scholarly journals A Multibacteriocin Cheese Starter System, Comprising Nisin and Lacticin 3147 in Lactococcus lactis, in Combination with Plantaricin from Lactobacillus plantarum

2017 ◽  
Vol 83 (14) ◽  
Author(s):  
S. Mills ◽  
C. Griffin ◽  
P. M. O'Connor ◽  
L. M. Serrano ◽  
W. C. Meijer ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Lactobacillus Plantarum ◽  
Class Ii ◽  
Recipient Strain ◽  
Starter Cultures ◽  
Class I ◽  
Genetic Determinants ◽  
Content Type ◽  
Bacteriocin Producer ◽  
Lacticin 3147

ABSTRACT Functional starter cultures demonstrating superior technological and food safety properties are advantageous to the food fermentation industry. We evaluated the efficacies of single- and double-bacteriocin-producing starters of Lactococcus lactis capable of producing the class I bacteriocins nisin A and/or lacticin 3147 in terms of starter performance. Single producers were generated by mobilizing the conjugative bacteriophage resistance plasmid pMRC01, carrying lacticin genetic determinants, or the conjugative transposon Tn5276, carrying nisin genetic determinants, to the commercial starter L. lactis CSK2775. The effect of bacteriocin coproduction was examined by superimposing pMRC01 into the newly constructed nisin transconjugant. Transconjugants were improved with regard to antimicrobial activity and bacteriophage insensitivity compared to the recipient strain, and the double producer was immune to both bacteriocins. Bacteriocin production in the starter was stable, although the recipient strain proved to be a more efficient acidifier than transconjugant derivatives. Overall, combinations of class I bacteriocins (the double producer or a combination of single producers) proved to be as effective as individual bacteriocins for controlling Listeria innocua growth in laboratory-scale cheeses. However, using the double producer in combination with the class II bacteriocin producer Lactobacillus plantarum or using the lacticin producer with the class II producer proved to be most effective for reducing bacterial load. As emergence of bacteriocin tolerance was reduced 10-fold in the presence of nisin and lacticin, we suggest that the double producer in conjunction with the class II producer could serve as a protective culture providing a food-grade, multihurdle approach to control pathogenic growth in a variety of industrial applications. IMPORTANCE We generated a suite of single- and double-bacteriocin-producing starter cultures capable of generating the class I bacteriocin lacticin 3147 or nisin or both bacteriocins simultaneously via conjugation. The transconjugants exhibited improved bacteriophage resistance and antimicrobial activity. The single producers proved to be as effective as the double-bacteriocin producer at reducing Listeria numbers in laboratory-scale cheese. However, combining the double producer or the lacticin-producing starter with a class II bacteriocin producer, Lactobacillus plantarum LMG P-26358, proved to be most effective at reducing Listeria numbers and was significantly better than a combination of the three bacteriocin-producing strains, as the double producer is not inhibited by either of the class I bacteriocins. Since the simultaneous use of lacticin and nisin should reduce the emergence of bacteriocin-tolerant derivatives, this study suggests that a protective starter system produced by bacteriocin stacking is a worthwhile multihurdle approach for food safety applications.

Technological characterisation, antibiotic susceptibility and antimicrobial activity of wild-type Leuconostoc strains isolated from north Italian traditional cheeses

2013 ◽  
Vol 80 (4) ◽  
pp. 457-466 ◽  
Author(s):  
Stefano Morandi ◽  
Paola Cremonesi ◽  
Tiziana Silvetti ◽  
Milena Brasca
Keyword(s):  
Antimicrobial Activity ◽  
Antibiotic Susceptibility ◽  
Tetracycline Resistance ◽  
Raw Milk ◽  
Starter Cultures ◽  
Genetic Determinants ◽  
Tetracycline Resistance Genes ◽  
Reduction Activity ◽  
Genes Encoding ◽  
High Degree

