Antibacterial and anticancer potential of marine endophytic actinomycetes Streptomyces coeruleorubidus GRG 4 (KY457708) compound against colistin resistant uropathogens and A549 lung cancer cells

Probiotic potential of a novel endophytic Streptomyces griseorubens CIBA-NS1 isolated from Salicornia sp. against Vibrio campbellii infection in shrimp

A novel endophytic Streptomyces griseorubens CIBA-NS1 was isolated from a salt marsh plant Salicornia sp. The antagonistic effect of S. griseorubens against Vibrio campbellii, was studied both in vitro and in vivo. The strain was validated for its endophytic nature and characterized through scanning electron microscopy, morphological and biochemical studies and 16SrDNA sequencing. The salinity tolerance experiment has shown that highest antibacterial activity was at 40‰ (16 ± 1.4 mm) and lowest was at 10 ‰ salinity (6.94 ± 0.51 mm). In vivo exclusion of Vibrio by S. griseorubens CIBA-NS1 was studied in Penaeus indicus post larvae and evaluated for its ability to improve growth and survival of P. indicus. After 20 days administration of S. griseorubens CIBA-NS1, shrimps were challenged with V. campbellii. The S. griseorubens CIBA-NS1 reduced Vibrio population in test group when compared to control, improved survival (60.5 ± 6.4%) and growth, as indicated by weight gain (1.8 ± 0.05g). In control group survival and growth were 48.4 ± 3.5% and 1.4 ± 0.03 g respectively. On challenge with V. campbellii, the S. griseorubens CIBA-NS1 administered group showed better survival (85.6 ± 10%) than positive control (64.3 ± 10%). The results suggested that S. griseorubens CIBA-NS1 is antagonistic to V. campbellii, reduce Vibrio population in the culture system and improve growth and survival. This is the first report on antagonistic activity of S. griseorubens isolated from salt marsh plant Salicornia sp, as a probiotic candidate to prevent V. campbellii infection in shrimps.

Biotechnological potential of actinomycetes in the 21st century: a brief review

This brief review aims to draw attention to the biotechnological potential of actinomycetes. Their main uses as sources of antibiotics and in agriculture would be enough not to neglect them; however, as we will see, their biotechnological application is much broader. Far from intending to exhaust this issue, we present a short survey of the research involving actinomycetes and their applications published in the last 23 years. We highlight a perspective for the discovery of new active ingredients or new applications for the known metabolites of these microorganisms that, for approximately 80 years, since the discovery of streptomycin, have been the main source of antibiotics. Based on the collected data, we organize the text to show how the cosmopolitanism of actinomycetes and the evolutionary biotic and abiotic ecological relationships of actinomycetes translate into the expression of metabolites in the environment and the richness of biosynthetic gene clusters, many of which remain silenced in traditional laboratory cultures. We also present the main strategies used in the twenty-first century to promote the expression of these silenced genes and obtain new secondary metabolites from known or new strains. Many of these metabolites have biological activities relevant to medicine, agriculture, and biotechnology industries, including candidates for new drugs or drug models against infectious and non-infectious diseases. Below, we present significant examples of the antimicrobial spectrum of actinomycetes, which is the most commonly investigated and best known, as well as their non-antimicrobial spectrum, which is becoming better known and increasingly explored.

Volatile Organic Compounds Produced by a Deep-Sea Bacterium Efficiently Inhibit the Growth of Pseudomonas aeruginosa PAO1

The deep-sea bacterium Spongiibacter nanhainus CSC3.9 has significant inhibitory effects on agricultural pathogenic fungi and human pathogenic bacteria, especially Pseudomonas aeruginosa, the notorious multidrug-resistant pathogen affecting human public health. We demonstrate that the corresponding antibacterial agents against P. aeruginosa PAO1 are volatile organic compounds (VOCs, namely VOC-3.9). Our findings show that VOC-3.9 leads to the abnormal cell division of P. aeruginosa PAO1 by disordering the expression of several essential division proteins associated with septal peptidoglycan synthesis. VOC-3.9 hinders the biofilm formation process and promotes the biofilm dispersion process of P. aeruginosa PAO1 by affecting its quorum sensing systems. VOC-3.9 also weakens the iron uptake capability of P. aeruginosa PAO1, leading to reduced enzymatic activity associated with key metabolic processes, such as reactive oxygen species (ROS) scavenging. Overall, our study paves the way to developing antimicrobial compounds against drug-resistant bacteria by using volatile organic compounds.

