Test Microbes Research Articles

Antidermatophytic Activity of Ethanolic Leaves Extract of <i>Limonia acidissima</i> Groff

In the present study Limonia acidissima Groff. ethanolic leaves extract was used for the detection of its antidermatophytic assay. It results broad spectrum of antifungals and antibacterial. Where the antimycotic activity against Trichophyton rubrum, Trichophyton tonsurans, Trichophyton mentagrophytes, Microsporium gypseum, Candida albicans and four Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa were more pronounced. The effective antidermatophytic activity observed against M. gypseum, T. tonsurans,E. coli and B. subtilis. Minimum Inhibitory Concentration of all the test microbes was determined using broth dilution technique. MFC, MBC also standardized. Preliminary Phytochemical tests were carried for the revealing basics antimicrobial responsible molecules of secondary metabolites.

Activity of Bacteria and Moulds on Surfaces of Commercial Wooden Composites

Bacteria and mould exposures are reported to be associated with allergies, respiratory symptoms and asthma. Wood products with antimicrobial surface would reduce the risk of spreading microbial infections especially in healthcare facilities and public buildings. In future is perspective of their use.In this study, twenty five wooden composites commercially produced in Slovakia having different surfaces were tested both against moulds – microscopic fungiAspergillus nigerandPenicilliumspp., and also against bacteriaEscherichia coliandStaphylococcus aureus. These organisms are commonly applied as test microbes in laboratory experiments. On the basis of bacteria and mould’s growth on the surfaces of used wooden composites, the tested surfaces have been divided to three groups: (1) wooden composites with high resistant surface, (2) wooden composites with medium resistance surface, (3) and wooden composites with not resistant surface.

TaqMan real-time PCR assay for the detection and quantification of Sclerospora graminicola, the causal agent of pearl millet downy mildew

Early detection and quantification of Sclerospora graminicola, causal agent of pearl millet downy mildew, from seed, plant and infested soil could help in initiating preventive measures to control the spread of the disease. Two sensitive assays, SgK PCR (conventional PCR) and SgTqK q-PCR (real-time PCR), were developed for the detection of S. graminicola. Both assays were targeted on the 28S region of the nuclear large subunit (nuLSU) of the rDNA cluster. In conventional PCR, the species-specific primers (SgK F/R) amplified a 436 bp product in S. graminicola. TaqMan real-time PCR specifically amplified an 86 bp fragment in diverse DNA samples of S. graminicola obtained from infected seed, root, leaves and infested soil. Both assays did not amplify or produce any fluorescent signal from DNA obtained from other test microbes or from healthy pearl millet leaves. The absolute quantity of target molecules (28S) in the DNA sample obtained from S. graminicola sporangia (6 × 108/ml) was estimated at 25 pg/μl and the copy number was calculated as 2.69 × 108 molecules/μl. The copy number of target molecules in a diploid nucleus (2n) of S. graminicola was estimated to be ~27 molecules/nucleus. This assay can be used as a rapid and efficient detection tool for the identification and diagnosis of S. graminicola, and will be helpful in ensuring safe exchange of S. graminicola-free pearl millet germplasm across borders.

Antibacterial Activity of Aqueous, Ethanol and Acetone Extracts of <i>Ocimum sanctum</i> Linn

Aqueous, ethanol and acetone leaf and root extracts of <i>Ocimum sanctum</i> Linn were investigated for their antibacterial activities at various concentrations against <i>Escherichia coli, Staphylococcus aureus</i> and <i>Pseudomonas aeruginosa</i> using standard methods. Antimicrobial studies indicated that both the acetone leaf and root extracts of <i>O. sanctum</i> were found comparatively more effective against these bacteria than any other extract tested while aqueous extract being the least effective against the tested microbes. The highest mean zone of inhibition of acetone leaf extract against <i>P. aeruginosa</i> was 20.74± 0.68 followed by 19.36± 0.29 at concentration 150mg/ml and 100 mg/ml respectively. The aqueous and ethanol root extracts of <i>O. sanctum</i> for had no inhibitory effect against the test microorganisms. Generally the acetone crude extracts showed activity against the three bacteria species with highest average zone of inhibition compared to other extracts. The antimicrobial activity of the leaf extract was more pronounced against test microbes than root extract. The study revealed that the plant possessed antimicrobial properties and could be a potential source of antibacterial agent in the treatment of bacterial infections.

