Microbial Nanotechnology

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Microbial Biotechnology".

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 31727

Special Issue Editor

Plant Pathology Research Institute, Agricultural Research Center, Giza 12619, Egypt
Interests: agricultural nanotechnology; rapid diagnostic methods; breeding resistant varieties; pathogen genomes; eco-friendly nanomaterials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This issue offers insight into the use of microorganisms including bacteria, actinomycetes, fungi, algae, and diatoms, all of which contribute to the microbial production of nanomaterials. The inherent variety of microbiological systems necessitates more standardization of processes in order to create nanomaterials with increasingly uniform and repeatable chemical–physical properties. It will cover the state of knowledge, microbial synthesis mechanisms, and problems in microbial-mediated biosynthesis. A comprehensive understanding of biosynthetic pathways and the possibilities of genetic engineering are fueling research into breakthrough production of microbial-based nanosynthesis for future scaling up and possible commercial usage of these exciting “microbial cell nanofactories”. The creation of sensoristic devices, therapeutic/diagnostic applications, and the control of numerous microbial illnesses in plants, animals, and people are all possible applications for nano-based materials. Recent developments in microbial nanostructures have focused on the treatment of food-borne infections, plant pathogens, as nutrients, and biological uses. Microorganisms are regarded not just as biofactories for nanomaterial creation, but also as agents for removing hazardous metals from the environment. The sources of microbially generated nanoparticles’ exposure and ecotoxicity are also examined. In this issue, we will focus on research that addresses a variety of important features of nanomaterials: 1) the kind of microbial green synthesis, 2) biosynthetic methods and routes, 3) characterization, and 4) applications, as well as the key data gathered in 5) regulations, 6) nanotoxicity, and 7) challenges.

This Special Issue on “Microbial Nanotechnology” seeks to offer contemporary research on any element of the development of microbial-based nanosynthesis for future scaling up and prospective commercial exploitation, as well as their applications in the biomedical, environmental, and agri-food sectors.

Some of its focal points include but are not limited to the following:

  • Microbial biosurfactants
  • Microbially synthesized nanoparticles
  • Algae-mediated nanoparticles
  • Actinobacteria-mediated nanoparticles
  • Actinomycetes-mediated nanoparticles
  • Bacteria-mediated nanoparticles
  • Fungi-mediated nanoparticles
  • Lichens-mediated nanoparticles
  • Yeast-mediated nanoparticles
  • Sensoristic devices 
  • Nanotheranostics
  • Nano-antimicrobial 
  • Microbial nanocomposites
  • Antimicrobial mechanisms
  • Microbicidal effects
  • Antibiofilm agents
  • Nano-based drug delivery
  • Nanotoxicity 

Prof. Dr. Kamel A. Abd-Elsalam
Guest Editor

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Published Papers (16 papers)

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Editorial

Jump to: Research, Review

6 pages, 183 KiB  
Editorial
Special Issue: Microbial Nanotechnology
by Kamel A. Abd-Elsalam
Microorganisms 2024, 12(2), 352; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms12020352 - 08 Feb 2024
Viewed by 504
Abstract
Microbial nanotechnology (MN), or microbial nanobiotechnology, is a rapidly expanding research area with the potential to transform various fields, including bioremediation, energy production, medicine, and agriculture [...] Full article
(This article belongs to the Special Issue Microbial Nanotechnology)

