The Facile Synthesis of Eco-Friendly Zinc Magnesium Bimetal Nanoparticles and its Application in the Eradication of Xanthomonas oryzae pv. oryzae that Causes Leaf Blight Disease of Rice.

In this research work, we formulated and successfully assessed the antibacterial capability of zinc magnesium bimetal nanoparticles (ZnMgNPs) against Xanthomonas oryzae pv. oryzae (Xoo), the pathogenic microorganism responsible for causing the destructive leaf blight disease in rice. Successful preparation of ZnMgNPs were determined by UV-vis spectroscopy, EDX (Energy dispersive X-ray), FTIR (Fourier transform infrared) and SEM (Scanning Electron Microscopy). ZnMgNPs had antibacterial efficacy towards Xoo at MIC (minimum inhibitory concentration) 50 µg/ml. ZnMgNPs impeded the formation of biofilm of Xoo by drastically reducing the amount of EPS (extracellular polymeric substances) production and number of sessile cells. The ZnMgNPs also reduced several pathogenic traits of Xoo like motility, xanthomonadin and exoenzymes production. ZnMgNPs target cell membrane of Xoo and also induced oxidative damage as mechanisms of its antibacterial activity. As revealed by an ex-vivo study, ZnMgNPs diminished BLB (bacterial leaf blight) disease symptoms in rice leaves, ZnMgNPs had no effect on rice seed germination, and that following foliar application, the length and biomass of roots and shoots of rice seedling were unaffected, low cytotoxic to A549 cell line showing that ZnMgNPs are non-toxic. However, with ZnMgNPs treatment, the chlorophyll content index (CCI) increased significantly, indicating a good impact on rice physiology. All of these findings suggest that ZnMgNPs could be applied in agriculture to combat the Xoo-caused BLB disease.

A novel probiotic strain of Lactobacillus fermentum TIU19 isolated from Haria beer showing both in vitro antibacterial and antibiofilm properties upon two multi resistant uro-pathogen strains.

Probiotics with antimicrobial activity are gaining interest as a topic in the research field. Urinary tract infections (UTIs), acquired in the hospital or the community, are among the most prevalent infections. The emergence of multidrug resistance (MDR) uro-pathogens has made the current situation more critical in terms of global public health. To face this situation, in this study, Lactobacillus fermentum TIU19 (L. fermentum TIU19) was isolated and characterized as a new probiotic strain of the rice-based fermented beverage Haria. Subsequently, we also investigated its application as a biological agent that inhibits the growth of multidrug-resistant uro-pathogens, Escherichia coli, and Enterococcus faecalis. The results showed that, the isolated strain L. fermentum TIU19 was sensitive to all antibiotics tested except vancomycin and was devoid of virulence factors, such as haemolytic and gelatinase activities. Therefore, it may be considered safe for public health. It has many probiotic properties, such as survival in simulated gastrointestinal fluid, antioxidant activity, ß-galactosidase producing ability, high cell surface hydrophobicity, adhesion ability to epithelial cells, and strong biofilm producer. The growth inhibitory and antibiofilm activities were shown against two uro-pathogens. All these results suggest that L. fermentum TIU19 can be explored as a potential probiotic with antagonistic activity against MDR uro-pathogenic E. coli and E. faecalis.

Photodynamic antibacterial and antibiofilm activity of riboflavin against Xanthomonas oryzae pv oryzae: an ecofriendly strategy to combat bacterial leaf blight (BLB) rice disease.

Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv oryzae (Xoo), is one of the most damaging rice diseases, causing severe production losses depending on the rice variety. The purpose of this study was to develop an antibacterial photodynamic treatment (aPDT) using riboflavin for the treatment of BLB disease. Combining light and riboflavin (RF) therapy significantly reduced bacterial planktonic cells compared to RF alone. Photoactivated riboflavin also decreased biofilm biomass by reducing the number of viable sessile cells and the production of extracellular polymeric substances (EPS). Reactive oxygen species (ROS) levels in Xoo cells treated with photoactivated riboflavin were found to be significantly higher than in cells treated with riboflavin and light individually. Malondialdehyde (MDA) increased greatly in photoactivated riboflavin treated cells, indicating that severe oxidative damage was induced. Subsequently, a reduction in lactate dehydrogenase (LDH) activity in photoactivated riboflavin treated Xoo cells indicates that oxidative stress has disrupted the respiratory system, leading to bacterial cell death. In an ex vivo aPDT assay, photoactivated riboflavin successfully eradicated Xoo on the surface of rice leaves. Photoactivated riboflavin had no side effects on rice seed germination in subsequent trials, indicating that it is safe for agricultural applications. Therefore, all these findings suggest that aPDT is a potential alternative management strategy for BLB disease.