Antidiarrhoeal Activities of Some Medicinal Plants

The phytochemical screening, extraction and antimicrobial analysis of the crude extracts from the seeds and pods of Acacia nilotica Linn, the roots of Uvaria afzelii Sc and Terminalia avicennioides Guill & Perr were carried out using standard methods. The results of the phytochemical screening showed that the plants contained saponins, flavonoids, phenols, tannins, terpenoids and triterpenoids. The results of the antibacterial screening showed that the ethyl acetate extract of Acacia nilotica Linn exhibited the highest activities against the test microbes with zones of inhibition diameter ranging from 27-32 mm. It was closely followed by the ethyl acetate extract of Terminalia aviccenoides with zones of inhibition diameter ranging from 25-30 mm and finally, the ethyl acetate extract of Uvaria afzelii with zones of inhibition ranging from 24-29 mm. The results of Minimum Inhibitory Concentration (MIC) showed that the extracts of the plants gave MIC values at a concentration of 800, 700, 600 μg/cm3 against Escherichia coli, Vibro cholerea, Shigella dysentriae and Salmonella enteritidis respectively. The Minimum Bactericidal Concentration (MBC) values occur at the same concentration against the same microbes. The results of this study showed that the ethylacetate extract of the seeds and pods of Acacia nilotica was the most active against diarrhoea causing organisms and may be a potential source of a broad spectrum antibiotic for the treatment of diarrhoea.

A Head-to-Head Comparison of the Antimicrobial Activities of 30 Ultra-Short Antimicrobial Peptides Against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans

The rapid emergence of drug-resistant bacteria and the lack of new antibiotics entering the market is a major worldwide concern. Antimicrobial peptides (AMPs) are deemed plausible drug candidates as they specifically target and disrupt microbial cell membranes, causing death by cell lysis. However, their instability towards plasma proteases and perceived high manufacturing cost limit their potential for further drug development. A plausible solution is to identify and develop very short linear peptides as topical agents for treating skin and soft tissue infections. A literature survey yielded 30 ultra-short AMPs up to 9 residues in length with antimicrobial activities. They were commercially synthesized and a head-to-head antimicrobial activity comparison was conducted on common skin pathogens including meticillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. The topical broad-spectrum antibiotic Gentamicin and antifungal Nystatin were included as controls. Experimental results revealed only 2 peptides with potent broad-spectrum activities; octapeptide IRIRIRIR-NH2 and nonapeptide Ac-KWRRWVRWI-NH2 exhibited MICs of 6.25 μM against all test microbes. Both peptides have been reported to be non-cytotoxic to human cells, suggesting that they could potentially be further developed as topical antimicrobial agents.

Amorphophallus species as potential source of antimicrobial agent

Medicinal plants are the mirror image of wealthy India. Medicinal plants are the great source of various natural compounds that have important medicinal values and can be used for the well being of human welfare and for the safety of environment. Amorphophallus species related to the Arid Zone of India. Arid zone plants have specific antifungal, antibacterial and Anti- inflammatory activity because of the some specific bioactive compounds, that makes these plants adaptable to be growing in the desert environment. The present study was performed to screen the antimicrobial ability of Amorphophallus species against selected test microbes using its methanolic and petroleum ether extract. Petroleum ether extract and methanolic extract both shows appreciable antimicrobial activity against test microbes. Petroleum ether shows maximum activity against S. sonnei (10mg/disc, IZ=15, AI= 0.46) and K. pneumonia (10mg/disc, IZ= 14, AI= 0.35) and minimum activity against T. rubrum and negative against C. albicans. The result of methanolic extract activity was excellent. The activity was maximum against P. aeruginosa (5mg/disc, IZ= 20, AI= 1.42) and low against Klebsiella pneumonia.