Research

Jump to: Editorial, Review

20 pages, 3238 KiB  
Article
A Comparative Study of the Synthesis and Characterization of Biogenic Selenium Nanoparticles by Two Contrasting Endophytic Selenobacteria
by Eulàlia Sans-Serramitjana, Carla Gallardo-Benavente, Francisco Melo, José M. Pérez-Donoso, Cornelia Rumpel, Patricio Javier Barra, Paola Durán and María de La Luz Mora
Microorganisms 2023, 11(6), 1600; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms11061600 - 16 Jun 2023
Cited by 1 | Viewed by 1439
Abstract
The present study examined the biosynthesis and characterization of selenium nanoparticles (SeNPs) using two contrasting endophytic selenobacteria, one Gram-positive (Bacillus sp. E5 identified as Bacillus paranthracis) and one Gram-negative (Enterobacter sp. EC5.2 identified as Enterobacter ludwigi), for further use [...] Read more.
The present study examined the biosynthesis and characterization of selenium nanoparticles (SeNPs) using two contrasting endophytic selenobacteria, one Gram-positive (Bacillus sp. E5 identified as Bacillus paranthracis) and one Gram-negative (Enterobacter sp. EC5.2 identified as Enterobacter ludwigi), for further use as biofortifying agents and/or for other biotechnological purposes. We demonstrated that, upon regulating culture conditions and selenite exposure time, both strains were suitable “cell factories” for producing SeNPs (B-SeNPs from B. paranthracis and E-SeNPs from E. ludwigii) with different properties. Briefly, dynamic light scattering (DLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM) studies revealed that intracellular E-SeNPs (56.23 ± 4.85 nm) were smaller in diameter than B-SeNPs (83.44 ± 2.90 nm) and that both formulations were located in the surrounding medium or bound to the cell wall. AFM images indicated the absence of relevant variations in bacterial volume and shape and revealed the existence of layers of peptidoglycan surrounding the bacterial cell wall under the conditions of biosynthesis, particularly in the case of B. paranthracis. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) showed that SeNPs were surrounded by the proteins, lipids, and polysaccharides of bacterial cells and that the numbers of the functional groups present in B-SeNPs were higher than in E-SeNPs. Thus, considering that these findings support the suitability of these two endophytic stains as potential biocatalysts to produce high-quality Se-based nanoparticles, our future efforts must be focused on the evaluation of their bioactivity, as well as on the determination of how the different features of each SeNP modulate their biological action and their stability. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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18 pages, 3210 KiB  
Article
An In Vitro Small Intestine Model Incorporating a Food Matrix and Bacterial Mock Community for Intestinal Function Testing
by Mridu Malik, Jacob V. Tanzman, Sanat Kumar Dash, Cláudia N. H. Marques and Gretchen J. Mahler
Microorganisms 2023, 11(6), 1419; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms11061419 - 27 May 2023
Cited by 1 | Viewed by 929
Abstract
Consumed food travels through the gastrointestinal tract to reach the small intestine, where it interacts with the microbiota, forming a complex relationship with the dietary components. Here we present a complex in vitro cell culture model of the small intestine that includes human [...] Read more.
Consumed food travels through the gastrointestinal tract to reach the small intestine, where it interacts with the microbiota, forming a complex relationship with the dietary components. Here we present a complex in vitro cell culture model of the small intestine that includes human cells, digestion, a simulated meal, and a microbiota represented by a bacterial community consisting of E. coli, L. rhamnosus, S. salivarius, B. bifidum, and E. faecalis. This model was used to determine the effects of food-grade titanium dioxide nanoparticles (TiO2 NPs), a common food additive, on epithelial permeability, intestinal alkaline phosphatase activity, and nutrient transport across the epithelium. Physiologically relevant concentrations of TiO2 had no effect on intestinal permeability but caused an increase in triglyceride transport as part of the food model, which was reversed in the presence of bacteria. Individual bacterial species had no effect on glucose transport, but the bacterial community increased glucose transport, suggesting a change in bacterial behavior when in a community. Bacterial entrapment within the mucus layer was reduced with TiO2 exposure, which may be due to decreased mucus layer thickness. The combination of human cells, a synthetic meal, and a bacterial mock community provides an opportunity to understand the implications of nutritional changes on small intestinal function, including the microbiota. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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17 pages, 5124 KiB  
Article
Biogenic Silver Nanoparticles Produced by Soil Rare Actinomycetes and Their Significant Effect on Aspergillus-derived mycotoxins
by Mohamed N. Abd El-Ghany, Salwa A. Hamdi, Shereen M. Korany, Reham M. Elbaz, Ahmed N. Emam and Mohamed G. Farahat
Microorganisms 2023, 11(4), 1006; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms11041006 - 12 Apr 2023
