Isolation and Characterization of a New Thermophilic Methanosarcina, the Strain CHTI 55

Abstract

Summary A new thermophilic, acetoclastic methanogen (strain CHTI 55) was isolated from enrichment cultures on sodium acetate from a bench scale digester treating a mixture of solid wastes at 55 °C. Morphologically, the strain has the characteristic appearance of Methanosarcina but it forms very large aggregates and coccoid units which are released from the clumps of organisms in old cultures. The isolate uses acetate, methanol, methylamines but neither H2+CO2 nor formate for growth and methane production. Growth of strain CHTI 55 occured throughout a pH range between 6.5 and 8 and at temperatures ranging from 35 °C to 63 °C. The maximal growth rate on acetate (0.085 h-1) was at pH 6.8 and 57°C. The affinity constant for acetate and cell yield were 9.6 mM and 1.4 g/mol, respectively. The G + C content of DNA was 39.3 mol%.