Leaf Extracts of Vernonia amygdalina Del. from Northern Ghana Contain Bioactive Agents that Inhibit the Growth of Some Beta-lactamase Producing Bacteria in vitro

Aims: The current study was aimed at evaluating the phytochemical profile and in vitro bacteria growth inhibitory potential of different solvent leaf extracts of V. amygdalina from northern Ghana. Study Design: Different solvent extracts of the plant were quantitatively and qualitatively evaluated for phytochemicals. In vitro bacteria sensitivity assay of the extracts was evaluated using some beta-lactamase producing bacteria as test microbes. Methodology: Ethanolic, methanolic, petroleum ether and aqueous leaf extracts of Vernonia amygdalina were studied in vitro for growth inhibition against beta-lactamase producing bacteria such as Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa using agar well diffusion method. Saponins, flavonoids, glycosides, alkaloids, tannins, phenolics, reducing sugars, anthracenosides, terpenes and phytosteroids were determined qualitatively and quantified. Results: All the phytochemicals tested were found to be present in both the methanolic and ethanolic leaf extracts. The aqueous extract showed the presence of saponins, reducing sugars and anthracenosides. Glycosides, flavonoids, saponins and alkaloids were the only groups of phytochemicals found in the petroleum ether extract. The methanolic extract showed the greatest amount of saponins (14.23%), flavonoids (2.15%), alkaloids (7.49%), tannins (5.4%), terpenes (10.20%) and phenolics (8.24%). The methanolic extract at concentration of 4 mg/ml showed growth inhibitory activities against all the test organisms with zone of inhibitions ranging from 16.00+0.50 (against E. coli) to 20.50+0.03 mm (against S. aureus). The ethanolic extract showed activity against only two of the test organisms viz. 23.00+0.33 mm against P. aeruginosa and 12.00+0.00 mm against S. aureus at similar concentration. All test organisms were resistant to both aqueous and pet ether extracts. Conclusion: The antibacterial activities of the methanolic and ethanolic extracts were significant (P &lt; 0.05) and may be mediated by the presence of saponins, flavonoids, tannins, terpenes and alkaloids. Results from present study corroborate previous findings and also presents methanolic leaf extract of the plant as a credible candidate for the discovery of new phytotherapeutic agents against the beta-lactamase producing bacteria tested.

Isolation and Biological Activity of the Triterpene Β-Amyrin from the Aerial Plant Parts of Maesobotrya Barteri (Baill)

Maesobotrya barteri (Baill), belonging to the family EUPHORBIACEAE, is a medicinal plant growing widely in tropical Africa. The Aerial plant parts of Maesobotrya barteri (Bail) were collected fresh from Orokam, Ogbadibo local Government of Benue State, Nigeria in July, 2013. Taxonomical identification was done by Mallam Musa Abdullahi at the Herbarium unit of Biological sciences Department, ABU, Zaria, Nigeria. Pulverized aerial parts of Maesobotrya barteri (960g) was exhaustively extracted successively using petroleum ether, chloroform, ethyl acetate and methanol and concentrated in the rotary evaporator at 40°C. The ethyl acetate fraction having the highest activity against test microbes from preliminary crude microbial screenings was subjected to phytochemical studies, antimicrobial analysis and column chromatography (CC). The column chromatography yielded fraction EN, which was further purified using preparative thin layer chromatography to give EN1. The structure of the isolated compound was established using 1-D NMR and 2-D NMR spectroscopic analysis and by direct comparism with data reported in literature was confirmed to be β-amyrin. The bioactivity of this compound was carried out using some clinical pathogens and the activity compared with standard drugs and this was found to be comparable with the standard drug.

