Enhanced Fouling Resistance and Antibacterial Properties of Novel Graphene Oxide-Arabic Gum Polyethersulfone Membranes

Membrane biofouling has proved to be a major obstacle when it comes to membrane efficiency in membrane-based water treatment. Solutions to this problem remain elusive. This study presents novel polyethersulfone (PES) membranes that are fabricated using the phase inversion method at different loadings of graphene oxide (GO) and 1 wt. % arabic gum (AG) as nanofiller and pore forming agents. Synthesized GO was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for morphological studies and energy-dispersive X-ray spectroscopy (EDX) for elemental analysis. The prepared GO flakes showed a high content of oxygen-containing groups (~31%). The fabricated membranes were extensively characterized, including water contact angle analysis for hydrophilicity, zeta potential measurements for surface charge, SEM, total porosity and pore size measurements. The prepared membranes underwent fouling tests using bovine serum albumin (BSA) solutions and biofouling tests using model Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial suspensions as well as real treated sewage effluent (TSE). The results showed that the novel PES/GO membranes possessed strong hydrophilicity and negative surface charge with an increase in porosity, pore size and water flux. The PES/GO membranes exhibited superior antibacterial action against both Gram-positive and Gram-negative bacterial species, implicating PES membranes which incorporate GO and AG as novel membranes that are capable of high antibiofouling properties with high flux.

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Antibacterial Properties of Polysulfone Membranes Blended with Arabic Gum

Membranes ◽

10.3390/membranes9020029 ◽

2019 ◽

Vol 9 (2) ◽

pp. 29 ◽

Cited By ~ 6

Author(s):

Souhir Sabri ◽

Ahmad Najjar ◽

Yehia Manawi ◽

Nahla Eltai ◽

Asma Al-Thani ◽

...

Keyword(s):

Bacterial Colonization ◽

Membrane Surface ◽

Bacterial Species ◽

Antibacterial Properties ◽

Bacterial Attachment ◽

Inversion Method ◽

Klebsiella Pneumonia ◽

Gram Positive ◽

Arabic Gum ◽

Gram Negative

Polysulfone (PS) membranes blended with different loadings of arabic gum (AG) were synthesized using phase inversion method and the antibacterial properties of the synthesized membranes were tested using a number Gram-negative (Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacterial species. It was shown that AG addition to the dope polymer solutions essentially changed porous structure, hydrophilicity and zeta potential of the cast PS/AG membranes. These changes were due to the amphiphilic properties of AG macromolecules that contained negatively charged hydrophilic residues. A pronounced decrease in bacterial attachment was seen in the field emission scanning electron microscopy (FESEM) images for PS/AG membrane samples compared to both commercial (Microdyn-Nadir) and bare PS (without AG) membranes. AG loading dependent trend was observed where the prevention of bacterial colonization on the membrane surface was strongest at the highest (7 wt. %) AG loading in the casting solution. Possible mechanisms for the prevention of bacterial colonization were discussed. Significantly, the inhibition of bacterial attachment and growth on PS/AG membranes was observed for both Gram-positive and Gram-negative bacterial models, rendering these novel membranes with strong biofouling resistance attractive for water treatment applications.

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Antibiofouling Performance by Polyethersulfone Membranes Cast with Oxidized Multiwalled Carbon Nanotubes and Arabic Gum

Membranes ◽

10.3390/membranes9020032 ◽

2019 ◽

Vol 9 (2) ◽

pp. 32 ◽

Cited By ~ 10

Author(s):

Ahmad Najjar ◽

Souhir Sabri ◽

Rashad Al-Gaashani ◽

Muataz Ali Atieh ◽

Viktor Kochkodan

Keyword(s):

Electron Microscopy ◽

Carbon Nanotubes ◽

Multiwalled Carbon Nanotubes ◽

Performance Testing ◽

Inversion Method ◽

Gram Positive ◽

Multiwalled Carbon ◽

Arabic Gum ◽

Gram Negative ◽

Oxidized Multiwalled Carbon Nanotubes

Despite extensive research efforts focusing on tackling membrane biofouling, one of the biggest problems associated with membrane technology, there has been little headway in this area. This study presents novel polyethersulfone (PES) membranes synthesized via a phase inversion method at incremental loadings of functionalized oxidized multiwalled carbon nanotubes (OMWCNT) along with 1 wt. % arabic gum (AG). The synthesized OMWCNT were examined using scanning electron microscopy and transmission electron microscopy for morphological changes compared to the commercially obtained carbon nanotubes. Additionally energy-dispersive X-ray spectroscopy was carried out on the raw and OMWCNT materials, indicating an almost 2-fold increase in oxygen content in the latter sample. The cast PES/OMWCNT membranes were extensively characterized, and underwent a series of performance testing using bovine serum albumin solution for fouling tests and model Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial species for anti-biofouling experiments. Results indicated that the composite PES membranes, which incorporated the OMWCNT and AG, possessed significantly stronger hydrophilicity and negative surface charge as evidenced by water contact angle and zeta potential data, respectively, when compared to plain PES membranes. Furthermore atomic force microscopy analysis showed that the PES/OMWCNT membranes exhibited significantly lower surface roughness values. Together, these membrane surface features were held responsible for the anti-adhesive nature of the hybrid membranes seen during biofouling tests. Importantly, the prepared membranes were able to inhibit bacterial colonization upon incubation with both Gram-positive and Gram-negative bacterial suspensions. The PES/OMWCNT membranes also presented more resilient normalized flux values when compared to neat PES and commercial membrane samples during filtration of both bacterial suspensions and real treated sewage effluents. Taken together, the results of this study allude to OMWCNT and AG as promising additives, for incorporation into polymeric membranes to enhance biofouling resistance.

