Effects of Heat, Acid, and Freeze-Thaw Challenges on Survival of Starved Vibrio parahaemolyticus in Minimal Salt Medium, Tryptic Soy Broth, and Filtered Oyster Homogenate Medium

Vibrio parahaemolyticus is a ubiquitous gram-negative enteropathogenic bacterium. To evaluate the risk of stress-adapted V. parahaemolyticus cells in food, we investigated the survivability of starvation-adapted and starvation-low salinity–adapted cells of this pathogen in different media against different stresses. Logarithmically grown bacterial cells were starved at 25°C in a minimal salt medium with 0.5 or 3.0% NaCl for 24 h. Resistances against challenges of heat, acid, and freeze-thaw treatment exhibited by the starvation-adapted cells were similar to those exhibited by the starvation-low salinity–adapted cells but substantially higher than those of the unadapted control cells. The increased stress resistance of the adapted cells against freeze-thaw challenge was lower in tryptic soy broth than in the starving medium. Resistance of the adapted bacteria against heat and freeze-thaw treatment was completely eliminated in filter-sterilized oyster homogenate medium. Practically, these results help to assess the risk of stress-adapted V. parahaemolyticus in food.

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Biodegradation α-endosulfan and α-cypermethrin by Acinetobacter schindleri B7 isolated from the microflora of grasshopper (Poecilimon tauricola)

10.21203/rs.3.rs-282404/v1 ◽

2021 ◽

Author(s):

Ozlem Gur Ozdal ◽

Omer Faruk ALGUR

Keyword(s):

Pseudomonas Aeruginosa ◽

Bacillus Megaterium ◽

Biological Treatment ◽

Minimal Salt Medium ◽

Salt Medium ◽

Negative Bacterium ◽

Pesticide Degradation ◽

Gram Negative ◽

Degrading Bacteria ◽

Brevibacillus Parabrevis

Abstract Extensive applications of pesticides have led to the contamination of ecosystem. Therefore, the isolation of new pesticide degrading bacteria is important. For the biodegradation of α-endosulfan and α-cypermethrin, new bacteria isolates were isolated from grasshopper (Poecilimon tauricola). According to different tests, these isolated bacteria were identified as Pseudomonas aeruginosa B5, Acinetobacter johnsonii B6, Acinetobacter schindleri B7, Bacillus megaterium B9 and Brevibacillus parabrevis B12. The first two of these bacteria have been isolated as those that can use only α-endosulfan and the last two only use α-cypermethrin. Moreover, A. schindleri B7 was determined to be able to degrade both pesticides. When glucose was added to non-sulfur medium containing α-endosulfan (100 mg/L) and minimal salt medium containing α-cypermethrin (100 mg/L), both pesticide degradation and bacterial growth was increased. As a result, A. schindleri, a new gram negative bacterium, can inevitably be used in the biological treatment of environments exposed to pesticides.

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Production and use of monoclonal antibodies for identification of Bradyrhizobium japonicum strains

Canadian Journal of Microbiology ◽

10.1139/m88-018 ◽

1988 ◽

Vol 34 (1) ◽

pp. 88-92 ◽

Cited By ~ 7

Author(s):

D. Velez ◽

J. D. Macmillan ◽

L. Miller

Keyword(s):

Monoclonal Antibodies ◽

Bradyrhizobium Japonicum ◽

Chemical Nature ◽

Periodate Oxidation ◽

Enzyme Linked Immunosorbent Assay ◽

Gram Negative Bacteria ◽

Bacterial Cells ◽

Gram Negative ◽

Polyclonal Antisera ◽

Somatic Antigens

Thirteen murine hybridomas capable of producing monoclonal antibodies to somatic antigens on Bradyrhizobium japonicum were developed and an indirect enzyme-linked immunosorbent assay was used to test reactivity of the antibodies against 20 strains of B. japonicum. Although polyclonal antisera from mice immunized with strains of B. japonicum reacted with bacterial cells of all 20 strains, individual monoclonals were more specific. Some antibodies reacted with as few as 2 and one with as many as 11 strains. On the basis of reactivity with the set of 13 monoclonal antibodies, the 20 strains of B. japonicum could be divided arbitrarily into five groups. Three of five monoclonal antibodies tested reacted with bacteroids taken directly from soybean nodules. One monoclonal bound to cells of five species of Rhizobium, but none of the 13 reacted with gram-negative bacteria representing six other genera. Treatment of cells with reagents and heat indicated the chemical nature of the antigens to five of the monoclonals. Antigen reactive with one antibody was destroyed by periodate oxidation indicating that it was a polysaccharide. Two antigens were probably proteins as they could be digested by trypsin and denatured by heat. Two others were inactivated by all three treatments suggesting they were glycoproteins.

