Dzung Diep

Dzung Diep
Norwegian University of Life Sciences (NMBU) · Department of Chemistry, Biotechnology and Food Science (IKBM)

Ph.D, professor

About

154
Publications
21,418
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7,599
Citations
Citations since 2017
49 Research Items
3251 Citations
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20172018201920202021202220230200400600
20172018201920202021202220230200400600
20172018201920202021202220230200400600

Publications

Publications (154)
Article
Full-text available
The rise of antibiotic-resistant bacteria is among the biggest challenges in human and veterinary medicine. One of the major factors that contributes to resistance is use of frontline clinical antibiotics in veterinary practices. To avoid this problem, searching for antimicrobials aimed at veterinary applications is becoming especially important. T...
Article
Full-text available
Bacteriocins are ribosomally synthesized antimicrobial peptides, that either kill target bacteria or inhibit their growth. Bacteriocins are used in food preservation and are of increasing interest as potential alternatives to conventional antibiotics. In the present study, we show that Lactococcus petauri B1726, a strain isolated from fermented bal...
Article
Full-text available
Enterocin K1 (EntK1), a bacteriocin that is highly potent against vancomycin-resistant enterococci, depends on binding to an intramembrane protease of the site-2 protease family, RseP, for its antimicrobial activity. RseP is highly conserved in both EntK1-sensitive and EntK1-resistant bacteria, and the molecular mechanisms underlying the interactio...
Method
Bacteriocins are antimicrobial peptides with activity against antibiotic resistant bacterial pathogens. Here, we describe a set of methods aimed at purifying, identifying, and characterizing new bacteriocins. The purification consists of ammonium sulphate precipitation, cation-exchange chromatography, and reversed-phase chromatography. The yield of...
Article
Full-text available
Infections caused by multiresistant pathogens have become a major problem in both human and veterinary medicine. Due to the declining efficacy of many antibiotics, new antimicrobials are needed. Promising alternatives or additions to antibiotics are bacteriocins, antimicrobial peptides of bacterial origin with activity against many pathogens, inclu...
Article
The study aimed to evaluate the antibacterial efficacy of Lugol's solution 5% and Gentian violet 1% against methicillin‐resistant Staphylococcus aureus (MRSA) biofilm in vivo. The bactericidal efficacy for treatment of MRSA‐biofilm skin wound infection was tested in a murine model. Luciferase‐tagged S. aureus Xen31, a MRSA‐strain derived from S. au...
Article
Full-text available
Bacteriocins are emerging as a viable alternative to antibiotics due to their ability to inhibit growth or kill antibiotic resistant pathogens. Herein, we evaluated the ability of the bacteriocin Garvicin KS (GarKS) produced by Lactococcus garvieae KS1546 isolated from cow milk to inhibit the growth of fish and foodborne bacterial pathogens. We fou...
Article
Full-text available
Background The bacteriocin nisin is naturally produced by Lactococcus lactis as an inactive prepeptide that is modified posttranslationally resulting in five (methyl-)lanthionine rings characteristic for class Ia bacteriocins. Export and proteolytic cleavage of the leader peptide results in release of active nisin. By targeting the universal peptid...
Article
Full-text available
Bovine mastitis infection in dairy cattle is a significant economic burden for the dairy industry globally. To reduce the use of antibiotics in treatment of clinical mastitis, new alternative treatment options are needed. Antimicrobial peptides from bacteria, also known as bacteriocins, are potential alternatives for combating mastitis pathogens. I...
Article
Resistance to non-ribosomally synthesized peptide antibiotics affecting the cell envelope is well-studied and mostly associated with the action of peptide-sensing and detoxification (PSD) modules which consist of a two-component system (TCS) and an ATP-binding cassette (ABC) transporter. In contrast, the resistance mechanisms to ribosomally synthes...