Cited by 2 | Viewed by 2425
Abstract
The current investigation addressed the green synthesis of silver nanoparticles (AgNPs) using newly isolated silver-resistant rare actinomycetes, Glutamicibacter nicotianae SNPRA1 and Leucobacter aridicollis SNPRA2, and investigated their impact on the mycotoxigenic fungi Aspergillus flavus ATCC 11498 and Aspergillus ochraceus ATCC 60532. The formation [...] Read more.
The current investigation addressed the green synthesis of silver nanoparticles (AgNPs) using newly isolated silver-resistant rare actinomycetes, Glutamicibacter nicotianae SNPRA1 and Leucobacter aridicollis SNPRA2, and investigated their impact on the mycotoxigenic fungi Aspergillus flavus ATCC 11498 and Aspergillus ochraceus ATCC 60532. The formation of AgNPs was evidenced by the reaction’s color change to brownish and the appearance of the characteristic surface plasmon resonance. The transmission electron microscopy of biogenic AgNPs produced by G. nicotianae SNPRA1 and L. aridicollis SNPRA2 (designated Gn-AgNPs and La-AgNPs, respectively) revealed the generation of monodispersed spherical nanoparticles with average sizes of 8.48 ± 1.72 nm and 9.67 ± 2.64 nm, respectively. Furthermore, the XRD patterns reflected their crystallinity and the FTIR spectra demonstrated the presence of proteins as capping agents. Both bioinspired AgNPs exhibited a remarkable inhibitory effect on the conidial germination of the investigated mycotoxigenic fungi. The bioinspired AgNPs caused an increase in DNA and protein leakage, suggesting the disruption of membrane permeability and integrity. Interestingly, the biogenic AgNPs completely inhibited the production of total aflatoxins and ochratoxin A at concentrations less than 8 μg/mL. At the same time, cytotoxicity investigations revealed the low toxicity of the biogenic AgNPs against the human skin fibroblast (HSF) cell line. Both biogenic AgNPs exhibited feasible biocompatibility with HSF cells at concentrations up to 10 μg/mL and their IC50 values were 31.78 and 25.83 μg/mL for Gn-AgNPs and La-AgNPs, respectively. The present work sheds light on the antifungal prospect of the biogenic AgNPs produced by rare actinomycetes against mycotoxigenic fungi as promising candidates to combat mycotoxin formation in food chains at nontoxic doses. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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19 pages, 5444 KiB  
Article
Histopathological, Immunohistochemical, Biochemical, and In Silico Molecular Docking Study of Fungal-Mediated Selenium Oxide Nanoparticles on Biomphalaria alexandrina (Ehrenberg, 1831) Snails
by Amina M. Ibrahim, Mahassen Ghazy, Heba El-Sayed, Rehab M. Abd El-Hameed, Rehab G. Khalil, Shereen M. Korany, Abeer S. Aloufi, Olfat A. Hammam and Mostafa Y. Morad
Microorganisms 2023, 11(3), 811; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms11030811 - 22 Mar 2023
Cited by 1 | Viewed by 1559
Abstract
Daphnia magna and freshwater snails are used as delicate bioindicators of contaminated aquatic habitats. Due to their distinctive characteristics, selenium oxide nanoparticles (SeONPs) have received interest regarding their possible implications on aquatic environments. The current study attempted to investigate the probable mechanisms of [...] Read more.
Daphnia magna and freshwater snails are used as delicate bioindicators of contaminated aquatic habitats. Due to their distinctive characteristics, selenium oxide nanoparticles (SeONPs) have received interest regarding their possible implications on aquatic environments. The current study attempted to investigate the probable mechanisms of fungal-mediated selenium nanoparticles’ ecotoxicological effects on freshwater Biomphalaria alexandrina snails and Daphnia magna. SeONPs revealed a toxicological impact on D. magna, with a half-lethal concentration (LC50) of 1.62 mg/L after 24 h and 1.08 mg/L after 48 h. Survival, fecundity, and reproductive rate were decreased in B. alexandrina snails exposed to SeONPs. Furthermore, the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were markedly elevated, while albumin and total protein levels decreased. Histopathological damage in the hermaphrodite and digestive glands was detected by light, electron microscopy, and immunohistochemistry studies. The molecular docking study revealed interactions of selenium oxide with the ALT and AST. In conclusion, B. alexandrina snails and D. magna could be employed as bioindicators of selenium nanomaterial pollution in aquatic ecosystems. This study emphasizes the possible ecological effects of releasing SeONPs into aquatic habitats, which could serve as motivation for regulatory organizations to monitor and control the use and disposal of SeONPs in industry. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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13 pages, 3791 KiB  
Article
Antimicrobial Activity of Green Synthesized Silver Nanoparticles Using Waste Leaves of Hyphaene thebaica (Doum Palm)
by Nadiyah M. Alabdallah and Essam Kotb
Microorganisms 2023, 11(3), 807; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms11030807 - 22 Mar 2023
Cited by 1 | Viewed by 1354
Abstract
