Extracellular cholesterol oxidase production by Streptomyces aegyptia, in vitro anticancer activities against rhabdomyosarcoma, breast cancer cell-lines and in vivo apoptosis

Purification and Immobilization of Burkholderia gladioli Cholesterol Oxidase on Calcium Alginate, with Robust Catalytic Stability for Cholesterol Oxidation In Vitro

Cholesterol oxidase (COX) is a key enzyme in diagnostic kits of cardiovascular diseases via oxidation of cholesterol producing smart enantiomerically compounds; however, the enzyme catalytic stability is the challenge. So, the objective of this study was to purify COX from novel endophytic bacterial isolates of medicinal plants that could have unique catalytic efficiency for the desired applications. Among the recovered forty bacterial isolates, Burkholderia gladioli EFBL PQ721377, an endophyte of Eruca sativa, had the highest COX productivity (14.7 μmol/mg/min). The COX productivity of B. gladioli has been maximized by with the response surface methodology, giving the highest productivity 30.9 μmol/mg/min, by ~ 2.0-fold increment compared to control. The enzyme was purified to its molecular homogeneity with subunit structure 40 kDa. The enzyme was entrapped in Ca-alginate with immobilization yield 87.5%, and the efficiency and homogeneity in Ca-alginate beads were assessed by FTIR and SEM-EDX analyses. The free and Ca-alginate-COX conjugates have the same maximum reaction temperature at 37-40 °C, reaction pH at 7.5 and pH stability at 6.5-8.0. The thermal stability of Ca-alginate-COX was increased by ~ 7.0 folds compared to the free one, ensuring the protective role of alginate beads on enzyme tertiary structure. Ca-alginate-COX had a higher potency of oxidation of human serum cholesterol, than the free one, confirming the feasibility of the product release, and allosteric activation of the enzyme, with a reliable operative stability till the fifth cycle, for production of cholest-4-en-3-one, as the precursor of various drugs.

Biofabrication of zinc oxide nanoparticles using Moringa oleifera, characterization and statistical optimization for their application in crystal violet adsorption

Crystal violet (Cry) is an essential textile dye belonging to the triphenylmethane group, that is widely used in the textile industry. It is also applied for paper printing and Gram staining. Previously, it was significant as a topical antiseptic due to its antibacterial, antifungal, and anthelmintic properties. Despite its various applications, crystal violet has been recognized as a biohazard dye due to its toxic and carcinogenic properties. It persists in the environment with long-lasting effects and has detrimental impacts. In this research, water extract from Moringa oleifera leaves is employed as environmentally friendly methods to synthesize zinc oxide nanoparticles (Mo/ZnO-NPs), and characterized by TEM, EDX, FT-IR, and Zeta potential. Mo/ZnO-NPs exhibit a Zeta potential of - 21.9 mV, and X-ray diffraction (XRD) analysis confirms their crystallographic structure. The size of the biogenic Mo/ZnO-NPs ranges from 5.52 to 41.59 nm. This study was designed to estimate and maximize the ability of Mo/ZnO-NPs to remove crystal violet using Central Composite Design (CCD), considering pH (ranging from 3 to 11), incubation time (ranging from 30 to 150), nanoparticles concentrations (ranging from 0.2 to 1.8 mg/mL), and crystal violet concentrations (ranging from 25 to 125 ppm). The maximum percentage value of removal of crystal violet by Mo/ZnO-NPs was 97.26 with optimal conditions of pH 9, incubation time 120 min, Mo/ZnO-NPs 1.4 mg/mL, and crystal violet concentration of 50 ppm. The best-predicted conditions that caused the highest removal of crystal violet (97.8%) were determined using the desirability function as pH 10, incubation time of 140 min, Mo/ZnO-NPs concentrations of 1.3 mg/mL, and a concentration of crystal violet of 80 ppm. Under these optimal conditions, the maximum experimental crystal violet removal% by Mo/ZnO-NPs was (98.7%) was verified. Mo/ZnO-NPs synthesized by Moringa oleifera can be a promising candidate for the adsorption of crystal violet.

Synthesis, Characterization, and Cytotoxicity Evaluation of Chlorambucil-Functionalized Mesoporous Silica Nanoparticles

This study describes the synthesis and characterization of chlorambucil (CLB)-functionalized mesoporous silica nanoparticles (MSNs) for potential application in cancer therapy. The nanoparticles were designed with a diameter between 20 and 50 nm to optimize cellular uptake and avoid rapid clearance from the bloodstream. The synthesis method involved modifying a previously reported technique to reduce particle size. Successful functionalization with CLB was confirmed through various techniques, including Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The cytotoxicity of the CLB-functionalized nanoparticles (MSN@NH2-CLB) was evaluated against human lung adenocarcinoma cells (A549) and colon carcinoma cells (CT26WT). The results suggest significantly higher cytotoxicity of MSN@NH2-CLB compared to unbound CLB, with improved selectivity towards cancer cells over normal cells. This suggests that MSN@NH2-CLB holds promise as a drug delivery system for targeted cancer therapy.