Article
Haloarchaea are adapted to survive under extreme saline conditions by accumulating osmolytes and salts to counteract the high osmotic pressure in their habitats. As a consequence, their proteins have evolved to remain active, or even most active, at very high ionic strength. Halocins are proteinaceous antimicrobial substances that are ribosomally-s...
Article
Superficial infections in chronic wounds can prevent the wound healing process by the development of persistent infections and drug-resistant biofilms. Topically applied antimicrobial formulations with stabilized and controlled release offer significant benefits for the effective treatment of wound infections. Bacteriocins are the antimicrobial pep...
Article
Bacteriocins are antimicrobial peptides produced by bacteria to inhibit competitors in their natural environments. Some of these peptides have emerged as commercial food preservatives and, due to the rapid increase in antibiotic resistant bacteria, are also discussed as interesting alternatives to antibiotics for therapeutic purposes. Currently, co...
Article
Full-text available
Listeria monocytogenes is an important food-borne pathogen and a serious concern to food industries. Bacteriocins are antimicrobial peptides produced naturally by a wide range of bacteria mostly belonging to the group of lactic acid bacteria (LAB), which also comprises many strains used as starter cultures or probiotic supplements. Consequently, mu...
Article
Full-text available
Bacteriocins are ribosomally-synthesized antimicrobial peptides, showing great potential as novel treatment options for multidrug-resistant pathogens. In this study, we designed a novel hybrid bacteriocin, Hybrid 1 (H1), by combing the N-terminal part and the C-terminal part of the related bacteriocins enterocin K1 (K1) and enterocin EJ97 (EJ97), r...
Article
Full-text available
Antibiotic-resistant bacterial pathogens have become a serious threat worldwide. One of these pathogens is methicillin-resistant Staphylococcus aureus (MRSA), a major cause of skin and soft tissue infections. In this study we identified a strain of Staphylococcus equorum producing a substance with high antimicrobial activity against many Gram-posit...
Article
Full-text available
Background Antimicrobial peptides (AMPs) have gained wide interest as viable alternatives to antibiotics owing to their potent antimicrobial effects and the low propensity of resistance development. However, their physicochemical properties (solubility, charge, hydrophobicity/hydrophilicity), stability issues (proteolytic or enzymatic degradation,...
Article
Full-text available
There is a growing interest in the use of antimicrobial peptides (AMPs) as potent alternatives for conventional antibiotics, especially in chronic infected wounds. The development of a suitable topical formulation requires a thorough assessment of the photostability profiles of AMPs. In this study, we sought to investigate the photostability of nov...
Article
Full-text available
The membrane-bound protease Eep is an important virulence factor in pathogenic enterococci. The protein is involved in stress response via the RIP pathway which is crucial for pathogenic enterococci to evade host immune attacks during infection. Eep serves also as a receptor for the bacteriocins enterocin K1 and enterocin EJ97. The bacteriocins kil...
Article
Full-text available
Staphylococci, like Staphylococcus aureus and S. epidermidis, are common colonizers of the human microbiota. While being harmless in many cases, many virulence factors result in them being opportunistic pathogens and one of the major causes of hospital-acquired infections worldwide. One of these virulence factors is the ability to form biofilms—thr...
Article
Full-text available
Antibiotic-resistant and biofilm-associated infections brought about by methicillin-resistant Staphylococcus aureus (MRSA) strains is a pressing issue both inside as well as outside nosocomial environments worldwide. Here, we show that a combination of two bacteriocins with distinct structural and functional characteristics, garvicin KS, and microc...
Article
Full-text available
The emergence of antibiotic resistant pathogens has caused a serious world-wide problem in infection treatments in recent years. One of these pathogens is the methicillin-resistant Staphylococcus aureus (MRSA) which is a major cause of skin and soft tissue infections. Alternative strategies and novel sources of antimicrobials to solve antibiotic re...
Article
Full-text available
Enterococci are commensals of human and other animals’ gastrointestinal tracts. Only making up a small part of the microbiota, they have not played a significant role in research, until the 1980s. Although the exact year is variable according to different geographical areas, this was the decade when vancomycin-resistant enterococci (VRE) were disco...
