RT Journal Article SR Electronic(1) A1 Mori, K A1 Yamamoto, H A1 Kamagata, Y A1 Hatsu, M A1 Takamizawa, KYR 2000 T1 Methanocalculus pumilus sp. nov., a heavy-metal-tolerant methanogen isolated from a waste-disposal site. JF International Journal of Systematic and Evolutionary Microbiology, VO 50 IS 5 SP 1723 OP 1729 DO https://doi.org/10.1099/00207713-50-5-1723 PB Microbiology Society, SN 1466-5034, AB A mesophilic hydrogenotrophic methanogen, strain MHT-1T, was isolated from the leachate of a sea-based site for solid waste disposal (the port of Osaka, Japan). Strain MHT-1T was found to be an irregular coccus and was able to use H2/CO2 and formate as energy sources. Acetate was required for growth. The optimum temperature and pH for growth were 35 degrees C and 6.5-7.5, respectively. Strain MHT-1T was resistant to high concentrations of several heavy metals such as CdCl2 and CuSO4. The G+C content of the DNA was 51.9 mol%. Analysis of the 16S rRNA gene revealed that the isolate was a member of the genus Methanocalculus but distinct from its nearest neighbour, Methanocalculus halotolerans, there being a sequence similarity of 98.9%. DNA-DNA hybridization analysis revealed 51% relatedness with the DNA of M. halotolerans strain SEBR 4845T. The optimum NaCl concentration was 1.0%, whereas the optimum in M. halotolerans was 5.0%. A new species, Methanocalculus pumilus, is proposed for strain MHT-1T. The type strain is MHT-1T (= DSM 12632T = JCM 10627T)., UL https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/00207713-50-5-1723