A sustainable green-approach for biofabrication of chitosan nanoparticles, optimization, characterization, its antifungal activity against phytopathogenic Fusarium culmorum and antitumor activity

Chitosan is a natural non-toxic, biocompatible, biodegradable, and mucoadhesive polymer. It also has a broad spectrum of applications such as agriculture, medical fields, cosmetics and food industries. In this investigation, chitosan nanoparticles were produced by an aqueous extract of Cympopogon citratus leaves as a reducing agent. According to the SEM and TEM micrographs, CNPs had a spherical shape, and size ranging from 8.08 to 12.01 nm. CNPs have a positively charged surface with a Zeta potential of + 26 mV. The crystalline feature of CNPs is determined by X-ray diffraction. There are many functional groups, including C꞊C, CH2-OH, C-O, C-S, N-H, CN, CH and OH were detected by FTIR analysis. As shown by the thermogravimetric study, CNPs have a high thermal stability. For the optimization of the green synthesis of CNPs, a Face centered central composite design (FCCCD) with 30 trials was used. The maximum yield of CNPs (13.99 mg CNPs/mL) was produced with chitosan concentration 1.5%, pH 4.5 at 40 °C, and incubation period of 30 min. The antifungal activity of CNPs was evaluated against phytopathogenic fungus; Fusarium culmorum. A 100% rate of mycelial growth inhibition was gained by the application of 20 mg CNPs/mL. The antitumor activity of the green synthesized CNPs was examined using 6 different cell lines, the viability of the cells reduced when the concentration of green synthesized CNPs increased, the IC50 dose of the green synthesized CNPs on the examined cell lines HePG-2, MCF-7, HCT-116, PC-3, Hela and WI-38 was 36.25 ± 2.3, 31.21 ± 2.2, 67.45 ± 3.5, 56.30 ± 3.3, 44.62 ± 2.6 and 74.90 ± 3.8; respectively.

Bionanofactory for green synthesis of collagen nanoparticles, characterization, optimization, in-vitro and in-vivo anticancer activities

Collagen nanoparticles (collagen-NPs) are promising biological polymer nanoparticles due to their exceptional biodegradability and biocompatibility. Collagen-NPs were bio-fabricated from pure marine collagen using the cell-free supernatant of a newly isolated strain, Streptomyces sp. strain NEAA-3. Streptomyces sp. strain NEAA-3 was identified as Streptomyces plicatus strain NEAA-3 based on its cultural, morphological, physiological properties and 16S rRNA sequence analysis. The sequence data has been deposited under accession number OR501412.1 in the GenBank database. The face-centered central composite design (FCCD) was used to improve collagen-NPs biosynthesis. The maximum yield of collagen-NPs was 9.33 mg/mL with a collagen concentration of 10 mg/mL, an initial pH of 7, an incubation time of 72 h, and a temperature of 35 °C. Using the desirability function approach, the collagen-NPs biosynthesis obtained after FCCD optimization (9.53 mg/mL) was 3.92 times more than the collagen-NPs biosynthesis obtained before optimization process (2.43 mg/mL). The TEM analysis of collagen-NPs revealed hollow sphere nanoscale particles with an average diameter of 33.15 ± 10.02 nm. FTIR spectra confirmed the functional groups of the collagen, collagen-NPs and the cell-free supernatant that are essential for the efficient capping of collagen-NPs. The biosynthesized collagen-NPs exhibited antioxidant activity and anticancer activity against HeP-G2, MCF-7 and HCT116 cell lines. Collagen-NPs assessed as an effective drug loading carrier with methotrexate (MTX), a chemotherapeutic agent. The TEM analysis revealed that the average size of MTX-loaded collagen-NPs was 35.4 ± 8.9 nm. The percentages of drug loading (DL%) and encapsulation efficiency (EE%) were respectively 22.67 and 45.81%.

Green synthesis of collagen nanoparticles by Streptomyces xinghaiensis NEAA-1, statistical optimization, characterization, and evaluation of their anticancer potential

Collagen nanoparticles (collagen-NPs) are promising biopolymeric nanoparticles due to their superior biodegradability and biocompatibility. The low immunogenicity and non-toxicity of collagen-NPs makes it preferable for a wide range of applications. A total of eight morphologically distinct actinomycetes strains were newly isolated from various soil samples in Egypt. The cell-free supernatants of these strains were tested for their ability. These strains' cell-free supernatants were tested for their ability to synthesize collagen-NPs. Five isolates had the ability to biosynthesize collagen-NPs. Among these, a potential culture, Streptomyces sp. NEAA-1, was chosen and identified as Streptomyces xinghaiensis NEAA-1 based on 16S rRNA sequence analysis as well as morphological, cultural and physiological properties. The sequence data has been deposited at the GenBank database under the accession No. OQ652077.1. Face-centered central composite design (FCCD) has been conducted to maximize collagen-NPs biosynthesis. Maximum collagen-NPs was 8.92 mg/mL under the condition of 10 mg/mL of collagen concentration, initial pH 7, incubation time of 48 h and temperature of 35 °C. The yield of collagen-NPs obtained via FCCD optimization (8.92 mg/mL) was 3.32-fold compared to the yield obtained under non-optimized conditions (2.5 mg/mL). TEM analysis of collagen-NPs showed hollow sphere nanoscale particles with mean of 32.63 ± 14.59 nm in diameter. FTIR spectra showed major peaks of amide I, amide II and amide III of collagen and also the cell-free supernatant involved in effective capping of collagen-NPs. The biosynthesized collagen-NPs exhibited anti-hemolytic, antioxidant and cytotoxic activities. The inhibitory concentrations (IC50) against MCF-7, HeP-G2 and HCT116 cell lines were 11.62 ± 0.8, 19.60 ± 1.2 and 41.67 ± 2.2 µg/mL; respectively. The in-vivo investigation showed that collagen-NPs can suppress Ehrlich ascites carcinoma (EAC) growth in mice. The collagen-NPs/DOX combination treatment showed considerable tumor growth suppression (95.58%). Collagen-NPs evaluated as nanocarrier with a chemotherapeutic agent, methotrexate (MTX). The average size of MTX loaded collagen-NPs was 42.73 ± 3.5 nm. Encapsulation efficiency percentage (EE %) was 48.91% and drug loading percentage (DL %) was 24.45%.

