Simultaneous aerobic nitrogen and phosphate removal capability of novel salt-tolerant strain, Pseudomonas mendocina A4: Characterization, mechanism and application potential.

A salt-tolerant strain, Pseudomonas mendocina A4, was isolated from brackish-water ponds showing simultaneous heterotrophic nitrification-aerobic denitrification and phosphorus removal capability. The optimal conditions for nitrogen and phosphate removal of strain A4 were pH 7-8, carbon/nitrogen ratio 10, phosphorus/nitrogen ratio 0.2, temperature 30 °C, and salinity range of 0-5 % using sodium succinate as the carbon source. The nitrogen and phosphate removal efficiencies were 96-100 % and 88-96 % within 24 h, respectively. The nitrogen and phosphate removal processes were matched with the modified Gompertz model, and the underlying mechanisms were confirmed by the activities of key metabolic enzymes. Under 10 % salinity, the immobilization technology was employed to enhance the nitrogen and phosphate removal efficiencies of strain A4, achieving 87 % and 76 %, respectively. These findings highlight the potential application of strain A4 in both freshwater and marine culture wastewater treatment.

Scalable Production of Biomedical Microparticles via High-Throughput Microfluidic Step Emulsification.

Drug microcarriers are widely used in disease treatment, and microfluidics is well established in the preparation of microcarrier particles. A proper design of the microfluidic platform toward scalable production of drug microcarriers can extend its application values in wound healing, where large numbers of microcarriers are required. Here, a microfluidic step emulsification method for the preparation of monodisperse droplets is presented. The droplet size depends primarily on the microchannel depth rather than flow rate, making the system robust for high-throughput production of droplets and hydrogel microparticles. Based on this platform, basic fibroblast growth factor (bFGF) is uniformly encapsulated in the microparticles, and black phosphorus (BP) is incorporated for controllable release via near-infrared (NIR) stimulation. The microparticles serve as drug carriers to be applied to the wound site, inducing angiogenesis and collagen deposition, thereby accelerating wound repair. These results indicate that the step emulsification technique provides a promising solution to scalable production of drug microcarriers for wound healing as well as tissue regeneration.

Acrylamide-Hemoglobin Adduct Levels in a Japanese Population and Comparison with Acrylamide Exposure Assessed by the Duplicated Method or a Food Frequency Questionnaire.

The levels of hemoglobin adducts of acrylamide (AA-Hb), a biomarker of acrylamide exposure, have not been reported for Japanese subjects. Herein, we determined the AA-Hb levels in a Japanese population and compared them with the estimated dietary intake from the duplicate diet method (DM) and a food frequency questionnaire (FFQ). One-day DM samples, FFQ, and blood samples were collected from 89 participants and analyzed for acrylamide. AA-Hb was analyzed using liquid chromatography tandem mass spectrometry and the N-alkyl Edman method. Participants were divided into tertiles of estimated acrylamide intake and geometric means (GMs) of AA-Hb adjusted for sex and smoking status. A stratified analysis according to smoking status was also performed. The average AA-Hb levels for all participants, never, past, and current smokers were 46, 38, 65, and 86 pmol/g Hb, respectively. GMs of AA-Hb levels in all participants were significantly associated with tertiles of estimated acrylamide intake from DM (p for trend = 0.02) and FFQ (p for trend = 0.04), although no association with smokers was observed. AA-Hb levels reflected smoking status, which were similar to values reported in Western populations, and they were associated with estimated dietary intake of acrylamide when adjusted for sex and smoking status.

Fiber-Integrated Reversibly Wavelength-Tunable Nanowire Laser Based on Nanocavity Mode Coupling.

As an ideal miniaturized light source, wavelength-tunable nanolasers capable of emitting a wide spectrum stimulate intense interests for on-chip optoelectronics, optical communications, and spectroscopy. However, realization of such devices remains a major challenge because of extreme difficulties in achieving continuously reversibly tunable gain media and high quality (Q)-factor resonators on the nanoscale simultaneously. Here, exploiting single bandgap-graded CdSSe NWs and a Fabry-Pérot/whispering gallery mode (FP/WGM) coupling cavity, a free-standing fiber-integrated reversibly wavelength-tunable nanolaser covering a 42 nm wide spectrum at room temperature with high stability and reproducibility is demonstrated. In addition, a 1.13 nm tuning spectral resolution is realized. The substrate-free device design enables integration in optical fiber communications and information. With reversible and wide, continuous tunability of emission color and precise control per step, our work demonstrates a general approach to nanocavity coupling affording high Q-factors, enabling an ideal miniaturized module for a broad range of applications in optics and optoelectronics, with optical fiber integration.

Dietary exposure to acrylamide in a group of Japanese adults based on 24-hour duplicate diet samples.

Acrylamide is a probable human carcinogen and known human neurotoxin that can be generated in food through heating. Using a mathematical modelling approach, our previous study estimated long-term average dietary exposure to acrylamide in the Japanese people; however, the validity of these estimates remained unknown. Here, we aimed to obtain a more accurate estimate of acrylamide exposure that would reflect the usual practice of heat processing and consumption of foods in the population. We collected duplicate diet samples and dietary records during 24 h from a group of Japanese adults. A total of 110 duplicate diet samples were analysed for acrylamide by LC-MS/MS. Data from individual dietary records were used to examine the association between dietary acrylamide exposure and consumption of selected food groups (e.g., coffee, tea, confectioneries, and vegetables prepared at high temperature [deep-frying, stir-frying, sautéing, and baking]). Of the 110 homogenised diet samples, 108 contained detectable levels of acrylamide. Dietary exposure to acrylamide ranged from 8 to 1582 ng/kg body weight (bw)/day, with the mean value of 215 ng/kg-bw/day and median value of 143 ng/kg-bw/day. This mean value was higher than the value we previously estimated for Japanese adults using a mathematical approach. Multiple linear regression analysis showed log dietary acrylamide exposure was significantly associated with consumption of coffee and vegetables prepared at high temperature during 24-hr of sampling (adj. R2 = 0.250, p < 0.001). We revealed significant difference in dietary acrylamide exposure between participants who had coffee and vegetables prepared at high temperature (median, 169 ng/kg-bw/day; range, 35-1224 ng/kg-bw/day, n = 42) and those who had none of them (median, 75 ng/kg-bw/day; range, 8-311 ng/kg-bw/day, n = 15) (Steel-Dwass test, p < 0.05).

