Elucidation of the growth stimulating mechanism of previously uncultured microorganisms

2017 Fiscal Year Final Research Report

• Project/Area Number: 26450093
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Applied microbiology
• Research Institution: Hiroshima University
• Principal Investigator: MURAKAMI CHIHO 広島大学, 工学研究科, 日本学術振興会特別研究員(RPD) (50649077)
• Co-Investigator(Kenkyū-buntansha): 青井 議輝 広島大学, 先端物質科学研究科, 准教授 (40386636)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 難培養性微生物 / 亜硝酸酸化細菌 / 増殖促進因子

Outline of Final Research Achievements

Previously uncultured microorganisms Nitrospira which are also nitrite oxidizing microorganisms resist the cultivation of agar plates. Nitrospira are co-existing with heterotrophs in the enrichment culture. Growth of those heterotrophs are completely dependent on the organic compounds excreted from autotrophs as metabolic by-products. However, it is unclear whether the symbiotic relationships are commensal or mutualistic.
Then we screened 16 isolates of heterotrophs, co-cultured with and tested growth promoting activity on Nitrospira. The growth of Nitrospira was clearly stimulated by co-cultivation with 4 isolates, suggesting to have a benefit to be co-existing with each other. We next tested those isolates to identify whether the growth promoting on Nitrospira are derived from, 1) removal of inhibiting factor for Nitrospira or, 2) supply of growth promoting factor. The result suggested that heterotrophs provide unknown growth promoting factor to Nitrospira.

Free Research Field

環境微生物学