Improved production of Bacillus subtilis cholesterol oxidase by optimization of process parameters using response surface methodology

BACKGROUND

Cholesterol oxidase has numerous biomedical and industrial applications. In the current study, a new bacterial strain was isolated from sewage and was selected for its high potency for cholesterol degradation (%) and production of high cholesterol oxidase activity (U/OD600).

RESULTS

Based on the sequence of 16S rRNA gene, the bacterium was identified as Bacillus subtilis. The fermentation conditions affecting cholesterol degradation (%) and the activity of cholesterol oxidase (U/OD600) of B. subtilis were optimized through fractional factorial design (FFD) and response surface methodology (RSM). According to this sequential optimization approach, 80.152% cholesterol degradation was achieved by setting the concentrations of cholesterol, inoculum size, and magnesium sulphate at 0.05 g/l, 6%, and 0.05 g/l, respectively. Moreover, 85.461 U of cholesterol oxidase/OD600 were attained by adjusting the fermentation conditions at initial pH, 6; volume of the fermentation medium, 15 ml/flask; and concentration of cholesterol, 0.05 g/l. The optimization process improved cholesterol degradation (%) and the activity of cholesterol oxidase (U/OD600) by 139% and 154%, respectively. No cholesterol was detected in the spectroscopic analysis of the optimized fermented medium via gas chromatography-mass spectroscopy (GC-MS).

CONCLUSION

The current study provides principal information for the development of efficient production of cholesterol oxidase by B. subtilis that could be used in various applications.

Artificial neural network approach for prediction of AuNPs biosynthesis by Streptomyces flavolimosus, characterization, antitumor potency in-vitro and in-vivo against Ehrlich ascites carcinoma

Gold nanoparticles (AuNPs) have emerged as promising and versatile nanoparticles for cancer therapy and are widely used in drug and gene delivery, biomedical imaging, diagnosis, and biosensors. The current study describes a biological-based strategy for AuNPs biosynthesis using the cell-free supernatant of Streptomyces flavolimosus. The biosynthesized AuNPs have an absorption peak at 530-535 nm. The TEM images indicate that AuNPs were spherical and ranged in size from 4 to 20 nm. The surface capping molecules of AuNPs are negatively charged, having a Zeta potential of - 10.9 mV. FTIR analysis revealed that the AuNPs surface composition contains a variety of functional groups as -OH, C-H, N-, C=O, NH3+, amine hydrochloride, amide group of proteins, C-C and C-N. The bioprocess variables affecting AuNPs biosynthesis were optimized by using the central composite design (CCD) in order to maximize the AuNPs biosynthesis. The maximum yield of AuNPs (866.29 µg AuNPs/mL) was obtained using temperature (35 °C), incubation period (4 days), HAuCl4 concentration (1000 µg/mL) and initial pH level 6. Comparison was made between the fitness of CCD versus Artificial neural network (ANN) approach based on their prediction and the corresponding experimental results. AuNPs biosynthesis values predicted by ANN exhibit a more reasonable agreement with the experimental result. The anticancer activities of AuNPs were assessed under both in vitro and in vivo conditions. The results revealed a significant inhibitory effect on the proliferation of the MCF-7 and Hela carcinoma cell lines treated with AuNPs with IC50 value of 13.4 ± 0.44 μg/mL and 13.8 ± 0.45 μg/mL for MCF-7 and Hela cells; respectively. Further, AuNPs showed potential inhibitory effect against tumor growth in tumor-bearing mice models. AuNPs significantly reduced the tumor volume, tumor weight, and decreased number of viable tumor cells in EAC bearing mice.