Tetracycline-loaded magnesium oxide nanoparticles with a potential bactericidal action against multidrug-resistant bacteria: In vitro and in vivo evidence.

Worldwide, the emergence of diarrhoea-causing multi-drug resistant (MDR) bacteria has become a crucial problem in everyday life. Tetracycline (TC) is a bacteriostatic agent that has a wide spectrum of antibacterial activity. One potential strategy to enhance the penetration and antibacterial activity of antibiotics is the use of nanotechnology. In this context, this study dealt with the synthesis of TC loading in biocompatible magnesium oxide nanoparticles (MgONPs), its characterization, and the potency of killing against diarrhoea-causing MDR bacteria E. coli and S. flexneri. TC loaded- MgONPs (MgONPs-TC) were characterized by DLS, SEM-EDS, UV-vis spectroscopy, and FTIR techniques with adequate physical properties. Antibacterial and antibiofilm studies indicate that this nanoparticle successfully eradicated both planktonic and sessile forms of those bacteria. It also significantly reduced the production of bacterial EPS, different levels of antioxidant enzymes, and induced reactive oxygen species (ROS) in the bacterial cell as a mode of antibacterial action. In particular, MgONPs-TC were efficient in reducing the colonization of MDR E. coli and S. flexneri in the C. elegans model. Therefore, all these data suggest that MgONPs-TC are a highly promising approach to combating diseases associated with diarrhoea-causing MDR bacteria in the medical field with limited health care budgets.

Exploring the antibacterial, antibiofilm, and antivirulence activities of tea tree oil-containing nanoemulsion against carbapenem-resistant Serratia marcescens associated infections.

Carbapenem-resistant Serratia marcescens (CRE-S. marcescens) has recently emerged as an opportunistic human pathogen that causes various nosocomial and respiratory tract infections. The prognosis for CRE-S. marcescens-related infections is very poor and these infections are difficult to treat. This study investigated the synthesis of tea tree oil nanoemulsion (TTO-NE) and its impact on CRE-S. marcescens both in vitro and in vivo. TTO-NE was characterized by dynamic light scattering (DLS) and effectively eradicated bacterial planktonic and sessile forms, reduced bacterial virulence factors, and generated reactive oxygen species (ROS) in the bacterial cell. Notably, TTO-NE was efficient in reducing the colonization of CRE-S. marcescens in a C. elegans in vivo model. The data suggest that TTO-NE might be an excellent tool to combat infections associated with CRE-S. marcescens.

Oxidative stress, DNA, and membranes targets as modes of antibacterial and antibiofilm activity of facile synthesized biocompatible keratin-copper nanoparticles against multidrug resistant uro-pathogens.

Escherichia coli and Enterococcus faecalis are two of the most prevalent uro-pathogens and are difficult to treat as they acquire multidrug-resistant traits. In this study, the main objective was to develop biocompatible copper nanoparticles using chicken feather keratin protein (CuNPs-K) and to investigate their impact on multidrug-resistant (MDR) uro-pathogens, E. coli and E. faecalis, under both single and mixed culture conditions. CuNPs-K were characterised by UV-Vis spectroscopy, dynamic light scattering, X-ray diffraction, Fourier transform infrared spectroscopy, and docking experiments. The MIC values of CuNPs-K against single and mixed planktonic cultures were 50 µg/ml and 75 µg/ml, respectively. CuNPs-K efficiently disrupted the biofilm of single and mixed uro-pathogen cultures by eliminating sessile cells. This biofilm disruption may be attributed to a decline in the production of extracellular polymeric substances in both single and mixed bacterial cultures treated with CuNPs-K. Moreover, selective antimicrobial activity was determined by selectivity assays using T24 cells. CuNPs-K targets both the bacterial membrane and DNA with elevated reactive oxygen species (ROS) as their bactericidal mode of action. This comprehensive antimicrobial activity of CuNPs-K was further confirmed in vivo by using the zebra fish model. In this study, CuNPs-K effectively reduced bacterial load with increased survivability of infected zebrafish. All these results suggest that CuNPs-K can be explored as an exceptional antibacterial agent against MDR uro-pathogenic E. coli and E. faecalis.

