Rhizobium trifolii Mutant Interactions During the Establishment of Nodulation in White Clover

A more refined bacteroid isolation procedure was developed and used to investigate the establishment of nodulation of white clovers by Rhizobium tri/olii strain T1. Combinations of a variety of bacterial strains were mixed together for inoculation of clovers. The results showed that in nodules containing two different strains of Rhizobium only one type of inoculum strain could be reisolated from any one plant cell. Furthermore, it was found that nodules which resulted from inoculation with cell mixtures containing the non-invasive Agrobacterium tume/aciens strain B6S3 and a nodulating Rhizobium strain at various cell ratios did not contain strain B6S3. However, a number of invasive but non-nodulating mutants of Rhizobium could be readily reisolated from nodules resulting from inoculation with cell mixtures containing both the mutant and its parent strain. Moreover, some combinations of symbiotic mutants showed a cooperative interaction giving rise to nitrogen-fixing nodules. From an investigation of the genetic characteristics of the bacterial cells isolated from nodules, it was concluded that this interaction between different symbiotically defective mutants of Rhizobium is a form of cross-feeding and not genetic complementation. Furthermore, there are four possible steps in the nodulation process where the intra-nodule interactions can occur between different strains of Rhizobium.

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Antioxidant and Antibacterial Activities of Artemisia herba-alba Asso Essential Oil from Middle Atlas, Morocco

Phytothérapie ◽

10.3166/phyto-2018-0057 ◽

2018 ◽

Vol 16 (S1) ◽

pp. S48-S54

Author(s):

Y. Ez zoubi ◽

S. Lairini ◽

A. Farah ◽

K. Taghzouti ◽

A. El Ouali Lalami

Keyword(s):

Antibacterial Activity ◽

Essential Oil ◽

Foodborne Pathogens ◽

Food Systems ◽

Antibacterial Activities ◽

Culture Collection ◽

Bornyl Acetate ◽

Bacterial Strains ◽

Disk Diffusion Assay ◽

Different Strains

The purpose of this study was to determine the chemical composition and to evaluate the antioxidant and antibacterial effects of the Moroccan Artemisia herba-alba Asso essential oil against foodborne pathogens. The essential oil of Artemisia herba-alba was analyzed by gas chromatography coupled with mass spectroscopy. The antibacterial activity was assessed against three bacterial strains isolated from foodstuff and three bacterial strains referenced by the ATCC (American Type Culture Collection) using the disk diffusion assay and the macrodilution method. The antioxidant activity was evaluated using the DPPH (2, 2-diphenyl-1- picrylhydrazyl) method. The fourteen compounds of the Artemisia herba-alba essential oil were identified; the main components were identified as β-thujone, chrysanthenone, α-terpineol, α-thujone, α-pinene, and bornyl acetate. The results of the antibacterial activity obtained showed a sensitivity of the different strains to Artemisia herba-alba essential oil with an inhibition diameter of 8.50 to 17.00 mm. Concerning the MICs (minimum inhibitory concentrations), the essential oil exhibited much higher antibacterial activity with MIC values of 2.5 μl/ml against Bacillus subtilis ATCC and Lactobacillus sp. The essential oil was found to be active by inhibiting free radicals with an IC50 (concentration of an inhibitor where the response is reduced by half) value of 2.9 μg/ml. These results indicate the possible use of the essential oil on food systems as an effective inhibitor of foodborne pathogens, as a natural antioxidant, and for potential pharmaceutical applications. However, further research is needed in order to determine the toxicity, antibacterial, and antioxidant effects in edible products.

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Plasma-Activated Water (PAW) as a Disinfection Technology for Bacterial Inactivation with a Focus on Fruit and Vegetables

Foods ◽

10.3390/foods10010166 ◽

2021 ◽

Vol 10 (1) ◽

pp. 166

Author(s):

Aswathi Soni ◽

Jonghyun Choi ◽

Gale Brightwell

Keyword(s):

