Biosynthesis of silver nanoparticles by Nocardiopsis sp.-MW279108 and its antimicrobial activity

The utilization of microorganisms like bacteria in the biological synthesis of silver nanoparticles (AgNPs) has attracted widespread attention due to their ability to synthesize different shape sizes, states, and morphology nanoparticles. In the current study, the green synthesis of AgNPs by Nocardiopsis sp. 16S ribosomal RNA analysis was used to characterize the Nocardiopsis sp. The synthesized AgNPs were characterized through multi-instrument platforms such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, scanning electron microscope (SEM), and X-ray diffraction analysis (XRD). The antimicrobial activity of the synthesized AgNPs was determined by the agar plate diffusion method. The UV-Vis absorbance analysis of the synthesized AgNPs has a significant absorbance at 384 nm, confirming the AgNPs' surface plasmon resonance. The SEM and TEM characterizations indicate that the particle size ranges from 2 to 10 nm and is spherical. Additionally, the FTIR spectra revealed bands from 476 to 3819cm⁻¹, respectively. The XRD planes study pronounced strong bands ranging are between 111 and 311 corresponding to cubic face-center of the silver. Also, the antimicrobial activity of AgNPs indicated the biogenic AgNPs could control the growth of the clinical isolates. The AgNPs produced by Nocardiopsis sp. supernatant could be used in different nanomedicinal applications.     

Anti-bacterial activity of Corchorus olitorius L. and Acmella caulirhiza Del. on Streptococcus mutans,a cariogenic bacterium

BackgroundDental caries remains a global oral health challenge with the prevalence reported as high as 66.7% in adults. Despite the use of modern medicines, the prevalence of dental caries remains high. This has led to extensive screening of natural products particularly from plants such as Corchorus olitorius L. and Acmella caulirhiza Del. for anti-cariogenic activity.AimTo assess the anti-bacterial activity of Corchorus olitorius L. and Acmella caulirhiza Del. on Streptococcus mutans, a cariogenic bacteria.MethodsPlant materials of C. olitorius L. and A. caulirhiza Del. were extracted using diethyl ether, methanol, distilled water by cold maceration. Agar well diffusion method was used for sensitivity and susceptibility tests on S. mutans (ATCC 6519).ResultsThe aqueous plant extract of C. olitorius L. and the ether plant extract of A. caulirhiza Del. had the highest zones of inhibition (16.10mm and 12.03mm respectively) at a concentration of 1000mg/ml. The lowest MIC and MBC were 62.5mg/ml and 250mg/ml respectively.ConclusionBoth C. olitorius L. and A. caulirhiza Del. as used in oral health practices have been found to have antibacterial activity against the cariogenic S. mutans. Further studies should be conducted to isolate bioactive compounds against S. mutans.     

Characterization of a novel biosurfactant produced by Staphylococcus sp. strain 1E with potential application on hydrocarbon bioremediation

A biosurfactant-producing bacterium (Staphylococcus sp. strain 1E) was isolated from an Algerian crude oil contaminated soil. Biosurfactant production was tested with different carbon sources using the surface tension measurement and the oil displacement test. Olive oil produced the highest reduction in surface tension (25.9 dynes cm(-1)). Crude oil presented the best substrate for 1E biosurfactant emulsification activity. The biosurfactant produced by strain 1E reduced the growth medium surface tension below 30 dynes cm(-1). This reduction was also obtained in cell-free filtrates. Biosurfactant produced by strain 1E showed stability in a wide range of pH (from 2 to 12), temperature (from 4 to 55 °C) and salinity (from 0 to 300 g l(-1)) variations. The biosurfactant produced by strain 1E belonged to lipopeptide group and also constituted an antibacterial activity againt the pathogenic bacteria such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis. Phenanthrene solubility in water was enhanced by biosurfactant addition. Our results suggest that the 1E biosurfactant has interesting properties for its application in bioremediation of hydrocarbons contaminated sites.     

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.     

Effect of salinity on denitrification under limited single carbon source by Marinobacter sp. isolated from marine sediment

Marinobacter comprises Gram‐negative, aerobic, motile, and rod‐shaped bacteria within the γ‐subclass of the Proteobacteria and is known to be halophilic or halotolerant, heterotrophic neutrophile. Two strains classified as belonging to Marinobacter, named PAD‐2 and SeT‐1, were isolated from marine sediment. The most closely related species of PAD‐2 and SeT‐1 are M. alkaliphilus and M. guinea, respectively. The strain PAD‐2 exhibited remarkably higher denitrification at concentrations of 0.5 to 1 M NaCl (3–6% w/w) than at other salinities (2 and 3 M NaCl, 12–18% w/w), and optimal denitrification was observed in media with 0.5 M NaCl. The effect of pH on denitrification by strain PAD‐2 was also examined, and the optimum denitrification occurred at neutral pH rather than under alkaline conditions. Overall, strain PAD‐2 appears to be a novel halotolerant species belonging to the genus Marinobacter that shares many characteristics, such as substrate utilization profile and optimum NaCl concentration for growth with M. alkaliphilus. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Antibacterial,antioxidant and anticancer activities of biphenyls from Streptomyces sp. BO-07: an endophyte in Boesenbergia rotunda (L.) Mansf A.