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Evaluation of MicroScan Bacterial Identification Panels for Low-Resource Settings

Diagnostics ◽

10.3390/diagnostics11020349 ◽

2021 ◽

Vol 11 (2) ◽

pp. 349

Author(s):

Sien Ombelet ◽

Alessandra Natale ◽

Jean-Baptiste Ronat ◽

Olivier Vandenberg ◽

Liselotte Hardy ◽

...

Keyword(s):

Bacterial Species ◽

Ease Of Use ◽

Bacterial Identification ◽

Gram Positive ◽

Gram Negative ◽

Low Resource Settings ◽

Low Resource ◽

Bacillus Spp ◽

Gram Negative Organisms ◽

Instructions For Use

Bacterial identification is challenging in low-resource settings (LRS). We evaluated the MicroScan identification panels (Beckman Coulter, Brea, CA, USA) as part of Médecins Sans Frontières’ Mini-lab Project. The MicroScan Dried Overnight Positive ID Type 3 (PID3) panels for Gram-positive organisms and Dried Overnight Negative ID Type 2 (NID2) panels for Gram-negative organisms were assessed with 367 clinical isolates from LRS. Robustness was studied by inoculating Gram-negative species on the Gram-positive panel and vice versa. The ease of use of the panels and readability of the instructions for use (IFU) were evaluated. Of species represented in the MicroScan database, 94.6% (185/195) of Gram-negative and 85.9% (110/128) of Gram-positive isolates were correctly identified up to species level. Of species not represented in the database (e.g., Streptococcus suis and Bacillus spp.), 53.1% out of 49 isolates were incorrectly identified as non-related bacterial species. Testing of Gram-positive isolates on Gram-negative panels and vice versa (n = 144) resulted in incorrect identifications for 38.2% of tested isolates. The readability level of the IFU was considered too high for LRS. Inoculation of the panels was favorably evaluated, whereas the visual reading of the panels was considered error-prone. In conclusion, the accuracy of the MicroScan identification panels was excellent for Gram-negative species and good for Gram-positive species. Improvements in stability, robustness, and ease of use have been identified to assure adaptation to LRS constraints.

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The Development of an Effective Bacterial Single-Cell Lysis Method Suitable for Whole Genome Amplification in Microfluidic Platforms

Micromachines ◽

10.3390/mi9080367 ◽

2018 ◽

Vol 9 (8) ◽

pp. 367 ◽

Cited By ~ 6

Author(s):

Yuguang Liu ◽

Dirk Schulze-Makuch ◽

Jean-Pierre de Vera ◽

Charles Cockell ◽

Thomas Leya ◽

...

Keyword(s):

Single Cell ◽

Single Cells ◽

Bacterial Species ◽

Cell Manipulation ◽

Microfluidic Platforms ◽

Gram Positive ◽

Gram Negative ◽

Genome Amplification ◽

Single Cell Sequencing ◽

Wide Range

Single-cell sequencing is a powerful technology that provides the capability of analyzing a single cell within a population. This technology is mostly coupled with microfluidic systems for controlled cell manipulation and precise fluid handling to shed light on the genomes of a wide range of cells. So far, single-cell sequencing has been focused mostly on human cells due to the ease of lysing the cells for genome amplification. The major challenges that bacterial species pose to genome amplification from single cells include the rigid bacterial cell walls and the need for an effective lysis protocol compatible with microfluidic platforms. In this work, we present a lysis protocol that can be used to extract genomic DNA from both gram-positive and gram-negative species without interfering with the amplification chemistry. Corynebacterium glutamicum was chosen as a typical gram-positive model and Nostoc sp. as a gram-negative model due to major challenges reported in previous studies. Our protocol is based on thermal and chemical lysis. We consider 80% of single-cell replicates that lead to >5 ng DNA after amplification as successful attempts. The protocol was directly applied to Gloeocapsa sp. and the single cells of the eukaryotic Sphaerocystis sp. and achieved a 100% success rate.

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Graphene oxide exhibits differential mechanistic action towards Gram-positive and Gram-negative bacteria

Colloids and Surfaces B Biointerfaces ◽

10.1016/j.colsurfb.2019.05.023 ◽

2019 ◽

Vol 181 ◽

pp. 6-15 ◽

Cited By ~ 25

Author(s):

Thiruchelvi Pulingam ◽

Kwai Lin Thong ◽

Md. Eaqub Ali ◽

Jimmy Nelson Appaturi ◽

Ignatius Julian Dinshaw ◽

...