Tapping the biosynthetic potential of marine Bacillus licheniformis LHG166, a prolific sulphated exopolysaccharide producer: structural insights, bio-prospecting its antioxidant, antifungal, antibacterial and anti-biofilm potency as a novel anti-infective lead

The escalating global threat of antimicrobial resistance necessitates prospecting uncharted microbial biodiversity for novel therapeutic leads. This study mines the promising chemical richness of Bacillus licheniformis LHG166, a prolific exopolysaccharide (EPSR2-7.22 g/L). It comprised 5 different monosaccharides with 48.11% uronic acid, 17.40% sulfate groups, and 6.09% N-acetyl glucosamine residues. EPSR2 displayed potent antioxidant activity in DPPH and ABTS+, TAC and FRAP assays. Of all the fungi tested, the yeast Candida albicans displayed the highest susceptibility and antibiofilm inhibition. The fungi Aspergillus niger and Penicillium glabrum showed moderate EPSR2 susceptibility. In contrast, the fungi Mucor circinelloides and Trichoderma harzianum were resistant. Among G+ve tested bacteria, Enterococcus faecalis was the most susceptible, while Salmonella typhi was the most sensitive to G-ve pathogens. Encouragingly, EPSR2 predominantly demonstrated bactericidal effects against both bacterial classes based on MBC/MIC of either 1 or 2 superior Gentamicin. At 75% of MBC, EPSR2 displayed the highest anti-biofilm activity of 88.30% against B. subtilis, while for G-ve antibiofilm inhibition, At 75% of MBC, EPSR2 displayed the highest anti-biofilm activity of 96.63% against Escherichia coli, Even at the lowest dose of 25% MBC, EPSR2 reduced biofilm formation by 84.13% in E. coli, 61.46% in B. subtilis. The microbial metabolite EPSR2 from Bacillus licheniformis LHG166 shows promise as an eco-friendly natural antibiotic alternative for treating infections and oxidative stress.

Novel jointured green synthesis of chitosan‑silver nanocomposite: An approach towards reduction of nitroarenes, anti-proliferative, wound healing and antioxidant applications

Here we present the simple green synthesis of chitosan‑silver nanocomposite (CS-Ag NC) by employing kiwi fruit juice as reducing agent. The structure, morphology, and composition of CS-Ag NC were determined using characterization techniques such as XRD, SEM-EDX, UV-visible, FT-IR, particle size, and zeta potential. The prepared CS-Ag nanocomposite was effectively used as catalyst in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4 as reductant, in aqueous medium at room temperature. The toxicity of CS-Ag NC was assessed on Normal (L929) cell line, Lung cancer (A549) cell line and Oral cancer (KB-3-1) cell line and their respective IC50values observed were 83.52 μg/mL, 66.74 μg/mL and 75.11 μg/mL. The CS-Ag NC displayed significant cytotoxic activity and the cell viability percentage for normal, lung and oral cancer cell lines were found to be 42.87 ± 0.0060, 31.28 ± 0.0045 and 35.90 ± 0.0065 respectively. Stronger cell migration was exemplified by CS-Ag NC and the percentage of wound closure (97.92%) was substantially identical to that of the standard drug ascorbic acid (99.27%). Further CS-Ag nanocomposite was subjected for in vitro antioxidant activity.