Antibacterial, anti-biofilm, and anti-virulence potential of tea tree oil against leaf blight pathogen Xanthomonas oryzae pv. oryzae instigates disease suppression.

Bacterial leaf blight (BLB) disease, caused by Xanthomonas oryzae pv. oryzae (Xoo), causes major annual economic losses around the world. Inorganic copper compounds and antibiotics are conventionally used to control BLB disease. They often cause environmental pollution, contributing to adverse effects on human health. Therefore, research is now leading to the search for alternative control methods. Tea tree oil (TTO) is obtained from a traditional medicinal plant, Melaleuca alternifolia, with antibacterial properties. In this study, we found that TTO showed antibacterial activity against Xoo with a minimum inhibitory concentration (MIC) of 18 mg/ml. These antagonistic activities were not limited only to planktonic cells, as further studies have shown that TTO effectively eradicated sessile cells of Xoo in both initial and mature biofilms. Furthermore, it was also observed that TTO reduced various key virulence properties of Xoo, such as swimming, swarming motility, and the production of extracellular polymeric substances, xanthomonadin, and exoenzymes. TTO triggered ROS generation with cell membrane damage as an antibacterial mode of action against Xoo. The in silico study revealed that 1,8-cineole of TTO was effectively bound to two essential proteins, phosphoglucomutase and peptide deformylase, responsible for the synthesis of EPS and bacterial survival, respectively. These antibacterial and anti-virulence activities of TTO against Xoo were further confirmed by an ex vivo virulence assay where TTO significantly reduced the lesion length caused by Xoo on rice leaves. All these data concluded that TTO could be a safe, environment-friendly alternative approach for the comprehensive management of BLB disease.

Allelochemical catechol comprehensively impedes bacterial blight of rice caused by Xanthomonas oryzae pv. oryzae.

Xanthomonas oryzae pv. oryzae (Xoo) induces bacterial leaf blight (BLB), is known to be the most devastating disease of rice. The present investigation for the first time explains the antibacterial, anti-biofilm, and antivirulence potential of the simplest allelochemical catechol. Bacterial viability and growth are significantly reducing in catechol treatment. Further study also reveals that catechol also inhibits primary attachment and preformed biofilm of Xoo even at half MIC concentration. The half MIC concentration of catechol also induce a significant decrease in virulence factors like swimming, swarming, exopolysaccharide, and xanthomonadin production. Next, we investigate the possible antibacterial mode of action of catechol against Xoo. Results show that, the catechol caused oxidative stress and targets cell membrane for its antibacterial activity. Whereas, in silico study reveals that, catechol binds with the catalytic domain of XanA protein and this may be consider as a reason for antibiofilm activity of catechol. Moreover, in virulence assay on rice plants, we observe significant decrement in lesion length in catechol and Xoo co-treated rice leaves as compared with only Xoo treated leaves. All the results clearly show, allelochemical catechol to be a potential compound for the antibacterial, anti-biofilm, and antivirulence agent against Xoo and consequently mitigating the BLB disease advancement in rice.

Photodynamic antimicrobial chemotherapy (PACT) using riboflavin inhibits the mono and dual species biofilm produced by antibiotic resistant Staphylococcus aureus and Escherichia coli.