Keyword(s):

Graphene Oxide ◽

Gram Negative Bacteria ◽

Gram Positive ◽

Gram Negative

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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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Efficient capture and photothermal ablation of planktonic bacteria and biofilms using reduced graphene oxide–polyethyleneimine flexible nanoheaters

Journal of Materials Chemistry B ◽

10.1039/c8tb01676c ◽

2019 ◽

Vol 7 (17) ◽

pp. 2771-2781 ◽

Cited By ~ 15

Author(s):

Milica Budimir ◽

Roxana Jijie ◽

Ran Ye ◽

Alexandre Barras ◽

Sorin Melinte ◽

...

Keyword(s):

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Gram Positive ◽

Nanohole Array ◽

Gram Negative ◽

Planktonic Bacteria ◽

Photothermal Ablation ◽

Reduced Graphene

A flexible nanoheater device, consisting of a Au nanohole array coated with reduced graphene oxide–polyethyleneimine, was applied to capture and eradicate both Gram-positive and Gram negative planktonic bacteria and their biofilms.

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Diversity profiling of xenic cultures of Dientamoeba fragilis following systematic antibiotic treatment and prospects for genome sequencing

Parasitology ◽

10.1017/s0031182019001173 ◽

2019 ◽

Vol 147 (1) ◽

pp. 29-38

Author(s):

Rory Gough ◽

Joel Barratt ◽

Damien Stark ◽

John Ellis

Keyword(s):

Antibiotic Treatment ◽

Genome Sequencing ◽

Ribosomal Dna ◽

Bacterial Species ◽

Nutritional Requirement ◽

Gram Negative Bacteria ◽

Gram Positive ◽

Gram Negative ◽

Dientamoeba Fragilis ◽

The Impact

AbstractThe presence of bacterial DNA in Dientamoeba fragilis DNA extracts from culture poses a substantial challenge to sequencing the D. fragilis genome. However, elimination of bacteria from D. fragilis cultures has proven difficult in the past, presumably due to its dependence on some unknown prokaryote/s. This study explored options for removal of bacteria from D. fragilis cultures and for the generation of genome sequence data from D. fragilis. DNA was extracted from human faecal samples and xenic D. fragilis cultures. Extracts were subjected to 16S ribosomal DNA bacterial diversity profiling. Xenic D. fragilis cultures were then subject to antibiotic treatment regimens that systematically removed bacterial species depending on their membrane structure (Gram-positive or Gram-negative) and aerobic requirements. The impact of these treatments on cultures was assessed by 16S amplicon sequencing. Prior to antibiotic treatment, the cultures were dominated by Gram-negative bacteria. Addition of meropenem to cultures eliminated anaerobic Gram-negative bacteria, but it also led to protozoan death after 5 days incubation. The seeding of meropenem resistant Klebsiella pneumoniae strain KPC-2 into cultures before treatment by meropenem prevented death of D. fragilis cells beyond this 5 day period, suggesting that one or more species of Gram-negative bacteria may be an essential nutritional requirement for D. fragilis. Gram-positive cells were completely eliminated using vancomycin without affecting trophozoite growth. Finally, this study shows that genome sequencing of D. fragilis is feasible following bacterial elimination from cultures as the result of the major advances occurring in bioinformatics. We provide evidence on this fact by successfully sequencing the D. fragilis 28S large ribosomal DNA subunit gene using culture-derived DNA.

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Effect of Organochlorine Pesticides on Growth and Biological Activities of Bacterial Species Important to the Dairy Food Industry

Journal of Milk and Food Technology ◽

10.4315/0022-2747-39.2.90 ◽

1976 ◽

Vol 39 (2) ◽

pp. 90-94 ◽

Cited By ~ 1

Author(s):

MARY L. SANDFORD ◽

B. E. LANGLOIS

Keyword(s):

Food Industry ◽

Biological Activities ◽

Bacterial Species ◽

Inhibitory Effect ◽

Growth Patterns ◽

Gram Positive ◽

Dairy Food ◽

Gram Negative ◽

Generation Times ◽

Slight Inhibition

Three growth patterns (no effect, slight inhibition, or complete inhibition) were observed when bacterial species common to the dairy-food industry were grown in media containing 50 or 100 ppm DDT, dieldrin, or endrin. The pattern obtained appeared to depend on species and type and concentration of pesticide. All pesticides studied had a greater inhibitory effect on gram positive species than they had on gram negative species when grown in broth. Acid production by lactic acid bacteria was inhibited in broth plus 5 ppm chlordane or heptachlor but unaffected in skimmilk plus up to 100 ppm of these pesticides. Generation times for gram negative species grown in broth plus 10 ppm chlordane or heptachlor were similar to those obtained in controls. Growth of gram positive species was inhibited in broth plus 10 ppm of these pesticides but unaffected in skimmilk containing similar pesticide concentrations. Generation times for several gram negative species were increased by 10 ppm heptachlor in skimmilk.

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