Survival strategy of silicate-utilizing Bacillus species in activated sludge and the related excess sludge reduction

Research Project

Project/Area Number	25660061
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Applied microbiology
Research Institution	Hiroshima University
Principal Investigator	Ikeda Takeshi 広島大学, 先端物質科学研究科, 助教 (10505754)
Project Period (FY)	2013-04-01 – 2016-03-31
Project Status	Completed (Fiscal Year 2015)
Budget Amount *help	¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000) Fiscal Year 2015: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000) Fiscal Year 2014: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000) Fiscal Year 2013: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Keywords	細菌 / 胞子 / 活性汚泥
Outline of Final Research Achievements	Bacillus cereus and its close relatives take up soluble silicate (Si[OH]4) from the environment and accumulate it as insoluble silica (SiO2) in and around a spore coat layer. We hypothesized that silica deposition in Bacillus spores plays an important role in silicate-induced dominance of Bacillus species in activated sludge. Since some wastewater treatment plants use hypochlorite in addition to silicate to facilitate the predominance of Bacillus species, we investigated the mechanism underlying this and found that silica deposition enhances spore resistance to hypochlorite.