Ariyo Kanno

Potential bioremediation of mercury-contaminated substrate using filamentous fungi isolated from forest soil

The use of filamentous fungi in bioremediation of heavy metal contamination has been developed recently. This research aims to observe the capability of filamentous fungi isolated from forest soil for bioremediation of mercury contamination in a substrate. Six fungal strains were selected based on their capability to grow in 25 mg/L Hg(2+)-contaminated potato dextrose agar plates. Fungal strain KRP1 showed the highest ratio of growth diameter, 0.831, thus was chosen for further observation. Identification based on colony and cell morphology carried out by 18S rRNA analysis gave a 98% match to Aspergillus flavus strain KRP1. The fungal characteristics in mercury(II) contamination such as range of optimum pH, optimum temperature and tolerance level were 5.5-7 and 25-35°C and 100 mg/L respectively. The concentration of mercury in the media affected fungal growth during lag phases. The capability of the fungal strain to remove the mercury(II) contaminant was evaluated in 100 mL sterile 10 mg/L Hg(2+)-contaminated potato dextrose broth media in 250 mL Erlenmeyer flasks inoculated with 10(8) spore/mL fungal spore suspension and incubation at 30°C for 7 days. The mercury(II) utilization was observed for flasks shaken in a 130 r/min orbital shaker (shaken) and non-shaken flasks (static) treatments. Flasks containing contaminated media with no fungal spores were also provided as control. All treatments were done in triplicate. The strain was able to remove 97.50% and 98.73% mercury from shaken and static systems respectively. A. flavus strain KRP1 seems to have potential use in bioremediation of aqueous substrates containing mercury(II) through a biosorption mechanism.

Statistical Combination of Spatial Interpolation and Multispectral Remote Sensing for Shallow Water Bathymetry

There is often a need for making a high-resolution or a complete bathymetric map based on sparse point measurements of water depth. Well-known feasible methods for this problem include spatial interpolation and passive remote sensing using readily available multispectral imagery, whose accuracies depend strongly on geometric and optical conditions, respectively. For a more accurate and robust water-depth mapping, in this letter, the two methods are combined into a new method in a statistically reasonable and beneficial manner. The new method is based on a semiparametric regression model that consists of a parametric imagery-based term and a nonparametric spatial interpolation term that complement one another. An accuracy comparison in a test site shows that the new method is more accurate than either of the existing methods when sufficient training data are available and far more accurate than the spatial interpolation method when the training data are scarce.

Delignification of disposable wooden chopsticks waste for fermentative hydrogen production by an enriched culture from a hot spring

Hydrogen (H2) production from lignocellulosic materials may be enhanced by removing lignin and increasing the porosity of the material prior to enzymatic hydrolysis. Alkaline pretreatment conditions, used to delignify disposable wooden chopsticks (DWC) waste, were investigated. The effects of NaOH concentration, temperature and retention time were examined and it was found that retention time had no effect on lignin removal or carbohydrate released in enzymatic hydrolysate. The highest percentage of lignin removal (41%) was obtained with 2% NaOH at 100°C, correlated with the highest carbohydrate released (67 mg/g pretreated DWC) in the hydrolysate. An enriched culture from a hot spring was used as inoculum for fermentative H2 production, and its optimum initial pH and temperature were determined to be 7.0 and 50°C, respectively. Furthermore, enzymatic hydrolysate from pretreated DWC was successfully demonstrated as a substrate for fermentative H2 production by the enriched culture. The maximum H2 yield and production rate were achieved at 195 mL H2/g total sugars consumed and 116 mL H2/(L·day), respectively.

Comparison of disinfection effect of pressurized gases of CO2, N2O, and N2 on Escherichia coli

Based on the production of gas bubbles with the support of a liquid film-forming apparatus, a device inducing contact between gas and water was used to inactivate pathogens for water disinfection. In this study, the inactivation effect of CO2 against Escherichia coli was investigated and compared with the effects of N2O and N2 under the same pressure (0.3-0.9 MPa), initial concentration, and temperature. The optimum conditions were found to be 0.7 MPa and an exposure time of 25 min. Under identical treatment conditions, a greater than 5.0-log reduction in E. coli was achieved by CO2, while 3.3 log and 2.4 log reductions were observed when N2O and N2 were used, respectively. Observation under scanning electron microscopy and measurement of bacterial cell substances by UV-absorbance revealed greater cell rupture of E. coli following treatment with CO2 than when treatment was conducted using N2O, N2 and untreated water. The physical effects of the pump, acidified characteristics and the release of intracellular substances caused by CO2 were bactericidal mechanism of this process. Overall, the results of this study indicate that CO2 has the disinfection potential without undesired by-product forming.