Green fabrication of chitosan nanoparticles using Lavendula angustifolia, optimization, characterization and in‑vitro antibiofilm activity

Chitosan nanoparticles (CNPs) are promising polymeric nanoparticles with exceptional physicochemical, antimicrobial and biological characteristics. The CNPs are preferred for a wide range of applications in the food industry, cosmetics, agriculture, medical, and pharmaceutical fields due to their biocompatibility, biodegradability, eco-friendliness, and non-toxicity. In the current study, a biologically based approach was used to biofabricate CNPs using an aqueous extract of Lavendula angustifolia leaves as a reducing agent. The TEM images show that the CNPs were spherical in shape and ranged in size from 7.24 to 9.77 nm. FTIR analysis revealed the presence of several functional groups, including C-H, C-O, CONH₂, NH₂, C-OH and C-O-C. The crystalline nature of CNPs is demonstrated by X-ray diffraction. The thermogravimetric analysis revealed that CNPs are thermally stable. The CNPs' surface is positively charged and has a Zeta potential of 10 mV. For optimising CNPs biofabrication, a face-centered central composite design (FCCCD) with 50 experiments was used. The artificial intelligence-based approach was used to analyse, validate, and predict CNPs biofabrication. The optimal conditions for maximum CNPs biofabrication were theoretically determined using the desirability function and experimentally verified. The optimal conditions that maximize CNPs biofabrication (10.11 mg/mL) were determined to be chitosan concentration 0.5%, leaves extract 75%, and initial pH 4.24. The antibiofilm activity of CNPs was evaluated in‑vitro. The results show that 1500 μg/mL of CNPs suppressed P. aeruginosa, S. aureus and C. albicans biofilm formation by 91.83 ± 1.71%, 55.47 ± 2.12% and 66.4 ± 1.76%; respectively. The promising results of the current study in biofilm inhibition by necrotizing biofilm architecture, reducing its significant constituents and inhibiting microbial cell proliferation encourage their use as natural biosafe and biocompatible anti-adherent coating in antibiofouling membranes, medical bandage/tissues and food packaging materials.

Artificial intelligence-based optimization for chitosan nanoparticles biosynthesis, characterization and in‑vitro assessment of its anti-biofilm potentiality

Chitosan nanoparticles (CNPs) are promising biopolymeric nanoparticles with excellent physicochemical, antimicrobial, and biological properties. CNPs have a wide range of applications due to their unique characteristics, including plant growth promotion and protection, drug delivery, antimicrobials, and encapsulation. The current study describes an alternative, biologically-based strategy for CNPs biosynthesis using Olea europaea leaves extract. Face centered central composite design (FCCCD), with 50 experiments was used for optimization of CNPs biosynthesis. The artificial neural network (ANN) was employed for analyzing, validating, and predicting CNPs biosynthesis using Olea europaea leaves extract. Using the desirability function, the optimum conditions for maximum CNPs biosynthesis were determined theoretically and verified experimentally. The highest experimental yield of CNPs (21.15 mg CNPs/mL) was obtained using chitosan solution of 1%, leaves extract solution of 100%, initial pH 4.47, and incubation time of 60 min at 53.83°C. The SEM and TEM images revealed that CNPs had a spherical form and varied in size between 6.91 and 11.14 nm. X-ray diffraction demonstrates the crystalline nature of CNPs. The surface of the CNPs is positively charged, having a Zeta potential of 33.1 mV. FTIR analysis revealed various functional groups including C-H, C-O, CONH2, NH2, C-OH and C-O-C. The thermogravimetric investigation indicated that CNPs are thermally stable. The CNPs were able to suppress biofilm formation by P. aeruginosa, S. aureus and C. albicans at concentrations ranging from 10 to 1500 µg/mL in a dose-dependent manner. Inhibition of biofilm formation was associated with suppression of metabolic activity, protein/exopolysaccharide moieties, and hydrophobicity of biofilm encased cells (r ˃ 0.9, P = 0.00). Due to their small size, in the range of 6.91 to 11.14 nm, CNPs produced using Olea europaea leaves extract are promising for applications in the medical and pharmaceutical industries, in addition to their potential application in controlling multidrug-resistant microorganisms, especially those associated with post COVID-19 pneumonia in immunosuppressed patients.

Current Trends and Perspectives in Microbial Bioconversions of Steroids

The microbiological transformation of sterols is currently the technological basis for the industrial production of valuable steroid precursors, the so-called synthons, from which a wide range of steroid and indane isoprenoids are obtained by combined chemical and enzymatic routes. These compounds include value-added corticoids, neurosteroids, sex hormones, bile acids, and other terpenoid lipids required by the medicine, pharmaceutical, food, veterinary, and agricultural industries.Progress in understanding the molecular mechanisms of microbial degradation of steroids, and the development and implementation of genetic technologies, opened a new era in steroid biotechnology. Metabolic engineering of microbial producers makes it possible not only to improve the biocatalytic properties of industrial strains by enhancing their target activity and/or suppressing undesirable activities in order to avoid the formation of by-products or degradation of the steroid core, but also to redirect metabolic fluxes in cells towards accumulation of new metabolites that may be useful for practical applications. Along with whole-cell catalysis, the interest of researchers is growing in enzymatic methods that make it possible to carry out selective structural modifications of steroids, such as the introduction of double bonds, the oxidation of steroidal alcohols, or the reduction of steroid carbonyl groups. A promising area of research is strain engineering based on the heterologous expression of foreign steroidogenesis systems (bacterial, fungal, or mammalian) that ensure selective formation of demanded hydroxylated steroids.Here, current trends and progress in microbial steroid biotechnology over the past few years are briefly reviewed, with a particular focus on the application of metabolic engineering and synthetic biology techniques to improve existing and create new whole-cell microbial biocatalysts.