Cultivable endophytic fungal community associated with the karst endemic plant Nervilia fordii and their antimicrobial activity

Endophytic fungi from medicinal plants with specific pharmacological functions attract much attention to provide the possibility of discovering valuable natural drugs with novel structures and biological activities. Nervilia fordii is a rare and endangered karst endemic plant that is used as medicine and food homology in Guangxi, China. These plants have been reported to have antimicrobial, antitumor, antiviral, and anti-inflammatory activities. However, few studies have focused on the diversity and antibacterial activity of endophytic fungi from N. fordii. In the present study, 184 endophytic fungi were isolated from the healthy tissues of N. fordii, and their molecular diversity and antimicrobial activities were analyzed for the first time. These fungi were categorized into 85 different morphotypes based on the morphological characteristics and the similarity between the target sequence and the reference sequence in the GenBank database. With the exception of 18 unidentified fungi, the fungal isolates belonged to at least 2 phyla, 4 classes, 15 orders, 45 known genera, and 45 different species, which showed high abundance, rich diversity, and obvious tissue specificity. All isolates were employed to screen for their antimicrobial activities via the agar diffusion method against Escherichia coli, Staphylococcus aureus, and Candida tropicalis. Among these endophytes, eight strains (9.41%) displayed inhibitory activity against E. coli, 11 strains (12.94%) against S. aureus, and two strains (2.35%) against C. tropicalis, to some extent. In particular, our study showed for the first time that the fungal agar plugs of Penicillium macrosclerotiorum 1151# exhibited promising antibacterial activity against E. coli and S. aureus. Moreover, the ethyl acetate (EA) extract of P. macrosclerotiorum 1151# had antibacterial effects against E. coli and S. aureus with a minimum inhibitory concentration (MIC) of 0.5 mg ml-1. Further research also confirmed that one of the antimicrobial compounds of P. macrosclerotiorum 1151# was methyl chloroacetate and exhibited excellent antibacterial activity against E. coli and S. aureus up to 1.71-fold and 1.13-fold compared with tetracycline (TET) (5 mg ml-1), respectively. Taken together, the present data suggest that various endophytic fungi of N. fordii could be exploited as sources of novel natural antimicrobial agents.

Identification and antibacterial evaluation of endophytic actinobacteria from Luffa cylindrica

The emergence of antibiotic-resistant bacteria has limited treatment options and led to the untreatable infections, thereby necessitating the discovery of new antibiotics to battel against bacteria. Natural products from endophytic actinobacteria (EA) serve as a reservoir for discovery of new antibiotics. Therefore, the current study focused on the isolation and antibacterial properties of EA isolated from Luffa cylindrica. Six strains were identified using morphological characterization, SEM analyses and 16S rRNA gene sequencing from the roots and leaves of the plant. They were taxonomically classified as Streptomycetaceae family. This is the first report on EA form L. cylindrica. The strains produced a chain of oval, cubed or cylindrical shaped spores with spiny or smooth surfaces. Three strains; KUMS-B3, KUMS-B4 and KUMS-B6 were reported as endophytes for the first time. Fifty percent of isolates were isolated from leaves samples using YECD medium. Our results showed that the sampling time and seasons may affect the bacterial diversity. All six strains had antibacterial activity against at least one of the tested bacteria S. aureus, P. aeruginosa, and E. coli. Among the strains, KUMS-B6 isolate, closely related to S. praecox, exhibited the highest antibacterial activity against both gram-positive and negative bacteria. KUMS-B6, KUMS-B5 and KUMS-B4 isolates strongly inhibited the growth of P. aeruginosa. Interestingly, the strains, isolated from leaves exhibited stronger antagonist activities compared to those isolated from the roots. The study revealed that the isolated strains from Luffa produce a plethora of bioactive substances that are potential source of new drug candidates for the treatment of infections.

Synthesis and Characterization of Silver Nanoparticles from Rhizophora apiculata and Studies on Their Wound Healing, Antioxidant, Anti-Inflammatory, and Cytotoxic Activity