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Impact of the Resistance Responses to Stress Conditions Encountered in Food and Food Processing Environments on the Virulence and Growth Fitness of Non-Typhoidal Salmonellae

Foods ◽

10.3390/foods10030617 ◽

2021 ◽

Vol 10 (3) ◽

pp. 617

Author(s):

Silvia Guillén ◽

Laura Nadal ◽

Ignacio Álvarez ◽

Pilar Mañas ◽

Guillermo Cebrián

Keyword(s):

Stress Resistance ◽

Food Processing ◽

Current Knowledge ◽

Foodborne Pathogen ◽

Stress Conditions ◽

Bacterial Cells ◽

Modified Atmospheres ◽

Development Of Resistance ◽

Salmonella Virulence ◽

Short Time

The success of Salmonella as a foodborne pathogen can probably be attributed to two major features: its remarkable genetic diversity and its extraordinary ability to adapt. Salmonella cells can survive in harsh environments, successfully compete for nutrients, and cause disease once inside the host. Furthermore, they are capable of rapidly reprogramming their metabolism, evolving in a short time from a stress-resistance mode to a growth or virulent mode, or even to express stress resistance and virulence factors at the same time if needed, thanks to a complex and fine-tuned regulatory network. It is nevertheless generally acknowledged that the development of stress resistance usually has a fitness cost for bacterial cells and that induction of stress resistance responses to certain agents can trigger changes in Salmonella virulence. In this review, we summarize and discuss current knowledge concerning the effects that the development of resistance responses to stress conditions encountered in food and food processing environments (including acid, osmotic and oxidative stress, starvation, modified atmospheres, detergents and disinfectants, chilling, heat, and non-thermal technologies) exerts on different aspects of the physiology of non-typhoidal Salmonellae, with special emphasis on virulence and growth fitness.

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Elucidating the mechanism by which synthetic helper peptides sensitize Pseudomonas aeruginosa to multiple antibiotics

PLoS Pathogens ◽

10.1371/journal.ppat.1009909 ◽

2021 ◽

Vol 17 (9) ◽

pp. e1009909

Author(s):

Yushan Xia ◽

Rubén Cebrián ◽

Congjuan Xu ◽

Anne de Jong ◽

Weihui Wu ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Treatment Strategies ◽

Infection Model ◽

Bacterial Cells ◽

Membrane Phospholipids ◽

Gram Negative ◽

Atp Production ◽

Rapid Spread ◽

New Treatment ◽

Multiple Antibiotics

The emergence and rapid spread of multi-drug resistant (MDR) bacteria pose a serious threat to global healthcare. There is an urgent need for new antibacterial substances or new treatment strategies to deal with the infections by MDR bacterial pathogens, especially the Gram-negative pathogens. In this study, we show that a number of synthetic cationic peptides display strong synergistic antimicrobial effects with multiple antibiotics against the Gram-negative pathogen Pseudomonas aeruginosa. We found that an all-D amino acid containing peptide called D-11 increases membrane permeability by attaching to LPS and membrane phospholipids, thereby facilitating the uptake of antibiotics. Subsequently, the peptide can dissipate the proton motive force (PMF) (reduce ATP production and inhibit the activity of efflux pumps), impairs the respiration chain, promote the production of reactive oxygen species (ROS) in bacterial cells and induce intracellular antibiotics accumulation, ultimately resulting in cell death. By using a P. aeruginosa abscess infection model, we demonstrate enhanced therapeutic efficacies of the combination of D-11 with various antibiotics. In addition, we found that the combination of D-11 and azithromycin enhanced the inhibition of biofilm formation and elimination of established biofilms. Our study provides a realistic treatment option for combining close-to-nature synthetic peptide adjuvants with existing antibiotics to combat infections caused by P. aeruginosa.

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Wild type Bacillus subtilis treated with ethyl methyl sulphonate produced catabolite insensitive mutants with improved cellulase production

10.21203/rs.3.rs-278081/v1 ◽

2021 ◽

Author(s):

Oladipo Olaniyi

Keyword(s):

Bacillus Subtilis ◽

Carbon Source ◽

Enzyme Production ◽

Cellulase Activity ◽

Cellulase Production ◽

Minimal Salt Medium ◽

Salt Medium ◽

Production Medium ◽

Wild Type ◽

Ethyl Methyl

Abstract The goal of this present investigation was to mutagenize Bacillus subtilis with Ethyl Methyl Sulphonate (EMS), screen the mutants for cellulase production and evaluate the influence of different glucose concentrations on their cellulase production potentials. The wild type B. subtilis was treated with 20, 40, 60 and 80 µl of EMS and the mutants generated were screened for cellulase production in minimal salt medium containing carboxylmethylcellulose (CMC) as the carbon source. Quantitatively, cellulase activity and protein contents were determined by dinitrosalicylic acid and Lowry methods respectively. Seven mutants were developed from each of the EMS concentration bringing the total to twenty-eight from all the concentrations. Approximately 14 and 57% of the mutants developed from 40 and 60µl of EMS had higher cellulase activities than the wild type, while none of the mutants developed from 20 and 80 µl of EMS had better activities than the wild type. The supplementation of 0.2, 0.5, 1.0 and 1.5% glucose in enzyme production medium caused approximately 100, 14, 29 and 14% cellulase repression respectively in the mutants developed from 60µl EMS. Mutants MSSS02 and MSSS05 were considered as catabolite insensitive mutants because their cellulase production were enhanced in comparison to wild type.