Fruit And Vegetables ◽

Atmospheric Plasma ◽

Model Systems ◽

Thermal Treatments ◽

Bacterial Cells ◽

Bacterial Inactivation ◽

Gas Temperature ◽

Bacterial Strains ◽

Sensory Qualities ◽

Plasma Activated Water

Plasma-activated water (PAW) is generated by treating water with cold atmospheric plasma (CAP) using controllable parameters, such as plasma-forming voltage, carrier gas, temperature, pulses, or frequency as required. PAW is reported to have lower pH, higher conductivity, and higher oxygen reduction potential when compared with untreated water due to the presence of reactive species. PAW has received significant attention from researchers over the last decade due to its non-thermal and non-toxic mode of action especially for bacterial inactivation. The objective of the current review is to develop a summary of the effect of PAW on bacterial strains in foods as well as model systems such as buffers, with a specific focus on fruit and vegetables. The review elaborated the properties of PAW, the effect of various treatment parameters on its efficiency in bacterial inactivation along with its usage as a standalone technology as well as a hurdle approach with mild thermal treatments. A section highlighting different models that can be employed to generate PAW alongside a direct comparison of the PAW characteristics on the inactivation potential and the existing research gaps are also included. The mechanism of action of PAW on the bacterial cells and any reported effects on the sensory qualities and shelf life of food has been evaluated. Based on the literature, it can be concluded that PAW offers a significant potential as a non-chemical and non-thermal intervention for bacterial inactivation, especially on food. However, the applicability and usage of PAW depend on the effect of environmental and bacterial strain-based conditions and cost-effectiveness.

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Application of Bacteriophages on Shiga Toxin-Producing Escherichia coli (STEC) Biofilm

Antibiotics ◽

10.3390/antibiotics10111423 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1423

Author(s):

Nicola Mangieri ◽

Roberto Foschino ◽

Claudia Picozzi

Keyword(s):

Escherichia Coli ◽

Shiga Toxin ◽

Biofilm Formation ◽

Pathogenic Bacteria ◽

Antimicrobial Agents ◽

Bacterial Cells ◽

Abiotic Surfaces ◽

Continuous Presence ◽

Different Strains ◽

Better Than

Shiga toxin-producing Escherichia coli are pathogenic bacteria able to form biofilms both on abiotic surfaces and on food, thus increasing risks for food consumers. Moreover, biofilms are difficult to remove and more resistant to antimicrobial agents compared to planktonic cells. Bacteriophages, natural predators of bacteria, can be used as an alternative to prevent biofilm formation or to remove pre-formed biofilm. In this work, four STEC able to produce biofilm were selected among 31 different strains and tested against single bacteriophages and two-phage cocktails. Results showed that our phages were able to reduce biofilm formation by 43.46% both when used as single phage preparation and as a cocktail formulation. Since one of the two cocktails had a slightly better performance, it was used to remove pre-existing biofilms. In this case, the phages were unable to destroy the biofilms and reduce the number of bacterial cells. Our data confirm that preventing biofilm formation in a food plant is better than trying to remove a preformed biofilm and the continuous presence of bacteriophages in the process environment could reduce the number of bacteria able to form biofilms and therefore improve the food safety.

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IN VITRO ANTIOXIDANT AND IN VIVO ANTIDIABETIC ACTIVITY OF TWO POTENTIAL PROBIOTIC ENTEROCOCCUS SPP. ON ALLOXAN-INDUCED DIABETIC RATS

Asian Journal of Pharmaceutical and Clinical Research ◽

10.22159/ajpcr.2021.v14i3.40321 ◽

2021 ◽

pp. 94-98

Author(s):

KAMNI RAJPUT ◽

RAMESH CHANDRA DUBEY

Keyword(s):

Diabetic Rats ◽

Antidiabetic Activity ◽

Control Group ◽

Albino Rats ◽

Bacterial Cells ◽

Bacterial Strains ◽

Animal Group ◽

Enterococcus Spp

Objective: In vitro antioxidant activity, in vivo antidiabetic property and intestinal attachment by two potential probiotic bacterial strains, namely, Enterococcus faecium and Enterococcus hirae were studied using albino rats. Methods: Antioxidant the activity was assessed using 2,2-Diphenyl-1-picrylhydrazyl radicals scavenging assay. Alloxan was administered intraperitoneally to induce diabetic conditions in experimental rats. Animals were treated with oral administration of Enterococcus spp., such as E. faecium, and E. hirae isolated from goat and sheep milk. The control animal group received normal saline for the same days. Glibenclamide drug was used as a positive control against probiotic bacterial cells. Results: However, administration of probiotic bacterial strains E. faecium and E. hirae, in albino rats significantly (p<0.05) at varying doses lowered blood glucose levels in diabetic rats as compared to the diabetic control group. Both the species of Enterococcus increased the bodyweight of experimental rats. However, E. faecium was the best antidiabetic strain having the antioxidant activities also in comparison to E. hirae. The attachment of probiotic bacterial cells E. faecium on the rat’s intestine wall against pathogens was examined. Furthermore, E. faecium showed its aggregation with pathogens by attachment of the intestines of albino rats. This showed that both the bacterial strains exhibited in vivo antidiabetic effect. Conclusion: The results of this study showed that probiotic bacteria possess antioxidant, antidiabetic activities, and attachment of intestine.

