Biofilm-overproducing Bacillus amyloliquefaciens P29ΔsinR decreases Pb availability and uptake in lettuce in Pb-polluted soil.

In this study, one mutant strain P29ΔsinR with increased biofilm production was constructed from a biofilm-producing Bacillus amyloliquefaciens strain P29. Then, the effect of strain P29 and its biofilm-overproducing mutant strain P29ΔsinR on Pb availability and accumulation in lettuce and the associated mechanisms were characterized in the Pb-contaminated soil. The live strains P29 and P29ΔsinR increased the dry masses of roots and edible tissues by 31-74% compared to the controls.

A Combination of Genomics, Transcriptomics, and Genetics Provides Insights into the Mineral Weathering Phenotype of Pseudomonas azotoformans F77.

Silicate mineral weathering (dissolution) plays important roles in soil formation and global biogeochemical cycling. In this study, a combination of genomics, transcriptomics, and genetics was used to identify the molecular basis of mineral weathering activity and acid tolerance in Pseudomonas azotoformans F77. Biotite was chosen as a silicate mineral to investigate mineral weathering.

Wheat-associated Pseudomonas taiwanensis WRS8 reduces cadmium uptake by increasing root surface cadmium adsorption and decreasing cadmium uptake and transport related gene expression in wheat.

Metal-resistant bacteria can reduce Cd accumulation in plants, but mechanisms underlying this effect are poorly understood. In this study, a highly effective Cd-resistant WRS8 strain was obtained from the rhizoshere soil of Triticum aestivum L. Yangmai-13 and identified as Pseudomonas taiwanensis based on 16S rRNA gene sequence analysis.

Interactions between Biotite and the Mineral-Weathering Bacterium F77.

In this study, the mineral-weathering bacterium F77, which was isolated from the soil of a debris flow area, was evaluated for its weathering activity under direct contact with biotite or without contact. Then, biotite-weathering behaviors of strain F77, mutants that had been created by deleting the and genes (which are involved in gluconic acid metabolism and pilus formation, respectively), and the double mutant F77ΔΔ were compared. The relative gene expression levels of F77 and its mutants F77Δ and F77Δ were also analyzed in the presence of biotite.

Rice-derived facultative endophytic Serratia liquefaciens F2 decreases rice grain arsenic accumulation in arsenic-polluted soil.

In this study, an arsenic (As)-resistant facultative endophytic bacterial strain, F2, was isolated from the root of Oryza sativa Longliangyou Huazhan and identified as Serratia liquefaciens according to 16S rRNA gene sequence analysis. Strain F2 was characterized for i) its impacts on As immobilization in solution and rice tissue As accumulation, and ii) the mechanisms involved for different levels of As-pollution in soils. In strain F2-inoculated culture medium, the concentration of As decreased, while the pH, cell growth, and cell-immobilized As significantly increased over time.

Isolation and characterization of mineral-dissolving bacteria from different levels of altered mica schist surfaces and the adjacent soil.

Microorganisms play important role in mineral weathering. However, little is known about rock-associated mineral-dissolving bacteria. In this study, 129 bacterial isolates were obtained from the less and more weathered mica schist surfaces and the adjacent soil and characterized for mineral dissolving activity, population, and the linkage of rock weathering level and distribution of the bacteria.

Ralstonia eutropha Q2-8 reduces wheat plant above-ground tissue cadmium and arsenic uptake and increases the expression of the plant root cell wall organization and biosynthesis-related proteins.

In this study, the molecular mechanisms involved in Ralstonia eutropha Q2-8-induced increased biomass and reduced cadmium (Cd) and arsenic (As) uptake in wheat plants (Triticum aestivum cv. Yangmai 16) were investigated in growth chambers. Strain Q2-8 significantly increased plant biomass (22-75%) without and with Cd (5 μM) + As (10 μM) stress and reduced plant above-ground tissue Cd (37%) and As (34%) contents compared to those in the controls.

Metal(loid)-resistant bacteria reduce wheat Cd and As uptake in metal(loid)-contaminated soil.

This study characterized the effect of the metal(loid)-resistant bacteria Ralstonia eutropha Q2-8 and Exiguobacterium aurantiacum Q3-11 on Cd and As accumulation in wheat grown in Cd- and As-polluted soils (1 mg kg of Cd + 40 mg kg of As and 2 mg kg of Cd + 60 mg kg of As). The influence of strains Q2-8 and Q3-11 on water-soluble Cd and As and NHconcentration and pH in the soil filtrate were also analyzed. Inoculation with these strains significantly reduced wheat plant Cd (12-32%) and As (9-29%) uptake and available Cd (15-28%) and As (22-38%) contents in rhizosphere soils compared to the controls.