Silver nanoparticles (AgNPs) were biosynthesized for the first time from waste leaves extract of local doum palms in Tabuk, Saudi Arabia. The transmission electron microscope (TEM) revealed a spherical shape with a particle size from 18 to 33 nm. The d-spacing is about [...] Read more.
Silver nanoparticles (AgNPs) were biosynthesized for the first time from waste leaves extract of local doum palms in Tabuk, Saudi Arabia. The transmission electron microscope (TEM) revealed a spherical shape with a particle size from 18 to 33 nm. The d-spacing is about 2.6 Å, which confirms a face-centered cubic crystalline building. The biosynthesized AgNPs were evaluated as an antimicrobial agent against several pathogenic bacteria, including Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853. The highest action was exerted against S. aureus ATCC 29213 (MIC = 1.5 µg/mL). Interestingly, AgNPs also showed anticandidal activity against the pathogenic yeasts Candida albicans ATCC 14053 (MIC = 24 µg/mL) and Candida tropicalis ATCC 13803 (MIC = 96 µg/mL). Scanning electron microscope (SEM) revealed deep morphological changes in Candida spp. due to the treatment of the AgNPs. Scarce pseudohyphae, perforation, exterior roughness, irregularly shaped cells, and production of protective exopolysaccharide (EPS) were the main features. In conclusion, the process of biosynthesis of AgNPs from the aqueous leaf extract of Hyphaene thebaica is environmentally compatible and induces the biosynthesis of tiny AgNPs that could be a promising candidate in biomedical applications, including antimicrobials against some pathogenic bacteria and yeasts. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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18 pages, 6519 KiB  
Article
Biosynthesis of Novel Tellurium Nanorods by Gayadomonas sp. TNPM15 Isolated from Mangrove Sediments and Assessment of Their Impact on Spore Germination and Ultrastructure of Phytopathogenic Fungi
by Mohamed N. Abd El-Ghany, Salwa A. Hamdi, Shereen M. Korany, Reham M. Elbaz and Mohamed G. Farahat
Microorganisms 2023, 11(3), 558; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms11030558 - 22 Feb 2023
Cited by 7 | Viewed by 2804
Abstract
The biosynthesis of nanoparticles using green technology is emerging as a cost-efficient, eco-friendly and risk-free strategy in nanotechnology. Recently, tellurium nanoparticles (TeNPs) have attracted growing attention due to their unique properties in biomedicine, electronics, and other industrial applications. The current investigation addresses the [...] Read more.
The biosynthesis of nanoparticles using green technology is emerging as a cost-efficient, eco-friendly and risk-free strategy in nanotechnology. Recently, tellurium nanoparticles (TeNPs) have attracted growing attention due to their unique properties in biomedicine, electronics, and other industrial applications. The current investigation addresses the green synthesis of TeNPs using a newly isolated mangrove-associated bacterium, Gayadomonas sp. TNPM15, and their impact on the phytopathogenic fungi Fusarium oxysporum and Alternaria alternata. The biogenic TeNPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared (FTIR). The results of TEM revealed the intracellular biosynthesis of rod-shaped nanostructures with a diameter range from 15 to 23 nm and different lengths reaching up to 243 nm. Furthermore, the successful formation of tellurium nanorods was verified by SEM-EDX, and the XRD pattern revealed their crystallinity. In addition, the FTIR spectrum provided evidence for the presence of proteinaceous capping agents. The bioinspired TeNPs exhibited obvious inhibitory effect on the spores of both investigated phytopathogens accomplished with prominent ultrastructure alternations, as evidenced by TEM observations. The biogenic TeNPs impeded spore germination of F. oxysporum and A. alternata completely at 48.1 and 27.6 µg/mL, respectively. Furthermore, an increase in DNA and protein leakage was observed upon exposure of fungal spores to the biogenic TeNPs, indicating the disruption of membrane permeability and integrity. Besides their potent influence on fungal spores, the biogenic TeNPs demonstrated remarkable inhibitory effects on the production of various plant cell wall-degrading enzymes. Moreover, the cytotoxicity investigations revealed the biocompatibility of the as-prepared biogenic TeNPs and their low toxicity against the human skin fibroblast (HSF) cell line. The biogenic TeNPs showed no significant cytotoxic effect towards HSF cells at concentrations up to 80 μg/mL, with a half-maximal inhibitory concentration (IC50) value of 125 μg/mL. The present work spotlights the antifungal potential of the biogenic TeNPs produced by marine bacterium against phytopathogenic fungi as a promising candidate to combat fungal infections. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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16 pages, 2824 KiB  
Article
Biofilm Inhibitory Activity of Actinomycete-Synthesized AgNPs with Low Cytotoxic Effect: Experimental and In Silico Study
by Sabah A. AboElmaaty, Ali A. Shati, Mohammad Y. Alfaifi, Serag Eldin I. Elbehairi, Norhan S. Sheraba, Mervat G. Hassan, Mona Shaban E. M. Badawy, Ahmed Ghareeb, Ahmed A. Hamed and Ebtsam Z. Gabr
Microorganisms 2023, 11(1), 102; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms11010102 - 30 Dec 2022
Cited by 4 | Viewed by 2203
Abstract
