However, the evolutionary dynamics of KPC plasmids and their fitness costs are not well characterized. Here, two carbapenemase-producing plasmids from , pT18 and pT211 (both carrying ), were characterized through whole genome sequencing. pT211 is a 24.2 kbp N-type plasmid that contains and a single copy of the IS-family insertion sequence IS. pT18 is a 59 kbp cointegrate plasmid comprised of sequences derived from three different plasmids: a close relative of pT211 (containing ), an FII-33 plasmid ( , , and ) and a rolling-circle plasmid. The segments of pT18 derived from each of the different plasmids are separated by copies of IS, and sequence analysis indicated that pT18 was likely generated by both conservative and replicative IS-mediated cointegrate formation. pT18 and pT211 were transferred into DH5α separately to assess the impact of plasmids on host fitness. Only DH5α harbouring pT18 grew slower than the wild type in antibiotic-free media. However, in sub-inhibitory concentrations of fosfomycin and amikacin, cells containing pT18 grew faster than the wild type, and the minimum concentrations of fosfomycin and amikacin required to observe an advantage for plasmid-carrying cells were 1/3 and 1/20 the DH5α MIC, respectively. This study highlights the importance of the role of cointegrate plasmids in the dissemination of antibiotic resistance genes between pathogenic bacterial species, and highlights the importance of sub-inhibitory concentrations of antibiotics to the persistence of such plasmids.
Topics: Amikacin; Bacterial Proteins; Drug Resistance, Multiple, Bacterial; Escherichia coli; Evolution, Molecular; Female; Fosfomycin; Genetic Fitness; Genome Size; High-Throughput Nucleotide Sequencing; Humans; Male; Middle Aged; Plasmids; Proteus mirabilis; Sputum; Whole Genome Sequencing; beta-Lactamases
PubMed: 32438864
DOI: 10.1080/22221751.2020.1773322 -
Journal of Global Antimicrobial... Jun 2022The prevalence of tet(X) genes threatens the clinical use of last-line tigecycline. The tet(X6) gene has been reported in Proteus strains, but its genetic context is...
OBJECTIVES
The prevalence of tet(X) genes threatens the clinical use of last-line tigecycline. The tet(X6) gene has been reported in Proteus strains, but its genetic context is rarely reported. This study aimed to investigate the prevalence and genetic contexts of tet(X6) gene in Proteus spp.
METHODS
A tet(X6) variant-bearing P. terrae subsp. cibarius strain was subjected to susceptibility testing, determination of growth curves, scanning electron microscopy, transmission electron microscopy and whole-genome sequencing (WGS). The genomic contexts of the tet(X6)-positive strain were analysed by sequence comparison and annotation.
RESULTS
ZJ19PC, a P. terrae subsp. cibarius strain harbouring the tet(X6) variant, was isolated from 20 cecum samples collected in Zhejiang, China. The chromosome size of ZJ19PC was 3 952 084 bp; the GC content was 38.2%; and hugA, sul2, tet(H), floR, dfra1, aadA1, aac(3)-IV and aph(4)-la were found in addition to the tet(X6) variant. Proteus spp. could be classified into three groups based on the tet(X6) gene contexts. Strain ZJ19PC belongs to group 1 (sra-sul2-ISCR2-floR-ISCR2-floR-ISCR2- tet(X6) variant-tnpA-ISEc59-aph(4)-la-aac(3)-Iva-IS26), and this region of group 1 was inserted between modA and guaA. The common antimicrobial resistance (AMR) genes of the three types of AMR gene islands were sul2, floR, tet(X6) and aac(3). The tet(X6) gene contexts and SNP tree showed that ZJ19PC was homologous to HNCF44W and HNCF43W, which indicated that these strains may be clonally transmitted.
CONCLUSION
This study analysed the genetic contexts of the tet(X6) gene in Proteus spp. and highlighted the significance of monitoring tigecycline-resistant P. terrae subsp. cibarius.
Topics: Animals; Anti-Bacterial Agents; Cecum; Proteus; Tigecycline
PubMed: 35218939
DOI: 10.1016/j.jgar.2022.02.011