Genotypic and technological properties, antibiotic susceptibility and antimicrobial activity of 35 Leuconostoc strains, isolated from different Italian raw milk cheeses, were investigated. RAPD-PCR was used to study genetic variability and to distinguish closely related strains. The results showed a high degree of heterogeneity among isolates. All the strains had weak acidifying activity and showed low proteolytic and lipolytic activities. Reduction activity, was generally low. All the Leuconostoc were susceptible to ampicillin, mupirocin, erythromycin, quinupristin/dalfopristin and tetracycline. Many strains were classified as resistant to oxacillin, ciprofloxacin and nitrofurantonin, while all isolates were found resistant to vancomycin. PCR-based detection did not identify any of the common genetic determinants for vancomycin (vanA, vanB, vanC1, vanC2, vanC3, vanD, vanE, vanG) or erythromycin (ermB and ermC). Tetracycline resistance genes were detected in 25 tetracycline susceptible strains, the most frequent one being tetM. One strain, belonging to Ln. pseudomesenteroides species, was positive for the presence of the int gene of the Tn916/Tn1545 trasposon family. This is the first time the conjugative transposon Tn916 has been detected inside the Leuconostoc species. All strains showed antimicrobial activity against Enterococcus faecalis and Ent. faecium. The presence of genes encoding amino-acid decarboxylases (hdc and tdc) was not detected. Some strains are interesting in view of their use in cheese production as starter and non starter cultures.

scholarly journals Contribution of σ70 and σN Factors to Expression of Class II pilE in Neisseria meningitidis

2019 ◽  
Vol 201 (20) ◽  
Author(s):  
Mariya Lobanovska ◽  
Christoph M. Tang ◽  
Rachel M. Exley
Keyword(s):  
Neisseria Meningitidis ◽  
Antigenic Variation ◽  
Cell Interaction ◽  
Class Ii ◽  
Class I ◽  
Epidemic Disease ◽  
Content Type ◽  
Main Component ◽  
Host Cell Interaction

ABSTRACT Neisseria meningitidis expresses multicomponent organelles called type four pili (Tfp), which are key virulence factors required for attachment to human cells during carriage and disease. Pilin (PilE) is the main component of Tfp, and N. meningitidis isolates either have a class I pilE locus and express pilins that undergo antigenic variation or have a class II pilE locus and express invariant pilins. The transcriptional regulation of class I pilE has been studied in both N. meningitidis and Neisseria gonorrhoeae, while the control of expression of class II pilE has been elucidated in the nonpathogenic species Neisseria elongata. However, the factors that govern the regulation of the class II pilE gene in N. meningitidis are not known. In this work, we have bioinformatically and experimentally identified the class II pilE promoter. We confirmed the presence of conserved σ70 and σN-dependent promoters upstream of pilE in a collection of meningococcal genomes and demonstrated that class II pilE expression initiates from the σ70 family-dependent promoter. By deletion or overexpression of sigma factors, we showed that σN, σH, and σE do not affect class II pilin expression. These findings are consistent with a role of the housekeeping σD in expression of this important component of Tfp. Taken together, our data indicate that the σ-dependent network responsible for the expression of class II pilE has been selected to maintain pilE expression, consistent with the essential roles of Tfp in colonization and pathogenesis. IMPORTANCE The type four pilus (Tfp) of Neisseria meningitidis contributes to fundamental processes such as adhesion, transformation, and disease pathology. Meningococci express one of two distinct classes of Tfp (class I or class II), which can be distinguished antigenically or by the major subunit (pilE) locus and its genetic context. The factors that govern transcription of the class II pilE gene are not known, even though it is present in isolates that cause epidemic disease. Here we show that the transcription of class II pilE is maintained throughout growth and under different stress conditions and is driven by a σ70-dependent promoter. This is distinct from Tfp regulation in nonpathogenic Neisseria spp. and may confer an advantage during host-cell interaction and infection.

