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Klebsiella pneumoniae is a 2,3-butanediol producer, and R-acetoin is an intermediate of 2,3-butanediol production. R-acetoin accumulation and dissimilation in K. pneumoniae was studied here. A budC mutant, which has lost 2,3-butanediol dehydrogenase activity, accumulated high levels of R-acetoin in culture broth. However, after glucose was exhausted, the accumulated R-acetoin could be reused by the cells as a carbon source. Acetoin dehydrogenase enzyme system, encoded by acoABCD, was responsible for R-acetoin dissimilation. acoABCD mutants lost the ability to grow on acetoin as the sole carbon source, and the acetoin accumulated could not be dissimilated. However, in the presence of another carbon source, the acetoin accumulated in broth of acoABCD mutants was converted to 2,3-butanediol. Parameters of R-acetoin production by budC mutants were optimized in batch culture. Aerobic culture and mildly acidic conditions (pH 6–6.5) favored R-acetoin accumulation. At the optimized conditions, in fed-batch fermentation, 62.3 g/L R-acetoin was produced by budC and acoABCD double mutant in 57 h culture, with an optical purity of 98.0 %, and a substrate conversion ratio of 28.7 %. 相似文献
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Mattika Abhisingha Jureeporn Dumnil Chetsadaporn Pitaksutheepong 《Probiotics and antimicrobial proteins》2018,10(2):218-227
Three hundred and sixty presumptive lactic acid bacteria (LAB) isolated from pregnant sows, newborn, suckling, and weaned piglets were preliminarily screened for anti-Salmonella activity. Fifty-eight isolates consisting of Lactobacillus reuteri (n = 32), Lactobacillus salivarius (n = 10), Lactobacillus mucosae (n = 8), Lactobacillus johnsonii (n = 5), and Lactobacillus crispatus (n = 3) were selected and further characterized for probiotic properties including production of antimicrobial substances, acid and bile tolerance, and cell adherence to Caco-2 cells. Eight isolates including Lact. johnsonii LJ202 and Lact. reuteri LR108 were identified as potential probiotics. LJ202 was selected for further use in co-culture studies of two-bacterial and multiple-bacterial species to examine its inhibitory activity against Salmonella enterica serovar Enteritidis DMST7106 (SE7106). Co-culture of LJ202 and SE7106 showed that LJ202 could completely inhibit the growth of SE7106 in 10 h of co-culture. In co-culture of multiple-bacterial species, culturable fecal bacteria from pig feces were used as representative of multiple-bacterial species. The study was performed to examine whether interactions among multiple-bacterial species would influence antagonistic activity of LJ202 against SE7106 and fecal coliform bacteria. Co-culture of SE7106 with different combinations of fecal bacteria and probiotic (LJ202 and LR108) or non-probiotic (Lact. mucosae LM303) strains revealed that the growth of SE7106 was completely inhibited either in the presence or in the absence of probiotic strains. Intriguingly, LJ202 exhibited notable inhibitory activity against fecal coliform bacteria while LR108 did not. Taken together, the results of co-culture studies suggested that LJ202 is a good probiotic candidate for further study its inhibitory effects against pathogen infections in pigs. 相似文献
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In this study, Lactobacillus
fermentum (L. fermentum) F1 reduced cholesterol 48.87%. The strain was screened from cattle feces using an API 50 CHL system and the 16S rRNA sequence contrasting method. L. fermentum F1 showed acid and bile tolerance, and antimicrobial activity against pathogenic Escherichia coli and Staphylococcus aureus. L. fermentum F1 deconjugated 0.186 mM of free cholalic acid after it was incubated at 37°C in 0.20% sodium taurocholate (TCA) broth for
24 h. Heat-killed and resting cells of L. fermentum F1 showed small amounts of cholesterol removal (6.85 and 25.19 mg/g, respectively, of dry weight) compared with growing cells
(33.21 mg/g of dry weight). The supernatant fluid of the broth contained 50.85% of the total cholesterol, while the washing