Strain BO-07 was isolated from the root tissue of Boesenbergia rotunda (L.) Mansf A. and identified as Streptomyces sp. on the basis of morphology, chemotaxonomy and 16S rDNA sequencing. The fractionation of the crude extract from strain BO-07 cultures led to the isolation of two biphenyls: 3′-hydroxy-5-methoxy-3,4-methylenedioxybiphenyl (1) and 3′-hydroxy-5,5′-dimethoxy-3,4-methylenedioxybiphenyl (2); these compounds and the crude extract had potent antibacterial activity against Gram-positive bacteria, and antioxidant and anticancer activities. These compounds showed the highest activity against Staphylococcus aureus ATCC25932, Bacillus cereus ATCC7064 and Bacillus subtilis ATCC6633 with a minimum inhibitory concentration value of 0.5?µg/ml and minimum bactericidal concentration of 2–8?µg/ml. Compounds 1 and 2 showed the highest (1, 1diphenyl-2-picryl hydrazyl) DPPH antioxidant activity with a scavenging concentration (SC₅₀) value of 85.84 and 88.26?µg/ml, respectively, and also showed strong cytotoxicity against all the three cancer cell lines (HeLa, HepG2 and Huh7) at an IC₅₀ value of 3.04–20.30?μg/ml. Both the compounds were less toxic on normal cells (L929) than on the investigated cancer cell lines.     

Streptococcus sp. and Staphylococcus aureus Isolates from Patients with Psoriasis Possess Genes That Code for Toxins (Superantigens): Clinical and Therapeutic Implications

Superantigens are powerful T lymphocyte–stimulating agents that are believed to contribute to the pathogenesis of certain diseases such as psoriasis. Toxins produced by Streptococcus pyogenes and Staphylococcus aureus are superantigens. The aim of this study was to detect genes that code for superantigens in Streptococcus and Staphylococcus aureus isolates from psoriatic patients. Primers to amplify streptococcal pyrogenic exotoxin A, B, and C and streptolysin O genes and staphylococcal enterotoxin A, B, C, and D genes were used. Streptococcal exotoxin B was detected in five streptococcal isolates. Staphyloccocus aureus enterotoxin A and/or C genes were detected in nine S. aureus isolates. Isolates from 13 of 22 patients possesed gene(s) that code for toxin(s) (superantigens). These results might support the role of superantigens in the exacerbation of psoriasis.     

A novel way to enhance the oil recovery ratio by Streptococcus sp. BT‐003

Degrading hydrocarbon by Streptococcus sp. BT‐003 as a kind of microbe for oil recovery was analyzed in this paper. The Streptococcus sp. BT‐003 showed that it could use crude oil as the sole source of carbon and produce organic acid, bio‐gas and polysaccharide which were propitious to emulsify and reduce the viscosity of crude oil. After cultivating 8–14 h, the viscosity of crude oil reduced from 8000–15000 mPa · s to 50–250 mPa · s. The content of organic acid increased 8–15 times, and carbon dioxide and polysaccharide reached 55 ml/l and 8 g/l respectively. Paraffin and resin reduced by 60–95%, and light components increased obviously. Fluid rheology was better than before, the interfacial tension between the crude oil and water were reduced effectively. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Isolation and identification of a psychrotrophic Acinetobacter sp. CR9 and characterization of its alkaline lipase

Forty three psychrotrophic bacteria were isolated from soil samples collected from Chandra river in sub-alpine region of western Himalaya, India. Among these, 11 isolates were found positive for lipase production at low temperature. Of 11 isolates, CR9 produced largest zone of clearance on plate assay and was able to produce lipase under wide range of pH. The isolate CR9 was identified as Acinetobacter sp. based on morphological and physiochemical characterization and 16S rRNA gene sequencing analysis. According to 16S rRNA gene sequencing data the closest phylogenetic neighbor for strain CR9 was Acinetobacter lwoffii (98.9%). The partially purified lipase from strain CR9 exhibited maximum activity at temperature 40 degrees C and pH optima at 8.0. Cu(2+), Mo(2+), Mg(2+), Zn(2+), phenylmethanesulfonyl fluoride (PMSF), dithiothreitol (DTT) and beta-mercaptoethanol (2-ME) enhanced the enzyme activity, whereas Ca(2+) and ethylenediaminetetraacetic acid (EDTA) had inhibitory effect. Lipase hydrolyzed wide range of short chain fatty acid esters of p-nitrophenyl. The organism CR9 also hydrolyzed tributyrin, Tween 80, soybean oil, mustard oil and olive oil. The results highlight the relevance of unexplored microbes from cold environments of western Himalaya for the isolation of novel lipase producing bacteria.     

