Exploring native arsenic (As)-resistant bacteria: unveiling multifaceted mechanisms for plant growth promotion under As stress.

Aims: This study explores the plant growth-promoting effect (PGPE) and potential mechanisms of the arsenic (As)-resistant bacterium Flavobacterium sp. A9 (A9 hereafter).

Methods And Results: The influences of A9 on the growth of Arabidopsis thaliana, lettuce, and Brassica napus under As(V) stress were investigated.

Inhibition of Fusarium graminearum growth and spore germination by a Streptomyces amritsarensis strain capable of killing and growing on Microcystis scum.

Aims: Developing energy-saving and ecofriendly strategies for treating harvested Microcystis biomass.

Methods And Results: Streptomyces amritsarensis HG-16 was first reported to effectively kill various morphotypes of natural Microcystis colonies at very high cell densities. Concurrently, HG-16 grown on lysed Microcystis maintained its antagonistic activity against plant pathogenic fungus Fusarium graminearum.

Dissolved organic matter, calcium ion and extracellular polymeric substances on living associated bacteria of Microcystis colony are crucial for unicellular Microcystis to efficiently form colonies.

Microcystis typically forms colonies under natural conditions, which contributes to occurrence and prevalence of algal blooms. The colonies consist of Microcystis and associated bacteria (AB), embedded in extracellular polymeric substances (EPS). Previous studies indicate that AB can induce Microcystis to form colonies, however the efficiency is generally low and results in a uniform morphotype.

Revealing the phosphate-solubilizing characteristics and mechanisms of the plant growth-promoting bacterium Agrobacterium deltaense C1.

Aims: This study explores the phosphate (Pi)-solubilizing characteristics and mechanisms of a novel phosphate-solubilizing bacterium, Agrobacterium deltaense C1 (C1 hereafter).

Methods And Results: The growth-promoting effects of C1 were investigated by gnotobiotic experiments, and the Pi-solubilizing mechanism was revealed by extracellular metabolomics, liquid chromatography analysis, and reverse transcription quantitative polymerase chain reaction. Results showed that C1 significantly increased Arabidopsis biomass and total phosphorus (P) content under P deficiency.

An insight into algicidal characteristics of Bacillus altitudinis G3 from dysfunctional photosystem and overproduction of reactive oxygen species.

Cyanobacterial blooms negatively affect aquatic ecosystems and human health. Algicidal bacteria can efficiently kill bloom-causing cyanobacteria. Bacillus altitudinis G3 isolated from Dianchi Lake shows high algicidal activity against Microcystis aeruginosa.

Algicidal effect of tryptoline against Microcystis aeruginosa: Excess reactive oxygen species production mediated by photosynthesis.

Cyanobacterial blooms significantly decrease water quality and can damage ecosystems and, as such, require efficient control methods. Algicidal bacteria and their associated substances are promising tools for controlling cyanobacterial blooms; however, their specific algicidal mechanisms remain unclear. Therefore, the current study sought to investigate the algicidal mechanism of tryptoline (1,2,3,4-tetrahydro-9 h-pyrido[3,4-b]indole) against Microcystis aeruginosa, with a specific focus on the contribution made by reactive oxygen species (ROS), the underlying mechanisms of ROS increase, as well as the photosystem response.

A Streptomyces globisporus strain kills Microcystis aeruginosa via cell-to-cell contact.

Cyanobacterial harmful algal blooms (CyanoHABs) bring economic loss, damage aquatic ecosystems, and produce cyanobacterial toxins that threaten human health. Algicidal bacteria as pathogens can expediate the decline of CyanoHABs. In this study, a Streptomyces globisporus strain (designated G9), isolated from soil near a eutrophic pond, showed high algicidal activity against Microcystis aeruginosa.

The characteristics and algicidal mechanisms of cyanobactericidal bacteria, a review.

Cyanobacterial blooms are a worldwide problem, especially in freshwaters. As one of the most abundant co-existing organisms of algae, bacteria play critical roles in cyanobacteria growth, particularly the cyanobactericidal bacteria which can efficiently kill cyanobacteria. Recent years, cyanobactericidal bacteria are highly recognized as a method that could potentially block cyanobacterial blooms.

The potential assessment of green alga Chlamydomonas reinhardtii CC-503 in the biodegradation of benz(a)anthracene and the related mechanism analysis.

Benz(a)anthracene (BaA) is a polycyclic aromatic hydrocarbons (PAHs), that belongs to a group of carcinogenic and mutagenic persistent organic pollutants found in a variety of ecological habitats. In this study, the efficient biodegradation of BaA by a green alga Chlamydomonas reinhardtii (C. reinhardtii) CC-503 was investigated.

Algicidal characterization and mechanism of Bacillus licheniformis Sp34 against Microcystis aeruginosa in Dianchi Lake.

Microcystis aeruginosa blooms are a worldwide serious environmental problem and bloom control with bacteria is promising. In this study, a Bacillus licheniformis strain Sp34 with potent algicidal and inhibitory effects on the microcystins synthesis against fast-growing M. aeruginosa was isolated from Dianchi Lake.

An algicidal Streptomyces amritsarensis strain against Microcystis aeruginosa strongly inhibits microcystin synthesis simultaneously.

Microcystis aeruginosa and hepatotoxic microcystins produced by it have posed a severe threat to aquatic ecological security and human health. In this study a Streptomyces amritsarensis HG-16, showing high algicidal activity against M. aeruginosa and strong inhibitory effect on microcystin synthesis, was obtained by screening some anti-Fusarium sp.