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Evidence for Enhanced Dissipation of Chlorpyrifos in an Agricultural Soil Inoculated with Serratia Rubidaea Strain ABS 10

10.21203/rs.3.rs-355675/v1 ◽

2021 ◽

Author(s):

Asma Ben Salem ◽

Hanene Chaabane ◽

Tesnime Ghazouani ◽

Pierluigi Caboni ◽

Valentina Coroneo ◽

...

Keyword(s):

16S Rrna ◽

Bacterial Strain ◽

Agricultural Soil ◽

Liquid Culture ◽

Minimal Salt Medium ◽

Salt Medium ◽

Sterile Soil ◽

Rrna Sequencing ◽

Biochemical Analyses ◽

Serratia Rubidaea

Abstract Important mineralization of 14C-chlorpyrifos was found in a Tunisian soil exposed repeatedly to this insecticide. A bacterial strain able to grow in minimal salt medium (MSM) supplemented with 25 mg L− 1 of chlorpyrifos was isolated from this soil. It was characterized as Serratia rubidaea strain ABS 10 using morphological and biochemical analyses, as well as 16S rRNA sequencing. In liquid culture S. rubidaea stain ABS 10 was able to almost entirely dissipate chlorpyrifos within 48 hours of incubation. Although, S. rubidaea strain ABS 10 was able to grow on MSM supplemented with chlorpyrifos and to dissipate it in liquid culture, it was not able to mineralize 14C-chlorpyrifos. Therefore, one can conclude that the dissipation capability of this bacteria might be attributed to its capacity to adsorb CHL. In both non-sterile and sterile soil inoculated with S. rubidaea strain ABS 10, chlorpyrifos was more rapidly dissipated than in respective controls.

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Evaluating Flinders Technology Associates card for transporting bacterial isolates and retrieval of bacterial DNA after various storage conditions

Veterinary World ◽

10.14202/vetworld.2020.2243-2251 ◽

2020 ◽

Vol 13 (10) ◽

pp. 2243-2251

Author(s):

Azhar G. Shalaby ◽

Neveen R. Bakry ◽

Abeer A. E. Mohamed ◽

Ashraf A. Khalil

Keyword(s):

Nucleic Acid ◽

Bacterial Species ◽

Storage Conditions ◽

Animal Origin ◽

Cell Detection ◽

Bacterial Cells ◽

Gram Positive ◽

Bacterial Dna ◽

Gram Negative ◽

Fta Cards

Background and Aim: Flinders Technology Associates (FTA) cards simplify sample storage, transport, and extraction by reducing cost and time for diagnosis. This study evaluated the FTA suitability for safe transport and storage of Gram-positive and Gram-negative bacterial cells of animal origin on its liquid culture form and from organ impression smears (tissues) under the same routine condition of microbiological laboratory along with detecting their nucleic acid over different storage conditions. Materials and Methods: Increase in bacterial count from 104 to 107 (colony-forming units/mL) of 78 isolates representing seven bacterial species was applied onto cards. FTA cards were grouped and inoculated by these bacteria and then stored at different conditions of 24-27°C, 4°C, and –20°C for 24 h, for 2 weeks, for 1 and 3 month storage, respectively. Bacteriological examination was done, after which bacterial DNA was identified using specific primers for each bacterial type and detected by polymerase chain reaction (PCR). Results: The total percentage of recovered bacteria from FTA cards was 66.7% at 24-27–C for 24 h, the detection limit was 100% in Gram-positive species, while it was 57.4% in Gram-negative ones. Regarding viable cell detection from organ impression smears, it was successful under the previous conditions. No live bacterial cells were observed by bacteriological isolation rather than only at 24-27°C for 24 h storage. All bacterial DNA were sufficiently confirmed by the PCR technique at different conditions. Conclusion: Overall, the FTA card method was observed to be a valid tool for nucleic acid purification for bacteria of animal origin in the form of culture or organ smears regardless of its Gram type and is used for a short time only 24 h for storage and transport of live bacteria specifically Gram-positive type. Moreover, the bacterial nucleic acid was intact after storage in –20°C for 3 months and was PCR amplifiable.

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Low Salinity and High-Level UV-B Radiation Reduce Single-Cell Activity in Antarctic Sea Ice Bacteria

Applied and Environmental Microbiology ◽

10.1128/aem.00829-09 ◽

2009 ◽

Vol 75 (23) ◽

pp. 7570-7573 ◽

Cited By ~ 13

Author(s):

Andrew Martin ◽

Julie Hall ◽

Ken Ryan

Keyword(s):

Sea Ice ◽

Metabolic Activity ◽

Cell Activity ◽

Ice Formation ◽

Freeze Thaw ◽

Low Salinity ◽

Antarctic Sea Ice ◽

Single Cell Activity ◽

Fast Ice ◽

High Level

ABSTRACT Experiments simulating the sea ice cycle were conducted by exposing microbes from Antarctic fast ice to saline and irradiance regimens associated with the freeze-thaw process. In contrast to hypersaline conditions (ice formation), the simulated release of bacteria into hyposaline seawater combined with rapid exposure to increased UV-B radiation significantly reduced metabolic activity.

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