Investigating the Extracellular-Electron-Transfer Mechanisms and Kinetics of Shewanella decolorationis NTOU1 Reducing Graphene Oxide via Lactate Metabolism.

Microbial graphene oxide reduction is a developing method that serves to reduce both production costs and environmental impact in the synthesis of graphene. This study demonstrates microbial graphene oxide reduction using Shewanella decolorationis NTOU1 under neutral and mild conditions (pH = 7, 35 °C, and 1 atm). Graphene oxide (GO) prepared via the modified Hummers' method is used as the sole solid electron acceptor, and the characteristics of reduced GO (rGO) are investigated. According to electron microscopic images, the surface structure of GO was clearly changed from smooth to wrinkled after reduction, and whole cells were observed to be wrapped by GO/rGO films. Distinctive appendages on the cells, similar to nanowires or flagella, were also observed. With regard to chemical-bonding changes, after a 24-h reaction of 1 mg mL-1, GO was reduced to rGO, the C/O increased from 1.4 to 3.0, and the oxygen-containing functional groups of rGO were significantly reduced. During the GO reduction process, the number of S. decolorationis NTOU1 cells decreased from 1.65 × 108 to 1.03 × 106 CFU mL-1, indicating the bactericide effects of GO/rGO. In experiments adding consistent concentrations of initial bacteria and lactate, it was shown that with the increase of GO additions (0.5-5.0 mg mL-1), the first-order reaction rate constants (k) of lactate metabolism and acetate production increased accordingly; in experiments adding consistent concentrations of initial bacteria and GO but different lactate levels (1 to 10 mM), the k values of lactate metabolism did not change significantly. The test results of adding different electron transfer mediators showed that riboflavin and potassium ferricyanide were able to boost GO reduction, whereas 2,6-dimethoxy-1,4-benzoquinone and 2,6-dimethyl benzoquinone completely eliminated bacterial activity.

[Clinical effects of Fu Fang Ya Tong Ding on gingivitis and pericoronitis].

OBJECTIVE: To evaluate the clinical effects of Fu Fang Ya Tong Ding on treatment of gingivitis and pericoronitis. METHODS: 120 clinical patients with gingivitis or pericoronitis were randomly divided into 3 groups (40 patients in each group). After routine rinse treatment for all patients, patients in the test group were treated with Fu Fang Ya Tong Ding, patients in the positive group were treated with iodine glycerol, while that time patients in the negative group received no treatment anymore. Ten minutes after treatment, visual analogue scale (VAS) was used to record the severity of pain for each patient. 3 days and 7 days later, pain and inflammation degree were also recorded by pain three-degree scoring method and index of gingivitis. The total treatment effects were evaluated under a comprehensive clinical treatment standard. RESULTS: 10 minutes after treatment, 40.0% of patients in the test group had almost no pain, while no obvious reduction of pain was found in the control group. 3 days, 7 days after the treatment, 92.5%, 95.0% of patients in the test group had no pain, and 55.0%, 90.0% of patients in the positive group had no pain. In the negative group, there were 47.5% of patients which pain was still remained in 7 days. 7 days after treatment, gingival index in the test group reduced by 25.0% and 42.8% compared with the positive and negative groups (P<0.05). 3 days after treatment, 62.5%, 45.0% and 30.0% patients separately in the test, positive and negative groups manifested good effects under the comprehensive clinical treatment standard; after 7 days, 97.5%, 92.5% and 77.5% patients in the 3 groups manifested good effect. The group using Fu Fang Ya Tong Ding had better effects than groups using iodine glycerol or only applying routine rinsing treatment group (P<0.05). CONCLUSION: Fu Fang Ya Tong Ding can treat gingivitis and pericoronitis through significantly reducing inflammation and pain.

Molecular characterization and hydrogen production of a new species of anaerobe.

For the fermentative hydrogen production process with carbohydrates, isolation and identification of hydrogen-producing bacteria (HPB) with high yield and high evolution rate are very important. Improved Hungater rolling tube technique and plate method of culture bottle (PMCB) were used to enumerate and isolate the HPB. The HPB-Li and Ren (HPB-LR) medium was designed to inoculate and isolate HPB under temperature of 37 degrees C and pH of 4.0-6.7. In this study, an isolate of HPB with high yield and high evolution rate was isolated, named Rennanqilyf3 (R3), which is a gram-positive, straight rod, non-spore forming, encapsulated, strict anaerobe, with long peritrichous flagella and three to four metachromatic granules. It performs ethanol-type fermentation, and glucose is its optimum carbon source for hydrogen production. The 16S rDNA sequencing of the R3 isolate indicated that it might be a new species. The hydrogen production capacity of the R3 isolate varied with the glucose concentration and pH. The optimum glucose concentration was 12.0 g/L (with H2 yield of 58.6 mmolH2/L-culture) and the optimum initial pH was 5.5 (with H2 yield of 34.2 mmolH2/L-culture). The maximum rate of cell proliferation were 0.46 and 0.63 g/L when glucose concentration was 15.0 g/L and pH was 5.5, respectively. The maximum yields of ethanol and acetic acid were achieved when the glucose concentration was 12.0 g/L and the pH was 5.5.