scholarly journals Identification and characterisation of antimicrobial activity of nisin a produced by Lactococcus lactis subsp. lactis LL27

2009 ◽  
Vol 27 (No. 1) ◽  
pp. 55-64 ◽  
Author(s):  
P. Şanlibaba ◽  
N. Akkoç ◽  
M. Akçelik
Keyword(s):  
Lactococcus Lactis ◽  
Ribosomal Rna ◽  
Heat Stability ◽  
Raw Milk ◽  
Inhibitory Effect ◽  
Proteinase K ◽  
Gram Negative Bacteria ◽  
Direct Pcr ◽  
Gene Encoding ◽  
Gram Negative

In this study, bacteriocin producing lactococcal strains were isolated from Turkish raw milk samples. Among these isolates, LL27 had the highest inhibition activity against Gram-positive indicator strains, and was selected for further analyses. DNA sequencing of 16S ribosomal RNA gene demonstrated that the isolate was <i>Lactococcus lactis</i> subsp. <i>lactis</i>. The gene encoding the bacteriocin in this strain was found to be identical to that of nisin A using direct PCR sequence methods. The bacteriocin was completely inactivated by α-chymotrypsin and proteinase K and partially inactivated by lipase and α-amylase. pH and heat stability characteristics were found to be identical with those of the control nisin. The inhibitory activity of the bacteriocin produced by LL27 was also evaluated against Gram-negative bacteria in combination with heat and freezing treatments. The results obviously showed that the production level of nisin of the <i>Lc. lactis</i> LL27 had a significant inhibitory effect on the pathogenic Gram-negative strains with the heating and freezing processes which are commonly used in the food processing.

scholarly journals Bacillus phage endolysin, lys46, bactericidal properties against Gram-negative bacteria

2020 ◽  
Author(s):  
Mohammad Reza Sarjoughian ◽  
Fereshte Rahmani ◽  
Shamsozoha Abolmaali ◽  
Shakiba Darvish Alipour Astaneh
Keyword(s):  
Bacillus Subtilis ◽  
Screening Program ◽  
Inhibitory Effect ◽  
Indicator Bacteria ◽  
Subtilis Strain ◽  
Gram Negative Bacteria ◽  
Gene Encoding ◽  
Gram Negative ◽  
Antibacterial Screening ◽  
Bacillus Phage

Background and Objectives: The great potential of bacteriophage for removing pathogen bacteria via targeting the cell wall is highly concerned. With a priority for overcoming drug-resistance, we screened against endolysins targeting Gram-negative bacteria to introduce a new antibacterial agent. This study was aimed to identify endolysins from the lysogenic phage of the Siphoviridea family in Bacillus subtilis. Materials and Methods: The Bacillus subtilis strain DDBCC46 was isolated from a preliminary antibacterial screening program. The endolysin (s) was extracted, concentrated with ammonium sulfate saturation, and their activity evaluated against the indicator bacteria. The phage particles were extracted from the bacteria using the minimum inhibition concentration of mitomycin C, followed by testing the phage inhibitory effect on the growth of indicator bacteria. The NCBI, Virus-Host DB, and EXPASY databases were used to obtain and confirm the sequences of the genes encoding PG hydrolases in Siphoviridea phages hosted in B. subtilis. Results: An 816 bp gene encoding an endolysin enzyme, was approved in the B. subtilis DDBCC 46, with specific primers of Bacillus phage SPP1. The purified-endolysin indicated antibacterial activity against Klebsiella pneumoniae, Salmonella typhimurium, Proteus (sp), and Escherichia coli. SDS-PAGE profiling followed by silica gel purification, led to introduceLys4630 as a therapeutic product and food preservative. Conclusion: lys4630 showed antibacterial effects on the common Gram-negative pathogens in clinics and food industries; E. coli, P. aeruginosa and Salmonella (sp).

scholarly journals Whole-Genome Sequencing of Gram-Negative Bacteria Isolated From Bovine Mastitis and Raw Milk: The First Emergence of Colistin mcr-10 and Fosfomycin fosA5 Resistance Genes in Klebsiella pneumoniae in Middle East