Silver nanoparticles (AgNPs) have recently gained interest in the medical field because of their biological features. The present study aimed at screening Rhizophora apiculata secondary metabolites, quantifying their flavonoids and total phenolics content, green synthesis and characterization of R. apiculata silver nanoparticles. In addition, an assessment of in vitro cytotoxic, antioxidant, anti-inflammatory and wound healing activity of R. apiculata and its synthesized AgNPs was carried out. The powdered plant material (leaves) was subjected to Soxhlet extraction to obtain R. apiculata aqueous extract. The R. apiculata extract was used as a reducing agent in synthesizing AgNPs from silver nitrate. The synthesized AgNPs were characterized by UV-Vis, SEM-EDX, XRD, FTIR, particle size analyzer and zeta potential. Further aqueous leaf extract of R. apiculata and AgNPs was subjected for in vitro antioxidant, anti-inflammatory, wound healing and cytotoxic activity against A375 (Skin cancer), A549 (Lung cancer), and KB-3-1 (Oral cancer) cell lines. All experiments were repeated three times (n = 3), and the results were given as the mean ± SEM. The flavonoids and total phenolics content in R. apiculata extract were 44.18 ± 0.086 mg/g of quercetin and 53.24 ± 0.028 mg/g of gallic acid, respectively. SEM analysis revealed R. apiculata AgNPs with diameters ranging from 35 to 100 nm. XRD confirmed that the synthesized silver nanoparticles were crystalline in nature. The cytotoxicity cell viability assay revealed that the AgNPs were less toxic (IC₅₀ 105.5 µg/mL) compared to the R. apiculata extract (IC₅₀ 47.47 µg/mL) against the non-cancerous fibroblast L929 cell line. Antioxidant, anti-inflammatory, and cytotoxicity tests revealed that AgNPs had significantly more activity than the plant extract. The AgNPs inhibited protein denaturation by a mean percentage of 71.65%, which was equivalent to the standard anti-inflammatory medication diclofenac (94.24%). The AgNPs showed considerable cytotoxic effect, and the percentage of cell viability against skin cancer, lung cancer, and oral cancer cell lines was 31.84%, 56.09% and 22.59%, respectively. R. apiculata AgNPs demonstrated stronger cell migration and percentage of wound closure (82.79%) compared to the plant extract (75.23%). The overall results revealed that R. apiculata AgNPs exhibited potential antioxidant, anti-inflammatory, wound healing, and cytotoxic properties. In future, R. apiculata should be further explored to unmask its therapeutic potential and the mechanistic pathways of AgNPs should be studied in detail in in vivo animal models.

Differential Chemical Profile of Metabolite Extracts Produced by the Diaporthe citri (G-01) Endophyte Mediated by Varying the Fermented Broth pH

Endophytic microorganisms show great potential for biotechnological exploitation because they are able to produce a wide range of secondary compounds involved in endophyte−plant adaptation, and their interactions with other living organisms that share the same microhabitat. Techniques used to chemically extract these compounds often neglect the intrinsic chemical characteristics of the molecules involved, such as the ability to form conjugate acids or bases and how they influence the solubilities of these molecules in organic solvents. Therefore, in this study, we aimed to evaluate how the pH of the fermented broth affects the process used to extract the secondary metabolites of the Diaporthe citri strain G-01 endophyte with ethyl acetate as the organic solvent. The analyzed samples, conducted by direct-infusion electrospray-ionization mass spectrometry, were grouped according to the pH of the fermented broth (i.e., <7 and ≥7). A more extreme pH (i.e., 2 or 12) was found to affect the chemical profile of the sample. Moreover, statistical analysis enabled us to determine the presence or absence of ions of high importance; for example, ions at 390.7 and 456.5 m/z were observed mainly at acidic pH, while 226.5, 298.3, and 430.1 m/z ions were observed at pH ≥ 7. Extraction at a pH between 4 and 9 may be of interest for exploring the differential secondary metabolites produced by endophytes. Furthermore, pH influences the chemical phenotype of the fungal metabolic extract.

Anti-ESBL derivatives of marine endophytic Streptomyces xiamenensis GRG 5 (KY457709) against ESBLs producing bacteria

The emerging threat of extended spectrum beta lactamases (ESBLs) producing gram negative bacteria still remains an important worldwide concern. Due to insufficient drug choice and treatment failure of existing drugs,...

Isolation and molecular identification of biofilm producing P. aeruginosa and K. pneumoniae from urinary tract infections patient urine sample

BACKGROUND

Recent years, multi drug resistant pathogens and their pathogenicity were increased worldwide due to unauthorized consumption of antibiotics. In addition, correlation between multi drug resistant bacteria and biofilm formation is heightened due to the production of more virulence behavior. There is no better identification methods are available for detection of biofilm producing gram negative bacteria.