buffer and cell extracts had 13.53 and 35.39%, respectively. These findings suggest that L. fermentum F1 may remove cholesterol by co-precipitating with deconjugated bile salt, assimilating with cells and by incorporation into
cellular membranes. Cholesterol assimilated by cells held 72.0% of the reduced cholesterol, while 21.65% of the reduced cholesterol
was coprecipitated with deconjugated bile salt and 5.89% was adsorbed into the surface of the cells. 相似文献
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Rodnei Dennis Rossoni Marisol dos Santos Velloso Lívia Mara Alves Figueiredo Carolina Pistille Martins Antonio Olavo Cardoso Jorge Juliana Campos Junqueira 《Folia microbiologica》2018,63(3):307-314
Candida albicans is the most common human fungal pathogen and can grow as yeast or filaments, depending on the environmental conditions. The filamentous form is of particular interest because it can play a direct role in adherence and pathogenicity. Therefore, the purpose of this study was to evaluate the effects of three clinical strains of Lactobacillus on C. albicans filamentation as well as their probiotic potential in pathogen-host interactions via an experimental candidiasis model study in Galleria mellonella. We used the reference strain Candida albicans ATCC 18804 and three clinical strains of Lactobacillus: L. rhamnosus strain 5.2, L. paracasei strain 20.3, and L. fermentum strain 20.4. First, the capacity of C. albicans to form hyphae was tested in vitro through association with the Lactobacillus strains. After that, we verified the ability of these strains to attenuate experimental candidiasis in a Galleria mellonella model through a survival curve assay. Regarding the filamentation assay, a significant reduction in hyphae formation of up to 57% was observed when C. albicans was incubated in the presence of the Lactobacillus strains, compared to a control group composed of only C. albicans. In addition, when the larvae were pretreated with Lactobacillus spp. prior to C. albicans infection, the survival rate of G. mellonela increased in all experimental groups. We concluded that Lactobacillus influences the growth and expression C. albicans virulence factors, which may interfere with the pathogenicity of these microorganisms. 相似文献
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Yu-Tze Horng Kai-Chih Chang Ta-Chung Chou Chung-Jen Yu Chih-Ching Chien Yu-Hong Wei Po-Chi Soo 《Journal of industrial microbiology & biotechnology》2010,37(7):707-716
1,3-Propanediol (1,3-PD) can be used for the industrial synthesis of a variety of compounds, including polyesters, polyethers,
and polyurethanes. 1,3-PD is generated from petrochemical and microbial sources. 1,3-Propanediol is a typical product of glycerol
fermentation, while acetate, lactate, 2,3-butanediol, and ethanol also accumulate during the process. Substrate and product
inhibition limit the final concentration of 1,3-propanediol in the fermentation broth. It is impossible to increase the yield
of 1,3-propanediol by using the traditional whole-cell fermentation process. In this study, dhaD and dhaK, the genes for glycerol dehydrogenase and dihydroxyacetone kinase, respectively, were inactivated by homologous recombination
in Klebsiella pneumoniae. The dhaD/dhaK double mutant (designated TC100), selected from 5,000 single or double cross homologous recombination mutants, was confirmed
as a double cross by using polymerase chain reaction. Analysis of the cell-free supernatant with high-performance liquid chromatography
revealed elimination of lactate and 2,3-butanediol, as well as ethanol accumulation in TC100, compared with the wild-type
strain. Furthermore, 1,3-propanediol productivity was increased in the TC100 strain expressing glycerol dehydratase and 1,3-PDO
dehydrogenase regulated by the arabinose PBAD promoter. The genetic engineering and medium formulation approaches used here should aid in the separation of 1,3-propanediol
from lactate, 2,3-butanediol, and ethanol and lead to increased production of 1,3-propanediol in Klebsiella pneumoniae. 相似文献
