Weathering-Associated Bacteria from the Damma Glacier Forefield: Physiological Capabilities and Impact on Granite Dissolution

ABSTRACT Several bacterial strains isolated from granitic rock material in front of the Damma glacier (Central Swiss Alps) were shown (i) to grow in the presence of granite powder and a glucose-NH4Cl minimal medium without additional macro- or micronutrients and (ii) to produce weathering-associated agents. In particular, four bacterial isolates (one isolate each of Arthrobacter sp., Janthinobacterium sp., Leifsonia sp., and Polaromonas sp.) were weathering associated. In comparison to what was observed in abiotic experiments, the presence of these strains caused a significant increase of granite dissolution (as measured by the release of Fe, Ca, K, Mg, and Mn). These most promising weathering-associated bacterial species exhibited four main features rendering them more efficient in mineral dissolution than the other investigated isolates: (i) a major part of their bacterial cells was attached to the granite surfaces and not suspended in solution, (ii) they secreted the largest amounts of oxalic acid, (iii) they lowered the pH of the solution, and (iv) they formed significant amounts of HCN. As far as we know, this is the first report showing that the combined action of oxalic acid and HCN appears to be associated with enhanced elemental release from granite, in particular of Fe. This suggests that extensive microbial colonization of the granite surfaces could play a crucial role in the initial soil formation in previously glaciated mountain areas.

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Graphene-Based Sensor for Detection of Bacterial Pathogens

Sensors ◽

10.3390/s21238085 ◽

2021 ◽

Vol 21 (23) ◽

pp. 8085

Author(s):

Santosh Pandit ◽

Mengyue Li ◽

Yanyan Chen ◽

Shadi Rahimi ◽

Vrss Mokkapati ◽

...

Keyword(s):

Antimicrobial Agents ◽

Bacterial Colonization ◽

Bacterial Species ◽

Complex Structure ◽

Growth Dynamics ◽

Microbial Colonization ◽

Bacterial Cells ◽

Resistance Change ◽

Biofilm Growth ◽

Adherence Pattern

Microbial colonization to biomedical surfaces and biofilm formation is one of the key challenges in the medical field. Recalcitrant biofilms on such surfaces cause serious infections which are difficult to treat using antimicrobial agents, due to their complex structure. Early detection of microbial colonization and monitoring of biofilm growth could turn the tide by providing timely guidance for treatment or replacement of biomedical devices. Hence, there is a need for sensors, which could generate rapid signals upon bacterial colonization. In this study, we developed a simple prototype sensor based on pristine, non-functionalized graphene. The detection principle is a change in electrical resistance of graphene upon exposure to bacterial cells. Without functionalization with specific receptors, such sensors cannot be expected to be selective to certain bacteria. However, we demonstrated that two different bacterial species can be detected and differentiated by our sensor due to their different growth dynamics, adherence pattern, density of adhered bacteria and microcolonies formation. These distinct behaviors of tested bacteria depicted distinguishable pattern of resistance change, resistance versus gate voltage plot and hysteresis effect. This sensor is simple to fabricate, can easily be miniaturized, and can be effective in cases when precise identification of species is not needed.

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Evaluating the Effects of Disinfectants on Bacterial Biofilms Using a Microfluidics Flow Cell and Time-Lapse Fluorescence Microscopy

Microorganisms ◽

10.3390/microorganisms8111837 ◽

2020 ◽

Vol 8 (11) ◽

pp. 1837

Author(s):

Milos Legner ◽

James Jonkman ◽

Dean Swift

Keyword(s):

Fluorescence Microscopy ◽

Bacterial Species ◽

Bacterial Biomass ◽

Time Lapse ◽

Flow Cell ◽

Bacterial Cells ◽

Bacterial Strains ◽

Microscopy Imaging ◽

Microscopy Method ◽

Time Lapse Imaging

A commercially available microfluidics flow cell was utilized together with widefield fluorescence microscopy to evaluate the effects of disinfectants on bacterial strains. The flow cell’s inner surface supports the formation of biofilms of numerous bacterial species. The modular setup of the flow cell accessories allows connection to syringes, pumps and collection vials, facilitating aseptic experiments in a controlled fluidics environment which can be documented with precisely timed microscopy imaging. The flow cell is inoculated with a suspension of bacteria in a nutrient medium and incubated for several days allowing bacterial cells to form a biofilm. Shortly before performing an assay, the biofilm is labelled with a dual-fluorescent DNA probe which distinguishes unharmed and damaged bacteria. Then a disinfectant sample (or control) is gently injected and time-lapse imaging is used for quantifying the course of bacterial biomass response. We use a simplified widefield microscopy method that allows intensive recording and quantification of time series of two-dimensional frames for tracking the course of disinfectant action on a variety of microbial strains. This procedure has potential for the rapid evaluation of novel products.