scholarly journals VpsR Directly Activates Transcription of Multiple Biofilm Genes in Vibrio cholerae

2020 ◽  
Vol 202 (18) ◽  
Author(s):  
Meng-Lun Hsieh ◽  
Christopher M. Waters ◽  
Deborah M. Hinton
Keyword(s):  
Rna Polymerase ◽  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Core Promoter ◽  
Class Ii ◽  
Class I ◽  
Dependent Manner ◽  
Mobility Shift ◽  
Content Type

ABSTRACT Vibrio cholerae biofilm biogenesis, which is important for survival, dissemination, and persistence, requires multiple genes in the Vibrio polysaccharides (vps) operons I and II as well as the cluster of ribomatrix (rbm) genes. Transcriptional control of these genes is a complex process that requires several activators/repressors and the ubiquitous signaling molecule, cyclic di-GMP (c-di-GMP). Previously, we demonstrated that VpsR directly activates RNA polymerase containing σ70 (σ70-RNAP) at the vpsL promoter (PvpsL), which precedes the vps-II operon, in a c-di-GMP-dependent manner by stimulating formation of the transcriptionally active, open complex. Using in vitro transcription, electrophoretic mobility shift assays, and DNase I footprinting, we show here that VpsR also directly activates σ70-RNAP transcription from other promoters within the biofilm formation cluster, including PvpsU, at the beginning of the vps-I operon, PrbmA, at the start of the rbm cluster, and PrbmF, which lies upstream of the divergent rbmF and rbmE genes. In this capacity, we find that VpsR is able to behave both as a class II activator, which functions immediately adjacent/overlapping the core promoter sequence (PvpsL and PvpsU), and as a class I activator, which functions farther upstream (PrbmA and PrbmF). Because these promoters vary in VpsR-DNA binding affinity in the absence and presence of c-di-GMP, we speculate that VpsR’s mechanism of activation is dependent on both the concentration of VpsR and the level of c-di-GMP to increase transcription, resulting in finely tuned regulation. IMPORTANCE Vibrio cholerae, the bacterial pathogen that is responsible for the disease cholera, uses biofilms to aid in survival, dissemination, and persistence. VpsR, which directly senses the second messenger c-di-GMP, is a major regulator of this process. Together with c-di-GMP, VpsR directly activates transcription by RNA polymerase containing σ70 from the vpsL biofilm biogenesis promoter. Using biochemical methods, we demonstrate for the first time that VpsR/c-di-GMP directly activates σ70-RNA polymerase at the first genes of the vps and ribomatrix operons. In this regard, it functions as either a class I or class II activator. Our results broaden the mechanism of c-di-GMP-dependent transcription activation and the specific role of VpsR in biofilm formation.

scholarly journals Nisin H Is a New Nisin Variant Produced by the Gut-Derived Strain Streptococcus hyointestinalis DPC6484

2015 ◽  
Vol 81 (12) ◽  
pp. 3953-3960 ◽  
Author(s):  
Paula M. O'Connor ◽  
Eileen F. O'Shea ◽  
Caitriona M. Guinane ◽  
Orla O'Sullivan ◽  
Paul D. Cotter ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Immune System ◽  
Bacteriocin Production ◽  
Genetic Determinants ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Wide Range ◽  
Similar Gene ◽  
Strain Genome