Diversity, Bioactivity and Drug Development of Cultivable Actinobacteria in Six Species of Bird Feces

In order to provide new lead compounds of drugs and other useful products, the diversity and some bioactivities of cultivable actinobacteria in bird feces were studied．Six species of bird fecal samples were collected from Yunnan Wild Animal Park and bank of Dian Lake. The pure cultures of actinobacteria were isolated from these samples by using 6 different media. The partial 16S rRNA gene sequences of 207 selected strains were determined, the phylogenetic analysis was carried out, and antimicrobial activities were determined by using agar diffusion method. The key biosynthase genes (CYP, AHBA and SAL) of antibiotics were also detected. Total 28 genera of actinobacteria from all the samples were identified. 18 genera were identified from Pavo cristatus feces, and the actinomycete community was the most complex. These actinobacteria had wide inhibition against 10 test microbes. In 30, 25, and 36 strains of actinobacteria isolated from Pavo cristatus, Grus japonensis and Larus ridibundus feces respectively, average 22.2%, 8.9% and 40.8% strains had the key biosynthase genes encoding CYP, AHBA and SAL. More than 30 bioactive secondary metabolites from several actinomycete strains of bird feces were isolated and characterized. The study shows that birds fecal actinobacteria are a new potential source for discovering new drugs and other industry products.

Inhibitory Effect of Cow Urine Extracts of Selected Plants against Pathogens Causing Rhizome Rot of Ginger

The present study was carried out to investigate the inhibitory effect of cow urine extracts of nine plants against two fungi viz., Fusarium oxysporum f.sp. zingiberi, Pythiumaphanidermatum and a bacterium Ralstonia solanacearum that are known to cause rhizome rot of ginger. Antifungal and antibacterial activity of cow urine extracts was investigated by poison food technique and agar well diffusion method respectively. The extent of growth of test fungi in plates poisoned with extracts was lesser when compared with the control plates. Among fungi, high susceptibility was recorded in case of F. oxysporum. Cow urine extract of Elaegnus kologa caused high inhibition of P. aphanidermatum whereas cow urine extract of Artocarpus lakoocha, Hemidesmus indicus, Croton roxburghii and Maesa indica caused high inhibition of F. oxysporum. All extracts caused inhibition of R. solanacearum. Extract of A. lakoocha caused maximum inhibition followed by H. indicus, E. kologa and others. Overall, cow urine extracts of plants selected in this study caused varied inhibition of test microbes. These extracts may find a possible application in agriculture against phytopathogenic microorganisms.

An Efficient Synthesis and Antimicrobial Studies of Bioactive 4H-1,4-Benzothiazine and Their Sulfone Derivatives

4H-1,4-benzothiazines were prepared by condensation followed by oxidative cyclization of substituted 2-aminobenzenethiols with β-diketones in dimethylsulfoxide. On refluxing with 30% hydrogen peroxide in glacial acetic acid, 4H-1,4-benzothiazines yielded 4H-1,4-benzothiazine-1,1-dioxides. Structural evaluation has been done by spectral and elemental analysis. All the synthesized compounds were evaluated for their antibacterial and antifungal activity and all these have shown moderate to high activity against the test microbes. Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional text, figures and tables.

Procedural Revision to the AOAC Germicidal Spray Products as Disinfectants Test Method: Establishment of Minimum and Maximum Log Density Values for Test Microbes on Inoculated Carriers

Abstract The AOAC Germicidal Spray Products as Disinfectants test method (AOAC Official Method 961.02) is used to measure the efficacy of spray products on hard inanimate surfaces; however, the method does not provide procedures to determine the population of the test microbe on inoculated glass slide carriers (e.g., carrier counts reported as CFU/carrier). Without a method to measure and monitor carrier counts, the associated efficacy data may not be reliable and repeatable. This report provides a standardized procedure to address this issue and, based on carrier count data collected by four laboratories from 2000 to 2010, proposes a specific range for the mean log density per carrier as a requirement. Laboratory-based carrier count data were collected concurrently with 116 Method 961.02 efficacy tests conducted on spray products bearing claims against Pseudomonas aeruginosa and Staphylococcus aureus. For many of the tests a soil load (SL) was added to the inoculum (as specified on the product label claim). Six carriers were assayed per test for a total of 696 carriers. All but two of the 116 mean log densities were at least 5.0 (a geometric mean of 1.0 × 105 CFU/carrier). Across the four combinations of microbes and SL treatments, the mean TestLD (mean log density across all enumerated carriers in a test) ranged from approximately 6.0 (a geometric mean of 0.9 × 106 CFU/carrier) to 6.3 (a geometric mean of 2.0 × 106 CFU/carrier). Across all microbes and SL treatments, the mean log density (±SEM) was 6.2 (±0.07) per carrier (a geometric mean of 1.5 × 106 CFU/carrier). The mean log density for six carriers per test showed good repeatability (0.32) and reproducibility (0.34). The proposed requirement for S. aureus tests and P. aeruginosa tests is a mean log density (across six carriers) between 5.0 and 6.5. A separate 2009 study at three laboratories was conducted to evaluate the persistence of P. aeruginosa, S. aureus, and Salmonella enterica on glass carriers. Based on the persistence data, a 2 h use period is proposed for using the inoculated carriers post drying. The persistence data set was also used to assess the carrier counts for S. enterica. The carrier counts were approximately one log lower for S. enterica compared to S. aureus and P. aeruginosa; a range of 4.0 to 5.5 logs is proposed as a requirement for S. enterica tests.