2021 ◽  
Vol 12 ◽  
Author(s):  
Yasmine H. Tartor ◽  
Norhan K. Abd El-Aziz ◽  
Rasha M. A. Gharieb ◽  
Hend M. El Damaty ◽  
Shymaa Enany ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Klebsiella Pneumoniae ◽  
Genome Sequencing ◽  
Bovine Milk ◽  
Bovine Mastitis ◽  
Raw Milk ◽  
Whole Genome ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli

Antimicrobial resistance is a major concern in the dairy industry. This study investigated the prevalence, antimicrobial resistance phenotypes, and genome sequencing of Gram-negative bacteria isolated from clinical (n = 350) and subclinical (n = 95) bovine mastitis, and raw unpasteurized milk (n = 125). Klebsiella pneumoniae, Aeromonas hydrophila, Enterobacter cloacae (100% each), Escherichia coli (87.78%), and Proteus mirabilis (69.7%) were the most prevalent multidrug-resistant (MDR) species. Extensive drug-resistance (XDR) phenotype was found in P. mirabilis (30.30%) and E. coli (3.33%) isolates. Ten isolates (four E. coli, three Klebsiella species and three P. mirabilis) that displayed the highest multiple antibiotic resistance (MAR) indices (0.54–0.83), were exposed to whole-genome sequencing (WGS). Two multilocus sequence types (MLST): ST2165 and ST7624 were identified among the sequenced E. coli isolates. Three E. coli isolates (two from clinical mastitis and one from raw milk) belonging to ST2165 showed similar profile of plasmid replicon types: IncFIA, IncFIB, IncFII, and IncQ1 with an exception to an isolate that contained IncR, whereas E. coli ST7624 showed a different plasmid profile including IncHI2, IncHI2A, IncI1α, and IncFII replicon types. ResFinder findings revealed the presence of plasmid-mediated colistin mcr-10 and fosfomycin fosA5 resistance genes in a K. pneumoniae (K1) isolate from bovine milk. Sequence analysis of the reconstructed mcr-10 plasmid from WGS of K1 isolate, showed that mcr-10 gene was bracketed by xerC and insertion sequence IS26 on an IncFIB plasmid. Phylogenetic analysis revealed that K1 isolate existed in a clade including mcr-10-harboring isolates from human and environment with different STs and countries [United Kingdom (ST788), Australia (ST323), Malawi (ST2144), Myanmar (ST705), and Laos (ST2355)]. This study reports the first emergence of K. pneumoniae co-harboring mcr-10 and fosA5 genes from bovine milk in the Middle East, which constitutes a public health threat and heralds the penetration of the last-resort antibiotics. Hence, prudent use of antibiotics in both humans and animals and antimicrobial surveillance plans are urgently required.

In Vitro antibacterial activity of lactic acid bacteria isolated from goat’s raw milk of Mostaganem (West Algeria) against Gram negative bacteria responsible for urinary tract infections

2016 ◽  
Vol 6 (1) ◽  
pp. 15-22
Author(s):  
Zergoug Amina ◽  
Cheriguene Abderrahim ◽  
Chougrani Fadela
Keyword(s):  
Antibacterial Activity ◽  
Lactic Acid ◽  
Urinary Tract ◽  
Lactic Acid Bacteria ◽  
Raw Milk ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Tract Infections ◽  
West Algeria

Urinary tract infections (UTI) are a serious bacterial pathological challenges all over the world, leading to respiratory infections, that’s why new strategies don’t cease to develop. Lactic acid bacteria having shown beneficial effects for years in various areas, may prove to be excellent candidates in medical field. The current research focused on the selection of lactic acid bacteria having the potential of an antibacterial activity against Gram negative bacteria responsible for UTI, for an eventual use as a therapeutic agent. A total of 40 isolates were isolated from goat’s raw milk of Mostaganem (West Algeria). In vitro tests were conducted in order to determine the efficiency of the isolates to produce antibacterial agents in interaction with uropathogens. Among 40 isolates, only 10 isolates identified as Lactobacilli and Lactococci were performant. The Screening showed that the inhibitor agent was proteinaceous substance. Therfore, it is noted that a treatment with presence of LAB is very encouraging as a result of the production of bacteriocin-like substance. On the other hand, LAB can be considered as a good alter-native to the large extent to the antibiotics in the treatment of UTI.