Innovative biosynthesis, artificial intelligence-based optimization, and characterization of chitosan nanoparticles by Streptomyces microflavus and their inhibitory potential against Pectobacterium carotovorum

Microbial-based strategy in nanotechnology offers economic, eco-friendly, and biosafety advantages over traditional chemical and physical protocols. The current study describes a novel biosynthesis protocol for chitosan nanoparticles (CNPs), employing a pioneer Streptomyces sp. strain NEAE-83, which exhibited a significant potential for CNPs biosynthesis. It was identified as Streptomyces microflavus strain NEAE-83 based on morphological, and physiological properties as well as the 16S rRNA sequence (GenBank accession number: MG384964). CNPs were characterized by SEM, TEM, EDXS, zeta potential, FTIR, XRD, TGA, and DSC. CNPs biosynthesis was maximized using a mathematical model, face-centered central composite design (CCFCD). The highest yield of CNPs (9.41 mg/mL) was obtained in run no. 27, using an initial pH of 5.5, 1% chitosan, 40 °C, and a 12 h incubation period. Innovatively, the artificial neural network (ANN), was used for validating and predicting CNPs biosynthesis based on the trials data of CCFCD. Despite the high precision degree of both models, ANN was supreme in the prediction of CNPs biosynthesis compared to CCFCD. ANN had a higher prediction efficacy and, lower error values (RMSE, MDA, and SSE). CNPs biosynthesized by Streptomyces microflavus strain NEAE-83 showed in-vitro antibacterial activity against Pectobacterium carotovorum, which causes the potato soft rot. These results suggested its potential application for controlling the destructive potato soft rot diseases. This is the first report on the biosynthesis of CNPs using a newly isolated; Streptomyces microflavus strain NEAE-83 as an eco-friendly approach and optimization of the biosynthesis process by artificial intelligence.

Exploration of a novel and efficient source for production of bacterial nanocellulose, bioprocess optimization and characterization

The demand for bacterial nanocellulose is expected to rise in the coming years due to its wide usability in many applications. Hence, there is a continuing need to screen soil samples from various sources to isolate a strain with a high capacity for bacterial nanocellulose production. Bacillus sp. strain SEE-12, which was isolated from a soil sample collected from Barhiem, Menoufia governorate, Egypt, displayed high BNC production under submerged fermentation. Bacillus sp. strain SEE-12 was identified as Bacillus tequilensis strain SEE-12. In static cultures, BNC was obtained as a layer grown in the air liquid interface of the fermentation medium. The response surface methodology was used to optimise the process parameters. The highest BNC production (22.8 g/L) was obtained using 5 g/L peptone, 5 g/L yeast extract, 50%, v/v Cantaloupe juice, 5 g/L Na₂HPO₄, 1.5 g/L citric acid, pH 5, medium volume of 100 mL/250 mL conical flask, inoculum size 5%, v/v, temperature 37 °C and incubation time 6 days. The BNC was purified and characterized by scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM).

Recombinant Extracellular Cholesterol Oxidase from Nocardioides simplex

Cholesterol oxidase is a highly demanded enzyme used in medicine, pharmacy, agriculture, chemistry, and biotechnology. It catalyzes oxidation of 3β-hydroxy-5-ene- to 3-keto-4-ene- steroids with the formation of hydrogen peroxide. Here, we expressed 6xHis-tagged mature form of the extracellular cholesterol oxidase (ChO) from the actinobacterium Nocardioides simplex VKM Ac-2033D (55.6 kDa) in Escherichia coli cells. The recombinant enzyme (ChO_Ns) was purified using affinity chromatography. ChO_Ns proved to be functional towards cholesterol, cholestanol, phytosterol, pregnenolone, and dehydroepiandrosterone. Its activity depended on the structure and length of the aliphatic side chain at C17 atom of the steroid nucleus and was lower with pregnenolone and dehydroepiandrosterone. The enzyme was active in a pH range of 5.25÷6.5 with the pH optimum at 6.0. Kinetic assays and storage stability tests demonstrated that the characteristics of ChO_Ns were generally comparable with or superior to those of commercial ChO from Streptomyces hygroscopicus (ChO_Sh). The results contribute to the knowledge on microbial ChOs and evidence that ChO from N. simplex VKM Ac-2033D is a promising agent for further applications.

Reactive oxygen species as a double-edged sword: The role of oxidative enzymes in antitumor therapy

A number of approaches have been developed over the years to manage cancer, such as chemotherapy using low-molecular-mass molecules and radiotherapy. Here, enzymes can also find useful applications. Among them, oxidases have attracted attention because of their ability to produce reactive oxygen species (ROS, especially hydrogen peroxide) in tumors and potentially modulate the production of this cytotoxic compound when enzymes active on substrates present in low amounts are used, such as the d-amino acid oxidase and d-amino acid couple system. These treatments have been also developed for additional cancer treatment approaches, such as phototherapy, nutrient starvation, and metal-induced hydroxyl radical production. In addition, to improve tumor specificity and decrease undesired side effects, oxidases have been targeted by means of nanotechnologies and protein engineering (i.e., by designing chimeric proteins able to accumulate in the tumor). The most recent advances obtained by using six different oxidases (i.e., the FAD-containing enzymes glucose oxidase, d- and l-amino acid oxidases, cholesterol oxidase and xanthine oxidase, and the copper-containing amine oxidase) have been reported. Anticancer therapy based on oxidase-based ROS production has now reached maturity and can be applied in the clinic.