ABSTRACTAccumulating evidence suggests that bacteriocin production represents a probiotic trait for intestinal strains to promote dominance, fight infection, and even signal the immune system. In this respect, in a previous study, we isolated from the porcine intestine a strain ofStreptococcus hyointestinalisDPC6484 that displays antimicrobial activity against a wide range of Gram-positive bacteria and produces a bacteriocin with a mass of 3,453 Da. Interestingly, the strain was also found to be immune to a nisin-producing strain. Genome sequencing revealed the genetic determinants responsible for a novel version of nisin, designated nisin H, consisting of thenshABTCPRKGEFgenes, with transposases encoded betweennshPandnshRand betweennshKandnshG. A similar gene cluster is also found inS. hyointestinalisLMG14581. Notably, the cluster lacks an equivalent of the nisin immunity gene,nisI. Nisin H is proposed to have the same structure as the prototypical nisin A but differs at 5 amino acid positions—Ile1Phe (i.e., at position 1, nisin A has Ile while nisin H has Phe), Leu6Met, Gly18Dhb (threonine dehydrated to dehydrobutyrine), Met21Tyr, and His31Lys—-and appears to represent an intermediate between the lactococcal nisin A and the streptococcal nisin U variant of nisin. Purified nisin H inhibits a wide range of Gram-positive bacteria, including staphylococci, streptococci,Listeriaspp., bacilli, and enterococci. It represents the first example of a natural nisin variant produced by an intestinal isolate of streptococcal origin.

Occipital plagiocephaly: a critical review of the literature

1998 ◽  
Vol 89 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Harold L. Rekate
Keyword(s):  
Diagnostic Criteria ◽  
Treatment Options ◽  
Surgical Techniques ◽  
Class Ii ◽  
Population Based ◽  
Class I ◽  
Weight Of Evidence ◽  
Class Iii ◽  
Content Type ◽  
Fine Print

Object. The literature on occipital plagiocephaly (OP) was critically reviewed to determine the feasibility of establishing treatment recommendations. Methods. Using standard computerized search techniques, medical literature databases containing peer-review articles dating from 1966 were queried for key words related to OP. The titles of all articles were scanned for relevance, and copies of potentially relevant articles published in English were reviewed. Articles in which treatment was discussed were categorized according to their weight of evidence as Class I (prospective randomized controlled trials), Class II (clinical studies in which data are collected prospectively or retrospective analyses based on clearly reliable data), and Class III (most studies based on retrospectively collected data) to evaluate their contribution to developing a consensus on the treatment of OP. Of the 4308 articles identified, all but 89 were excluded. Based on the review of these articles, the actual incidence of OP is unknown, and no population-based studies of its incidence or prevalence exist. The reported incidence of lambdoid craniosynostosis ranges from 3 to 20% with differences in diagnostic criteria accounting for the variability. With the possible exception of a lambdoid suture that is replaced by a dense ridge of bone, no other diagnostic criteria have been agreed on. There were no Class I studies and only one Class II study provided comparisons of outcomes in more than one treatment group with outcomes in an untreated group. Recommended treatment options included observation only, mechanical interventions, and a variety of surgical techniques. Conclusions. Controlled clinical trials are needed before any form of intervention can be recommended for the treatment of OP. If surgery, which is expensive and potentially dangerous, is to continue to play a role in the management of this condition, efforts should be made to determine if patients with untreated OP have suffered from lack of treatment.

scholarly journals A Class IHaemophilus ducreyiStrain Containing a Class IIhgbAAllele Is Partially Attenuated in Humans: Implications for HgbA Vaccine Efficacy Trials

2019 ◽  
Vol 87 (7) ◽  
Author(s):  
Isabelle Leduc ◽  
Kate R. Fortney ◽  
Diane M. Janowicz ◽  
Beth Zwickl ◽  
Sheila Ellinger ◽  
...  
Keyword(s):  
Vaccine Efficacy ◽  
Formation Rate ◽  
Class Ii ◽  
Human Infection ◽  
Open Reading Frames ◽  
Class I ◽  
Human Model ◽  
Polymorphism Analysis ◽  
Content Type ◽  
Efficacy Trials