Specific Inhibition of Endotoxin Coating of Red Cells by a Human Erythrocyte Membrane Component

1970 ◽  
Vol 1 (1) ◽  
pp. 98-108
Author(s):  
Georg F. Springer ◽  
Shankar V. Huprikar ◽  
Erwin Neter
Keyword(s):  
Human Erythrocyte ◽  
Inhibitory Effect ◽  
Red Cells ◽  
Ion Concentration ◽  
Gram Negative Bacteria ◽  
Hydrogen Ion Concentration ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Common Antigens ◽  
Vi Antigen

We have isolated from human erythrocyte ghosts a fraction which prevents the attachment of unheated as well as heated lipopolysaccharides of gram-negative bacteria to red cells. This material has no significant inhibitory effect either toward the Vi antigen of gram-negative bacteria or towards the group and common antigens of the gram-positive bacteria investigated. We, therefore, named this fraction “lipopolysaccharide receptor.” The receptor interacts with lipopolysaccharides and not with erythrocytes, it forms complexes with and blocks those groupings of lipopolysaccharides which attach to red cells. The effect of the receptor is physical and not enzymatic. The interaction of the receptor with the lipopolysaccharides is reversible, and the receptor removes lipopolysaccharides fixed to red cells. An equilibrium of lipopolysaccharide distribution between cells and receptor is established when receptor-lipopolysaccharide complexes are incubated with red cells. The receptor is labile toward heat and deviation of the hydrogen ion concentration from neutrality; aldehydes destroy its inhibitory activity.

scholarly journals Chemical Composition and in Vitro Antibacterial Activity of the Essential Oil of Minthostachys Mollis (Kunth) Griseb Vaught from the Venezuelan Andes

2009 ◽  
Vol 4 (7) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
Flor D. Mora ◽  
María Araque ◽  
Luis B. Rojas ◽  
Rosslyn Ramírez ◽  
Bladimiro Silva ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Essential Oil ◽  
Chemical Constituents ◽  
Salmonella Typhi ◽  
Inhibitory Effect ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Significant Inhibitory Effect ◽  
In Vitro Antibacterial Activity

Chemical constituents of the essential oil from the leaves of Minthostachys mollis (Kunth) Griseb Vaught var. mollis collected in January 2008 at Tuñame, Trujillo State, Venezuela, were separated and identified by GCMS analysis. The essential oil was obtained by hydrodistillation and thirteen components (98.5% of the sample) were identified by comparison with the Wiley GCMS library data base. The two major components were pulegone (55.2%) and trans-menthone (31.5%). The essential oil showed a significant inhibitory effect against Gram-positive and Gram-negative bacteria, especially Bacillus subtilis and Salmonella typhi (4 μg/mL).

Gram-Negative Bacteria in Raw Milk

1969 ◽  
Vol 2 (2) ◽  
pp. 69-71 ◽  
Author(s):  
G. Blankenagel ◽  
I. Okello-Uma
Keyword(s):  
Raw Milk ◽  
Gram Negative Bacteria ◽  
Gram Negative

scholarly journals Identification of Burkholderia cepacia complex bacteria with a lipopolysaccharide-specific monoclonal antibody

2010 ◽  
Vol 59 (1) ◽  
pp. 41-47 ◽  
Author(s):  
David P. AuCoin ◽  
Reva B. Crump ◽  
Peter Thorkildson ◽  
Dana E. Nuti ◽  
John J. LiPuma ◽  
...  
Keyword(s):  
Burkholderia Cepacia ◽  
Burkholderia Pseudomallei ◽  
Proteinase K ◽  
Burkholderia Cepacia Complex ◽  
Gram Negative Bacteria ◽  
Specific Monoclonal Antibody ◽  
Separate Species ◽  
Gram Negative ◽  
Ladder Pattern ◽  
Human Infections