MATERIALS AND METHODS

In this research work, multi drug resistant strains of Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumoniae (K. pneumoniae) were identified based on the specific antibiotics and third generation cephalosporin discs by disc diffusion assay. Subsequently, biofilm forming ability of selected pathogens were identified tissue culture plate and tube test. Based on the multi-drug resistant ability and biofilm production, the molecular identification of P. aeruginosa and K. pneumoniae were confirmed by PCR using universal primers.

RESULTS AND CONCLUSIONS

No zone of inhibition present around the discs of muller hinton agar plates were confirm, selected P. aeruginosa and K. pneumoniae strains were multi drug resistant pathogens. Performed third generation cephalosporin antibiotics were also highly sensitive to selected pathogens of P. aeruginosa and K. pneumoniae. Further, biofilm forming ability of selected P. aeruginosa and K. pneumoniae was confirmed by tissue culture plate and tube methods. Finally, molecular identification of P. aeruginosa and K. pneumoniae was named as P. aeruginosa and K. pneumoniae. Our result was conclude, selected P. aeruginosa and K. pneumoniae as biofilm producing pathogens and also highly resistant to current antibiotics.

Genes associated with antibiotic tolerance and synthesis of antimicrobial compounds in a mangrove with contrasting salinities

Salinity and wastewater pollution in mangrove ecosystems can affect microorganisms and the abundance of genes involved in response to these stressors. This research aimed to identify genes associated with resistance and biosynthesis of antimicrobial compounds in mangrove soils subjected to contrasting salinities and wastewater pollution. Samples of rhizospheric soil were taken from a mangrove at the mouth of the Ranchería River in La Guajira, Colombia. A functional analysis was performed using Illumina HiSeq 2500 sequencing data obtained from total DNA extracted. Increased salt concentration influenced metabolic pathways and differential abundance of genes associated with the synthesis of antimicrobial compounds (e.g., rfbB/rffG, INO1/ISYNA1, rfbA/rffH, sat/met3, asd). Also, among 33 genes involved in intrinsic antibiotic resistance, 16 were significantly influenced by salinity (e.g., cusR/copR/silR, vgb, tolC). We concluded that salt stress tolerance and adaptive mechanisms could favor the biosynthesis of antimicrobial compounds in mangroves contaminated by sewage.

Antimicrobial resistance in biofilms: Exploring marine actinobacteria as a potential source of antibiotics and biofilm inhibitors

Antimicrobial resistance (AMR) is one of the serious global public health threats that require immediate action. With the emergence of new resistance mechanisms in infection-causing microorganisms such as bacteria, fungi, and viruses, AMR threatens the effective prevention and treatment of diseases caused by them. This has resulted in prolonged illness, disability, and death. It has been predicted that AMR will lead to over ten million deaths by 2050. The rapid spread of multidrug-resistant bacteria is also causing old antibiotics to become ineffective. Among the diverse factors contributing to AMR, intrinsic biofilm development has been highlighted as an essential contributing facet. Moreover, biofilm-derived antibiotic tolerance leads to serious recurrent chronic infections. Therefore, the discovery of novel bioactive molecules is a potential solution that can help combat AMR. To achieve this, sustained mining of novel antimicrobial leads from actinobacteria, particularly marine actinobacteria, can be a promising strategy. Given their vast diversity and different habitats, the extraordinary capacity of actinobacteria can be tapped to synthesize new antibiotics or bioactive molecules for biofilm inhibition. Advanced screening strategies and novel approaches in the field of modern biochemical and molecular biology can be used to detect such new compounds. In view of this, the present review focuses on understanding some of the recent strategies to inhibit biofilm formation and explores the potential role of marine actinobacteria as sources of novel antibiotics and biofilm inhibitor molecules.

