title: Moorella humiferrea sp. nov., a thermophilic, anaerobic bacterium capable of growth via electron shuttling between humic acid and Fe(III).
abstract: An anaerobic, thermophilic, spore-forming bacterium (strain 64-FGQ(T)) was isolated from a terrestrial hydrothermal spring from the Kamchatka peninsula, Russia. This strain utilized lactate as an electron donor, insoluble poorly crystalline Fe(III) oxide incorporated into alginate beads as a potential electron acceptor and 9,10-anthraquinone-2,6-disulfonate (AQDS) as an electron-shuttling compound. Vegetative cells of strain 64-FGQ(T) were Gram-stain-positive, peritrichously flagellated, motile, straight rods, 0.3-0.5 µm in diameter and 2.0-5.0 µm long, growing singly or forming short chains. Cells formed round refractive endospores in terminal swollen sporangia. The temperature range for growth was 46-70 °C, with an optimum at 65 °C. The pH range for growth was 5.5-8.5, with an optimum at pH 7.0. The substrates utilized by strain 64-FGQ(T) in the presence of AQDS as an electron acceptor included lactate, malate, succinate, glycerol and yeast extract. The strain fermented galactose, fructose, maltose, sucrose, pyruvate and peptone. Strain 64-FGQ(T) used AQDS, humic acid, thiosulfate, nitrate and perchlorate as electron acceptors for growth. Fe(III) was not directly reduced, but strain 64-FGQ(T) was able to grow and reduce Fe(III) oxide in the presence of small amounts of AQDS or humic acid as electron-shuttling compounds. The G+C content of the DNA of strain 64-FGQ(T) was 51 mol%. 16S rRNA gene sequence analysis placed the isolate in the genus Moorella, with the type strain of Moorella glycerini as its closest relative (97.2% similarity). Based on phylogenetic analysis and physiological characteristics, strain 64-FGQ(T) is considered to represent a novel species of the genus Moorella, for which the name Moorella humiferrea sp. nov. is proposed; the type strain is 64-FGQ(T) (=DSM 23265(T)=VKM B-2603(T)).
authors.affiliation: Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia.
authors.forename: Y N
authors.initials: YN
authors.lastname: Nepomnyashchaya
authors.affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, 117312 Moscow, Russia.
authors.forename: G B
authors.initials: GB
authors.lastname: Slobodkina
authors.affiliation: Bioengineering Center, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/1, 117312 Moscow, Russia.
authors.forename: R V
authors.initials: RV
authors.lastname: Baslerov
authors.affiliation: Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia.
authors.forename: N A
authors.initials: NA
authors.lastname: Chernyh
authors.affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, 117312 Moscow, Russia.
authors.forename: E A
authors.initials: EA
authors.lastname: Bonch-Osmolovskaya
authors.affiliation: Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia.
authors.forename: A I
authors.initials: AI
authors.lastname: Netrusov
authors.affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, 117312 Moscow, Russia.
authors.forename: A I
authors.initials: AI
authors.lastname: Slobodkin
mesh_terms: D015373:Bacterial Typing Techniques; D001482:Base Composition; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005290:Ferric Compounds / Q000378:metabolism*; D005407:Flagella / Q000502:physiology; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000378:metabolism; D008124:Locomotion; D008969:Molecular Sequence Data; D058845:Moorella / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012426:Russia; D017422:Sequence Analysis, DNA; D013171:Spores, Bacterial / Q000166:cytology; D013696:Temperature
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D005290:Ferric Compounds; D006812:Humic Substances; D007773:Lactates; D012336:RNA, Ribosomal, 16S