Complete degradation of dimethyl phthalate by a Comamonas testosterone strain.

A Comamonas testosterone bacterial strain, named as DB-7, capable of utilizing dimethyl phthalate (DMP) as sole carbon source and energy for growth was isolated from soil with plastic film mulching by an enrichment culture technique. This bacterium was identified as C. testosterone by 16S rRNA sequence analysis and phospholipid fatty acid profile.

Distinct Network Interactions in Particle-Associated and Free-Living Bacterial Communities during a Bloom in a Plateau Lake.

Particle-associated bacteria (PAB) and free-living bacteria (FLB) from aquatic environments during phytoplankton blooms differ in their physical distance from algae. Both the interactions within PAB and FLB community fractions and their relationship with the surrounding environmental properties are largely unknown. Here, by using high-throughput sequencing and network-based analyses, we compared the community and network characteristics of PAB and FLB from a plateau lake during a bloom.

A Bacillus sp. strain with antagonistic activity against Fusarium graminearum kills Microcystis aeruginosa selectively.

Cyanobacterial harmful algal blooms (CyanoHABs) cause severe environmental problems, economic losses and threaten human health seriously. In the present study, a Bacillus sp. strain, designated as AF-1, with strong antagonistic activity against plant pathogenic fungus Fusarium graminearum was isolated from purple soil.

Mercury-methylating genes dsrB and hgcA in soils/sediments of the Three Gorges Reservoir.

Previous research found that the water-level fluctuating zone (WLFZ) of the Three Gorges Reservoir (TGR) was an Hg-sensitive area. However, little research has been conducted on the distribution of Hg-methylating microorganisms in this area. The goal of this research was to provide an initial description of the distribution of the dsrB (for sulfate-reducing bacteria) and hgcA (one gene confirmed for Hg methylation) genes.

[The in vitro refolding of β-barrel outer membrane protein of gram-negative bacteria--a review].

A cell of gram-negative bacteria is surrounded by two layers of membrane, the inner membrane and the outer membrane. Proteins are the major composition of outer membrane. Many outer membrane proteins carry a trans-membrane β-barrel structure that formed by multiple anti-parallel β-strands connected with hydrogen bonds.

[Research progress on the folding and membrane-insertion mechanisms of beta-barrel outer membrane protein of gram-negative bacteria--a review].

Beta-Barrel outer membrane proteins are the major components of the outer membrane of Gram-negative bacteria, which are in contact with the extracellular environment directly. Beta-barrel outer membrane proteins play key roles in nutrients absorption and keeping membrane integrity. They are also involved in the pathogenicity and multiple-antibiotic resistance of pathogenic bacteria.

Eicosapentaenoic acid facilitates the folding of an outer membrane protein of the psychrotrophic bacterium, Shewanella livingstonensis Ac10.

Polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA), are found in various cold-adapted microorganisms. We previously demonstrated that EPA-containing phospholipids (EPA-PLs) synthesized by the psychrotrophic bacterium Shewanella livingstonensis Ac10 support cell division, membrane biogenesis, and the production of membrane proteins at low temperatures. In this article, we demonstrate the effects of EPA-PLs on the folding and conformational transition of Omp74, a major outer membrane cold-inducible protein in this bacterium.

[Study on the atrazine-degrading genes in Arthrobacter sp. AG1].

Atrazine could be used as the sole carbon, nitrogen and energy sources for growth by strain Arthrobacter sp. AG1, and the atrazine-degrading genes of AG1 were found to be the combination of trzN, atzB and atzC. The atrazine chloride hydrolysase gene trzN was cloned by PCR amplification,whose sequence shared 99% identity with that of Norcardioides sp.

[Isolation and characterization of an atrazine-degrading bacterium strain SA1].

Atrazine (AT), a kind of herbicide for the pre and post-emergence control of annual and broad leaved weeds and perennial grasses, had been widely used in the world. However, the extensive use of atrazine had led to widespread environmental pollution. A bacterium strain SA1, which could degrade AT completely, was isolated from an atrazine-degrading consortium by long-time repeated alternative cultivation and plate striking.

[Construction of multifunctional genetically engineered pesticides-degrading bacteria by homologous recombination].

Construction of multifunctional pesticides-degrading genetically engineered microorganisms (GEMs) is increasing important in the bioremediation of various pesticides contaminants in environment. However, construction of genetically stable GEMs without any exogenous antibiotic resistance is thought to be one of the bottlenecks in GEMs construction. In this article, homologous recombination vectors with the recipient's 16S rDNA as homologous recombination directing sequence (HRDS) and sacB gene as double crossover recombinants positive selective marker were firstly constructed.

[Effects of atrazine and its degrader Exiguobaterium sp. BTAH1 on soil microbial community].

The study showed that the application of atrazine stimulated soil microorganisms obviously. In comparing with control(without atrazine), the respiration intensity of soil applied with 50 mg atrazine kg(-1) soil increased greatly, the concentrations of soil NH4(+)-N and NO3(-)-N changed significantly, and the individuals of soil microbes, especially bacteria and fungi, also increased greatly. The application of strain BTAH1 could degrade 98% of applied atrazine within one week, and led to the decrease of soil respiration intensity.

[Horizontal transfer of environmental pollutant-degrading gene and application in bioremediation].

Horizontal gene transfer, unlike vertical gene transfer, is a means of genetic communication in bacteria. In the special polluted environment, horizontal transfer of polluted-degrading gene has significant functions. Study on horizontal transfer of degrading gene in polluted environment may deepen our understanding of the mechanism of bacterial adaptation to the organic-polluted environment.