The emergence of resistance by biofilm-forming bacteria has reached alarming and dangerous levels that threaten human civilization. The current study sought to investigate the antibiofilm potential of green-synthesized silver nanoparticles, mediated by a new Streptomyces strain. Zeta potential, transmission electron microscopy (TEM), and [...] Read more.
The emergence of resistance by biofilm-forming bacteria has reached alarming and dangerous levels that threaten human civilization. The current study sought to investigate the antibiofilm potential of green-synthesized silver nanoparticles, mediated by a new Streptomyces strain. Zeta potential, transmission electron microscopy (TEM), and UV-Vis spectroscopy were used to analyze the biosynthesized AgNPs. Results revealed that silver nanoparticles had a size of (5.55 and 45.00 nm) nm and a spherical shape, with surface plasmon resonance (SPR) absorption at 400–460 nm in the UV-vis spectra establishing the formation of Streptomyces-Ag-NPs. The biosynthesized AgNPs showed a pronounced antibacterial efficacy against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. Moreover, the obtained Streptomyces-AgNPs exerted biofilm inhibition activity against nosocomial hospital-resistant bacteria, including Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. The mechanism of biogenic AgNPs antibacterial action was visualized using TEM, which indicated the AgNPs accumulation and disruption of bacterial cell membrane function. Additionally, a molecular docking study was conducted to evaluate the binding mode of AgNPs with an Escherichia coli outer membrane. Furthermore, the cytotoxic profile of the AgNPs was evaluated toward three cell lines (MCF-7, HepG2 & HCT 116), and the low cytotoxic effects of the obtained nanoparticles indicated their possible medical application with low risks to human health. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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15 pages, 2325 KiB  
Article
Rhizobium pusense-Mediated Selenium Nanoparticles–Antibiotics Combinations against Acanthamoeba sp.
by Pradnya B. Nikam, Jitendra D. Salunkhe, Kiran R. Marathe, Mousa A. Alghuthaymi, Kamel A. Abd-Elsalam and Satish V. Patil
Microorganisms 2022, 10(12), 2502; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms10122502 - 16 Dec 2022
Cited by 2 | Viewed by 1554
Abstract
Severe ocular infections by Acanthamoeba sp. lead to keratitis, resulting in irreversible vision loss in immune-compromised individuals. When a protozoal infection spreads to neural tissues, it causes granulomatous encephalitis, which can be fatal. Treatment often takes longer due to the transition of amoeba [...] Read more.
Severe ocular infections by Acanthamoeba sp. lead to keratitis, resulting in irreversible vision loss in immune-compromised individuals. When a protozoal infection spreads to neural tissues, it causes granulomatous encephalitis, which can be fatal. Treatment often takes longer due to the transition of amoeba from trophozoites to cyst stages, cyst being the dormant form of Acanthamoeba. A prolonged use of therapeutic agents, such as ciprofloxacin (Cipro), results in severe side effects; thus, it is critical to improve the therapeutic efficacy of these widely used antibiotics, possibly by limiting the drug-sensitive protozoal-phase transition to cyst formation. Owing to the biomedical potential of selenium nanoparticles (SeNPs), we evaluated the synergistic effects of ciprofloxacin and Rhizobium pusense–biogenic SeNPs combination. SeNPs synthesized using Rhizobium pusense isolated from root nodules were characterized using UV–Visible spectrophotometer, FT-IR, SEM with EDX, particle size analysis, and Zeta potential. The combination was observed to reduce the sub-lethal dose of Cipro, which may help reduce its side effects. The selenium and ciprofloxacin (SeNPs–Cipro) combination reduced the LC50 by 33.43%. The anti-protozoal efficacy of SeNPs–Cipro was found to transduce through decreased protozoal-cyst formations and the inhibition of the galactosidase and protease enzymes of trophozoites. Furthermore, high leakage of sugar, proteins, and amino acids during the SeNPs–Cipro treatment was one primary reason for killing the trophozoites. These experimental results may be helpful in the further pre-clinical evaluation of SeNPs–Cipro to combat protozoal infections. Future studies for combinations of SeNPs with other antibiotics need to be conducted to know the potential of SeNPs against antibiotic resistance in Acanthamoeba. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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15 pages, 2420 KiB  
Article
Living and Regenerative Material Encapsulating Self-Assembled Shewanella oneidensis-CdS Hybrids for Photocatalytic Biodegradation of Organic Dyes
by Mingyue Tao, Chenyang Jin, Hongfei Lu, Kai Jin, Lin Yu, Jinliang Liu, Jing Zhang, Xiaohui Zhu and Yihan Wu
Microorganisms 2022, 10(12), 2501; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms10122501 - 16 Dec 2022
Cited by 1 | Viewed by 1845
Abstract
Reductive biodegradation by microorganisms has been widely explored for detoxifying recalcitrant contaminants; however, the biodegradation capacity of microbes is limited by the energy level of the released electrons. Here, we developed a method to self-assemble Shewanella oneidensis-CdS nanoparticle hybrids with significantly improved [...] Read more.