Development of the dichlorvos-ammonia (DV-AM) method for the visual detection of aflatoxigenic fungi.

Aflatoxins (AFs) are carcinogenic and toxic secondary metabolites produced mainly by Aspergillus flavus and Aspergillus parasiticus. To monitor and regulate the AF contamination of crops, a sensitive and precise detection method for these toxigenic fungi in environments is necessary. We herein developed a novel visual detection method, the dichlorvos-ammonia (DV-AM) method, for identifying AF-producing fungi using DV and AM vapor on agar culture plates, in which DV inhibits the esterase in AF biosynthesis, causing the accumulation of anthraquinone precursors (versiconal hemiacetal acetate and versiconol acetate) of AFs in mycelia on the agar plate, followed by a change in the color of the colonies from light yellow to brilliant purple-red by the AM vapor treatment. We also investigated the appropriate culture conditions to increase the color intensity. It should be noted that other species producing the same precursors of AFs such as Aspergillus nidulans and Aspergillus versicolor could be discriminated from the Aspergillus section Flavi based on the differences of their phenotypes. The DV-AM method was also useful for the isolation of nonaflatoxigenic fungi showing no color change, for screening microorganisms that inhibit the AF production by fungi, and for the characterization of the fungi infecting corn kernels. Thus, the DV-AM method can provide a highly sensitive and visible indicator for the detection of aflatoxigenic fungi.

Limited surveillance of fumonisins in brown rice and wheat harvested in Japan.

Fumonisins are mycotoxins mainly produced by Fusarium verticillioides, which is a major contaminant of corn. However, there are sporadic reports of fumonisin contamination in wheat worldwide. The rice adherent fungus Gibberella fujikuroi is taxonomically closely related to F. verticillioides. Therefore, the potential risk of fumonisin contamination in rice and wheat is significant. Previously, a sensitive detection method utilizing liquid chromatography with tandem electrospray mass spectrometry (LC-ESI-MS-MS) was developed for the determination of fumonisins in brown rice. In the present study, the incidence of fumonisins in brown rice and wheat harvested in Japan was investigated using LC-ESI-MS-MS. Forty-eight rice samples and 47 wheat samples were screened and analyzed for the major B-type fumonisins: fumonisin B1 (FB1) and fumonisin B2 (FB2). About 1 kg of rice or wheat seed was divided into three subsamples, and 10 g from each subsample was used for the analysis. The limits of detection were 0.012 and 0.011 mg/kg for FBt and FB2, respectively, in rice samples and 0.010 and 0.008 mg/kg for FB1 and FB2, respectively, in wheat samples. The mean (standard deviation) recoveries of FB1 spiked at 0.50 mg/kg into toxin-free rice and wheat samples were 77.6 (4.2)% and 84.5 (3.1)%, respectively. One of the wheat samples was positive for FBt with a value greater than the limit of detection,but no fumonisin was found in any of the rice samples. This is the first report of fumonisins detected in Japanese wheat.

Mycotoxins in rice.

Mycotoxin contamination in rice is usually lower as in wheat or corn. However, there are some reports that rice has been contaminated with mycotoxins such as aflatoxin B1, B2, G1, G2 (AFS), citrinin, deoxynivalenol (DON), fumonisin B1, B2, B3 (FMS), fusarenon-X (Fus.-X), nivalenol (NIV), ochratoxin A (OTA), sterigmatocystin (STE), and zearalenone. Rice in Japan is preserved in warehouses where moisture content and temperature are regulated. Therefore, mycotoxin contamination from post harvest fungal growth occurs very seldom. Trichothecenes, aflatoxins, and STE in rice were recently analyzed in our laboratory. In 1998, a typhoon struck before rice harvesting in Japan, and the unpolished rice was found to be stained brown. Samples were collected and analyzed for the presence of trichothecenes. Mycotoxins DON, Fus.-X, and NIV were detected and confirmed with GC-MS. The quantity of trichothecenes was determined using GC-ECD. STE is a carcinogenic mycotoxin produced by Aspergillus versicolor and some other fungi. STE contamination of rice was studied in our laboratory since 1973. GC-MS, LC-MS, LC-MS/MS, and LC-UV methods for STE determination were examined, giving good results for the LC-UV method using a photo diode array detector. Different techniques for the extraction of STE from rice were also studied. Finally, brown rice was ground, and the ground rice was extracted with acetonitrile-water. An Autoprep MF-A 1000 column was used to clean up AFS and STE. The cleaned-up extract was analyzed with HPLC-UV. Forty-eight brown rice samples were analyzed, and none of them were contaminated with STE. These rice samples were also analyzed for AFS and FMS, and none of the samples were contaminated. The Ministry of Agriculture, Forestry and Fisheries in Japan is making the appropriate Institutes develop analytical methods for mycotoxins and survey mycotoxin contamination on rice as well as wheat, corn, and some other cereals.