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Development of a PCR Assay for Detection of Enterobacteriaceae in Foods

Journal of Food Protection ◽

10.4315/0362-028x-66.10.1798 ◽

2003 ◽

Vol 66 (10) ◽

pp. 1798-1804 ◽

Cited By ~ 22

Author(s):

SHIGERU NAKANO ◽

TORU KOBAYASHI ◽

KENICHI FUNABIKI ◽

ATSUSHI MATSUMURA ◽

YASUHIRO NAGAO ◽

...

Keyword(s):

Salmonella Enteritidis ◽

Enrichment Culture ◽

Simple Procedure ◽

Bacterial Species ◽

Brain Heart Infusion ◽

Rrna Gene ◽

Bacterial Cells ◽

Bacterial Strains ◽

Pcr Assay ◽

Chelex 100

A broad-range PCR assay for the detection of bacteria belonging to the Enterobacteriaceae family was developed in this study. Primers targeting the bacterial 16S rRNA gene were newly designed and used in this PCR assay. To determine the specificity of the assay, 72 different bacterial species (of 49 genera), 2 fungi, 3 animals, and 4 plants were tested. Results were positive for every tested Vibrioaceae or Enterobacteriaceae strain except Proteus mirabilis. For all other bacterial strains and eukaryotes tested, results were negative. Bacterial DNA for PCR was prepared by a simple procedure with the use of Chelex 100 resin from culture after growth in brain heart infusion medium. To test this PCR assay for the monitoring of the Enterobacteriaceae family, either Escherichia coli or Salmonella Enteritidis was inoculated into various foods as an indicator. Prior to the PCR, the inoculation of 10 to 40 CFU of bacteria per g of food was followed by a 5-h enrichment culture step, and the PCR assay allowed the detection of bacterial cells. When actual examinations of the contamination of 15 noodle foods with Enterobacteriaceae by this PCR assay were conducted, 33% (5 of 15) of the samples tested positive. These results agreed with those of the Petri film Enterobacteriaceae Count Plate assay. Including the enrichment culture step, the entire PCR detection process can be completed within 7 h.

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Modulation of Gut Microbiota through Dietary Phytochemicals as a Novel Anti-infective Strategy

Current Drug Discovery Technologies ◽

10.2174/1570163816666191107124214 ◽

2020 ◽

Vol 17 (4) ◽

pp. 498-506 ◽

Cited By ~ 2

Author(s):

Pavan K. Mujawdiya ◽

Suman Kapur

Keyword(s):

Microbial Community ◽

Quorum Sensing ◽

Population Density ◽

Gut Microbiota ◽

Biofilm Formation ◽

Chemical Interaction ◽

Bacterial Species ◽

Critical Role ◽

Bacterial Cells ◽

Gut Microbes

: Quorum Sensing (QS) is a phenomenon in which bacterial cells communicate with each other with the help of several low molecular weight compounds. QS is largely dependent on population density, and it triggers when the concentration of quorum sensing molecules accumulate in the environment and crosses a particular threshold. Once a certain population density is achieved and the concentration of molecules crosses a threshold, the bacterial cells show a collective behavior in response to various chemical stimuli referred to as “auto-inducers”. The QS signaling is crucial for several phenotypic characteristics responsible for bacterial survival such as motility, virulence, and biofilm formation. Biofilm formation is also responsible for making bacterial cells resistant to antibiotics. : The human gut is home to trillions of bacterial cells collectively called “gut microbiota” or “gut microbes”. Gut microbes are a consortium of more than 15,000 bacterial species and play a very crucial role in several body functions such as metabolism, development and maturation of the immune system, and the synthesis of several essential vitamins. Due to its critical role in shaping human survival and its modulating impact on body metabolisms, the gut microbial community has been referred to as “the forgotten organ” by O`Hara et al. (2006) [1]. Several studies have demonstrated that chemical interaction between the members of bacterial cells in the gut is responsible for shaping the overall microbial community. : Recent advances in phytochemical research have generated a lot of interest in finding new, effective, and safer alternatives to modern chemical-based medicines. In the context of antimicrobial research various plant extracts have been identified with Quorum Sensing Inhibitory (QSI) activities among bacterial cells. This review focuses on the mechanism of quorum sensing and quorum sensing inhibitors isolated from natural sources.

