Development of a dual-fluorescence reporter system for high-throughput screening of L-aspartate-α-decarboxylase.

β-Alanine (3-aminopropionic acid) holds great potential in industrial application. It can be obtained through a chemical synthesis route, which is hazardous to the environment. It is well known that l-aspartate-α-decarboxylase (ADC) can convert l-aspartate to β-alanine in bacteria.

Heterologous Expression and Characterization of Flavinadenine Dinucleotide Synthetase from for Flavin Adenine Dinucleotide Production.

Background: Flavin adenine dinucleotide (FAD) is a redox-active coenzyme that regulates several important enzymatic reactions during metabolism. FAD is used in the medicinal and food industries and FAD supplements have been used to treat some inheritable diseases. FAD can be biosynthesized from flavin mononucleotide (FMN) and adenosine triphosphate (ATP), catalyzed by FAD synthetase (FADS).

Histone-like Nucleoid-Structuring Protein (H-NS) Paralogue StpA Activates the Type I-E CRISPR-Cas System against Natural Transformation in Escherichia coli.

Working mechanisms of CRISPR-Cas systems have been intensively studied. However, far less is known about how they are regulated. The histone-like nucleoid-structuring protein H-NS binds the promoter of genes (P ) and suppresses the type I-E CRISPR-Cas system in Although the H-NS paralogue StpA also binds P , its role in regulating the CRISPR-Cas system remains unidentified.

Identification and characterization of a LuxI/R-type quorum sensing system in Pseudoalteromonas.

Bacteria usually produce, release and detect quorum sensing (QS)-based signal molecules, and successively orchestrate gene expression in respond to environmental changes. Pseudoalteromonas are typical marine bacteria, but knowledge on their QS systems is extremely fragmentary. In this study, genome sequencing of Pseudoalteromonas sp.

Inactivation of Polymyxin by Hydrolytic Mechanism.

Polymyxins are nonribosomal peptide antibiotics used as the last-resort drug for treatment of multidrug-resistant Gram-negative bacteria. However, strains that are resistant to polymyxins have emerged in many countries. Although several mechanisms for polymyxin resistance have been well described, there is little knowledge on the hydrolytic mechanism of polymyxin.

Enhanced NADH Metabolism Involves Colistin-Induced Killing of Bacillus subtilis and Paenibacillus polymyxa.

The commonly believed mechanism of colistin against Gram-negative bacteria is to cause cell membrane lysis, whereas the mechanism of colistin against Gram-positive bacteria is extremely fragmented. In this study, we found that colistin treatment on WB800, C12 and ATCC842 enhances not only the activities of α-ketoglutaric dehydrogenase and malate dehydrogenase in tricarboxylic acid (TCA) cycle, but also the relative expression levels of their encoding genes. Additionally, the oxaloacetate concentration also increases.

Chemical transformation mediated CRISPR/Cas9 genome editing in Escherichia coli.

Objectives: To develop a convenient chemical transformation mediated CRISPR/Cas9 (CT-CRISPR/Cas9) system for genome editing in Escherichia coli.

Results: Here, we have constructed a CT-CRISPR/Cas9 system, which can precisely edit bacterial genome (replacing, deleting, inserting or point mutating a target gene) through chemical transformation. Compared with the traditional electroporation mediated CRISPR/Cas9 (ET-CRISPR/Cas9) system, genome editing with the CT-CRISPR/Cas9 system is much cheaper and simpler.

Dissemination of Genetic Acquisition/Loss Provides a Variety of Quorum Sensing Regulatory Properties in Pseudoalteromonas.

bstract Quorum sensing (QS) enables single-celled bacteria to communicate with chemical signals in order to synchronize group-level bacterial behavior. are marine bacteria found in versatile environments, of which QS regulation for their habitat adaptation is extremely fragmentary. To distinguish genes required for QS regulation in s, comparative genomics was deployed to define the pan-genomics for twelve isolates and previously-sequenced genomes, of which acyl-homoserine lactone (AHL)-based QS traits were characterized.

Enhanced Production of Polymyxin E in by Replacement of Glucose by Starch.

Polymyxin E or colistin, produced by , is an important antibiotic against Gram-negative pathogens. The objective of this study is to evaluate the effect of starch in fermentation medium on colistin biosynthesis in . The results indicated that replacement of glucose by starch stimulated colistin production and biosynthesis rate.

Two different restriction-modification systems for degrading exogenous DNA in Paenibacillus polymyxa.

Accompanied by benefits from horizontally transferred genes, bacteria have to face the risk of the invasion of dangerous genes. Bacteria often use the restriction-modification (R-M) system, which is consisted of methyl transferase (MEase) and restrictase (REase), to protect self-DNA and defend against foreign DNA. Paenibacillus polymyxa, widely used as growth promoting rhizobacteria in agriculture, can also produce compounds of medical and industrial interests.

[Progress in regulatory mechanism for inducing β-lactamase in Gram-negative bacteria].

Beta-lactams are the most widely used antibiotics. One of the principle mechanisms for Gram-negative bacteria to resist β-lactams is by producing β-lactamases that degrade β-lactams. This review highlights two regulatory mechanisms for inducing β-lactamase in Gram-negative bacteria.

Deletion of PBP1a/LpoA complex compromises cell envelope integrity in Shewanella oneidensis.

High molecular weight penicillin-binding proteins (PBPs) are responsible for the biosynthesis of peptidoglycan. In Escherichia coli, PBP1a and PBP1b form multienzyme peptidoglycan-synthesizing complexes with outer membrane lipoproteins LpoA and LpoB, respectively. The two complexes appear to be largely redundant, although their distinct physiological roles remain unclear.

