Biosynthesis of Quantum Dots and Their Therapeutic Applications in the Diagnosis and Treatment of Cancer and SARS-CoV-2

Quantum dots (QDs) are semiconductor materials that range from 2 nm to 10 nm. These nanomaterials (NMs) are smaller and have more unique properties compared to conventional nanoparticles (NPs). One of the unique properties of QDs is their special optoelectronic properties, making it possible to apply these NMs in bioimaging. Different size and shape QDs, which are used in various fields such as bioimaging, biosensing, cancer therapy, and drug delivery, have so far been produced by chemical methods. However, chemical synthesis provides expensive routes and causes serious environmental and health issues. Therefore, various biological systems such as bacteria, fungi, yeasts, algae, and plants are considered as potent eco-friendly green nanofactories for the biosynthesis of QDs, which are both economic and environmentally safe. The review aims to provide a descriptive overview of the various microbial agents for the synthesis of QDs and their biomedical applications for the diagnosis and treatment of cancer and SARS-CoV-2

Isolation and Screening of a native Citrobacter sp. with high nicotine-tolerant and its application as a biocatalyst for biodegradation of nicotine

Introduction: Nicotine is a toxic plant alkaloid and it has been designated as hazardous by the United States Environmental Protection Agency (USEPA) since 1994. The present work was directed to screen nicotine resistant bacteria, that is used as biocatalyst in the biodegradation of nicotine from contaminated sites. Materials and methods: Collected soil samples from 12 tobacco farms were selected as target sites for sampling. Enrichment nicotine-degrading bacteria were performed in minimal salt media containing nicotine as the sole carbon and nitrogen sources. Agar dilution plate method was performed for determining intrinsic tolerance of bacterial isolates to nicotine. Phenotypic characterization and phylogenetic analysis were used to identify the selected bacterial isolate able to degrade nicotine. To determine the optimal conditions for the bio-removal of nicotine, the effects of initial nicotine concentration, incubation time and the addition of carbon and nitrogen sources in the selected strain were tested. The quantification of residual nicotine in the culture media was measured by high performance liquid chromatography (HPLC). Results: Among 20 bacterial isolates for degradation of nicotine, the strain TPS2 showed a high level of resistance and degradation efficiency. Results of phenotypic identification and phylogenetic analysis showed the native strain TPS2 belongs to the Citrobacter sp. strain TPS2 (GeneBank accession no. KM110046). According to the results of de-nicotination experiment, the native strain TPS2 is able to remove 100% of nicotine with an initial concentration 2.5 g/l in the presence of 2.5 g/l fructose. Discussion and conclusion: The results showed that the screened Citrobacter sp. was suitable candidate for degradation of nicotine from wastewater and sites that contaminated with nicotine. It is seemed by using of the microbial biocatalyst the ecosystem contamination of toxic nicotine can be decreased. The present work is the first report on the degradation of nicotine by native microorganisms

Green extracellular synthesis of the Fe2O3 nanoparticles by a native marine bacterium, Alcaligenes sp. strain NV06

This study investigated the potential of aquatic bacteria for their ability as a biocatalyst to synthesized Fe2O3 nanoparticles using iron precursor, FeCl3. A total of 25 aquatic bacterial strains were isolated in trypticase soy agar plus 10 mM FeCl3 with selective enrichment technique. Among the bacterial strains evaluated, NV06 was the only strain able to synthesize Fe2O3 nanoparticles extracellularly. The strain NV06 was identified as Alcaligenes sp., on the basis of phenotypic and molecular characteristics. Extracellular synthesis of Fe2O3 nanoparticles by this strain was investigated under the optimal conditions. The biosynthesized Fe2O3 nanoparticles were characterized using UV–visible spectrophotometry (UV-Vis), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FTIR) spectroscopy. The results showed that cell-free extract (CFE) of the bacterium strain can produce the rod-shaped Fe2O3 nanoparticles with mean edge lengths of 80.2 nm and mean diameters of 25.5 nm, after being exposed to FeCl3 solution (10 mM), at an optimum pH of 6 and an optimum temperature of 28 °C, after 96 hours of incubation at 150 rpm. This is the first report on the extracellular biosynthesis of Fe2O3 nanoparticles using the genus of Alcaligenes under the CFE strategy. It could be speculated that the results of the study can hopefully introduce the inherent capabilities of aquatic microbes as safe, simple, and effective biocatalysts in the production of Fe2O3 nanoparticles

Designing Matrix L18 Trials via Taguchi Model to Improve Performance of Trichosporon sp. Cas se5 in the Selenite Removal

Background & Objectives: Low selenium level is considered as an essential nutrient for humans and animals. However, selenium, in the form of selenite, is very toxic at high concentrations and leads to acute selenium poisoning (selenosis). The current project was done using the Taguchi method as an efficient, effective method, and without the need for a large number of experiments to optimize selenite removal. Materials & Methods: The independent variables at three levels include: initial concentrations of selenite, biomass and NaCl, initial pH, and agitation. L18 orthogonal array was designed for these variables. The experiments were repeated three times and their mean amounts were analyzed using Qualitek-4. Results: The factors which had a significant impact on the selenite removal in order of importance were as follows: selenite ion (8 g/L), agitation (80 rpm), NaCl (2.5% w/v), biomass (40 g/L), and pH 6.8. Under optimal conditions in the selected levels of these factors, approximately 92.1% of selenite was removed after 48 h of incubation, at the 5% significance level (p< 0/05). Conclusion: The current study is the first report of the successful application of the Taguchi method in the optimization of selenite removal under resting cells of Trichosporon sp. as biocatalysts. Therefore, the optimization techniques used in the present study can be proposed for the bio-remediation of contaminated environments