Reductive biodegradation by microorganisms has been widely explored for detoxifying recalcitrant contaminants; however, the biodegradation capacity of microbes is limited by the energy level of the released electrons. Here, we developed a method to self-assemble Shewanella oneidensis-CdS nanoparticle hybrids with significantly improved reductive biodegradation capacity and constructed a living material by encapsulating the hybrids in hydrogels. The material confines the nano-bacteria hybrids and protects them from environmental stress, thus improving their recyclability and long-term stability (degradation capacity unhindered after 4 weeks). The developed living materials exhibited efficient photocatalytic biodegradation of various organic dyes including azo and nitroso dyes. This study highlights the feasibility and benefits of constructing self-assembled nano-bacteria hybrids for bioremediation and sets the stage for the development of novel living materials from nano-bacteria hybrids. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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15 pages, 1369 KiB  
Article
Effect of Biogenic Silver Nanoparticles on the Quorum-Sensing System of Pseudomonas aeruginosa PAO1 and PA14
by Erika Kushikawa Saeki, Heloísa Moreira Martins, Larissa Ciappina de Camargo, Laís Anversa, Eliandro Reis Tavares, Sueli Fumie Yamada-Ogatta, Lucy Megumi Yamauchi Lioni, Renata Katsuko Takayama Kobayashi and Gerson Nakazato
Microorganisms 2022, 10(9), 1755; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms10091755 - 30 Aug 2022
Cited by 10 | Viewed by 1814
Abstract
The increase in multidrug-resistant microorganisms represents a global threat requiring the development novel strategies to fight bacterial infection. This study aimed to assess the effect of silver nanoparticles (bio-AgNPs) on bacterial growth, biofilm formation, production of virulence factors, and expression of genes related [...] Read more.
The increase in multidrug-resistant microorganisms represents a global threat requiring the development novel strategies to fight bacterial infection. This study aimed to assess the effect of silver nanoparticles (bio-AgNPs) on bacterial growth, biofilm formation, production of virulence factors, and expression of genes related to the quorum-sensing (QS) system of P. aeruginosa PAO1 and PA14. Biofilm formation and virulence assays were performed with bio-AgNPs. RT-qPCR was carried out to determine the effect of bio-AgNPs on the QS regulatory genes lasI, lasR, rhlI, rhlR, pqsA, and mvfR. Bio-AgNPs had an MIC value of 62.50 μM, for both strains. Phenotypic and genotypic assays were carried out using sub-MIC values. Experimental results showed that treatment with sub-MICs of bio-AgNPs reduced (p < 0.05) the motility and rhamnolipids and elastase production in P. aeruginosa PAO1. In PA14, bio-AgNPs stimulated swarming and twitching motilities as well as biofilm formation and elastase and pyocyanin production. Bio-AgNP treatment increased (p < 0.05) the expression of QS genes in PAO1 and PA14. Despite the different phenotypic behaviors in both strains, both showed an increase in the expression of QS genes. Demonstrating that the bio-AgNPs acted in the induction of regulation. The possible mechanism underlying the action of bio-AgNPs involves the induction of the rhl and/or pqs system of PAO1 and of the las and/or pqs system of PA14. These results suggest that exposure to low concentrations of bio-AgNPs may promote the expression of QS regulatory genes in P. aeruginosa, consequently inducing the production of virulence factors such as elastase, pyocyanin, and biofilms. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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16 pages, 3805 KiB  
Article
Assessing the Synergistic Activity of Clarithromycin and Therapeutic Oils Encapsulated in Sodium Alginate Based Floating Microbeads
by Ikram Ullah Khan, Mehwish Shoukat, Muhammad Asif, Syed Haroon Khalid, Sajid Asghar, Muhammad Usman Munir, Muhammad Irfan, Akhtar Rasul, Sameer H. Qari, Alaa T. Qumsani, Mohamed M. Hassan, Maryam A. Alahdal, Muhammad Usman and Zulqurnain Khan
Microorganisms 2022, 10(6), 1171; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms10061171 - 07 Jun 2022
Cited by 7 | Viewed by 2064
Abstract
We developed alginate-based floating microbeads of clarithromycin with therapeutic oils for the possible eradication of Helicobacter pylori (H. pylori) infections by enhancing the residence time of the carrier at the site of infection. In pursuit of this endeavor, the alginate was [...] Read more.