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The Conservation of Low Complexity Regions in Bacterial Proteins Depends on the Pathogenicity of the Strain and Subcellular Location of the Protein

Genes ◽

10.3390/genes12030451 ◽

2021 ◽

Vol 12 (3) ◽

pp. 451

Author(s):

Pablo Mier ◽

Miguel A. Andrade-Navarro

Keyword(s):

Membrane Proteins ◽

Outer Membrane ◽

Bacterial Species ◽

Outer Membrane Proteins ◽

Subcellular Location ◽

Low Complexity ◽

Extracellular Proteins ◽

Bacterial Strains ◽

Bacterial Proteins ◽

Protein Subcellular Location

Low complexity regions (LCRs) in proteins are characterized by amino acid frequencies that differ from the average. These regions evolve faster and tend to be less conserved between homologs than globular domains. They are not common in bacteria, as compared to their prevalence in eukaryotes. Studying their conservation could help provide hypotheses about their function. To obtain the appropriate evolutionary focus for this rapidly evolving feature, here we study the conservation of LCRs in bacterial strains and compare their high variability to the closeness of the strains. For this, we selected 20 taxonomically diverse bacterial species and obtained the completely sequenced proteomes of two strains per species. We calculated all orthologous pairs for each of the 20 strain pairs. Per orthologous pair, we computed the conservation of two types of LCRs: compositionally biased regions (CBRs) and homorepeats (polyX). Our results show that, in bacteria, Q-rich CBRs are the most conserved, while A-rich CBRs and polyA are the most variable. LCRs have generally higher conservation when comparing pathogenic strains. However, this result depends on protein subcellular location: LCRs accumulate in extracellular and outer membrane proteins, with conservation increased in the extracellular proteins of pathogens, and decreased for polyX in the outer membrane proteins of pathogens. We conclude that these dependencies support the functional importance of LCRs in host–pathogen interactions.

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Isolation and efficacy of two bacterial strains antagonists of Erwinia amylovora and Pectobacterium carotovorum

Egyptian Journal of Biological Pest Control ◽

10.1186/s41938-021-00443-0 ◽

2021 ◽

Vol 31 (1) ◽

Author(s):

M’hamed BENADA ◽

Boualem BOUMAAZA ◽

Sofiane BOUDALIA ◽

Omar KHALADI

Keyword(s):

Fire Blight ◽

Erwinia Amylovora ◽

Bacterial Species ◽

Crop Protection ◽

Soft Rot ◽

Causal Agent ◽

Plant Diseases ◽

Ecological Niches ◽

Pectobacterium Carotovorum ◽

Bacterial Strains

Abstract Background The development of ecofriendly tools against plant diseases is an important issue in crop protection. Screening and selection process of bacterial strains antagonists of 2 pathogenic bacterial species that limit very important crops, Erwinia amylovora, the causal agent of the fire blight disease, and Pectobacterium carotovorum, the causal agent of bacterial potato soft rot, were reported. Bacterial colonies were isolated from different ecological niches, where both pathogens were found: rhizosphere of potato tubers and fruits and leaves of pear trees from the northwest region of Algeria. Direct and indirect confrontation tests against strains of E. amylovora and P. carotovorum were performed. Results Results showed a significant antagonistic activity against both phytopathogenic species, using direct confrontation method and supernatants of cultures (p<0.005). In vitro assays showed growth inhibitions of both phytopathogenic species. Furthermore, results revealed that the strains of S. plymuthica had a better inhibitory effect than the strains of P. fluorescens against both pathogens. In vivo results on immature pear fruits showed a significant decrease in the progression of the fire blight symptoms, with a variation in the infection index from one antagonistic strain to another between 31.3 and 50%, and slice of potato showed total inhibition of the pathogen (P. carotovorum) by the antagonistic strains of Serratia plymuthica (p<0.005). Conclusion This study highlighted that the effective bacteria did not show any infection signs towards plant tissue, and considered as a potential strategy to limit the fire blight and soft rot diseases.

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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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Bacteria in the global atmosphere – Part 2: Modeling of emissions and transport between different ecosystems

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-9281-2009 ◽

2009 ◽

Vol 9 (23) ◽

pp. 9281-9297 ◽

Cited By ~ 190

Author(s):

S. M. Burrows ◽

T. Butler ◽

P. Jöckel ◽

H. Tost ◽

A. Kerkweg ◽

...

Keyword(s):