Article
Full-text available
Bacteriocins are antimicrobial peptides produced by bacteria to compete with other bacteria for nutrients and ecological niches. The antimicrobial effect of these peptides on the bacterial populations in the gut is likely dynamic as the survival of the microbes in this environment depends on both competition and cooperation. In this study, we evalu...
Article
Full-text available
Antimicrobial peptides (AMPs) are emerging as a viable alternative to antibiotics attributable to their potent antimicrobial effects and low propensity for resistance development, especially in chronic infected wounds. The development of an optimized topical formulation of AMPs is thus warranted. Preformulation studies for determination of the suit...
Article
Full-text available
Streptococcus pneumoniae infections are one of the major causes of morbility and mortality worldwide. Although vaccination and antibiotherapy constitute fundamental and complementary strategies against pneumococcal infections, they present some limitations including the increase in non-vaccine serotypes and the emergence of multidrug-resistances, r...
Article
Thioridazine, a well-known antipsychotic drug, has shown promising effects on several bacterial strains (including Mycobacterium tuberculosis and methicillin-resistant Staphylococcus aureus). Suppressive effects towards selected cancer cell-lines have also been reported. However, due to adverse effects, the compound is no longer in use for the prim...
Article
Antimicrobial peptides (AMPs) are the natural antibiotics recognized for their potent antibacterial and wound healing properties. Bare AMPs have limited activity following topical application attributable to their susceptibility to environment (hydrolysis, oxidation, photolysis), and wound (alkaline pH, proteolysis) related factors as well as minim...
Article
One of the relatively widespread properties of many enterococcal strains is the production of bacteriocins, which could be useful as natural food preservatives inhibiting pathogenic and spoilage microorganisms. However, knowledge of the distribution and spectrum of bacteriocin activity as well as the distribution of bacteriocin-encoding genes in en...
Article
There is currently a lack of experimental evidence for horizontal gene transfer (HGT) mechanisms in the human gut microbiota. The aim of this study was therefore to experimentally determine the HGT potential in the microbiota of a healthy preterm infant twin pair and to evaluate the global occurrence of the mobilized elements. Stool samples were co...
Article
The antimicrobial activity of Lactobacillus curvatus BCS35 is due to the production of, at least, two class IIa bacteriocins: sakacin P-H12Y (SakP-H12Y), which is a sakacin P (SakP) variant with tyrosine (Tyr) instead of histidine (His) at position 12, and sakacin X (SakX). Moreover, DNA sequence analysis revealed the presence of the genes encoding...
Article
The leaderless bacteriocin Garvicin KS (GarKS) is a potent antimicrobial, being active against a wide range of important pathogens. GarKS production by the native producer Lactococcus garvieae KS1546 is, however, relatively low (80 BU/ml) under standard laboratory growth conditions (batch culture in GM17 at 30°C). To improve the production, we syst...
Article
Full-text available
Abstract: The aim of the project was to isolate and characterize bacteriocin-producing enterococci, as well as determine the prevalence of enterocin structural genes in 187 enterococcal clinical isolates from the northwest of Iran. The isolates were screened for antibacterial activity against 15 different indicator strains. The proteinaceous nature...
Article
Full-text available
Mannose phosphotransferase system (Man-PTS) serves as a receptor for several bacteriocins in sensitive bacterial cells, namely subclass IIa bacteriocins (pediocin-like; pediocins) and subclass IId ones-lactococcin A (LcnA), lactococcin B (LcnB) and garvicin Q (GarQ). Here, to identify the receptor for three other narrow-spectrum subclass IId bacter...
Preprint
The leaderless bacteriocin Garvicin KS (GarKS) is a potent antimicrobial, being active against a wide range of important pathogens. GarKS production by the native producer Lactococcus garvieae KS1546 was however relatively low (80 BU/ml) under standard laboratory growth conditions (batch culture in GM17 at 30°C). To improve the production of GarKS,...