We developed alginate-based floating microbeads of clarithromycin with therapeutic oils for the possible eradication of Helicobacter pylori (H. pylori) infections by enhancing the residence time of the carrier at the site of infection. In pursuit of this endeavor, the alginate was blended with hydroxy propyl methyl cellulose (HPMC) as an interpenetrating polymer to develop beads by ionotropic gelation using calcium carbonate as a gas generating agent. The developed microbeads remained buoyant under gastric conditions for 24 h. These microbeads initially swelled and afterwards decreased in size, possibly due to the erosion of the polymer. Furthermore, swelling was also affected by the type of encapsulated oil, i.e., swelling decreased with increasing concentrations of eucalyptus oil and increased with increasing concentrations of oleic acid. Antibacterial assays of the formulations showed significant antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli); these assays also showed synergistic activity between clarithromycin and therapeutic oils as evident from the higher zone of inhibition of the microbeads as compared to the pure drug and oils. Scanning electron microscopy (SEM) images revealed a smoother surface for oleic acid containing the formulation as compared to eucalyptus oil containing the formulation. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) revealed the development of a stable formulation, while Fourier transform infrared spectrophotometry (FTIR) studies did not reveal any interaction between the polymers and the active ingredients. Optimized formulations (CLM3 and CLM6) were designed to release the drug in a controlled manner in gastric media by Fickian diffusion. Conclusively, the developed microbeads are a promising carrier to overcome the narrow therapeutic index and low bioavailability of clarithromycin, while the presence of therapeutic oils will produce synergistic effects with the drug to eradicate infection effectively. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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14 pages, 5495 KiB  
Article
Biomimetic Synthesis of Silver Nanoparticles Using Ethyl Acetate Extract of Urtica diocia Leaves; Characterizations and Emerging Antimicrobial Activity
by Mohammed Binsalah, Sandhanasamy Devanesan, Mohamad S. AlSalhi, Abdullrahman Nooh, Osama Alghamdi and Nasser Nooh
Microorganisms 2022, 10(4), 789; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms10040789 - 08 Apr 2022
Cited by 13 | Viewed by 2221
Abstract
The current work reports the biosynthesis of silver nanoparticles (AgNPs) using the antimicrobial activities of ethyl acetate extract of Urtica diocia (UD) leaves as a reducing and capping agent. The synthesized UD-AgNPs were characterized using UV–visible spectroscopy, scanning electron microscopy (SEM), transmission electron [...] Read more.
The current work reports the biosynthesis of silver nanoparticles (AgNPs) using the antimicrobial activities of ethyl acetate extract of Urtica diocia (UD) leaves as a reducing and capping agent. The synthesized UD-AgNPs were characterized using UV–visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and dynamic light scattering (DLS). The UD-AgNPs were evaluated against Gram-positive and Gram-negative bacteria, and their size, shape, and distribution were recorded. The average size of an NP was 19.401 nm. The zone of inhibition (ZOI) for 75 µL of UD-AgNPs against Pseudomonas aeruginosa (P. aeruginosa) was 21 ± 0.4 mm more than that of the control drug Ciprofloxacin (16 ± 10 mm). The minimum inhibitory concentration (MIC) was the lowest against Escherichia coli (E. coli) (36 ± 3 µg/mL) and Staphylococcusepidermidis (S. epidermidis) (38 ± 3 µg/mL). Moreover, the minimum bactericidal concentration (MBC) was the lowest against E.coli (75 ± 00 µg/mL) and Enterococcus faecalis (E. faecalis (83 ± 16 µg/mL). Thus, the UD-AgNPs synthesized using the ethyl acetate extract of UD can be used as a new antimicrobial drug. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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18 pages, 4834 KiB  
Article
Trichogenic Silver-Based Nanoparticles for Suppression of Fungi Involved in Damping-Off of Cotton Seedlings
by Shimaa A. Zaki, Salama A. Ouf, Kamel A. Abd-Elsalam, Amal A. Asran, Mohamed M. Hassan, Anu Kalia and Fawziah M. Albarakaty
Microorganisms 2022, 10(2), 344; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms10020344 - 02 Feb 2022
Cited by 16 | Viewed by 2031
Abstract
Mycogenic silver nanoparticles (AgNPs) produced by some biocontrol agents have shown the ability to inhibit the growth of numerous plant pathogenic fungi, which may be a unique method of disease management. This study describes the extracellular production of AgNPs by Trichoderma harzianum. [...] Read more.
Mycogenic silver nanoparticles (AgNPs) produced by some biocontrol agents have shown the ability to inhibit the growth of numerous plant pathogenic fungi, which may be a unique method of disease management. This study describes the extracellular production of AgNPs by Trichoderma harzianum. The size, shape, charge, and composition of the AgNPs were subsequently studied by UV-visible spectroscopy, DLS, zeta potential, TEM, SEM, and EDX, among other methods. The AgNPs had sizes ranging from 6 to 15 nm. The antifungal activities of bio-synthesized AgNPs and two commercial fungicides (Moncut and Maxim XL) were tested against three soil-borne diseases (Fusarium fujikuroi, Rhizoctonia solani, and Macrophomina phaseolina). Cotton seedling illnesses were significantly reduced under greenhouse settings after significant in vitro antifungal activity was documented for the control of plant pathogenic fungi. The use of biocontrol agents such as T. harzianum, for example, may be a safe strategy for synthesizing AgNPs and using them to combat fungus in Egyptian cotton. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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Review