Production and characterization of a bioactive extracellular homopolysaccharide produced by Haloferax sp. BKW301

The production of extracellular polysaccharides (EPS) by haloarchaeal members, with novel and unusual physicochemical properties, is of special importance and has the potential for extensive biotechnological exploitation. An extremely halophilic archaeon, Haloferax sp. BKW301 (GenBank Accession No. KT240044) isolated from a solar saltern of Baksal, West Bengal, India has been optimized for the production of EPS under batch culture. It produced a considerable amount (5.95 g/L) of EPS in the medium for halophiles with 15% NaCl, 3% glucose, 0.5% yeast extract, and 6% inoculum under shake flask culture at 120 rpm. The purified EPS, a homopolymer of galactose as revealed by chromatographic methods and Fourier-transform infrared spectroscopy, is noncrystalline (CI_xrd, 0.82), amorphous, and could emulsify hydrocarbons like kerosene, petrol, xylene, and so forth. Moreover, the polymer is highly thermostable (up to 420°C) and displayed pseudoplastic rheology. Biologically, the EPS was able to scavenge DPPH (2,2-diphenyl-1-picrylhydrazyl) radical efficiently and inhibit the proliferation of the Huh-7 cell line at an IC₅₀ value of 6.25 µg/ml with a Hill coefficient of 0.844. Large-scale production of this thermostable, pseudoplastic homopolysaccharide, therefore, could find suitable applications in industry and biotechnology.     

Biodegradation of bis(2-hydroxyethyl) terephthalate by a newly isolated Enterobacter sp. HY1 and characterization of its esterase properties

Bis(2-hydroxyethyl) terephthalate (BHET) is an important compound produced from poly(ethylene terephthalate) (PET) cleavage. It was selected as the representative substance for the study of PET degradation. A bacterial strain HY1 that could degrade BHET was isolated and identified as Enterobacter sp. The optimal temperature and pH for BHET biodegradation were determined to be 30°C and 8.0, respectively. The half-life of degradation was 70.20 h at an initial BHET concentration of 1,000 mg/L. The results of metabolites' analysis by liquid chromatograph–mass spectrometer revealed that BHET was first converted to mono-(2-hydroxyethyl) terephthalate (MHET) and then to terephthalic acid. Furthermore, an esterase-encoding gene, estB, was cloned from strain HY1, and the expressed enzyme EstB was characterized. The esterase has a molecular mass of approximately 25.13 kDa, with an isoelectric point of 4.68. Its optimal pH and temperature were pH 8.0 and 40°C, respectively. The analysis of the enzymatic products showed that EstB could hydrolyze one ester bond of BHET to MHET. To the best of authors' knowledge, this is the first report on the biodegradation characteristics of BHET by a member of the Enterobacter genus.     

Bioprospecting and characterization of pigmented halophilic archaeal strains from Algerian hypersaline environments with analysis of carotenoids produced by Halorubrum sp. BS2

A set of 110 extremely halophilic archaeal strains were isolated from seven distinct saline habitats located in different regions of Algeria. The physicochemical characterization of the samples showed that these habitats were thalassohaline. The carotenoid production from isolated strains varied from 0.1 to 3.68 µg/ml. Based on their physiological characteristics and pigment production, 43 strains were selected and identified by means of phenotypic tests and 16S ribosomal RNA gene sequencing. Phylogenetic analysis indicated that the isolates corresponded to the class Halobacteria and were closely related to genera Halorubrum, Haloarcula, Haloferax, Natrinema, Halogeometricum, Haloterrigena, and Halopiger. Carotenoids of the highest producer, strain Halorubrum sp. BS2 were identified using high-performance liquid chromatography–diode array detector and liquid chromatography–mass spectrometry. Bacterioruberin and bisanhydrobacterioruberin were the predominant carotenoids. The scavenging activity of these carotenoids reached 99% at a concentration of 18 μg/ml, which was much higher than that of ascorbic acid used as a reference compound. These carotenoids also exhibited significant antibacterial activities against four human-pathogenic strains and four fish-pathogenic strains. Variations in salinity, agitation rate, temperature, and light intensity were found to influence growth and carotenoid production of Halorubrum sp. BS2. Our results suggest that halophilic archaea represent a potential source for carotenoids, which are characterized by high antioxidant and antibacterial activities.     