Role of Curculigo Orchioides in the Proliferation and Apoptosis of Breast Cancer Michigan Cancer Foundation-7 (MCF-7) Cells Under Network Pharmacology

Based on network pharmacology (NP), the effects of curculigo orchioides (CO) granules alone or CO granules along with tamoxifen on the proliferation and apoptosis (P&A) of human breast cancer (BC) cells were explored. A search database was constructed to obtain the active components (ACs) of CO and related target genes to perform disease mapping, and a BC target map was constructed to perform related pathway enrichment analysis (PEA). The blank control group (CG), estrogen group (EG), and tamoxifen group (TG) were set as controls to observe the effects of CO granules alone and CO granules along with tamoxifen. The PEA showed that the effect of CO on BC may be related to the cooperation of its ACs. The target of action may be related to cell cycle and proliferation, growth factors, metabolic pathways, etc. Different concentrations of CO had different effects, CO granules of various concentrations had no obvious growth-promoting effect (P < 0.05), and so did CO combined with tamoxifen (P > 0.05); high-dose (H-D) CO combined with tamoxifen can induce cell apoptosis (P < 0.05). Through NP, the ACs of CO and related targets of BC were predicted and analyzed. At the same time, it was proved that CO granules are safe in clinical use, and the combined effect of tamoxifen is better in the treatment of estrogen-positive patients, providing reference for the follow-up use of CO in the treatment of BC.

Molecular Cloning, Expression, and Enzyme Activity of Glucose Oxidase Gene from Soil Thermophilic Streptomyces

Background

Glucose oxidase is an oxidoreductase that depletes oxygen in food processing and is used in biosensors, glucose diagnostic kits, food processing, cosmetics, and chemical industries. This enzyme is often isolated from fungi, such as Penicillium and Aspergillus Niger.

Objectives

The objective of this study was to clone and express a full-length GOX gene from soil thermophilic streptomyces for bioinformatic and enzyme activity evaluations.

Materials and Methods

After collecting samples from the Gandom Beryan area of Kerman province, Iran, Streptomyces strains were identified with specific biochemical and molecular tests. Streptomyces strains with glucose oxidase gene were detected by PCR, and the amplified gene fragment was cloned into Escherichia coli host bacterium using TA cloning technique. The expression of the cloned GOX gene in the host bacterium was measured using real-time PCR, and the recombinant plasmids were sequenced. The enzymatic activity was measured in the extracts of E. coli cells carrying the plasmids.

Results

After screening the samples, 12 strains of Streptomyces were identified, 4 of which carried the GOX gene. The GOX open reading frame, obtained by PCR, was cloned into a vector and transformed into Escherichia coli origami to generate GOX-producing bacteria. Enzyme activity was confirmed and a phylogenetic tree showed the degree of kinship between Streptomyces species and other species, including Streptomyces SP MI02-7b. The expression levels of GOX genes mRNA were found to be approximately 4-fold higher in transformed E. coli than in soil thermophilic Streptomyces (P <0.001).

Conclusion

This study showed that natural thermostable streptomyces producing glucose oxidase enzyme could be found in Iran. The enzyme gene was successfully transformed into Escherichia coli generating a recombinant host with high yield capability that can be a major step towards the production of this enzyme from indigenous strains. It should be emphasized that the GOX enzyme produced by these strains is profitable due to high production levels correlated to the optimum condition in cheap culture media, short fermentation cycles, high expression capability, and ease of growth.

Cytotoxic activity of cholesterol oxidase produced by Streptomyces sp. AKHSS against cancerous cell lines: mechanism of action in HeLa cells

Re-occurrence of cancer is the major drawback for the currently available anticancer therapies. Therefore, study of an efficient enzyme, cholesterol oxidase produced by various kinds of microbes especially obtained from unexplored marine actinobacterial species against human cancer cell lines and understanding its mechanism of action helps to identify an irreversible and potent anticancer agent. The cytotoxic potential of cholesterol oxidase produced by a marine Streptomyces sp. AKHSS against four different human cancer cell lines was demonstrated through MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. Fluorescent confocal microscopy and flow cytometry based experiments were performed to understand the efficiency of the enzymatic action on HeLa cells. Further, the apoptotic related proteins were detected through western blotting. Interestingly, the enzyme exhibited potent cytotoxicity at very low concentrations (0.093-0.327 µM) against all the cells tested. Fluorescent confocal microscopy revealed the morphological variations induced by the enzyme on cancer cell lines such as the formation of lipid droplets and condensation of nuclei. The enzyme treated cell-free extracts of HeLa cells analyzed through gas chromatography mass spectrometry showed the depletion of membrane cholesterol and the presence of substituted enzyme oxidized product, cholest-4-ene-3-one. The enzyme had induced significant inhibitory effects on the cell viability such as cell cycle arrest (G₁ phase), apoptosis and rise of reactive oxygen species as evident through flow cytometry. Besides, hyperpolarization of mitochondrial membrane, reduced rates of phosphorylation of pAkt and the expression of apoptotic death markers like Fas, Fas L, caspases (8 and 3) and PARP-1 were recorded in the enzyme treated HeLa cells. Thus, cholesterol oxidase purified from a marine Streptomyces sp. AKHSS exhibits potent cytotoxicity at very low concentrations against human cancer cell lines. All the ex vivo experiments portrayed the substantial inhibitory effect of the enzyme on HeLa cells suggesting that cholesterol oxidase of Streptomyces sp. AKHSS could be a prominent cancer chemotherapeutic agent.