Seasonal Variation ◽

Residence Time ◽

General Circulation ◽

Bacterial Species ◽

Circulation Model ◽

Cloud Condensation Nucleus ◽

Cloud Formation ◽

Emission Region ◽

Culturable Bacteria ◽

Bacterial Cells

Abstract. Bacteria are constantly being transported through the atmosphere, which may have implications for human health, agriculture, cloud formation, and the dispersal of bacterial species. We simulate the global transport of bacteria, represented as 1 μm and 3 μm diameter spherical solid particle tracers in a general circulation model. We investigate factors influencing residence time and distribution of the particles, including emission region, cloud condensation nucleus activity and removal by ice-phase precipitation. The global distribution depends strongly on the assumptions made about uptake into cloud droplets and ice. The transport is also affected, to a lesser extent, by the emission region, particulate diameter, and season. We find that the seasonal variation in atmospheric residence time is insufficient to explain by itself the observed seasonal variation in concentrations of particulate airborne culturable bacteria, indicating that this variability is mainly driven by seasonal variations in culturability and/or emission strength. We examine the potential for exchange of bacteria between ecosystems and obtain rough estimates of the flux from each ecosystem by using a maximum likelihood estimation technique, together with a new compilation of available observations described in a companion paper. Globally, we estimate the total emissions of bacteria-containing particles to the atmosphere to be 7.6×1023–3.5×1024 a−1, originating mainly from grasslands, shrubs and crops. We estimate the mass of emitted bacteria- to be 40–1800 Gg a−1, depending on the mass fraction of bacterial cells in the particles. In order to improve understanding of this topic, more measurements of the bacterial content of the air and of the rate of surface-atmosphere exchange of bacteria will be necessary. Future observations in wetlands, hot deserts, tundra, remote glacial and coastal regions and over oceans will be of particular interest.

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Microbial Photoinactivation by Visible Light Results in Limited Loss of Membrane Integrity

Antibiotics ◽

10.3390/antibiotics10030341 ◽

2021 ◽

Vol 10 (3) ◽

pp. 341

Author(s):

Katharina Hoenes ◽

Richard Bauer ◽

Barbara Spellerberg ◽

Martin Hessling

Keyword(s):

Visible Light ◽

Pseudomonas Fluorescens ◽

Bacterial Cell ◽

Bacterial Species ◽

Membrane Integrity ◽

Cell Lysis ◽

Microbial Inactivation ◽

Bacterial Cells ◽

Resistance Development ◽

Transmission Electron

Interest in visible light irradiation as a microbial inactivation method has widely increased due to multiple possible applications. Resistance development is considered unlikely, because of the multi-target mechanism, based on the induction of reactive oxygen species by wavelength specific photosensitizers. However, the affected targets are still not completely identified. We investigated membrane integrity with the fluorescence staining kit LIVE/DEAD® BacLight™ on a Gram positive and a Gram negative bacterial species, irradiating Staphylococcus carnosus and Pseudomonas fluorescens with 405 nm and 450 nm. To exclude the generation of viable but nonculturable (VBNC) bacterial cells, we applied an ATP test, measuring the loss of vitality. Pronounced uptake of propidium iodide was only observed in Pseudomonas fluorescens at 405 nm. Transmission electron micrographs revealed no obvious differences between irradiated samples and controls, especially no indication of an increased bacterial cell lysis could be observed. Based on our results and previous literature, we suggest that visible light photoinactivation does not lead to rapid bacterial cell lysis or disruption. However, functional loss of membrane integrity due to depolarization or inactivation of membrane proteins may occur. Decomposition of the bacterial envelope following cell death might be responsible for observations of intracellular component leakage.

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In vitro evaluation of the effect of nicotine, cotinine, and caffeine on oral microorganisms

Canadian Journal of Microbiology ◽

10.1139/w08-032 ◽

2008 ◽

Vol 54 (6) ◽

pp. 501-508 ◽

Cited By ~ 17

Author(s):

Karina Cogo ◽

Michelle Franz Montan ◽

Cristiane de Cássia Bergamaschi ◽

Eduardo D. Andrade ◽

Pedro Luiz Rosalen ◽

...

Keyword(s):

High Performance Liquid Chromatography ◽

Liquid Chromatography ◽

High Performance ◽

Culture Media ◽

Bacterial Species ◽

In Vitro Study ◽

Bacterial Strains ◽

Planktonic Cells ◽

Susceptibility Tests

The aim of this in vitro study was to evaluate the effects of nicotine, cotinine, and caffeine on the viability of some oral bacterial species. It also evaluated the ability of these bacteria to metabolize those substances. Single-species biofilms of Streptococcus gordonii , Porphyromonas gingivalis , or Fusobacterium nucleatum and dual-species biofilms of S. gordonii – F. nucleatum and F. nucleatum – P. gingivalis were grown on hydroxyapatite discs. Seven species were studied as planktonic cells, including Streptococcus oralis , Streptococcus mitis , Propionibacterium acnes , Actinomyces naeslundii , and the species mentioned above. The viability of planktonic cells and biofilms was analyzed by susceptibility tests and time-kill assays, respectively, against different concentrations of nicotine, cotinine, and caffeine. High-performance liquid chromatography was performed to quantify nicotine, cotinine, and caffeine concentrations in the culture media after the assays. Susceptibility tests and viability assays showed that nicotine, cotinine, and caffeine cannot reduce or stimulate bacterial growth. High-performance liquid chromatography results showed that nicotine, cotinine, and caffeine concentrations were not altered after bacteria exposure. These findings indicate that nicotine, cotinine, and caffeine, in the concentrations used, cannot affect significantly the growth of these oral bacterial strains. Moreover, these species do not seem to metabolize these substances.

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