Microbial production of docosahexaenoic acid by a low temperature‐adaptive strain Thraustochytriidae sp. Z105: screening and optimization

As an alternative source in addition to fish oil, microbial production of docosahexaenoic acid has been recieved more and more attentions owing to their culture advantage. A unicellular eukaryotic microbe with high DHA production and capable of low temperature‐adaptive growth was isolated from seawater and identified as Thraustochytriidae sp. Z105. The siginificant effect of temperature on cell growth and DHA synthesis by the strain was revealed. It could grow and produce DHA even at 4 °C, but hardly grow above 35 °C. Low temperature (15–25 °C) was favorable for formation of biomass, lipids and DHA, but DHA synthesis was completely blocked above 30 °C. Conditions for high level DHA production by Thraustochytriidae sp. Z105 in flask culture were optimized as follows: medium containing glucose 80 g/l, yeast extract 5.0 g/l, K₂HPO₄ · 3 H₂O 1.0 g/l, MgSO₄ · 7 H₂O 0.5 g/l, seawater crystal 20 g/l, pH 6.0, liquid volume 30 ml/250 ml, temperature 20 °C, agitation speed of 200 r/min, and culture for 120 h. Under the optimal conditions, biomass of 16.72 g/l, total lipids of 5.35 g/l, DHA yield of 1.71 g/l (accounting for 32% of the total lipids) were achieved, respectively. In flask cluture level, the DHA productivity of Thraustochytriidae sp. Z105 was higher than most reported results, which suggested the wild type strain was a potential superior candidate for industrialization of DHA production. Moreover, the strain is an unique and valuable resource for investigation of the low temperature adaptive mechanism related to DHA synthesis. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Sarcocystis arctosi sp. nov. (Apicomplexa, Sarcocystidae) from the brown bear ( Ursus arctos ), and its genetic similarity to schizonts of Sarcocystis canis -like parasite associated with fatal hepatitis in polar bears ( Ursus maritimus )

The tissues of herbivores are commonly infected with cysts of parasites belonging to the apicomplexan genus Sarcocystis, but such sarcocysts are rare in bears. Here, we describe a new species, Sarcocystis arctosi, based on the mature sarcocysts identified in two brown bears (Ursus arctos) from Alaska, USA. Microscopic sarcocysts (37–75 × 20–42 μm) had thin walls (<1 μm). The outer layer of the sarcocyst, the parasitophorous vacuolar membrane (pvm), was wavy in outline and had minute undulations that did not invaginate towards the sarcocyst interior; these undulations occurred at irregular intervals and measured up to 100 nm in length and up to 60 nm width. The ground substance layer beneath the pvm was smooth and lacked microtubules. Longitudinally cut bradyzoites measured 5.6–6.8 × 0.7–1.8 μm. A major portion of nuclear small subunit rDNA sequence obtained from these sarcocysts was similar to that previously obtained from the hepatic schizonts of a S. canis-like parasite from polar bears (Ursus maritimus).     

Antibacterial and Anticancer activity of ε ‐poly‐L‐lysine (ε ‐PL) produced by a marine Bacillus subtilis sp.

A marine Bacillus subtilis SDNS was isolated from sea water in Alexandria and identified using 16S rDNA sequence analysis. The bacterium produced a compound active against a number of gram negativeve bacteria. Moreover, the anticancer activity of this bacterium was tested against three different human cell lines (Hela S3, HepG2 and CaCo). The highest inhibition activity was recorded against Hela S3 cell line (77.2%), while almost no activity was recorded towards CaCo cell line. HPLC and TLC analyses supported evidence that Bacillus subtilis SDNS product is ?;‐poly‐L‐lysine. To achieve maximum production, Plackett‐Burman experimental design was applied. A 1.5 fold increase was observed when Bacillus subtilis SDNS was grown in optimized medium composed of g/l: (NH₄)₂SO₄, 15; K₂HPO₄, 0.3; KH₂PO₄, 2; MgSO₄ · 7 H₂O, 1; ZnSO₄ · 7 H₂O, 0; FeSO₄ · 7 H₂O, 0.03; glucose, 25; yeast extract, 1, pH 6.8. Under optimized culture condition, a product value of 76.3 mg/l could be obtained. According to available literature, this is the first announcement for the production of ?;‐poly‐L‐lysine (?;‐PL) by a member of genus Bacillus. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)