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B. Cukrowska I. Motyl H. Kozáková M. Schwarzer R. K. Górecki E. Klewicka K. Śliżewska Z. Libudzisz 《Folia microbiologica》2009,54(6):533-537
Three Lactobacillus strains (LOCK 0900, LOCK 0908, LOCK 0919) out of twenty-four isolates were selected according to their antagonistic activity
against pathogenic bacteria, resistance to low pH and milieu of bile salts. Intragastric administration of a mixture of these
strains to Balb/c mice affected cytokine TH1-TH2 balance toward nonallergic TH1 response. Spleen cells, isolated from lactobacilli-treated mice and re-stimulated in vitro with the mixture of heat-inactivated tested strains, produced significantly higher amounts of anti-allergic tumor necrosis
factor- and interferon-γ than control animals whereas the level of pro-allergic interleukin-5 was significantly lower. Lactobacillus cells did not translocate through the intestinal barrier into blood, liver and spleen; a few Lactobacillus cells found in mesenteric lymph nodes could create antigenic reservoir activating the immune system. The mixture of Lactobacillus LOCK 0900, LOCK 0908 and LOCK 0919 strains represents a probiotic bacterial preparation with possible use in prophylaxis
and/or therapy of allergic diseases. 相似文献
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Aminoglycoside resistance in six clinically isolated Staphylococcus aureus was evaluated. Genotypical examination revealed that three isolates (HLGR-10, HLGR-12, and MSSA-21) have aminoglycoside-modifying
enzyme (AME) coding genes and another three (GRSA-2, GRSA-4, and GRSA-6) lacked these genes in their genome. Whereas isolates
HLGR-10 and HLGR-14 possessed bifunctional AME coding gene aac(6′)-aph(2′′), and aph(3′)-III and showed high-level resistance to gentamycin and streptomycin, MSSA-21 possessed aph(3′)-III and exhibited low resistance to gentamycin, streptomycin, and kanamycin. The remaining three isolates (GRSA-2, GRSA-4, and
GRSA-6) exhibited low resistance to all the aminoglycosides because they lack aminoglycoside-modifying enzyme coding genes
in their genome. The transmission electron microscopy of the three isolates revealed changes in cell size, shape, and septa
formation, supporting the view that the phenomenon of adaptive resistance is operative in these isolates. 相似文献
10.
Zhu Y Chen XB Wang KB Li YX Bai KZ Kuang TY Ji HB 《Applied microbiology and biotechnology》2007,74(1):244-248
C-phycocyanin (C-PC) was extracted from fresh Spirulina platensis by deploying a species of non-pathogenic nitrogen-fixing bacteria, namely, Klebsiella pneumoniae. The algal slurry was neither washed nor centrifuged; the bacterial culture was poured into the slurry, the vessel sealed,
and crude C-PC extracted after about 24 h. The extraction was clean and efficient, and the purity and concentration of C-PC
proved to be of adequate quality. 相似文献
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Objectives
To investigate the outcomes of capsule lost on cell transformation efficiency and chemicals (1,3-propanediol, 2,3-butanediol, and 2-ketogluconic acid) production by Klebsiella pneumoniae.Results
The cps gene cluster showed low sequence homology with pathogenic strains. The wza is a highly conserved gene in the cps cluster that encodes an outer membrane protein. A non-capsulated mutant was constructed by deletion of wza. Phenotype studies demonstrated that non-capsulated cells were less buoyant and easy to sediment. The transformation efficiency of the non-capsulated mutant reached 6.4 × 105 CFU μg?1 DNA, which is 10 times higher than that of the wild strain. 52.2 g 1,3-propanediol L?1, 30.7 g 2,3-butanediol L?1, and 175.9 g 2-ketogluconic acid L?1 were produced by non-capsulated mutants, which were 10–40% lower compared to wild strain. Furthermore, viscosities of the three fermentation broths decreased to approximately 1.3 cP from the range of 1.8–2.2 cP.Conclusions
Non-capsulated K. pneumoniae mutants should allay concerns regarding biological safety, improve transformation efficiency, lower viscosity, and subsequently ameliorate the financial burden of the downstream process of chemicals production.12.