Biosynthesized silver nanoparticles using Caulerpa taxifolia against A549 lung cancer cell line through cytotoxicity effect/morphological damage

The Caulerpa taxifolia is excellent marine green algae, which produced enormous bioactive compounds with more biological activities. Also, it is an excellent source for synthesis of Ag NPs with increased bioactivity against various infections. In our study, the marine algae marine algae Caulerpa taxifolia mediated Ag NPs was synthesized effectively. The synthesized Ag NPs was characterized well using UV-spectrometer and X-ray powder diffraction (XRD) and confirmed as synthesized particle was Ag NPs. The available structure of the Ag NPs was morphologically identified by scanning electron microscope (SEM), and exact minimum size, polydispersive spherical shape of the entire Ag NPs structure was confirmed by Transmission electron microscope (TEM). Further, the anti-cancer efficiency of biosynthesized Ag NPs against A549 lung cancer cells was found at 40 µg/mL concentration by cytotoxicity experiment. In addition, the phase contrast images of the result were supported the Ag NPs, which damaged the A549 morphologically clearly. Finally, florescence microscopic images were effectively proved the anti-cancerous effect against A549 lung cancer cells due to the condensed morphology of increased death cells. All the confirmed in-vitro results were clearly stated that the Caulerpa taxifolia mediated Ag NPs has superior anti-cancer agent against A549 lung cancer cells.

Anti-cancer activity of biosynthesized silver nanoparticles using Avicennia marina against A549 lung cancer cells through ROS/mitochondrial damages

The biosynthesized Ag NPs was synthesized by using marine mangrove plant extract Avicennia marina. The synthesized Ag NPs was confirmed by various physiochemical characterization including UV-spectrometer and XRD analysis. In addition, the shape and of the synthesized Ag NPs was morphologically identified by SEM initially and TEM finally. After confirmation, the anti-cancer property of synthesized Ag NPs was confirmed at 50 µg/mL concentration against A549 lung cancer cells by MTT assay. Further, the ability to stimulate the ROS generation and mitochondrial membrane at the IC50 concentration of Ag NPs was confirmed by fluorescence microscopy using DCFH-DA and rhodamine 123 dyes respectively. Finally, the result was concluded that the synthesized Ag NPs has improved anti-cancer activity against A549 cells at lowest concentration.

Anti-bacterial activity of chitosan loaded plant essential oil against multi drug resistant K. pneumoniae

The development of antibiotic resistant in K. pneumoniae is an emerging thread worldwide due to the poor antimicrobial drugs. To overcome this issue, researchers are focused on plant material and their essential oils to fight against multi drug resistant bacteria. In this context, the current study was concentrated in medicinal plant of guva leaves and their essential oils to combat multi drug resistant bacterial infections. The essential oils were successfully screened and confirmed by HRLC-MS analysis. The anti-bacterial ability of the compounds were loaded into the chitosan nanoparticles and proved by FT-IR analysis. In addition, the chitosan loaded essential oils morphology was compared with chitosan alone in SEM analysis and suggested that the material was loaded successfully. Further, the anti-bacterial ability of the chitosan loaded essential oils were primarily confirmed by agar well diffusion method. At the 100 µg/mL of lowest concentration of chitosan loaded essential oils, the multi-drug resistant K. pneumoniae was inhibited with 96% and confirmed by minimum inhibition concentration experiment. Hence, all the experiments were proved that the essential oils were successfully loaded into the chitosan nanoparticles, and it has more anti-bacterial activity against multi-drug resistant K. pneumoniae.

Role of symbiosis in the discovery of novel antibiotics

Antibiotic resistance has been an ongoing challenge that has emerged almost immediately after the initial discovery of antibiotics and requires the development of innovative new antibiotics and antibiotic combinations that can effectively mitigate the development of resistance. More than 35,000 people die each year from antibiotic resistant infections in just the United States. This signifies the importance of identifying other alternatives to antibiotics for which resistance has developed. Virtually, all currently used antibiotics can trace their genesis to soil derived bacteria and fungi. The bacteria and fungi involved in symbiosis is an area that still remains widely unexplored for the discovery and development of new antibiotics. This brief review focuses on the challenges and opportunities in the application of symbiotic microbes and also provides an interesting platform that links natural product chemistry with evolutionary biology and ecology.