ABSTRACTHaemophilus ducreyicauses chancroid and is a major cause of cutaneous ulcers in children. Due to environmental reservoirs, both class I and class IIH. ducreyistrains persist in cutaneous ulcer regions of endemicity following mass drug administration of azithromycin, suggesting the need for a vaccine. The hemoglobin receptor (HgbA) is a leading vaccine candidate, but its efficacy in animal models is class specific. Controlled human infection models can be used to evaluate vaccines, but only a class I strain (35000HP) has been characterized in this model. As a prelude to evaluating HgbA vaccines in the human model, we tested here whether a derivative of 35000HP containing a class IIhgbAallele (FX548) is as virulent as 35000HP in humans. In eight volunteers infected at three sites with each strain, the papule formation rate was 95.8% for 35000HP versus 62.5% for FX548 (P = 0.021). Excluding doses of FX548 that were ≥2-fold higher than those of 35000HP, the pustule formation rate was 25% for 35000HP versus 11.7% for FX548 (P = 0.0053). By Western blot analysis, FX548 and 35000HP expressed equivalent amounts of HgbA in whole-cell lysates and outer membranes. The growth of FX548 and 35000HP was similar in media containing hemoglobin or hemin. By whole-genome sequencing and single-nucleotide polymorphism analysis, FX548 contained no mutations in open reading frames other thanhgbA. We conclude that by an unknown mechanism, FX548 is partially attenuated in humans and is not a suitable strain for HgbA vaccine efficacy trials in the model.

scholarly journals Complete Genome Sequence of Lactobacillus plantarum 10CH, a Potential Probiotic Lactic Acid Bacterium with Potent Antimicrobial Activity

2017 ◽  
Vol 5 (48) ◽  
Author(s):  
Nancy M. El Halfawy ◽  
Moustafa Y. El-Naggar ◽  
Simon C. Andrews
Keyword(s):  
Antimicrobial Activity ◽  
Lactic Acid ◽  
Nucleotide Sequence ◽  
Lactic Acid Bacterium ◽  
Lactobacillus Plantarum ◽  
Virulence Factors ◽  
Circular Chromosome ◽  
Content Type ◽  
Bacteriocin Gene ◽  
Single Circular Chromosome

ABSTRACT Lactobacillus plantarum 10CH is a bacteriocin-producing potential probiotic lactic acid bacterium (LAB) strain isolated from cheese. Its complete nucleotide sequence shows a single circular chromosome of 3.3 Mb, with a G+C content of 44.51%, a 25-gene plantaricin bacteriocin gene cluster, and the absence of recognized virulence factors.

scholarly journals Determination of antagonistic starter cultures for pickle and olive fermentation processes

2009 ◽  
Vol 27 (No. 3) ◽  
pp. 185-193 ◽  
Author(s):  
A.H. Çon ◽  
N. Karasu
Keyword(s):  
Antimicrobial Activity ◽  
Lactobacillus Plantarum ◽  
Starter Cultures ◽  
The West ◽  
Lactobacillus Pentosus ◽  
Fermentation Processes ◽  
West Part ◽  
Selection Of ◽  
Microbiological Properties

In the present study, the main purpose was the selection of antagonistic starter cultures for pickle and olive fermentation processes. The chemical and microbiological properties of fermented 70 pickle and 16 olive samples collected from the province of the west part of Turkey were analysed. Subsequently, lactic acid bacteria strains producing bacteriocin-like metabolites were isolated and identified. From 86 samples, 16 isolates were chosen, depending on their partial antimicrobial activity against at least one selected indicator. 13 out of this 16 isolates were identified as <i>Lactobacillus plantarum</i> whereas 3 of them proved to be <i>Lactobacillus pentosus</i>. Moreover, all the relevant isolates were found to be potent acid producers. All these results obviously suggest that the isolated <i>Lactobacillus plantarum</i> 9 and 25 were appropriate for them to be proposed as starter cultures in fermented pickle and olive production.

scholarly journals Pseudomycoicidin, a Class II Lantibiotic from Bacillus pseudomycoides