Anti-Aspergillus activity of selected medicinal plants

BackgroundAs described in Unani and Ayurveda, herbal medicines are sources of treating the morbid conditions. The drugs that obtained from trees, shrubs or herbs contribute about 25 percent of the total prescription drugs. Antimicrobial potential of ten medicinal plants i.e. Picrorhiza kurroa, Datura metel, Acacia catechu, Cissus quadrangularis, Cassia tora, Berberis aristata, Pongamia pinnata, Emblica officinalis, Saraca asoca and Tinospora cordifolia was evaluated against three fungal strains of. Aspergillus i.e. Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger. MethodsCrude extracts were prepared using Soxhlet extraction and aqueous extraction methods. Total sixty extracts of ten different plants were screamed for antifungal activity using microbroth dilution assay, disc diffusion assay and spore germinatery inhibitory assay. Results & discussionPercent yields of petroleum ether and chloroform extracts of plant leaves was found to be in the range of 0.80–2.98%. Percent yields of acetone, methanol and water extract were found to ranging from 2.87 to 5.77%. Minimum inhibitory concentration of extracts was determined by microtiter dilution assay. Water extract of S. asoca showed maximum activity against A. fumigatus (0.65 mg/ml). The extracts with MIC ranging from 2.5 mg/ml to 0.65 mg/ml were further evaluated for their potential using disc diffusion assay. It was observed that only eight out of sixty plants extracts were found to be endowed with antifungal activity at a preset concentration of 25 μg/disc by disc diffusion assay. Maximum zone of inhibition at this concentration was 13.2 ± 0.5 mm against A. fumigatus by water extract of S. asoca. ConclusionIt was observed that leave water extracts of S. asoca could be potential reservoir of bioactive compounds. Further proteomics study of the test microbes could reconnoiter potential anti-bacterial targets.

Texture and topography analysis of doxycycline hyclate thermosensitive systems comprising zinc oxide

To characterize the thermal behavior and texture analysis of doxycycline hyclate thermosensitive gels developed for periodontitis treatment containing zinc oxide prepared by using poloxamer (Lutrol(®) F127) as polymeric material and N-methyl pyrrolidone was used as cosolvent. The thermosensitive gel comprising doxycycline hyclate, Lutrol(®) F127, and N-methyl pyrrolidone were characterized for the thermal behavior and texture analysis. The topography of the system after the dissolution test was characterized with scanning electron microscope. Differential scanning calorimetric thermogram exhibited the endothermic peaks in the systems containing high amount of N-methyl pyrrolidone in solvent. The sol-gel transition temperature of the systems decreased as the zinc oxide amount was increased. The addition of doxycycline hyclate, zinc oxide, and N-methyl pyrrolidone affected the syringeability of systems. The addition of zinc oxide into the doxycycline hyclate-Lutrol(®) F127 systems decreased the diameter of inhibition zone against Staphylococcus aureus, Escherichia coli, and Candida albicans since zinc oxide decreased the diffusion and prolonged release of doxycycline hyclate. From scanning electron microscope analysis, the porous surface of 20% w/w Lutrol(®) F127 system was notably different from that of gel comprising doxycycline hyclate which had interconnected pores and smooth surfaces. The number of pores was decreased with increasing zinc oxide and the porous structure was smaller and more compact. Therefore, the addition of zinc oxide could increase the syringeability of doxycycline hyclate-Lutrol(®) F127 system with the temperature dependence. Zinc oxide decreased inhibition zone against test microbes because of prolongation of doxycycline hyclate release and reduced size of continuous cells. Furthermore, zinc oxide also increased the compactness of wall surfaces of Lutrol(®) F127.