Identification of cholesterol-assimilating actinomycetes strain and application of statistical modeling approaches for improvement of cholesterol oxidase production by Streptomyces anulatus strain NEAE-94

Background

Cholesterol oxidase biosensors have been used to determine the level of cholesterol in different serum and food samples. Due to a wide range of industrial and clinical applications of microbial cholesterol oxidase, isolation and identification of a new microbial source (s) of cholesterol oxidase are very important.

Results

The local isolate Streptomyces sp. strain NEAE-94 is a promising source of cholesterol oxidase. It was identified based on cultural, morphological and physiological characteristics; in addition to the 16S rRNA sequence. The sequencing product had been deposited in the GenBank database under the accession number KC354803. Cholesterol oxidase production by Streptomyces anulatus strain NEAE-94 in shake flasks was optimized using surface response methodology. The different process parameters were first screened using a Plackett-Burman design and the parameters with significant effects on the production of cholesterol oxidase were identified. Out of the 15 factors screened, agitation speed, cholesterol and yeast extract concentrations had the most significant positive effects on the production of cholesterol oxidase. The optimal levels of these variables and the effects of their mutual interactions on cholesterol oxidase production were determined using Box-Behnken design. Cholesterol oxidase production by Streptomyces anulatus strain NEAE-94 was 11.03, 27.31 U/mL after Plackett-Burman Design and Box-Behnken design; respectively, with a fold of increase of 6.06 times compared to the production before applying the Plackett-Burman design (4.51 U/mL).

Conclusions

Maximum cholesterol oxidase activity was obtained at the following fermentation conditions: g/L (cholesterol 4, yeast extract 5, NaCl 0.5, K₂HPO₄ 1, FeSO₄.7H₂O 0.01, MgSO₄.7H₂O 0.5), pH 7, inoculum size 4% (v/v), temperature 37°C, agitation speed of 150 rpm, medium volume 50 mL and incubation time 5 days.

Aerobic and anaerobic removal of lead and mercury via calcium carbonate precipitation mediated by statistically optimized nitrate reductases

The nonbiodegradability nature of heavy metals renders them resident in food chain and subsequently, destructing the entire ecosystem. Therefore, this study aimed to employ nitrate reduction-driven calcium carbonate precipitation in remediation of lead and mercury aerobically and anaerobically by Proteus mirabilis 10B, for the first time. Initially, Plackett-Burman design was employed to screen of 16 independent variables for their significances on periplasmic (NAP) and membrane-bound (NAR) nitrate reductases. The levels for five significant variables and their interaction effects were further optimized by central composite design. The maximum activities of NAP and NAR recorded 2450 and 3050 U/mL by 2-fold enhancement, comparing with non-optimized medium. Under aerobic and anaerobic optimized remediation conditions, the changes in media chemistry revealed positive correlation among bacterial growth, nitrate reductase activity, pH, NO₃^- and NO₂^- consumption and removal of Ca²⁺, Pb²⁺ and Hg²⁺. Subsequently, the remediated precipitates were subjected to mineralogical analysis; energy dispersive X-ray patterns exhibited characteristic peaks of C, O and Ca in addition to Pb and Hg. Scanning electron microscope depicted the presence of bacterial imprints and protrusions on rough and smooth surface bioliths. However, X-ray diffraction indicated entrapment of PbCO₃, Pb₂O, CaPbO₃, Hg and Hg₂O in calcite lattice. Interestingly, such approach is feasible, efficient, cost-effective and ecofriendly for heavy metals remediation.

Purification, characterization, and biological cytotoxic activity of the extracellular cholesterol oxidase produced by Castellaniella sp. COX

A new bacterial strain producing extracellular cholesterol oxidase (ChOx) was isolated and identified as Castellaniella sp. COX. The ChOx was purified by salting-out and ion-exchange chromatography up to 10.4-fold, with a specific activity of 15 U/mg with a molecular mass of 59 kDa. The purified ChOx exhibited pH 8.0 and temperature 40°C for its optimum activity. The enzyme showed stability over a wide pH range and was most stable at pH value 7.0, and at pH 8.0, it retained almost 86% of its initial activity after 3 h of incubation at 37°C. The enzyme possessed a half-life of 8 h at 37°C, 7 h at 40°C, and 3 h at 50°C. A Lineweaver-Burk plot was calibrated to determine its K_m (0.16 mM) and V_max (18.7 μmol·mg^-1 ·min^-1 ). The ChOx activity was enhanced with Ca²⁺ , Mg²⁺ , and Mn²⁺ while it was inhibited by Hg²⁺ , Ba²⁺ , Fe²⁺ , Cu²⁺ , and Zn²⁺ ions. Organic solvents like acetone, n-butanol, toluene, dimethyl sulfoxide, chloroform, benzene, and methanol were well tolerated by the enzyme while iso-propanol and ethanol were found to enhance the activity of purified ChOx. ChOx induced cytotoxicity with an IC₅₀ value of 1.78 and 1.88 U/ml against human RD and U87MG established cell lines, respectively, while broadly sparing the normal human cells.