The genus Burkholderia includes many bacteria that cause serious human infections. As is the case with other Gram-negative bacteria, Burkholderia species produce LPS, which is an abundant component of the bacterial cell surface. Burkholderia cepacia complex (Bcc) bacteria (which include at least 17 separate species) produce LPS structures that are quite different. In an attempt to determine the degree of LPS epitope variation among Bcc species, a mAb was produced, designated 5D8, specific for the LPS of B. cepacia. Western blot analysis determined that mAb 5D8 was able to produce the classic ‘ladder pattern’ when used to probe B. cepacia and Burkholderia anthina lysates, although 5D8 did not produce this pattern with the other seven Bcc species tested. mAb 5D8 reacted with varying intensity to most but not all of the additional B. cepacia and B. anthina strains tested. Therefore, there seems to be significant epitope variation among Bcc LPS both between and within species. Additionally, mAb 5D8 reacted with a proteinase-K-sensitive 22 kDa antigen in all Bcc strains and also in a strain of Burkholderia pseudomallei.

scholarly journals Virulence Determinants and Plasmid-Mediated Colistin Resistance mcr Genes in Gram-Negative Bacteria Isolated From Bovine Milk

2021 ◽  
Vol 11 ◽  
Author(s):  
Yasmine H. Tartor ◽  
Rasha M. A. Gharieb ◽  
Norhan K. Abd El-Aziz ◽  
Hend M. El Damaty ◽  
Shymaa Enany ◽  
...  
Keyword(s):  
Virulence Genes ◽  
Raw Milk ◽  
Subclinical Mastitis ◽  
Clinical Mastitis ◽  
Gram Negative Bacteria ◽  
Colistin Resistance ◽  
Genetic Characteristics ◽  
Gram Negative ◽  
E Coli ◽  
Resistant Strains

A major increase of bacterial resistance to colistin, a last-resort treatment for severe infections, was observed globally. Using colistin in livestock rearing is believed to be the ground of mobilized colistin resistance (mcr) gene circulation and is of crucial concern to public health. This study aimed to determine the frequency and virulence characteristics of colistin-resistant Gram-negative bacteria from the milk of mastitic cows and raw unpasteurized milk in Egypt. One hundred and seventeen strains belonging to Enterobacteriaceae (n = 90), Pseudomonas aeruginosa (n = 10), and Aeromonas hydrophila (n = 17) were screened for colistin resistance by antimicrobial susceptibility testing. The genetic characteristics of colistin-resistant strains were investigated for mcr-1–9 genes, phylogenetic groups, and virulence genes. Moreover, we evaluated four commonly used biocides in dairy farms for teat disinfection toward colistin-resistant strains. Multidrug-resistant (MDR) and extensive drug-resistant (XDR) phenotypes were detected in 82.91% (97/117) and 3.42% (4/117) of the isolates, respectively. Of the 117 tested isolates, 61 (52.14%) were colistin resistant (MIC &gt;2 mg/L), distributed as 24/70 (34.29%) from clinical mastitis, 10/11 (90.91%) from subclinical mastitis, and 27/36 (75%) from raw milk. Of these 61 colistin-resistant isolates, 47 (19 from clinical mastitis, 8 from subclinical mastitis, and 20 from raw milk) harbored plasmid-borne mcr genes. The mcr-1 gene was identified in 31.91%, mcr-2 in 29.79%, mcr-3 in 34.04%, and each of mcr-4 and mcr-7 in 2.13% of the colistin-resistant isolates. Among these isolates, 42.55% (20/47) were E. coli, 21.28% (10/47) A. hydrophila, 19.12% (9/47) K. pneumoniae, and 17.02% (8/47) P. aeruginosa. This is the first report of mcr-3 and mcr-7 in P. aeruginosa. Conjugation experiments using the broth-mating technique showed successful transfer of colistin resistance to E. coli J53-recipient strain. Different combinations of virulence genes were observed among colistin-resistant isolates with almost all isolates harboring genes. Hydrogen peroxide has the best efficiency against all bacterial isolates even at a low concentration (10%). In conclusion, the dissemination of mobile colistin resistance mcr gene and its variants between MDR- and XDR-virulent Gram-negative isolates from dairy cattle confirms the spread of mcr genes at all levels; animals, humans, and environmental, and heralds the penetration of the last-resort antimicrobial against MDR bacteria. Consequently, a decision to ban colistin in food animals is urgently required to fight XDR and MDR bacteria.