Performance of the AOAC Use-Dilution Method with Targeted Modifications: Collaborative Study

The U.S. Environmental Protection Agency (EPA), in collaboration with an industry work group, spearheaded a collaborative study designed to further enhance the AOAC use-dilution method (UDM). Based on feedback from laboratories that routinely conduct the UDM, improvements to the test culture preparation steps were prioritized. A set of modifications, largely based on culturing the test microbes on agar as specified in the AOAC hard surface carrier test method, were evaluated in a five-laboratory trial. The modifications targeted the preparation of the Pseudomonas aeruginosa test culture due to the difficulty in separating the pellicle from the broth in the current UDM. The proposed modifications (i.e., the modified UDM) were compared to the current UDM methodology for P. aeruginosa and Staphylococcus aureus. Salmonella choleraesuis was not included in the study. The goal was to determine if the modifications reduced method variability. Three efficacy response variables were statistically analyzed: the number of positive carriers, the log reduction, and the pass/fail outcome. The scope of the collaborative study was limited to testing one liquid disinfectant (an EPA-registered quaternary ammonium product) at two levels of presumed product efficacies, high and low. Test conditions included use of 400 ppm hard water as the product diluent and a 5% organic soil load (horse serum) added to the inoculum. Unfortunately, the study failed to support the adoption of the major modification (use of an agar-based approach to grow the test cultures) based on an analysis of method's variability. The repeatability and reproducibility standard deviations for the modified method were equal to or greater than those for the current method across the various test variables. However, the authors propose retaining the frozen stock preparation step of the modified method, and based on the statistical equivalency of the control log densities, support its adoption as a procedural change to the current UDM. The current UDM displayed acceptable responsiveness to changes in product efficacy; acceptable repeatability across multiple tests in each laboratory for the control counts and log reductions; and acceptable reproducibility across multiple laboratories for the control log density values and log reductions. Although the data do not support the adoption of all modifications, the UDM collaborative study data are valuable for assessing sources of method variability and a reassessment of the performance standard for the UDM.

Evaluation of Antimicrobial and Anti-inflammatory Activities and Formulation Studies on the Leaf Extracts of &lt;i&gt;Psidium gaujava&lt;/i&gt; L.

Herbal therapy has been used for daily oral health care to prevent, treat or cure oral conditions from halitosis to periodontal disease. In the present study, Psidium guajava L. leaf which is used traditionally for oral diseases was evaluated for its antimicrobial and anti-inflammatory activities and then formulated with subsequent activity testing. The antimicrobial activity tests indicated that the acetone and methanol fractions exhibited relatively stronger activities against the commonly encountered bacterial and fungal pathogens than the other solvent fractions. Besides, the 80% methanol extract of P. guajava leaves inhibited the growth of the test microorganisms with minimum concentrations ranging from 0.65 - 5 mg/ml. Candida species were the least sensitive while S. pneumonia and S. aureus clinical isolates were the most sensitive microbes. The crude extract of P. guajava leaves at the dose levels of 300 and 500 mg/ml significantly decreased carrageenan-induced paw oedema for 5 h after administration of the extract (p &lt;0.001). The performance profiles of the oral gel and mouth wash formulations of the total extract (10% w/w) of P. guajava were also evaluated. Both gels and mouth wash formulations were active against all test microbes. The antifungal activities of the formulated oral gels were better than the commercially available oral gel product, Daktarin.Keywords: Psidium guajava L., antimicrobial activity, anti-inflammatory activity, oral gels, mouthwash

Structural characterization and antimicrobial properties of silver nanoparticles prepared by inverse microemulsion method