2015 ◽  
Vol 81 (10) ◽  
pp. 3419-3429 ◽  
Author(s):  
Shradha Basi-Chipalu ◽  
Jasmin Dischinger ◽  
Michaele Josten ◽  
Christiane Szekat ◽  
Annegret Zweynert ◽  
...  
Keyword(s):  
Amino Acids ◽  
Antimicrobial Activity ◽  
Posttranslational Modifications ◽  
Class Ii ◽  
Disulfide Bridge ◽  
Spectrometric Analysis ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
A Cell ◽  
Core Peptide

ABSTRACTLantibiotics are ribosomally synthesized antimicrobial peptides with substantial posttranslational modifications. They are characterized by the unique amino acids lanthionine and methyllanthionine, which are introduced by dehydration of Ser/Thr residues and linkage of the resulting dehydrated amino acids with Cys residues. BLAST searches using the mersacidin biosynthetic enzyme (MrsM) in the NCBI database revealed a new class II lantibiotic gene cluster inBacillus pseudomycoidesDSM 12442. Production of an antimicrobial substance with activity against Gram-positive bacteria was detectable in a cell wash extract of this strain. The substance was partially purified, and mass spectrometric analysis predicted a peptide of 2,786 Da in the active fraction. In order to characterize the putative lantibiotic further, heterologous expression of the predicted biosynthetic genes was performed inEscherichia coli. Coexpression of the prepeptide (PseA) along with the corresponding modification enzyme (PseM) resulted in the production of a modified peptide with the corresponding mass, carrying four out of eight possible dehydrations and supporting the presence of four thioether and one disulfide bridge. After the proteolytic removal of the leader, the core peptide exhibited antimicrobial activity. In conclusion, pseudomycoicidin is a novel lantibiotic with antimicrobial activity that was heterologously produced inE. coli.

Multiple subpial transections: outcome and complications in 20 patients who did not undergo resection

2002 ◽  
Vol 97 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Johannes Schramm ◽  
Ales F. Aliashkevich ◽  
Thomas Grunwald
Keyword(s):  
Mr Imaging ◽  
Class Ii ◽  
Class I ◽  
Class Iii ◽  
Content Type ◽  
Surgical Methods ◽  
Over Time ◽  
Class Iv ◽  
Fine Print

Object. The authors describe patient characteristics, surgical methods, complications, and outcome over time in a cohort of patients who underwent multiple subpial transection (MST) without concomitant cortical resection. Methods. Twenty consecutive patients in whom drug-resistant epilepsy had been diagnosed a mean of 16 ± 9 years earlier (mean ± standard deviation [SD]) were treated with MST without cortical resection. The mean follow-up period was 49.3 ± 18.3 months (mean ± SD, median 58 months). At 12 months of follow up, two of the 20 patients were Engel Class I, one was Class II, six were Class III, and 11 were Class IV. At latest follow up, one patient was Engel Class I, one was Class II, seven were Class III, and 11 were Class IV. According to an alternative five-tiered classification system, two outcomes were excellent, seven were good, one was fair, nine were poor, and one was worse. Outcome was found to be better in patients with no lesions observed on magnetic resonance (MR) imaging, and worse in those with large MST areas. Outcome had a tendency to change (this occurred in 13 of 20 cases). Five patients (25%) improved and seven (35%) deteriorated in Engel outcome class, and in one (5%) both developments occurred over time. Most outcome class changes occurred before the end of the 2nd year (nine), and four were observed in the 5th year. There where seven transient neurological deficits and four surgical complications. There was no permanent significant morbidity, and there were no deaths. Conclusions. Forty-five percent of patients achieved a worthwhile improvement after pure MST, if Engel outcome Class III is deemed a worthwhile improvement. The alternative five-tiered classification resulted in 50% with worthwhile improvement (excellent, good, or fair outcome), 45% with poor, and 5% with worse outcome. Lesions that are detectable on MR imaging, and large MST areas are predictive of worse results. Significant intraoperative problems may arise, but this happens infrequently. There is a notable rate of transient morbidity but the rate of permanent morbidity is not significant.

Sign in / Sign up

Export Citation Format

Share Document