Determination of the safety of Halomonas sp. KM-1-derived D-ß-hydroxybutyric acid and its fermentation-derived impurities in mice and Japanese adults.

The use of halophilic bacteria in industrial chemical and food production has received great interest because of the unique properties of these bacteria; however, their safety remains under investigation. Halomonas sp. KM-1 intracellularly stores poly-D-ß-hydroxybutyric acid under aerobic conditions and successively secretes D-ß-hydroxybutyric acid (D-BHB) under microaerobic conditions. Therefore, we tested the safety of Halomonas sp. KM-1-derived D-BHB and the impurities generated during D-BHB manufacturing at a 100-fold increased concentration in acute tests using mice and daily intake of 16.0 g D-BHB in Japanese adults for 12 weeks. In the mice test, there were no abnormalities in the body weights or health of mice fed the purified D-BHB or its impurities. In the Japanese adult test, blood parameters and body condition showed no medically problematic fluctuations. These findings indicate that Halomonas sp. KM-1 is safe and can be used for commercial production of D-BHB and its derivatives.

Production of docosahexaenoic acid by a novel isolated Aurantiochytrium sp. 6-2 using fermented defatted soybean as a nitrogen source for sustainable fish feed development.

We focused on the production of docosahexaenoic acid (DHA)-containing microbial lipids by Aurantiochytrium sp. using of defatted soybean (DS) as a nitrogen source. Defatted soybean is a plant biomass that could provide a sustainable supply at a low cost. Results showed that Aurantiochytrium sp. could not directly assimilate the DS as a nitrogen source but could grow well in a medium containing DS fermented with rice malt. When cultivated in a fermented DS (FDS) medium, Aurantiochytrium sp. showed vigorous growth with the addition of sufficient sulfate and chloride ions as inorganic nutrients without seawater salt. A novel isolated Aurantiochytrium sp. 6-2 showed 15.8 ± 3.4 g/L DHA productivity (in 54.8 ± 12.1 g/L total fatty acid production) in 1 L of the FDS medium. Therefore, DHA produced by Aurantiochytrium sp. using FDS enables a stable and sustainable DHA supply and could be an alternative source of natural DHA derived from fish oil.

Daily Intake of D-ß-Hydroxybutyric Acid (D-BHB) Reduces Body Fat in Japanese Adult Participants: A Randomized, Double-Blind, Placebo-Controlled Study.

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-ß-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 (OKETOATM) 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 cm2 (p=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.

Shewanella algae Relatives Capable of Generating Electricity from Acetate Contribute to Coastal-Sediment Microbial Fuel Cells Treating Complex Organic Matter.

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.