Silver nanoparticles have been synthesized in the inverse microemulsions formed using three different surfactants viz., cetyl-trimethyl ammonium bromide (CTAB), Tergitol and Triton X-100. We have done a systematic study of the effect of the surfactants on the particle size and properties of the silver nanoparticles. Microscopic studies show the formation of spheres, cubes and discs shaped silver nanostructures with the size in the range from 8 to 40nm. Surface plasmon resonance (SPR) peak was observed around 400nm and 500nm. In addition to SPR some extra peaks have also been observed due to the formation of silver metal clusters. The surface area increases from 3.45 to 15.06m2/g with decreasing the size of silver nanoparticles (40–8nm). To investigate the antimicrobial activity of silver nanoparticles, the nanoparticles were tested against the yeast, Candida albicans and the bacterium, E. coli. The results suggest very good antimicrobial activity of the silver nanoparticles against the test microbes. The mode of action of the antimicrobial activity was also proposed.

Procedural Revision to the Use-Dilution Methods: Establishment of Maximum Log Density Value for Test Microbes on Inoculated Carriers

(Staphylococcus aureus) and 964.02 (Pseudomonas aeruginosa), were revised in 2009 to include a standardized procedure to measure the log density of the test microbe and to establish a minimum mean log density value of 6.0 (geometric mean of 1.0 x 10(6) CFU/carrier) to qualify the test results. This report proposes setting a maximum mean log density value of 7.0 (geometric mean of 1.0 x 10(7) CFU/carrier) to further standardize the procedure. The minimum value was based on carrier count data collected by four laboratories over an 8-year period (1999-2006). The data have been updated to include an additional 4 years' worth of data (2006-2010) collected by the same laboratories. A total of 512 tests were conducted on products bearing claims against P. aeruginosa and S. aureus with and without an organic soil load (OSL) added to the inoculum (as specified on the product label claim). Six carriers were assayed in each test, for a total of 3072 carriers. Mean log densities for each of the 512 tests were at least 6.0. With the exception of two tests, one for P. aeruginosa without OSL and one for S. aureus with OSL, the mean log densities did not exceed 7.5 (geometric mean of 3.2 x 10(7) CFU/carrier). Across microbes and OSL treatments, the mean log density (+/- SEM) was 6.80 (+/- 0.07) per carrier (a geometric mean of 6.32 x 10(6) CFUlcarrier) and acceptable repeatability (0.28) and reproducibility (0.31) SDs were exhibited. A maximum mean log density per carrier of 7.0 is being proposed here as a validity requirement for S. aureus and P. aeruginosa. A modification to the method to allow for dilution of the final test cultures to achieve carrier counts within 6.0-7.0 logs is also being proposed. Establishing a range of 6.0-7.0 logs will help improve the reliability of the method and should allow for more consistent results within and among laboratories.

Ecotoxicological effects of decabromodiphenyl ether and cadmium contamination on soil microbes and enzymes

The ecotoxicological effects of decabromodiphenyl ether (BDE209) and cadmium (Cd) contamination on soil culturable microbial population, enzyme activity and bacterial community structure were investigated. Results of the indoor incubation test runs performed on many series of control and contaminated soil samples have demonstrated some notable toxic effects due to long term exposure to either or both contaminants. The two contaminants produced notable yet different toxic effects on the test microbes; the population of the exposed species generally declined according to certain dose–response relationships. The soil culturable microbial population and enzyme activity data show that the sensitivity to one or both contaminants followed the order of: bacteria>fungi>actinomycete and urease>saccharase, respectively. The interaction between BDE209 and Cd was dependent on both the exposure dose and time and that the joint toxic effects were synergistic, antagonistic or additive. The PCR-DGGE analysis data of species composition and richness suggest the synergistic combined effects on bacterial community structure during the 30d exposure. Pseudomonas tuomuerensis strain CCM 7280 and Pseudomonas alcaliphila strain AL15-21 were enriched, indicating these species might be major functional populations and highly tolerant. Such observations have provided the useful information of potential ecotoxicological effects of BDE209 and Cd contamination in the environment.