To identify exoelectrogens involved in the generation of electricity from complex organic matter in coastal sediment (CS) microbial fuel cells (MFCs), MFCs were inoculated with CS obtained from tidal flats and estuaries in the Tokyo bay and supplemented with starch, peptone, and fish extract as substrates. Power output was dependent on the CS used as inocula and ranged between 100 and 600 mW m -2 (based on the projected area of the anode). Analyses of anode microbiomes using 16S rRNA gene amplicons revealed that the read abundance of some bacteria, including those related to Shewanella algae, positively correlated with power outputs from MFCs. Some fermentative bacteria were also detected as major populations in anode microbiomes. A bacterial strain related to S. algae was isolated from MFC using an electrode plate-culture device, and pure-culture experiments demonstrated that this strain exhibited the ability to generate electricity from organic acids, including acetate. These results suggest that acetate-oxidizing S. algae relatives generate electricity from fermentation products in CS-MFCs that decompose complex organic matter.

Currently, there is considerable interest in ketone metabolism owing to the benefits for human health. Conventionally, strict dietary restrictions on carbohydrates are required to increase plasma ketone levels, while supplementation with d-b-hydroxybutyric acid (d-BHB) can easily increase plasma ketone levels. We hypothesized that a daily intake of d-BHB could promote weight loss, especially through fat reduction. Herein, d-BHB (OKETOA TM ) was produced via a proprietary fermentation process from sugar. In this randomized, double-blind, placebo-controlled study, we assessed the safety and fat-reduction effects after 12 wk of daily ingestion of d-BHB (2.9 g) in 22 healthy Japanese adults and 22 control participants. Blood samples were collected pre-and post-treatment. Blood chemistry, anthropometric variables, and the body composition of the participants were investigated. Data analysis revealed that visceral fat at 12 wk significantly decreased by 9.0 cm 2 (p5 0.037), as evidenced by analysis of covariance. Blood parameters and body condition showed no significant differences between the two groups, and the participants reported no adverse effects or discomfort. Furthermore, data were analyzed by regrouping the participants. After removing one suspicious diabetes participant, all others showed significant decreases in visceral fat, body weight, BMI, and fat weight. Additionally, those aged under 50 y old had significantly decreased abdominal circumference and body fat percentage, in addition to visceral fat, body weight, BMI, and fat weight. Overall, our findings indicate that daily d-BHB intake may reduce body fat without dieting or exercise intervention. This study was registered with the UMIN Clinical Trials Registry as UMIN000045322.