Removal of Nitrate Nitrogen by Rhodotorula graminis Immobilized in Alginate Gel for Groundwater Treatment

Groundwater is the source of all tap water in Kumamoto City, Japan. However, the concentration of nitrate nitrogen (NO3−-N) tends to increase every year due to the influences of overfertilization, field disposal of livestock manure, and inflow of domestic wastewater. A heterotrophic nitrification–aerobic denitrification (HN-AD) system is an attractive approach for nitrate-nitrogen removal. In this study, Rhodotorula graminis NBRC0190, a naturally occurring red yeast that shows high nitrogen removal performance in glucose, was immobilized on calcium alginate hydrogel beads. NO3−-N removal efficiency exceeded 98% in the region of NO3−-N concentration below 10 mg/L in the model groundwater. Even after the same treatment was repeated five times, the denitrification performance of the R. gra immobilized alginate hydrogel beads was maintained. Finally, when this treatment method was applied to actual groundwater in Kumamoto City, it was possible to make the water of even higher quality

Impact of tissue macrophage proliferation on peripheral and systemic insulin resistance in obese mice with diabetes

Introduction Obesity-related insulin resistance is a widely accepted pathophysiological feature in type 2 diabetes. Systemic metabolism and immunity are closely related, and obesity represents impaired immune function that predisposes individuals to systemic chronic inflammation. Increased macrophage infiltration and activation in peripheral insulin target tissues in obese subjects are strongly related to insulin resistance. Using a macrophage-specific proliferation inhibition mouse model (mac-p27Tg), we previously reported that suppressed plaque inflammation reduced atherosclerosis and improved plaque stabilization. However, the direct evidence that proliferating macrophages are responsible for inducing insulin resistance was not provided.Research design and methods The mac-p27Tg mice were fed a high-fat diet, and glucose metabolism, histological changes, macrophage polarization, and tissue functions were investigated to reveal the significance of tissue macrophage proliferation in insulin resistance and obesity.Results The mac-p27Tg mice showed improved glucose tolerance and insulin sensitivity, along with a decrease in the number and ratio of inflammatory macrophages. Obesity-induced inflammation and oxidative stress was attenuated in white adipose tissue, liver, and gastrocnemius. Histological changes related to insulin resistance, such as liver steatosis/fibrosis, adipocyte enlargement, and skeletal muscle fiber transformation to fast type, were ameliorated in mac-p27Tg mice. Serum tumor necrosis factor alpha and free fatty acid were decreased, which might partially impact improved insulin sensitivity and histological changes.Conclusions Macrophage proliferation in adipose tissue, liver, and skeletal muscle was involved in promoting the development of systemic insulin resistance. Controlling the number of tissue macrophages by inhibiting macrophage proliferation could be a therapeutic target for insulin resistance and type 2 diabetes