Article
Full-text available
Mannose phosphotransferase system (Man-PTS) is the main mannose permease in bacteria but it is also a known receptor for subclass IIa bacteriocins (pediocin-like group) as well as subclass IId lactococcin A (LcnA) and lactococcin B (LcnB) (LcnA-like group). Subclass IIa bacteriocins exhibit a strong activity against Listeria spp. but they are not a...
Article
Full-text available
The gut microbiota is considered an organ that co-develops with the host throughout its life. The composition and metabolic activities of the gut microbiota are subject to a complex interplay between the host genetics and environmental factors, such as lifestyle, diet, stress and antimicrobials. It is evident that certain prebiotics, and antimicrob...
Article
Full-text available
Very intriguing questions arise with our advancing knowledge on gut microbiota composition and the relationship with health, particularly relating to the factors that contribute to maintaining the population balance. However, there are limited available methodologies to evaluate these factors. Bacteriocins are antimicrobial peptides produced by man...
Article
Full-text available
Enterocin K1 (EntK1), enterocin EJ97 (EntEJ97), and LsbB are three sequence related leaderless bacteriocins. Yet LsbB kills only lactococci while EntK1 and EntEJ97 target wider spectra with EntK1 being particularly active against Enterococcus faecium, including nosocomial multidrug resistant isolates. NMR study of EntK1 showed that it had a structu...
Article
Full-text available
Introduction: Milk is considered to be a healthy, nutritious food product. Microbiological quality is an important aspect in evaluating the quality of milk. Methodology: A total of 603 bulk tank milk samples from 221 farms distributed across ten different regions were collected for milk quality assessment. Quality was judged by total viable count,...
Poster
By using a panel of multiple indicator strains of different bacterial species and genera, we screened a large collection of bacterial isolates (over 1800 isolates) derived from raw milk, for bacteriocin producers with broad inhibition spectra (BIS). Fourteen isolates with BIS were identified, and by 16S rDNA sequencing they were found to belong to...
Article
Full-text available
Introduction: Mastitis is one of the most frequent and costly disease in cattle. We studied milk samples from cattle with mastitis from farms in Kosovo to identify mastitis-causing pathogens and possible effective antibiotics. Our ultimate goal is to help implement adequate antibiotic management and treatment practices in Kosovo METHODOLOGY: A tot...
Article
Full-text available
Production of bacteriocins is a potential probiotic feature of many lactic acid bacteria (LAB) as it can help prevent the growth of pathogens in gut environments. However, knowledge on bacteriocin producers in situ and their function in the gut of healthy animals is still limited. In this study, we investigated five bacteriocin-producing strains of...
Data
Shannon indexes calculated as mean of ten iterations at equal subsampling size of 15,840. (XLSX)
Data
Comparison of relative abundance change of families by administrated strains compared to CON in treatment and post-treatment periods. The difference of the relative abundances from time 0 within each treatment was calculated. The changes at day 7 and day 14 were analyzed as “treatment”, while day 21 and day 28 were analyzed as “post-treatment” data...
Data
Relative abundances of OTUs at genus level. Different colored bars represent different genera with size showing relative abundance of this genus. Labels contain name of treatments and time with day numbers: 0 (day 0), 7 (day 7), 14 (day 14), 21 (day 21) and 28 (day 28). (TIF)
Data
Comparison of bacterial composition of pooled fecal samples and fecal samples from individual mice in CON cage. Principle coordinate analysis (PCoA) plot was generated based on the calculated distances in an unweighted UniFrac matrix. Samples were grouped by color and shape such that pool of fecal samples at indicated time point (red circle), day 0...
Data
Comparison of UniFrac distances of pooled and individual samples. The statistical significances of differences in unweighted UniFrac distances in terms of groups (pooled vs individual samples) and time were shown. The non-parametric p-values were calculated performing two-sample t-tests for the pairs of the groups with Monte Carlo permutations (n =...