A novel mechanism-based pharmacokinetic–pharmacodynamic (PKPD) model describing ceftazidime/avibactam efficacy against β-lactamase-producing Gram-negative bacteria

2019 ◽  
Author(s):  
Anders N Kristoffersson ◽  
Caterina Bissantz ◽  
Rusudan Okujava ◽  
Andreas Haldimann ◽  
Isabelle Walter ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Dose Finding ◽  
Gram Negative Bacteria ◽  
Data Set ◽  
Gram Negative ◽  
Pkpd Model ◽  
Index Approach ◽  
Antibiotic Effect ◽  
Time Kill

Abstract Background Diazabicyclooctanes (DBOs) are an increasingly important group of non β-lactam β-lactamase inhibitors, employed clinically in combinations such as ceftazidime/avibactam. The dose finding of such combinations is complicated using the traditional pharmacokinetic/pharmacodynamic (PK/PD) index approach, especially if the β-lactamase inhibitor has an antibiotic effect of its own. Objectives To develop a novel mechanism-based pharmacokinetic–pharmacodynamic (PKPD) model for ceftazidime/avibactam against Gram-negative pathogens, with the potential for combination dosage simulation. Methods Four β-lactamase-producing Enterobacteriaceae, covering Ambler classes A, B and D, were exposed to ceftazidime and avibactam, alone and in combination, in static time–kill experiments. A PKPD model was developed and evaluated using internal and external evaluation, and combined with a population PK model and applied in dosage simulations. Results The developed PKPD model included the effects of ceftazidime alone, avibactam alone and an ‘enhancer’ effect of avibactam on ceftazidime in addition to the β-lactamase inhibitory effect of avibactam. The model could describe an extensive external Pseudomonas aeruginosa data set with minor modifications to the enhancer effect, and the utility of the model for clinical dosage simulation was demonstrated by investigating the influence of the addition of avibactam. Conclusions A novel mechanism-based PKPD model for the DBO/β-lactam combination ceftazidime/avibactam was developed that enables future comparison of the effect of avibactam with other DBO/β-lactam inhibitors in simulations, and may be an aid in translating PKPD results from in vitro to animals and humans.

Exogenous Production of N-acetylmuramyl-L Alanine Amidase (LysM2) from Siphoviridae Phage Affecting Anti-Gram-Negative Bacteria: Evaluation of Its Structure and Function

2022 ◽  
Author(s):  
Morteza Miri ◽  
Sepideh Yazdianpour ◽  
Shamsozoha Abolmaali ◽  
Shakiba Darvish Alipour Astaneh
Keyword(s):  
In Silico ◽  
Alpha Helix ◽  
Salmonella Typhi ◽  
Structure And Function ◽  
Gram Negative Bacteria ◽  
Gene Encoding ◽  
Gram Negative ◽  
E Coli ◽  
Antigenic Properties ◽  
And Function

Background: To obtain endolysin with impact(s) on gram-negative bacteria as well as gram-positive bacteria, N-acetylmuramyl L-alanine-amidase (MurNAc-LAA) from a Bacillus subtilis-hosted Siphoviridae phage (SPP1 phage, Subtilis Phage Pavia 1) was exogenously expressed in Escherichia coli (E. coli).  Methods: The sequences of MurNAc-LAA genes encoding peptidoglycan hydrolases were obtained from the Virus-Host database. The sequence of MurNAc-LAA was optimized by GenScript software to generate MurNAc-LAA-MMI (LysM2) for optimal expression in E. coli. Furthermore, the structure and function of LysM2 was evaluated in silico. The optimized gene was synthesized, subcloned in the pET28a, and expressed in E. coli BL21(DE3). The antibacterial effects of the protein on the peptidoglycan substrates were studied. Results: LysM2, on 816 bp gene encoding a 33 kDa protein was confirmed as specific SPP1 phage enzyme. The enzyme is composed of 271 amino acids, with a half-life of 10 hr in E. coli. In silico analyses showed 34.2% alpha-helix in the secondary structure, hydrophobic N-terminal, and lysine-rich C-terminal, and no antigenic properties in LysM2 protein. This optimized endolysin revealed impacts against Proteus (sp) by turbidity, and an antibacterial activity against Klebsiella pneumoniae, Salmonella typhi-murium, and Proteus vulgaris in agar diffusion assays. Conclusion: Taken together, our results confirmed that LysM2 is an inhibiting agent for gram-negative bacteria.

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