Optimization of caffeine bioremoval by growing cells of Saccharomyces cerevisiae using Taguchi analysis methodology

Introduction: In the recent years, application of microorganisms as green biocatalysts for removing caffeine pollution from industrial wastes and food caffeinated have been extensively considered. This investigation reports on optimization of bio-decaffeination process under growing cells of Saccharomyces cerevisiae by using the Taguchi statistical approach.  Materials and methods: Five variables, i.e. caffeine, Zn+2, glucose, peptone concentrations and time incubation, which have significant effects on bio-decaffeination process, were selected and L16 (44× 13) orthogonal array was determined for experimental trials. Caffeine degradation was estimated by HPLC (High Performance Liquid Chromatography) analysis. Results: Use of Taguchi approach for optimization of design parameters resulted in about 82.8 % reduction of caffeine in 48 h incubation when 3g/l peptone, 5mM Zn+2 ion and 5 g/l of caffeine are present in the designed media. Under the optimized conditions, the yield of degradation of caffeine (5 g/l) by the growing cells of yeast strain TFS9 has been increased from 25.5 to 82.8 % which is 3.2 fold higher than the normal yield. The improvement of caffeine removal after best conditions were made shows the efficiency of Taguchi experimental design in such studies. Discussion and conclusion: The current investigation is the first report for successful application of the Taguchi experimental approach to the bio-decaffeination process. According to the analysis of experimental results, the present study proposes the potentiality of the Taguchi approach to enhance the bio-decaffeination performance with the native strain of Saccharomyces cerevisiae

Interaction of Epigallocatechin Gallate and Quercetin with Spike Glycoprotein (S-Glycoprotein) of SARS-CoV-2: In Silico Study

Severe acute respiratory syndrome (SARS)-CoV-2 from the family Coronaviridae is the cause of the outbreak of severe pneumonia, known as coronavirus disease 2019 (COVID-19), which was first recognized in 2019. Various potential antiviral drugs have been presented to hinder SARS-CoV-2 or treat COVID-19 disease. Side effects of these drugs are among the main complicated issues for patients. Natural compounds, specifically primary and secondary herbal metabolites, may be considered as alternative options to provide therapeutic activity and reduce cytotoxicity. Phenolic materials such as epigallocatechin gallate (EGCG, polyphenol) and quercetin have shown antibacterial, antifungal, antiviral, anticancer, and anti-inflammatory effects in vitro and in vivo. Therefore, in this study, molecular docking was applied to measure the docking property of epigallocatechin gallate and quercetin towards the transmembrane spike (S) glycoprotein of SARS-CoV-2. Results of the present study showed Vina scores of &minus;9.9 and &minus;8.3 obtained for EGCG and quercetin by CB-Dock. In the case of EGCG, four hydrogen bonds of OG1, OD2, O3, and O13 atoms interacted with the Threonine (THR778) and Aspartic acid (ASP867) amino acids of the spike glycoprotein (6VSB). According to these results, epigallocatechin gallate and quercetin can be considered potent therapeutic compounds for addressing viral diseases

Evaluation of Streptomyces spp. against Fusarium oxysporum f. sp. ciceris for the management of chickpea wilt

In this study, about 112 isolates of Streptomyces were isolated from chickpea rhizospheric soils. Among the isolated strains, five showed strong inhibitory effects against chickpea Fusarium wilt caused by Fusarium oxysporum f. sp. ciceris in vitro using plate assay and selected for further studies. The selected strains were identified as Streptomyces spp. based on morphological and biochemical characterization as well as 16S rDNA sequences analysis. Our results assigned them to strains related to genus of Streptomyces. In vitro, antagonistic effects of Streptomyces strains against the disease were evaluated through the dual-culture method, volatile and non-volatile metabolites, siderophore, protease and chitinase production. All bacterial strains inhibited mycelial growth of the pathogen ranging from 26 to 44.2% in dual culture assay. The non-volatile extract of five of the Streptomyces strains inhibited more than 50% growth of the pathogen, whereas volatile compounds were less effective on mycelial growth inhibition (20.2 to 33.4%). The ability of the biocontrol agents to produce siderophore and protease were varied, whereas, production of chitinase was detected for all strains. Results of the greenhouse assay indicated that all biocontrol agents reduced disease severity (ranging from 38.7 to 54.8%). Accordingly, strain KS62 showed higher control efficacy (54.8%). In addition, the biomass of chickpea plants (plant height and dry weight) significantly increased in plants treated with Streptomyces strains compared to non-bacterized control. The results of this study showed that it may be possible to manage chickpea Fusarium wilt disease effectively by using Streptomyces species, as biocontrol agents. Therefore, evaluating their efficiency under field conditions is needed