PURPOSE: Multispecies biofilms play a significant role in persistent infections. Furthermore, by interspecies transfer of antibiotic resistance genes, multispecies biofilms spread antibiotic resistance. The purpose of this study was to investigate the effect of Photodynamic Antimicrobial Chemotherapy (PACT) using riboflavin on mono and multi species biofilms. METHODS: For this we used two clinically relevant opportunistic pathogens species E. coli and S. aureus as mono-species and multispecies biofilms. We did broth dilution assay for antibacterial, crystal violet assay for biofilms and fluorometric study for reactive oxygen species (ROS) and extracellular polymeric substance (EPS) production by phenol-HCl method. RESULTS: Antibacterial study revealed that photo-illuminated riboflavin shows bactericidal effect against each bacteria and their mix culture. E. coli was found to be little more resistant than S. aureus. Crystal violet assay revealed photo-illuminated riboflavin shows anti-biofilms activity against both mono and mix species biofilms. But mix species biofilms were more resistant to PACT than mono species biofilms. Further study revealed this may be due to the interaction between different EPS production, hence in mix species biofilms EPS production is less affected after PACT than mono species biofilms. We found photo-illuminated riboflavin increased the intracellular ROS production. CONCLUSION: Photo-illuminated riboflavin shows bactericidal and anti-biofilms effect against each bacteria and their mix culture. Photo-illuminated increased intracellular ROS production, which may induce the oxidative stress and destroy the respiratory system of bacteria.

Sodium alginate-based edible coating containing nanoemulsion of Citrus sinensis essential oil eradicates planktonic and sessile cells of food-borne pathogens and increased quality attributes of tomatoes.

There is a growing interest from the worldwide scientific community in formulating edible- biodegradable coatings to replace non-biodegradable and expensive commercial wax-based coatings for preserving postharvest quality attributes of vegetables including tomatoes. Postharvest tomatoes are a suspected vehicle for both Salmonella and Listeria in food poisoning incidents. In this work, the effectiveness of edible nano-emulsion coatings containing sweet orange essential oil and sodium alginate were prepared and characterized, then evaluated antibacterial and antibiofilm activity against Salmonella and Listeria and simultaneously, examined its coating effect on various quality characteristics of tomatoes at 22 ± 2 °C over a 15 days storage period. DLS (Dynamic light scattering) study revealed stable nanoemulsion formulation with 43.23 nm particle size. The high whiteness index of nanoemulsion has a positive impact on product marketability and desirability. Antibacterial and antibiofilm studies revealed nanoemulsion effectively eradicate both sessile and planktonic forms of Salmonella and Listeria in both single and multi-species culture conditions. Tomatoes coated with edible coating significantly enhanced firmness up to 33%, decreased total mesophilic bacteria including Salmonella and Listeria, and reduced weight loss up to 3 fold lower than uncoated one. Sensory analysis revealed that the use of the edible coating increased the total acceptance scores of tomatoes.

Antibacterial, anti-biofilm activity and mechanism of action of pancreatin doped zinc oxide nanoparticles against methicillin resistant Staphylococcus aureus.

Staphylococcus aureus are known to cause diseases from normal skin wound to life intimidating infections. Among the drug resistant strain, management of methicillin resistant Staphylococcus aureus (MRSA) is very difficult by using conventional antibiotic treatment. Both Zinc oxide nanoparticles (ZnONPs) and pancreatin (PK) are known to have antibacterial activity. Our main objective is to dope PK on ZnONPs to reduced zinc-oxide toxicity but increased anti-bacterial and anti-biofilms activity. In present study, we showed that, functions of zinc oxide nanoparticles with pancreatin enzyme (ZnONPs-PK) have anti-bacterial, anti-biofilms, anti-motility and anti-virulence properties against MRSA. Moreover, ZnONPs-PK were more potent to eradicate MRSA than only ZnONPs and PK. Application of the produced nano-composites as treatment on infected swine dermis predominantly reflects the potential treatment property of it. The vancomycin sensitivity of MRSA was significantly increased on application with ZnONPs-PK. Further study revealed cell membrane was the target of the ZnONPs-PK and that leads to oxidative damage of the cells. The produced nanoparticles were found completely non-toxic to human's keratinocytes and lung epithelial cell lines at its bactericidal concentration. Overall, this study emphasizes the potential mechanisms underlying the selective bactericidal properties of ZnONPs-PK against MRSA. This novel nanoparticle strategy may provide the ideal solution for comprehensive management of MRSA and its associated diseases with minimising the use of antibiotics.