title: Culturable populations of Sporomusa spp. and Desulfovibrio spp. in the anoxic bulk soil of flooded rice microcosms.
abstract: Most-probable-number (MPN) counts were made of homoacetogenic and other bacteria present in the anoxic flooded bulk soil of laboratory microcosms containing 90- to 95-day-old rice plants. MPN counts with substrates known to be useful for the selective enrichment or the cultivation of homoacetogenic bacteria (betaine, ethylene glycol, 2, 3-butanediol, and 3,4,5-trimethoxybenzoate) gave counts of 2.3 x 10(3) to 2.8 x 10(5) cells per g of dry soil. Homoacetogens isolated from the terminal positive steps of these dilution cultures belonged to the genus Sporomusa. Counts with succinate, ethanol, and lactate gave much higher MPNs of 5.9 x 10(5) to 3.4 x 10(7) cells per g of dry soil and led to the isolation of Desulfovibrio spp. Counting experiments on lactate and ethanol which included Methanospirillum hungatei in the medium gave MPNs of 2.3 x 10(6) to 7.5 x 10(8) cells per g of dry soil and led to the isolation of Sporomusa spp. The latter strains could grow with betaine, ethylene glycol, 2, 3-butanediol, and/or 3,4,5-trimethoxybenzoate, but apparently most cells of Sporomusa spp. did not initiate growth in counting experiments with those substrates. Spores apparently accounted for 2. 2% or less of the culturable bacteria. It appears that culturable Desulfovibrio spp. and Sporomusa spp. were present in approximately equal numbers in the bulk soil. Multiple, phylogenetically-distinct, phenotypically-different, strains of each genus were found in the same soil system.
authors.affiliation: Max-Planck-Institut für terrestrische Mikrobiologie, D-35043 Marburg, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Rosencrantz
authors.forename: F A
authors.initials: FA
authors.lastname: Rainey
authors.forename: P H
authors.initials: PH
authors.lastname: Janssen
mesh_terms: D001406:Bacillaceae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D015169:Colony Count, Microbial; D003470:Culture Media; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D003901:Desulfovibrio / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D017753:Ecosystem; D008969:Molecular Sequence Data; D012275:Oryza; D010802:Phylogeny; D012988:Soil Microbiology; D013171:Spores, Bacterial / Q000302:isolation & purification
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial; D004275:DNA, Ribosomal