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PaReBrick: PArallel REarrangements and BReaks identification toolkit

Bioinformatics ◽

10.1093/bioinformatics/btab691 ◽

2021 ◽

Author(s):

Alexey Zabelkin ◽

Yulia Yakovleva ◽

Olga Bochkareva ◽

Nikita Alexeev

Keyword(s):

Antigenic Variation ◽

Phenotypic Diversity ◽

Genome Rearrangements ◽

Supplementary Information ◽

High Plasticity ◽

Bacterial Strains ◽

Bacterial Genomes ◽

Phyletic Pattern ◽

Bacterial Populations ◽

Different Strains

Abstract Motivation High plasticity of bacterial genomes is provided by numerous mechanisms including horizontal gene transfer and recombination via numerous flanking repeats. Genome rearrangements such as inversions, deletions, insertions, and duplications may independently occur in different strains, providing parallel adaptation or phenotypic diversity. Specifically, such rearrangements might be responsible for virulence, antibiotic resistance, and antigenic variation. However, identification of such events requires laborious manual inspection and verification of phyletic pattern consistency. Results Here we define the term “parallel rearrangements” as events that occur independently in phylogenetically distant bacterial strains and present a formalization of the problem of parallel rearrangements calling. We implement an algorithmic solution for the identification of parallel rearrangements in bacterial populations as a tool PaReBrick. The tool takes a collection of strains represented as a sequence of oriented synteny blocks and a phylogenetic tree as input data. It identifies rearrangements, tests them for consistency with a tree, and sorts the events by their parallelism score. The tool provides diagrams of the neighbors for each block of interest, allowing the detection of horizontally transferred blocks or their extra copies and the inversions in which copied blocks are involved.We demonstrated PaReBrick’s efficiency and accuracy and showed its potential to detect genome rearrangements responsible for pathogenicity and adaptation in bacterial genomes. Availability PaReBrick is written in Python and is available on GitHub https://github.com/ctlab/parallelrearrangements Supplementary information Supplementary data are available at Bioinformatics online.

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Effects of natural antimicrobials on bacterial cell hydrophobicity, adhesion, and zeta potential / Vpliv naravnih protimikrobnih snovi na bakterijsko hidrofobnost, adhezijo in zeta potencial

Archives of Industrial Hygiene and Toxicology ◽

10.1515/aiht-2016-67-2720 ◽

2016 ◽

Vol 67 (1) ◽

pp. 39-45 ◽

Cited By ~ 21

Author(s):

Marija Kurinčič ◽

Barbara Jeršek ◽

Anja Klančnik ◽

Sonja Smole Možina ◽

Rok Fink ◽

...

Keyword(s):

Zeta Potential ◽

Bacterial Adhesion ◽

Bacterial Cell ◽

Early Stage ◽

Experimental Studies ◽

Adhesion Prevention ◽

Bacterial Cells ◽

Bacterial Strains ◽

Natural Antimicrobials ◽

Cell Hydrophobicity

Abstract Interactions between bacterial cells and contact materials play an important role in food safety and technology. As bacterial strains become ever more resistant to antibiotics, the aim of this study was to analyse adhesion of selected foodborne bacterial strains on polystyrene surface and to evaluate the effects of natural antimicrobials on bacterial cell hydrophobicity, adhesion, and zeta potential as strategies of adhesion prevention. The results showed strain-specific adhesion rate on polystyrene. The lowest and the highest adhesion were found for two B. cereus lines. Natural antimicrobials ferulic and rosmarinic acid substantially decreased adhesion, whereas the effect of epigallocatechin gallate was neglectful. Similar results were found for the zeta potential, indicating that natural antimicrobials reduce bacterial adhesion. Targeting bacterial adhesion using natural extracts we can eliminate potential infection at an early stage. Future experimental studies should focus on situations that are as close to industrial conditions as possible.