Characterization and overproduction of cell-associated cholesterol oxidase ChoD from Streptomyces lavendulae YAKB-15

Cholesterol oxidases are important enzymes with a wide range of applications from basic research to industry. In this study, we have discovered and described the first cell-associated cholesterol oxidase, ChoD, from Streptomyces lavendulae YAKB-15. This strain is a naturally high producer of ChoD, but only produces ChoD in a complex medium containing whole yeast cells. For characterization of ChoD, we acquired a draft genome sequence of S. lavendulae YAKB-15 and identified a gene product containing a flavin adenine dinucleotide binding motif, which could be responsible for the ChoD activity. The enzymatic activity was confirmed in vitro with histidine tagged ChoD produced in Escherichia coli TOP10, which lead to the determination of basic kinetic parameters with K_m 15.9 µM and k_cat 10.4/s. The optimum temperature and pH was 65 °C and 5, respectively. In order to increase the efficiency of production, we then expressed the cholesterol oxidase, choD, gene heterologously in Streptomyces lividans TK24 and Streptomyces albus J1074 using two different expression systems. In S. albus J1074, the ChoD activity was comparable to the wild type S. lavendulae YAKB-15, but importantly allowed production of ChoD without the presence of yeast cells.

Microbiological synthesis of stereoisomeric 7(α/β)-hydroxytestololactones and 7(α/β)-hydroxytestolactones

Microbiological synthesis of 7α- and 7β-hydroxy derivatives of testololactone and testolactone was developed based on bioconversion of dehydroepiandrosterone (DHEA) by fungus of Isaria fumosorosea VKM F-881 with subsequent modification of the obtained stereoisomers by actinobacteria. The first stage included obtaining of the stereoisomers of 3β,7(α/β)-dihydroxy-17a-oxa-D-homo-androst-5-en-17-ones in the preparative amounts. Then the conversion of 7-hydroxylated D-lactones obtained by selected actinobacteria of Nocardioides simplex VKM Ac-2033D, Saccharopolyspora hirsuta VKM Ac-666, and Streptomyces parvulus MTOC Ac-21v was studied. Under the transformation of 3β,7α-dihydroxy-17a-oxa-D-homo-androst-5-en-17-one and its corresponding 7β-stereoisomer by N. simplex VKM Ac-2033D and S. hirsuta VKM Ac-666 the 7α- and 7β-hydroxy-17a-oxa-D-homo-androst-4-ene-3,17-dione (7α- and 7β-hydroxytestololactone), 7α- and 7β-hydroxy-17a-oxa-D-homo-androsta-1,4-diene-3,17-dione (7α- and 7β-hydroxytestolactone) were obtained with molar yields in a range of 60.3-90.9 mol%. The crystalline products of 7α-hydroxytestololactone, 7α-hydroxytestolactone, and their corresponding 7β-hydroxy stereoisomers were isolated, and their structures were confirmed by mass spectrometry and ¹H-NMR spectroscopy analyses. The strain of Str. parvulus MTOC Ac-21v transformed 3β,7(α/β)-dihydroxy-17a-oxa-D-homo-androst-5-en-17-ones into the corresponding 3-keto-4-ene analogs and did not show 3-ketosteroid 1(2)-dehydrogenase activity. The activity of actinobacteria towards steroid D-lactones was hitherto unreported.The results contribute to the knowledge of metabolic versatility of actinobacteria capable of transforming steroid substrates and may be applied in the synthesis of potential aromatase inhibitors.

Expression optimization, purification, and functional characterization of cholesterol oxidase from Chromobacterium sp. DS1

Cholesterol oxidase is a bifunctional bacterial flavoenzyme which catalyzes oxidation and isomerization of cholesterol. This valuable enzyme has attracted a great deal of attention because of its wide application in the clinical laboratory, synthesis of steroid derived drugs, food industries, and its potentially insecticidal activity. Therefore, development of an efficient protocol for overproduction of cholesterol oxidase could be valuable and beneficial in this regard. The present study examined the role of various parameters (host strain, culture media, induction time, isopropyl ß-D-1-thiogalactopyranoside concentration, as well as post-induction incubation time and temperature) on over-expression of cholesterol oxidase from Chromobacterium sp. DS1. Applying the optimized protocol, the yield of recombinant cholesterol oxidase significantly increased from 92 U/L to 2115 U/L. Under the optimized conditions, the enzyme was produced on a large-scale, and overexpressed cholesterol oxidase was purified from cell lysate by column nickel affinity chromatography. K_m and V_max values of the purified enzyme for cholesterol were estimated using Lineweaver-Burk plot. Further, the optimum pH and optimum temperature for the enzyme activity were determined. This study reports a straightforward protocol for cholesterol oxidase production which can be performed in any laboratory.