Jump to: Editorial, Research

32 pages, 10936 KiB  
Review
π-Conjugated Polymer Nanoparticles from Design, Synthesis to Biomedical Applications: Sensing, Imaging, and Therapy
by Nada Elgiddawy, Noha Elnagar, Hafsa Korri-Youssoufi and Abderrahim Yassar
Microorganisms 2023, 11(8), 2006; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms11082006 - 03 Aug 2023
Cited by 1 | Viewed by 1931
Abstract
In the past decade, π-conjugated polymer nanoparticles (CPNs) have been considered as promising nanomaterials for biomedical applications, and are widely used as probe materials for bioimaging and drug delivery. Due to their distinctive photophysical and physicochemical characteristics, good compatibility, and ease of functionalization, [...] Read more.
In the past decade, π-conjugated polymer nanoparticles (CPNs) have been considered as promising nanomaterials for biomedical applications, and are widely used as probe materials for bioimaging and drug delivery. Due to their distinctive photophysical and physicochemical characteristics, good compatibility, and ease of functionalization, CPNs are gaining popularity and being used in more and more cutting-edge biomedical sectors. Common synthetic techniques can be used to synthesize CPNs with adjustable particle size and dispersion. More importantly, the recent development of CPNs for sensing and imaging applications has rendered them as a promising device for use in healthcare. This review provides a synopsis of the preparation and functionalization of CPNs and summarizes the recent advancements of CPNs for biomedical applications. In particular, we discuss their major role in bioimaging, therapeutics, fluorescence, and electrochemical sensing. As a conclusion, we highlight the challenges and future perspectives of biomedical applications of CPNs. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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35 pages, 2147 KiB  
Review
Advances in Antimicrobial Peptide Discovery via Machine Learning and Delivery via Nanotechnology
by Alexa Sowers, Guangshun Wang, Malcolm Xing and Bingyun Li
Microorganisms 2023, 11(5), 1129; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms11051129 - 26 Apr 2023
Cited by 6 | Viewed by 2485
Abstract
Antimicrobial peptides (AMPs) have been investigated for their potential use as an alternative to antibiotics due to the increased demand for new antimicrobial agents. AMPs, widely found in nature and obtained from microorganisms, have a broad range of antimicrobial protection, allowing them to [...] Read more.
Antimicrobial peptides (AMPs) have been investigated for their potential use as an alternative to antibiotics due to the increased demand for new antimicrobial agents. AMPs, widely found in nature and obtained from microorganisms, have a broad range of antimicrobial protection, allowing them to be applied in the treatment of infections caused by various pathogenic microorganisms. Since these peptides are primarily cationic, they prefer anionic bacterial membranes due to electrostatic interactions. However, the applications of AMPs are currently limited owing to their hemolytic activity, poor bioavailability, degradation from proteolytic enzymes, and high-cost production. To overcome these limitations, nanotechnology has been used to improve AMP bioavailability, permeation across barriers, and/or protection against degradation. In addition, machine learning has been investigated due to its time-saving and cost-effective algorithms to predict AMPs. There are numerous databases available to train machine learning models. In this review, we focus on nanotechnology approaches for AMP delivery and advances in AMP design via machine learning. The AMP sources, classification, structures, antimicrobial mechanisms, their role in diseases, peptide engineering technologies, currently available databases, and machine learning techniques used to predict AMPs with minimal toxicity are discussed in detail. Full article
(This article belongs to the Special Issue Microbial Nanotechnology)
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