Anti-biofilm investigation of graphene/chitosan nanocomposites against biofilm producing P. aeruginosa and K. pneumoniae

In this study graphene/chitosan nanoparticles (GR/CS NCs) were developed. The homogenous combination of GR and CS was confirmed by FTIR spectroscopy. The combination of CS with GR sheets reduced the XRD intensity of the GR peak in GR/CS NCs, while TEM images revealed the immobile CS coating of GR sheets. Further, the anti-biofilm activity of GR/CS NCs was tested. The tests showed that the formation of biofilm by Pseudomonas aeruginosa and Klebsiella pneumoniae was inhibited at 40□g/mL GR/CS NCs up to 94 and 92 %, respectively. The intracellular and cell surface damage of the bacteria was observed by CLSM and SEM. Also, GR/CS NCs produced a toxic effect of 90 % on Artemia franciscana at 70□g/mL upon 24 h incubation. The recorded properties of the synthesized GR/CS NCs qualify them as potential agents against multi-drug resistant bacteria.

Graphene/nickel oxide nanocomposites against isolated ESBL producing bacteria and A549 cancer cells

The synthesis of nickel oxide nanoparticles (NiO NPs) and graphene/nickel oxide nanocomposites (Gr/NiO NCs) was performed using a simple chemical reduction method. Powder X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to examine the crystalline nature and thermal stability of the synthesized NiO NPs and Gr/NiO NCs, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to observe the morphology of NiO NPs and Gr/NiO NCs and estimate their size range. TEM suggested that the NiO NPs were speared onto the surface of Gr nanosheet. The efficiency of NiO NPs and Gr/NiO NCs against extended spectrum β-lacamase (ESBL) producing bacteria, which was confirmed by specific HEXA disc Hexa G-minus 24 (HX-096) and MIC strip methods (CLSI); namely Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) was investigated using the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) methods. MIC results suggested that the NiO NPs and Gr/NiO NCs possess maximum growth inhibition of 86%, 82% and 94%, 92% at 50 and 30 μg/mL concentrations, respectively. Similarly, both nanomaterials were found to inhibit the β-lacamase enzyme at concentrations of 60 μg/mL and 40 μg/mL, respectively. The cytotoxicity of NiO NPs and Gr/NiO NCs was quantified against A549 human lung cancer cells. Cell death percentage values of 52% at 50 μg/mL against NiO NPs and 54% at 20 μg/mL against Gr/NiO NCs were obtained, respectively. The NCs were found to reduce cell viability, increase the level of reactive oxygen species (ROS) and modify both the mitochondrial membrane permeability and cell cycle arrest.

Molecular identification and structural characterization of marine endophytic actinomycetes Nocardiopsis sp. GRG 2 (KT 235641) and its antibacterial efficacy against isolated ESBL producing bacteria

The present study was designed to identify the potential bioactive compound from endophytic actinomycetes (EA) Nocardiopsis sp. GRG 2 (KT 235641) against selected extended spectrum beta lactamase (ESBL) producing Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumoniae (K. pneumoniae). Initially, the multi drug resistance (MDR) effect of selected uropathogens was confirmed by respective UTI panel of Hexa antibiotics disc methods. The zone of inhibition ≤22 mm for ceftazidime, ≤ 27 mm for cefotaxime and ≤8 mm zone of MIC stripe against both the uropathogens of phenotypic methods confirmed, the selected strains were ESBL producer. Among the various EA extracts, GRG 2 extract showed excellent antibacterial activity against both ESBL producing P. aeruginosa and K. pneumonia by agar well diffution method. The molecular identification of selected GRG 2 strain was named as Nocardiopsis sp. GRG 2 (KT235641). The antibacterial metabolites present in the TLC elution was exhibited at 274 nm by UV visible spectrometer. The partial purification of preparative HPLC fraction 3 showed 14, 16 mm against P. aeruginosa and K. pneumoniae, respectively. Based on the antibacterial effect, the FT-IR, GC-MS and LC-MS analysis of fraction 3 was confirmed as 1, 4-diaza-2, 5-dioxo-3-isobutyl bicyclo[4.3.0]nonane (DDIBN). Further, the dose dependent inhibition of DDIBN against both ESBL producing pathogens was observed at 75 μg/mL by minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC). The increased cell death and disrupted cell membrane integrity were observed at MIC of DDIBN by confocal laser scanning electron microscope (CLSM) and scanning electron microscope (SEM). The results were proved that the DDIBN has potential antibacterial metabolites against ESBL producing pathogens and it can be applied for various other biomedical fields.