Data
Comparison of UniFrac distances between treatments. The statistical significances of differences in unweighted UniFrac distances between treatments and time points were shown. The treatments that were compared for each bacteriocin group included control, bacteriocin positive and bacteriocin negative treatments. The nonparametric p-values were calcu...
Data
Changes in relative abundance of LAB and bacteriocin-targeted bacterial groups at family level during treatment and post-treatment periods. Change in relative abundances of families corresponding to day 0 of treatments were compared to CON. Significance degree is represented as followings: P<0.1 with dot (.); P<0.05 with one star (*); P<0.01 with t...
Data
Lactic acid bacteria count in treatment samples. *The log values in bacteriocin positive and negative treatments were compared pairwise using two-sided Student's t-test for each bacteriocin group. (XLSX)
Data
In vitro antimicrobial activity assay of bacteriocins against the indicator strains listed. (XLSX)
Article
Full-text available
Here, we report the draft genome sequence of Enterococcus faecalis DBH18, a bacteriocinogenic lactic acid bacterium (LAB) isolated from mallard ducks ( Anas platyrhynchos ). The assembly contains 2,836,724 bp, with a G+C content of 37.6%. The genome is predicted to contain 2,654 coding DNA sequences (CDSs) and 50 RNAs.
Article
The Zn-dependent membrane-located protease YvjB has previously been shown to serve as a target receptor for LsbB, a class II leaderless lactococcal bacteriocin. Although yvjB is highly conserved in the genus Lactococcus , the bacteriocin appears to be active only against the subspecies L. lactis subsp. lactis . Comparative analysis of the YvjB prot...
Article
From raw milk we found ten Lactococcus garvieae isolates that produce a new broad spectrum bacteriocin. Though the isolates were obtained from different farms, they turned out to possess identical inhibitory spectra, fermentation profiles of sugars and repetitive sequence-based PCR (rep-PCR) DNA patterns, indicating that they produce the same bacte...
Article
Full-text available
Enterococcus faecium M3K31 is a bacteriocinogenic lactic acid bacterium (LAB) isolated from griffon vulture ( Gyps fulvus subsp. fulvus ) feces. The draft genome sequence of this strain provides genetic data that support its biotechnological potential.
Article
Full-text available
Staphylococcus aureus is known as a frequent colonizer of the skin and mucosa. Among bacterial factors involved in colonization are adhesins such as the microbial surface components recognizing adhesive matrix molecules (MSCRAMMs). Serine aspartate repeat containing protein D (SdrD) is involved in adhesion to human squamous cells isolated from the...
Article
Bacteriocin producers normally possess dedicated immunity systems to protect themselves from their own bacteriocins. Lactococcus lactis strains LMG2081 and BGBM50 are known as lactococcin G producers. However, BGBM50 was sensitive to LMG2081, which indicated that LMG2081 might produce additional bacteriocins that are not present in BGBM50. Therefor...
Article
Full-text available
Dietary fibers contribute to health and physiology primarily via the fermentative actions of the host's gut microbiome. Physicochemical properties such as solubility, fermentability, viscosity, and gel-forming ability differ among fiber types and are known to affect metabolism. However, few studies have focused on how they influence the gut microbi...
Article
Full-text available
Background Bacteriocins produced by lactic acid bacteria (LAB) attract considerable interest as natural and nontoxic food preservatives and as therapeutics whereas the bacteriocin-producing LAB are considered potential probiotics for food, human and veterinary applications, and in the animal production field. Within LAB the lactobacilli are increas...
Chapter
The classification of lactic acid bacteria (LAB) bacteriocins is frequently revised as the diversity increases and more bacteriocins with novel features are characterized, but the main distinction is made between the Class Ia lantibiotics, which undergo post-translational modifications, and the Class II non-modified peptides. In order to effectivel...