Ma C Wang A Qin J Li L Ai X Jiang T Tang H Xu P 《Applied microbiology and biotechnology》2009,82(1):49-57
Enhanced 2,3-butanediol (BD) production was carried out by Klebsiella pneumoniae SDM. The nutritional requirements for BD production by K. pneumoniae SDM were optimized statistically in shake flask fermentations. Corn steep liquor powder and (NH4)2HPO4 were identified as the most significant factors by the two-level Plackett–Burman design. Steepest ascent experiments were
applied to approach the optimal region of the two factors and a central composite design was employed to determine their optimal
levels. The optimal medium was used to perform fed-batch fermentations with K. pneumoniae SDM. BD production was then studied in a 5-l bioreactor applying different fed-batch strategies, including pulse fed batch,
constant feed rate fed batch, constant residual glucose concentration fed batch, and exponential fed batch. The maximum BD
concentration of 150 g/l at 38 h with a diol productivity of 4.21 g/l h was obtained by the constant residual glucose concentration
feeding strategy. To the best of our knowledge, these results were new records on BD fermentation.
Cuiqing Ma and Ailong Wang contributed equally to this work. 相似文献
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KiBeom Lee 《World journal of microbiology & biotechnology》2007,23(9):1317-1320
Lactobacillus
delbrueckii subsp. lactis strains were developed having increased activity, by gradually acclimatizing the bacteria to acidic conditions over repeated
batch culture. Cells from one batch culture were used as the inoculum for the subsequent batch culture and thereby an adapted
strain of Lactobacillus was obtained showing improved lactic acid productivity, cell growth and total glucose utilization. Furthermore, the acclimatized
cells used significantly less nitrogen for a given level of lactic acid production, which is significant from an industrial
point of view. The developed procedure decreases fermentation time and nutrient use, leading to reduced operation costs, while
providing a lactic acid yield superior to previously reported methods. 相似文献
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Background
Little is known regarding the extent or targets of phosphorylation in mycoplasmas, yet in many other bacterial species phosphorylation is known to play an important role in signaling and regulation of cellular processes. To determine the prevalence of phosphorylation in mycoplasmas, we examined the CHAPS-soluble protein fractions of Mycoplasma genitalium and Mycoplasma pneumoniae by two-dimensional gel electrophoresis (2-DE), using a combination of Pro-Q Diamond phosphoprotein stain and 33P labeling. Protein spots that were positive for phosphorylation were identified by peptide mass fingerprinting using MALDI-TOF-TOF mass spectrometry. 相似文献15.
Six bacterial genera containing species commonly used as probiotics for human consumption or starter cultures for food fermentation
were compared and contrasted, based on publicly available complete genome sequences. The analysis included 19 Bifidobacterium genomes, 21 Lactobacillus genomes, 4 Lactococcus and 3 Leuconostoc genomes, as well as a selection of Enterococcus (11) and Streptococcus (23) genomes. The latter two genera included genomes from probiotic or commensal as well as pathogenic organisms to investigate
if their non-pathogenic members shared more genes with the other probiotic genomes than their pathogenic members. The pan-
and core genome of each genus was defined. Pairwise BLASTP genome comparison was performed within and between genera. It turned
out that pathogenic Streptococcus and Enterococcus shared more gene families than did the non-pathogenic genomes. In silico multilocus sequence typing was carried out for all
genomes per genus, and the variable gene content of genomes was compared within the genera. Informative BLAST Atlases were
constructed to visualize genomic variation within genera. The clusters of orthologous groups (COG) classes of all genes in
the pan- and core genome of each genus were compared. In addition, it was investigated whether pathogenic genomes contain
different COG classes compared to the probiotic or fermentative organisms, again comparing their pan- and core genomes. The
obtained results were compared with published data from the literature. This study illustrates how over 80 genomes can be
broadly compared using simple bioinformatic tools, leading to both confirmation of known information as well as novel observations. 相似文献