Increased biomass and reduced rapeseed Cd accumulation of oilseed rape in the presence of Cd-immobilizing and polyamine-producing bacteria.

Two Cd-immobilizing and polyamine-producing bacteria Serratia liquefaciens CL-1 and Bacillus thuringiensis X30 were characterized for their effects on Cd immobilization, pH, and polyamine production in the solution and the rapeseed biomass and Cd uptake of Brassica napus Qinyou-10 in Cd-contaminated soil. These strains significantly increased pH and reduced water-soluble Cd concentration (25-76%) compared to the controls. Furthermore, strain CL-1 produced more polyamine (71-192%) in the solution than strain X30.

Increased biomass and quality and reduced heavy metal accumulation of edible tissues of vegetables in the presence of Cd-tolerant and immobilizing Bacillus megaterium H3.

A Cd-resistant and immobilizing Bacillus megaterium H3 was characterized for its impact on the biomass and quality and heavy metal uptake of edible tissues of two vegetables (Brassica campestris L. var. Aijiaohuang and Brassica rapa L.

Cd immobilization and reduced tissue Cd accumulation of rice (Oryza sativa wuyun-23) in the presence of heavy metal-resistant bacteria.

Two metal-resistant Bacillus megaterium H3 and Neorhizobium huautlense T1-17 were investigated for their immobilization of Cd in solution and tissue Cd accumulation of rice (Oryza sativa wuyun-23) in the Cd-contaminated soil. Strains H3 and T1-17 decreased 79-96% of water-soluble Cd in solution and increased grain biomass in the high Cd-contaminated soil. Inoculation with H3 and T1-17 significantly decreased the root (ranging from 25% to 58%), above-ground tissue (ranging from 13% to 34%), and polished rice (ranging from 45% to 72%) Cd contents as well as Cd bioconcentration factor of the rice compared to the controls.

Inoculation with endophytic Bacillus megaterium H3 increases Cd phytostabilization and alleviates Cd toxicity to hybrid pennisetum in Cd-contaminated aquatic environments.

A hydroponic culture experiment was performed to investigate the effects of endophytic Bacillus megaterium H3 on the plant biomass, Cd accumulation and tolerance of hybrid pennisetum, and the mechanisms involved in the different levels of Cd-contaminated aquatic environments. Strain H3 significantly increased the plant growth (ranging from 13 to 71 %) and total Cd uptake (ranging from 41 to 160 %) but decreased Cd translocation factors of hybrid pennisetum treated with 0-20 μM Cd compared with the controls. Furthermore, most of Cd (71-77 %) was accumulated in the roots of the bacterial-inoculated hybrid pennisetum.

Saccharibacillus qingshengii sp. nov., isolated from a lead-cadmium tailing.

A Gram-stain-positive, strictly aerobic strain, H6T, was isolated from a soil sample of lead-cadmium tailing in Qixia district, Nanjing (China). Cells of the strain are rod-shaped and colonies on LB agar are red. Strain H6T has subpolar and polar flagella and the optimal condition for growth is 30 °C, with 1 % (w/v) NaCl and at pH 7.

Distinct Mineral Weathering Behaviors of the Novel Mineral-Weathering Strains Rhizobium yantingense H66 and Rhizobium etli CFN42.

Unlabelled: Bacteria play important roles in mineral weathering, soil formation, and element cycling. However, little is known about the interaction between silicate minerals and rhizobia. In this study, Rhizobium yantingense H66 (a novel mineral-weathering rhizobium) and Rhizobium etli CFN42 were compared with respect to potash feldspar weathering, mineral surface adsorption, and metabolic activity during the mineral weathering process.

Synergistic effects of plant growth-promoting Neorhizobium huautlense T1-17 and immobilizers on the growth and heavy metal accumulation of edible tissues of hot pepper.

A plant growth-promoting Neorhizobium huautlense T1-17 was evaluated for its immobilization of Cd and Pb in solution. Meanwhile, the impacts of T1-17, immobilizers (vermiculite and peat) and their combination on the fruit biomass and heavy metal accumulation of hot pepper were characterized. T1-17 could significantly reduced water-soluble Cd and Pb in solution.

Increased growth and root Cu accumulation of Sorghum sudanense by endophytic Enterobacter sp. K3-2: Implications for Sorghum sudanense biomass production and phytostabilization.

