Screening and Selection of Ferric Reducing Bacteria by Electrical Current for Microbial Fuel Cell

The efficiency of microbial fuel cell (MFC) performance depends on the competence of microorganisms on being an essential role in primarily converting organic compound into electricity. In this study, the possibility of using electrical current to select electrochemical active bacteria from sub-sediment for use in MFC was conducted. By using an alternating current (AC) of 0.6 - 12 mA and selective media, 16 Gram-positive ferric reducing bacteria (GP-FRB), 15 Gram-negative ferric reducing bacteria (GN-FRB) and 9 Gram-negative non FRB (GN-nonFRB) were characterized. GN-FRB and GP-FRB were obtained from the current of 0.6 - 6 and 9 - 12 mA, respectively. After tested in MFC, GN-FRB had a greater current density and power density than those from GN-nonFRB and GP-FRB. However, the greatest voltage was obtained from GP-FRB, followed by those of GN-nonFRB and GN-FRB, respectively. The highest current and power density of 13.33 mA/m2 and 0.32 mW/m2, respectively were from GN-FRB namely KL14 which was identified later as Proteus sp. This research could contribute a promising method for screening and selection of ferric reducing bacteria using electrical current. MFC inoculated with our selected bacteria could be a model for next study in wastewater treatment

Development of competitive lateral flow immunoassay coupled with silver enhancement for simple and sensitive salivary cortisol detection

Cortisol is known as a stress biomarker. The measurement of cortisol levels is an early warning indicator for health conditions and diagnosis of stress-related diseases. Herein, a lateral flow immunoassay using a gold nanoparticle label with a silver enhancement system was developed for the simple, sensitive and rapid detection of cortisol. The developed assay was based on a competitive platform of which cortisol-BSA conjugate was immobilized at the test zone to compete with an analyte. The quantitative analysis was performed using gold nanoparticles (AuNPs) as signal labeling. Sequentially, the silver enhancement solution was applied in order to enhance the sensitivity of the assay with the results easily seen by the naked eye. Using this system, the limit of detection (LOD) was found to be 0.5 ng/mL with a 3.6 fold more sensitive detection than without the enhancement system (LOD = 1.8 ng/mL). The salivary cortisol analysis was in the range of 0.5-150 ng/mL (R2 = 0.9984), which is in the clinical acceptable range. For the semi-quantitative analysis, the intensity color of the results was analyzed using an image processing program. The proposed method was successfully applied to detect cortisol in saliva. In addition, the results from our method also complied with the ones of those obtained by using the commercial enzyme-linked immunosorbent assay (ELISA). This developed assay offers great promise for a non-invasive screening test of salivary cortisol

Development and characterization of a novel, antimicrobial, sterile hydrogel dressing for burn wounds: single-step production with gamma irradiation creates silver nanoparticles and radical polymerization

Patients with burn wounds are susceptible to wound infection and sepsis. This research introduces a novel burn wound dressing that contains silver nanoparticles (SNPs) to treat infection in a 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS-Na(+) ) hydrogel. Silver nitrate was dissolved in AMPS-Na(+) solution and then exposed to gamma irradiation to form SNP-infused hydrogels. The gamma irradiation results in a cross-linked polymeric network of sterile hydrogel dressing and a reduction of silver ions to form SNPs infused in the hydrogel in a one-step process. About 80% of the total silver was released from the hydrogels after 72 h immersion in simulated body fluid solution; therefore, they could be used on wounds for up to 3 days. All the hydrogels were found to be nontoxic to normal human dermal fibroblast cells. The silver-loaded hydrogels had good inhibitory action against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. Results from a pilot study on a porcine burn model showed that the 5-mM silver hydrogel was efficient at preventing bacterial colonization of wounds, and the results were comparable to the commercially available silver dressings (Acticoat(TM) , PolyMem Silver(®) ). These results support its use as a potential burn wound dressing

Screening and Selection of Ferric Reducing Bacteria by Electrical Current for Microbial Fuel Cell

The efficiency of microbial fuel cell (MFC) performance depends on the competence of microorganisms on being an essential role in primarily converting organic compound into electricity. In this study, the possibility of using electrical current to select electrochemical active bacteria from sub-sediment for use in MFC was conducted. By using an alternating current (AC) of 0.6 - 12 mA and selective media, 16 Gram-positive ferric reducing bacteria (GP-FRB), 15 Gram-negative ferric reducing bacteria (GN-FRB) and 9 Gram-negative non FRB (GN-nonFRB) were characterized. GN-FRB and GP-FRB were obtained from the current of 0.6 - 6 and 9 - 12 mA, respectively. After tested in MFC, GN-FRB had a greater current density and power density than those from GN-nonFRB and GP-FRB. However, the greatest voltage was obtained from GP-FRB, followed by those of GN-nonFRB and GN-FRB, respectively. The highest current and power density of 13.33 mA/m2 and 0.32 mW/m2, respectively were from GN-FRB namely KL14 which was identified later as Proteus sp. This research could contribute a promising method for screening and selection of ferric reducing bacteria using electrical current. MFC inoculated with our selected bacteria could be a model for next study in wastewater treatment

Gamma irradiation versus microbial contamination of Thai medicinal herbs

Seventeen species of herbs established in Thai traditional remedies were microbially decontaminated by gamma-irradiation doses of 7.7 and 8.8 kGy. The herb samples were randomly collected four times from producers in Chiangmai during a 1-year period. These were tested, qualitatively and quantitatively, for total aerobic bacteria, Staphylococcus spp., Salmonella spp., coliform bacteria, and fungi before and after gamma treatment. No microorganisms were found after gamma treatment; and the color, aroma, and texture of the herbs remained normal. The applied dose of gamma irradiation was within the regulatory limits in Thailand (<10 kGy) and the main export country (USA< 30 kGy). Gamma irradiation is an effective treatment for microbial decontamination of Thai export herbs