Responses of soil microbiome to steel corrosion.

The process of microbiologically influenced corrosion (MIC) in soils has received widespread attention. Herein, long-term outdoor soil burial experiments were conducted to elucidate the community composition and functional interaction of soil microorganisms associated with metal corrosion. The results indicated that iron-oxidizing (e.g., Gallionella), nitrifying (e.g., Nitrospira), and denitrifying (e.g., Hydrogenophaga) microorganisms were significantly enriched in response to metal corrosion and were positively correlated with the metal mass loss. Corrosion process may promote the preferential growth of the abundant microbes. The functional annotation revealed that the metabolic processes of nitrogen cycling and electron transfer pathways were strengthened, and also that the corrosion of metals in soil was closely associated with the biogeochemical cycling of iron and nitrogen elements and extracellular electron transfer. Niche disturbance of microbial communities induced by the buried metals facilitated the synergetic effect of the major MIC participants. The co-occurrence network analysis suggested possible niche correlations among corrosion related bioindicators.

Acidibrevibacterium fodinaquatile gen. nov., sp. nov., isolated from acidic mine drainage.

A heterotrophic and acidophilic bacterial strain, G45-3T, was isolated from acidic mine drainage sampled in Fujian Province, PR China. Cells of strain G45-3T were Gram-stain-negative, non-spore-forming, non-motile and rod-shaped. Catalase and oxidase activities were positive. Strain G45-3T grew aerobically at 20-45 °C (optimum, 37 °C) and at pH 2.5-5.0 (optimum, pH 4.0). Photosynthetic pigments were not produced. Analysis of 16S rRNA gene sequences showed that strain G45-3T was phylogenetically related to different members of the family Acetobacteraceae, and the sequence identities to Acidisphaera rubrifaciens JCM 10600T, Rhodovastum atsumiense G2-11T and Rhodopila globiformis ATCC 35887T were 95.9 , 95.3 and 95.3 %, respectively. Strain G45-3T contained ubiquinone-10 as its respiratory quinone. The major polar lipids were determined to be diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an unidentified aminophospholipid and an unidentified aminolipid. The predominant fatty acids were cyclo-C19 : 0ω8c, C18 : 1ω7c, C16 : 0 and C18 : 0. The genome of G45-3T consists of one chromosome (3 907 406 bp) and three plasmids (68 344, 45 771 and 16 090 bp), with an average G+C content of 65.9 mol%. Based on the results of phenotypic and genomic analyses, it is concluded that strain G45-3T represents a novel species of a new genus, for which the name Acidibrevibacterium fodinaquatile gen. nov., sp. nov. is proposed. A. fodinaquatile is nominated as type species and its type strain is G45-3T (=CGMCC 1.16069T=KCTC 62275T).

Thauera hydrothermalis sp. nov., a thermophilic bacterium isolated from hot spring.

A Gram-stain-negative, non-spore-forming, rod-shaped, motile bacterial strain, designated GD-2T, was isolated from a sediment sample collected from a hot spring in the Tibet Autonomous Region, China. Strain GD-2T grew at a temperature range of 37-55 °C (optimum, 45-50 °C), a pH range of 5.5-11.0 (pH 7.0-7.5) and a NaCl concentration range of 0-4.0 % (0 %). The phylogenetic analysis based on 16S rRNA gene sequencing showed that strain GD-2T represented a member of the genus Thauera within the family Zoogloeaceae. Strain GD-2T was closely related to Thauera linaloolentis 47LolT with the highest 16S rRNA gene sequence similarity of 95.5 %. The whole genomic average nucleotide identity value for GD-2T and 47LolT was 75.3 %. The predominant cellular fatty acids of the strain were C16 : 0, summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), C10 : 0 3-OH and C12 : 0. The main polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, three unidentified phospholipids and two unidentified aminolipids. The major isoprenoid quinone was ubiquinone 8. Genome sequencing revealed that the genome size of GD-2T was 3 059 321 bp with a G+C content of 63.57 mol%. On the basis of phylogenetic, phenotypic and chemotaxonomic characteristics, strain GD-2T is considered to represent a novel species of the genus Thauera, for which the name Thauera hydrothermalis sp. nov. is proposed. The type strain is GD-2T (=NBRC 112472T=CGMCC 1.15527T).

Hymenobacter cavernae sp. nov., isolated from a karst cave.

A novel Gram-stain-negative, rod-shaped, non-motile and red-pigmented bacterial strain, designated K1E01-27T, was isolated from an animal excrement sample which was found in a karst cave located in Guizhou province, China. The phylogenetic analysis based on 16S rRNA gene sequences indicated that strain K1E01-27T represented a member of the genus Hymenobacter within the family Cytophagaceae of the phylum Bacteroidetes. Strain K1E01-27T was most closely related to Hymenobacter algoricola VUG-A23aT, with 95.1 % 16S rRNA gene sequence similarity. Growth of strain K1E01-27T occurred at 4-35 °C, at pH 5-9 and in the presence of 0-0.5 % (w/v) NaCl. The major fatty acids were iso-C15 : 0, anteiso-C15 : 0, C16 : 1ω5c, summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c) and summed feature 4 (comprising iso-C17 : 1 I/anteiso-C17 : 1 B). The major isoprenoid quinone was menaquinone 7 (MK-7). The major polar lipids were phosphatidylethanolamine, five unidentified aminophospholipids, three unidentified glycolipids, two unidentified phospholipids and one unidentified polar lipid. The DNA G+C content of the genomic DNA was 54.9 mol%. On the basis of phylogenetic, phenotypic and chemotaxonomic characteristics, strain K1E01-27T is considered to represent a novel species of the genus Hymenobacter, for which the name Hymenobacter cavernae sp. nov. is proposed. The type strain is K1E01-27T (=CGMCC 1.15197T=NBRC 112610T).

Parapedobacter defluvii sp. nov., isolated from the sewage treatment packing of a coking chemical plant.

Strain WY-1T, a Gram-stain-negative, non-spore-forming, rod-shaped, non-motile bacterium, was isolated from the sewage treatment packing of a coking chemical plant. Strain WY-1T grew over a temperature range of 15-45 °C (optimum, 30-37 °C), a pH range of 5.5-11.0 (optimum, pH 6.5-7.0) and an NaCl concentration range of 0-3 % (w/v; optimum, 0 %). 16S rRNA gene sequence analysis showed that strain WY-1T was closely related to Parapedobacter indicus RK1T with the highest sequence similarity of 96.0 %. The predominant cellular fatty acids of the novel strain were iso-C15 : 0, summed feature 3(C16 : 1ω6c and/or C16 : 1ω7c), iso-C17 : 0 3-OH, iso-C17 : 1ω9c, iso-C15 : 0 3-OH and C16 : 0. The respiratory quinone of the cells was menaquinone 7 (MK-7). The main polar lipid was phosphatidylethanolamine, an unidentified phospholipid, two unidentified aminolipids and two unknown lipids. The G+C content of the DNA was 47.1 mol%. Chemotaxonomic characteristics and phylogenetic analyses revealed that strain WY-1T belonged to the genus Parapedobacter. Strain WY-1T showed a range of phenotypic characteristics that differentiated it from species of the genus Parapedobacter with validly published names, including its assimilation from carbon sources, enzyme activities and having a wider pH range for growth. Based on these results, it is concluded that strain WY-1T represents a novel species of the genus Parapedobacter, for which the name Parapedobacter defluvii sp. nov. is proposed. The type strain is WY-1T (=NBRC 112611T=CGMCC 1.15342T).