Mangrovicoccus ximenensis gen. nov., sp. nov., isolated from mangrove forest sediment.

A Gram-strain-negative, coccoid bacterium, lacking bacteriochlorophyll, designated strain T1lg56, was isolated from a sediment sample collected from Ximen island mangrove forest, Zhejiang province, China. Cells were halotolerant, and catalase- and oxidase-positive. Growth was observed at 18-42 °C (optimum, 35 °C), at pH 6.

Deletion of Lytic Transglycosylases Increases Beta-Lactam Resistance in .

Production of chromosome-encoded β-lactamases confers resistance to β-lactams in many Gram-negative bacteria. Some inducible β-lactamases, especially the class C β-lactamase AmpC in Enterobacteriaceae, share a common regulatory mechanism, the - paradigm. Induction of is intimately linked to peptidoglycan recycling, and the LysR-type transcriptional regulator AmpR plays a central role in the process.

Reactive oxygen species-scavenging system is involved in l-amino acid oxidase accumulation in sp. B3.

To date, the mechanisms underlying the flavoprotein l-amino acid oxidase (LAAO) accumulation in cells remain unclear. In this study, using LAAO-producer spp. as model organisms, we found that the cell biomass is negatively associated with LAAO accumulation, whereas the LAAO accumulation is positively associated with the reactive oxygen species (ROS)-scavenging capability.

Comparative Genomics of sp. SNP6 and KOL6 Revealing Genomic Regions of Plasticity Implicated in Extremely Thermophilic Profiles.

spp. are usually isolated from harsh niches, such as high osmotic pressure and extreme temperature. However, the molecular mechanisms for their environmental adaption are poorly understood.

Oxidative Stress Induced by Polymyxin E Is Involved in Rapid Killing of .

Historically, the colistin has been thought to kill bacteria through membrane lysis. Here, we present an alternative mechanism that colistin induces rapid death through reactive oxygen species production. This significantly augments our understanding of the mechanism of colistin action, which is critical knowledge toward the yield development of colistin in the future.

[Advances in molecular mechanisms of adaptive immunity mediated by type I-E CRISPR/Cas system--A review].

To better adapt to the environment, prokaryocyte can take up exogenous genes (from bacteriophages, plasmids or genomes of other species) through horizontal gene transfer. Accompanied by the acquisition of exogenous genes, prokaryocyte is challenged by the invasion of 'selfish genes'. Therefore, to protect against the risk of gene transfer, prokaryocyte needs to establish mechanisms for selectively taking up or degrading exogenous DNA.

Draft Genome Sequence of Pseudoalteromonas sp. Strain R3, a Red-Pigmented l-Amino Acid Oxidase-Producing Bacterium.

Here, we report a draft 5.58-Mb genome sequence of Pseudoalteromonas sp. strain R3, isolated from an intertidal-zone sludge sample, which has l-amino acid oxidase activity.

Polymyxin E Induces Rapid Paenibacillus polymyxa Death by Damaging Cell Membrane while Ca2+ Can Protect Cells from Damage.

Polymyxin E, produced by Paenibacillus polymyxa, is an important antibiotic normally against Gram-negative pathogens. In this study, we found that polymyxin E can kill its producer P. polymyxa, a Gram-positive bacterium, by disrupting its cell membrane.

Precursor Amino Acids Inhibit Polymyxin E Biosynthesis in Paenibacillus polymyxa, Probably by Affecting the Expression of Polymyxin E Biosynthesis-Associated Genes.

Polymyxin E belongs to cationic polypeptide antibiotic bearing four types of direct precursor amino acids including L-2,4-diaminobutyric acid (L-Dab), L-Leu, D-Leu, and L-Thr. The objective of this study is to evaluate the effect of addition of precursor amino acids during fermentation on polymyxin E biosynthesis in Paenibacillus polymyxa. The results showed that, after 35 h fermentation, addition of direct precursor amino acids to certain concentration significantly inhibited polymyxin E production and affected the expression of genes involved in its biosynthesis.

Exploring regulation genes involved in the expression of L-amino acid oxidase in Pseudoalteromonas sp. Rf-1.

Bacterial L-amino acid oxidase (LAAO) is believed to play important biological and ecological roles in marine niches, thus attracting increasing attention to understand the regulation mechanisms underlying its production. In this study, we investigated genes involved in LAAO production in marine bacterium Pseudoalteromonas sp. Rf-1 using transposon mutagenesis.

Antibacterial mechanisms of polymyxin and bacterial resistance.

Multidrug resistance in pathogens is an increasingly significant threat for human health. Indeed, some strains are resistant to almost all currently available antibiotics, leaving very limited choices for antimicrobial clinical therapy. In many such cases, polymyxins are the last option available, although their use increases the risk of developing resistant strains.

Advances in detection methods of L-amino acid oxidase activity.

L-amino acid oxidase (LAAO) is widely distributed in many different organisms and found to play important biological roles, thus attracting a great deal of attention for characterization of its activity. Diverse detection methods with their own properties have been established. This review advanced different LAAO activity assays based on substrate consumption, cofactor amount, and product accumulation.

Identification, cloning, and expression of L-amino acid oxidase from marine Pseudoalteromonas sp. B3.

L-amino acid oxidase (LAAO) is attracting more attentions due to its broad and important biological functions. Recently, an LAAO-producing marine microorganism (strain B3) was isolated from the intertidal zone of Dinghai sea area, China. Physiological, biochemical, and molecular identifications together with phylogenetic analysis congruously suggested that it belonged to the genus Pseudoalteromonas.