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Lidiane de Oliveira Dayane Cristina Silva Santos Marilena dos Anjos Martins Maria Walderez Szeszs Marcia Souza Carvalho Melhem 《Current fungal infection reports》2017,11(4):158-162
Purpose of Review
We reviewed data on amphotericin B (AmB) tolerance among Cryptococcus neoformans/C. gattii species complex clinical isolates and present our results of large recent study on this issue.Recent Findings
The standard method to detect antifungal susceptibility is based on MIC (minimal inhibitory concentration) determination; however, there is no interpretative clinical breakpoints defined for antifungal agents against Cryptococcus species, and to date, there is no correlation of MIC and clinical response. The time-kill curves (TKC) methodology seems to provide some correlation with outcome and it could identify distinct profiles of AmB-fungicidal activity.Summary
Our group analyzed 83 human isolates from cryptococcosis cases. The isolates were tested by TKC and showed up 8.3% of tolerance to AmB. Importantly, the AmB-MIC was low for all isolates, including tolerant ones. Our findings are similar to other authors, due the ability of TKC to identify distinct AmB-fungicidal activity and detecting low susceptible isolates.17.
Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes. 相似文献
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Christiaan A. Rees Katherine V. Nordick Flavio A. Franchina Alexa E. Lewis Elizabeth B. Hirsch Jane E. Hill 《Metabolomics : Official journal of the Metabolomic Society》2017,13(2):18
Introduction
Microorganisms catabolize carbon-containing compounds in their environment during growth, releasing a subset of metabolic byproducts as volatile compounds. However, the relationship between growth media and the production of volatile compounds has been largely unexplored to-date.Objectives
To assess the core and media-specific components of the Klebsiella pneumoniae volatile metabolome via growth in four in vitro culture media.Methods
Headspace volatiles produced by cultures of K. pneumoniae after growth to stationary phase in four rich media (brain heart infusion broth, lysogeny broth, Mueller-Hinton broth, and tryptic soy broth) were analyzed using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS). Differences in the composition of headspace volatiles as a function of growth media were assessed using hierarchical clustering analysis (HCA) and principal component analysis (PCA).Results
A total of 365 volatile compounds were associated with the growth of K. pneumoniae across all media, of which 36 (10%) were common to all growth media, and 148 (41%) were specific to a single medium. In addition, utilizing all K. pneumoniae-associated volatile compounds, strains clustered as a function of growth media, demonstrating the importance of media in determining the metabolic profile of this organism.Conclusion
K. pneumoniae produces a core suite of volatile compounds across all growth media studied, although the volatile metabolic signature of this organism is fundamentally media-dependent.19.
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Vincenzo Ierardi Paolo Domenichini Silvia Reali Gian Marco Chiappara Gianluigi Devoto Ugo Valbusa 《Journal of biosciences》2017,42(4):623-636
In the last decade the detection of the resistance of bacteria to antibiotics treatment, developed by different kind of bacteria, is becoming a huge problem. We hereby present a different approach to the current problem of detection of bacteria resistance to antibiotics. Our aims were to use the atomic force microscopy (AFM) to investigate bacteria morphological changes in response to antibiotics treatment and explore the possibility of reducing the time required to obtain information on their resistance. In particular, we studied Klebsiella pneumoniae bacteria provided by the Lavagna Hospital ASL4 Liguria (Italy), where there are cases linked with antibiotics resistance of the Klebsiella pneumoniae. By comparing AFM images of bacteria strains treated with different antibiotics is possible to identify unambiguously the Klebsiella pneumoniae strains resistant to antibiotics. In fact, the analysis of the AFM images of the antibiotic-sensitive bacteria shows clearly the presence of morphological alterations in the cell wall. While in the case of the antibiotic-resistant bacteria morphological alterations are not present. This approach is based on an easy and potentially rapid AFM analysis. 相似文献