Endophytic bacterial strain K3-2 was isolated from the roots of Sorghum sudanense (an bioenergy plant) grown in a Cu mine wasteland soils and characterized. Strain K3-2 was identified as Enterobacter sp. based on 16S rRNA gene sequence analysis.

Inoculation with endophytic Bacillus megaterium 1Y31 increases Mn accumulation and induces the growth and energy metabolism-related differentially-expressed proteome in Mn hyperaccumulator hybrid pennisetum.

In this study, a hydroponic culture experiment was conducted in a greenhouse to investigate the molecular and microbial mechanisms involved in the endophytic Bacillus megaterium 1Y31-enhanced Mn tolerance and accumulation in Mn hyperaccumulator hybrid pennisetum. Strain 1Y31 significantly increased the dry weights (ranging from 28% to 94%) and total Mn uptake (ranging from 23% to 112%) of hybrid pennisetum treated with 0, 2, and 10mM Mn compared to the control. Total 98 leaf differentially expressed proteins were identified between the live and dead bacterial inoculated hybrid pennisetum.

Characterization of Mn-resistant endophytic bacteria from Mn-hyperaccumulator Phytolacca americana and their impact on Mn accumulation of hybrid penisetum.

Three hundred Mn-resistant endophytic bacteria were isolated from the Mn-hyperaccumulator, Phytolacca americana, grown at different levels of Mn (0, 1, and 10mM) stress. Under no Mn stress, 90%, 92%, and 11% of the bacteria produced indole acetic acid (IAA), siderophore, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase, respectively. Under Mn stress, 68-94%, 91-92%, and 21-81% of the bacteria produced IAA, siderophore, and ACC deaminase, respectively.

Isolation and the interaction between a mineral-weathering Rhizobium tropici Q34 and silicate minerals.

The purposes of this study were to isolate and evaluate the interaction between mineral-weathering bacteria and silicate minerals (feldspar and biotite). A mineral-weathering bacterium was isolated from weathered rocks and identified as Rhizobium tropici Q34 based on 16S rRNA gene sequence analysis. Si and K concentrations were increased by 1.

Sinomonas susongensis sp. nov., isolated from the surface of weathered biotite.

A novel actinomycete, designated strain A31(T), was isolated from the surface of weathered biotite in Susong, Anhui Province, China. The organism grew optimally at 30 °C, at pH 8.0 and with 1% (w/v) NaCl.

Burkholderia susongensis sp. nov., a mineral-weathering bacterium isolated from weathered rock surface.

A novel type of mineral-weathering bacterium was isolated from the weathered surface of rock (mica schist) collected from Susong (Anhui, China). Cells of strain L226(T) were Gram-stain-negative. The strain grew optimally at 30 °C, with 1 % (w/v) NaCl and at pH 7.

Rhizobium yantingense sp. nov., a mineral-weathering bacterium.

A Gram-stain-negative, rod-shaped bacterial strain, H66(T), was isolated from the surfaces of weathered rock (purple siltstone) found in Yanting, Sichuan Province, PR China. Cells of strain H66(T) were motile with peritrichous flagella. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain H66(T) belongs to the genus Rhizobium.

Chitinophaga longshanensis sp. nov., a mineral-weathering bacterium isolated from weathered rock.

A Gram-stain-negative, aerobic, yellow-pigmented, non-motile, non-spore-forming, rod-shaped bacterial strain, Z29(T), was isolated from the surface of weathered rock (potassic trachyte) from Nanjing, Jiangsu Province, PR China. Phylogenetic analysis based on 16S rRNA gene sequences suggested that strain Z29(T) belongs to the genus Chitinophaga in the family Chitinophagaceae. Levels of 16S rRNA gene sequence similarity between strain Z29(T) and the type strains of recognized species of the genus Chitinophaga ranged from 92.

Arthrobacter nanjingensis sp. nov., a mineral-weathering bacterium isolated from forest soil.

A Gram-stain-positive, non-motile, rod- or coccoid-shaped actinobacterium, designated strain A33(T), was isolated from a forest soil sample from Nanjing, Jiangsu Province, PR China. The strain grew optimally at 30 °C, pH 7.0 and with 3 % NaCl (w/v).

Chitinophaga qingshengii sp. nov., isolated from weathered rock surface.

A novel mineral-weathering bacterium was isolated from weathered rock (potassic trachyte) surfaces collected from Nanjing (Jiangsu, PR China). Cells of strain JN246(T) were Gram-stain-negative, rod-shaped and non-motile. Strain JN246(T) was aerobic, catalase- and oxidase-positive, and grew optimally at 28 °C and pH 7.