Modified Lyzenga's Method for Estimating Generalized Coefficients of Satellite-Based Predictor of Shallow Water Depth

The multispectral method for the remote sensing of water depth proposed by Lyzenga has been widely applied to shallow-water bathymetry by researchers. The predictor of water depth used in this method is a linear function of image-derived variables for each visible band. The coefficients of the predictor are estimated by using a number of pixels with known depth as training data; this depth information is usually obtained by performing in situ depth measurements. Theoretically, if an appropriate set of coefficients is chosen, the predictor can be insensitive to some variations in the optical properties of the bottom material and water. However, it is sensitive to variations in atmospheric and water surface transmittance and sun and satellite elevations. Consequently, a single set of coefficients cannot always be applied to multiple images. In this letter, we propose a simple method to estimate a general set of coefficients for Lyzengas predictor that is relatively less affected by the aforementioned factors. We derive and utilize the theoretical fact that these factors affect only the intercept (constant term) of the predictor function. We demonstrate the effectiveness of the proposed method using WorldView-2 images of coral reefs. The proposed method will enable the application of a single set of coefficients (except for the intercept) to a broad range of images. This will significantly reduce the number of pixels with known depth required for the prediction of an image and thereby improve the feasibility of remote sensing of water depth.

Shallow-Water Benthic Identification Using Multispectral Satellite Imagery: Investigation on the Effects of Improving Noise Correction Method and Spectral Cover

Lyzengas method is used widely for radiative transfer analysis because of its simplicity of application to cases of shallow-water coral reef ecosystems with limited information of water properties. WorldView-2 imagery has been used previously to study bottom-type identification in shallow-water coral reef habitats. However, this is the first time WorldView-2 imagery has been applied to bottom-type identification using Lyzengas method. This research applied both of Lyzengas methods: the original from 1981 and the one from 2006 with improved noise correction that uses the near-infrared (NIR) band. The objectives of this study are to examine whether the utilization of NIR bands in the correction of atmospheric and sea-surface scattering improves the accuracy of bottom classification, and whether increasing the number of visible bands also improves accuracy. Firstly, it has been determined that the improved 2006 correction method, which uses NIR bands, is only more accurate than the original 1981 correction method in the case of three visible bands. When applying six bands, the accuracy of the 1981 correction method is

Generalized Lyzenga's Predictor of Shallow Water Depth for Multispectral Satellite Imagery

Multispectral satellite remote sensing can predict shallow-water depth distribution inexpensively and exhaustively, but it requires many in situ measurements for calibration. To extend its feasibility, we improved a recently developed technique, for the first time, to obtain a generalized predictor of depth. We used six WorldView-2 images and obtained a predictor that yielded a 0.648 m root-mean-square error against a dataset with a 5.544 m standard deviation of depth. The predictor can be used with as few as two pixels with known depth per image, or with no depth data, if only relative depth is needed.

The Potential use of Trichoderma Viride Strain FRP3 in Biodegradation of the Herbicide Glyphosate

ABSTRACT A Trichoderma strain was isolated and then identified as Trichoderma viride strain FRP3 based on colony morphology, cell morphology and 18S rRNA analysis. The optimum temperature for growth of T. viride strain FRP3 was found to be 25–27°C. This Trichoderma strain could grow well in a wide range of pH (pH 4–6.5) and the optimum pH was 5 and 5.5. Trichoderma viride strain FRP3 was also evaluated in vitro for potential use in bioremediation of soils contaminated with the herbicide glyphosate, through observation of the growth profiles and the total phosphorus in culture medium containing glyphosate as the sole phosphorus source. The growth profiles of Trichoderma viride strain FRP3 showed considerable growth in culture medium containing glyphosate as the sole phosphorus source. This result was supported by the decrease in the total phosphorus, which indicates a utilization process for glyphosate and perhaps shows that there may be a mechanism for degradation of this compound. This study indicates that the treatment of soil with Trichoderma viride strain FRP3 could be useful in some areas where this herbicide is extensively used.

Which Spectral Bands of WorldView-2 Are Useful in Remote Sensing of Water Depth? A Case Study in Coral Reefs

Although visible bands of high-resolution multispectral imagery are used for bathymetry, the relative utility of different bands is poorly understood. Therefore, we evaluated the relative utility of the six visible bands of WorldView-2. We statistically selected the visible bands that gave the best accuracy under different situations, tallying how often each band was included in the best combination. The average frequency was greater than 50% for every band and differed between bands by only 17%. We conclude that all visible bands are useful for remote sensing of water depth, although the utility depends on the image and number of training pixels available.

Inactivation effect of pressurized carbon dioxide on bacteriophage Qβ and ΦX174 as a novel disinfectant for water treatment

The inactivation effects of pressurized CO2 against bacteriophage Qβ and ΦX174 were investigated under the pressure of 0.3-0.9 MPa, initial concentration of 10(7)-10(9) PFU/mL, and temperature of 17.8°C-27.2°C. The optimum conditions were found to be 0.7 MPa and an exposure time of 25 min. Under identical treatment conditions, a greater than 3.3-log reduction in bacteriophage Qβ was achieved by CO2, while a nearly 3.0 log reduction was observed for phage ΦX174. The viricidal effects of N2O (an inactivation gas with similar characteristics to CO2), normal acid (HCl), and CO2 treatment with phosphate buffered saline affirmed the chemical nature of CO2 treatment. The pumping cycle, depressurization rate, and release of intracellular substances caused by CO2 were its viricidal mechanisms. The results indicate that CO2 has the potential for use as a disinfectant without forming disinfection by-products.