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The strategy of editing and modification of the genomes of bacterial viruses

Bacteriology ◽

10.20953/2500-1027-2020-1-48-59 ◽

2020 ◽

Vol 5 (1) ◽

pp. 48-59

Author(s):

A.S. Schurova ◽

◽

V.A. Bannov ◽

A.V. Popova ◽

◽

...

Keyword(s):

Antimicrobial Agents ◽

Phage Genome ◽

Genetically Engineered ◽

Bacterial Cells ◽

Practical Application ◽

Bacterial Strains ◽

Recombinant Phage ◽

Research Problems ◽

Genomic Editing

In recent decades, a major problem for health systems around the world is the wide spread of bacterial pathogens that are resistant to various antimicrobial agents. A possible approach to solving this problem is the use of bacteriophages, viruses that specifically infect bacterial cells, as well as enzymes and proteins encoded in their genomes. The development of genomic editing technologies, including those based on CRISPR-Cas editing, makes it possible to create genetically engineered or recombinant phage particles with desired properties that are important for further practical application. In this review, we consider issues related to the characterization of bacteriophages as biological objects and as promising candidates for controlling the spread of antibioticresistant bacterial strains. We discuss modern approaches and strategies for modifying the phage genomes using various methods of genetic engineering and molecular biology to solve a variety of practical and research problems. Keywords: bacteriophages, phage genome editing, CRISPR-Cas system

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Effect of milk chocolate supplementation with lyophilised Lactobacillus cells on its attributes

Czech Journal of Food Sciences ◽

10.17221/217/2009-cjfs ◽

2010 ◽

Vol 28 (No. 5) ◽

pp. 392-406 ◽

Cited By ~ 19

Author(s):

D. Żyżelewicz ◽

E. Nebesny ◽

I. Motyl ◽

Z. Libudzisz

Keyword(s):

Ambient Temperature ◽

High Temperatures ◽

Functional Food ◽

Lactobacillus Casei ◽

Probiotic Bacteria ◽

Live Cells ◽

Bacterial Cells ◽

Bacterial Strains ◽

Milk Chocolate ◽

Live Bacterial Cells

Manufacturing of novel foodstuffs supplemented with live probiotic bacteria has recently been intensively investigated. The supplementation of confectionery with probiotics is troublesome since some unit technological processes are conducted at high temperatures and the products are usually stored at ambient temperature. Our group has developed a method of the production of milk chocolate, sweetened with either sucrose or isomalt and aspartame, containing 32, 36, or 40 g/100 g fat, and supplemented with live cells of probiotic bacterial strains: Lactobacillus casei and paracasei. This new milk chocolate displayed the same sensory properties as the reference, probiotic-free chocolate. The number of live bacterial cells was maintained at the functional level of 10<sup>6</sup> ÷ 10<sup>8</sup> cfu/g after keeping for 12 months irrespective of the temperature. The highest number of live probiotic bacteria survived in the chocolate kept at 4°C. Thus the product can be regarded as functional food.

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Utilization of Mn-Doped ZnSe/ZnS Core/Shell Quantum Dots for Rapid Detection of Escherichia coli O157:H7 and Methicillin-Resistant Staphylococcus aureus

Advances in Materials Science and Engineering ◽

10.1155/2020/9718706 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Thi-Diem Bui ◽

Quang-Liem Nguyen ◽

Thi-Bich Luong ◽

Van Thuan Le ◽

Van-Dat Doan

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Quantum Dots ◽

Fluorescent Labeling ◽

Core Shell ◽

Bacterial Cells ◽

Bacterial Strains ◽

Methicillin Resistant ◽

E Coli ◽

Mn Doped

In this study, Mn-doped ZnSe/ZnS core/shell quantum dots (CSQDs) were synthesized in aqueous solution using polyethylene glycol as a surface stabilizer and successfully applied in the detection of Escherichia coli O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) for the first time. The CSQDs were conjugated with anti-E. coli antibody and anti-MRSA antibody via protein A supported by 1-ethyl-3-(-3-dimethylaminopropyl)carbodiimide hydrochloride for fluorescent labeling of the intact bacterial cells. The detection was performed for the bacterial strains cultivated in Luria-Bertani liquid medium. The obtained results indicate that E. coli O157:H7 and MRSA can be detected within 30 min at a high sensitivity of 101 CFU/mL. This labeling method based on the highly fluorescent CSQDs may have great potential for use in the food industry to check and prevent outbreaks of foodborne illness.

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