Strain Mg1 Research Articles

Complete Genome Sequence of Streptomyces Phage Shaeky.

Here, we present the genome of siphophage Shaeky, infecting the Gram-positive bacterium Streptomyces sp. strain Mg1. Shaeky has very low sequence identity to other phages, with phage phiC31 being the most closely related in the NCBI database. The Shaeky genome is 45,617 bp with 77 protein-coding genes and 16 tRNAs.

Complete Genome Sequence of Streptomyces Siphophage Sitrop.

Streptomyces sp. strain Mg1 is a Gram-positive soil bacterium capable of causing cell lysis and degradation of Bacillus subtilis colonies. Here, we report the 48,481-bp genome of Streptomyces sp. Mg1 siphophage Sitrop. With 77 predicted protein-coding genes and one tRNA, Sitrop shares 77% nucleotide sequence identity with the Streptomyces phage Verse.

Complete Genome Sequence of Streptomyces Siphophage Sycamore.

Streptomyces sp. strain Mg1 is a competitive soil-dwelling bacterium that secretes antibiotics that inhibit growth of Bacillus subtilis Here, we present the genome sequence of Sycamore, a 44,694-bp Streptomyces sp. Mg1 siphophage with 66 predicted protein-coding genes, that is similar to phage genome sequences in the Lomovskayavirus genus.

Complete Genome Sequence of Streptomyces Phage Sentinel.

The Streptomyces genus produces over two-thirds of clinically useful, natural antibiotics. Here, we describe the isolation and genome annotation of siphophage Sentinel, which utilizes Streptomyces sp. strain Mg1 as a host. It has a 50,272-bp genome and 83 protein-coding genes and shows similarity to other Streptomyces phages in the Arequatrovirus genus.

Complete Genome Sequence of Streptomyces Phage Spernnie.

Streptomyces spp. are Gram-positive soil bacteria that have been reported in some cases to cause acute and chronic infections, including mycetomas, pneumonia, and septicemia. Here, we present Streptomyces sp. strain Mg1 phage Spernnie. Spernnie is a temperate siphophage containing 89 predicted coding genes in a 50,834-bp genome sequence.

Complete Genome Sequence of Streptomyces Phage Salutena.

Streptomyces are Gram-negative soil bacteria that can degrade lignin and synthesize antibiotics. Some species cause mycetoma, pneumonitis, and bloodstream infections. Here, we present the genome sequence of the Streptomyces sp. strain Mg1 phage Salutena, a siphovirus in the subfamily Arquatrovirinae The genome is 51,993 bp, with 90 predicted protein-coding genes.

Complete Genome Sequence of Streptomyces Phage Shady.

Streptomyces spp. are saprophytic soil bacteria that produce secondary metabolites with therapeutic potential. This announcement describes the isolation and genome annotation of Streptomyces sp. strain Mg1 siphophage Shady. Learning more about Shady's novel 45-kb genome, containing 76 predicted protein-coding genes, could be industrially advantageous when using streptomycetes for their products.

Metabolomics Reveals the Response of the Phenylpropanoid Biosynthesis Pathway to Starvation Treatment in the Grape Endophyte Alternaria sp. MG1.

Phenylpropanoid (PPPN) compounds are widely used in agriculture, medical, food, and cosmetic industries because of their multiple bioactivities. Alternaria sp. MG1, an endophytic fungus isolated from grape, is a new natural source of PPPNs. However, the PPPN biosynthesis pathway in MG1 tends to be suppressed under normal growth conditions. Starvation has been reported to stimulate the PPPN pathway in plants, but this phenomenon has not been well studied in endophytic fungi. Here, metabolomics analysis was used to examine the profile of PPPN compounds, and quantitative reverse transcription-polymerase chain reaction was used to detect the expression of key genes in the PPPN biosynthesis pathway under starvation conditions. Starvation treatment significantly increased the accumulation of shikimate and PPPN compounds and upregulated the expression of key genes in their biosynthesis pathways. In addition to previously reported PPPNs, sinapate, 4-hydroxystyrene, piceatannol, and taxifolin were also detected under starvation treatment. These findings suggest that starvation treatment provides an effective way to optimize the production of PPPN compounds and may permit the investigation of compounds that are undetectable under normal conditions. Moreover, the diversity of its PPPNs makes strain MG1 a rich repository of valuable compounds and an extensive genetic resource for future studies.

Isolation, purification and characterization of an extracellular L-asparaginase produced by a newly isolated Bacillus megaterium strain MG1 from the water bodies of Moraghat forest, Jalpaiguri, India.

An extracellular L-asparaginase was isolated and purified from Bacillus megaterium MG1 to apparent homogeneity. The purification procedure involved a combination of ammonium sulfate precipitation, ion-exchange chromatography, and gel filtration techniques, resulting in a purification factor of 31.52 fold with a specific activity of 215 U mg-1. The molecular mass of the purified enzyme was approximately 47 kDa on SDS-PAGE and 185 kDa on native PAGE gel as well as in gel filtration column chromatography, revealing that the enzyme was a homotetramer. The Km and Vmax values of the purified enzyme were calculated to be 2.0 ⅹ 10-4 M and 1.198 mM s-1. Maximum enzyme activity was observed over a wide range of temperature and pH values with an optimum temperature of 37°C and pH 8.5. SDS and metal ions such as Fe2+, Cu2+, Mg2+, Co2+, Mn2+, and Ca2+ decreased the enzyme activity remarkably, whereas the addition of Na+ and K+ led to an increase in activity. The insensitivity of the protein in the presence of EDTA suggested that the enzyme might not essentially be a metalloprotein. Its marked stability and activity in organic solvents and reducing agents suggest that this asparaginase is highly suitable as a biotechnological tool with industrial applications.

Linearmycins are lytic membrane-targeting antibiotics.

The linearmycin family of polyketides was originally classified as antifungal metabolites. However, in addition to antifungal activity, we previously found that linearmycins cause cellular lysis and colony degradation of the Gram-positive bacterium Bacillus subtilis. We recently showed that Streptomyces sp. strain Mg1 incorporates linearmycins into extracellular vesicles, which are capable of lysing B. subtilis. However, the mechanism of linearmycin-induced lysis was hitherto unexplored. Therefore, we sought to determine how linearmycin-laden vesicles cause lysis. In this study, we found that linearmycins inhibited the growth of all Gram-positive bacteria that we tested, but lysis was limited to some Bacillus species. Next, we found that linearmycin-induced lysis occurred even when cellular metabolism and growth were inhibited, which suggested that linearmycins possess the intrinsic capacity to lyse cells, unlike cell-wall targeting antibiotics. We showed that linearmycin exposure caused changes consistent with rapid depolarization of the B. subtilis cytoplasmic membrane, which was correlated with a loss of viability. Finally, using liposomes as in vitro membrane models, we demonstrated that linearmycins are capable of disrupting lipid bilayers without any other cellular components. Taken together, our results strongly indicate that the cytoplasmic membrane is the direct antibacterial target of linearmycins.

Linearmycins Activate a Two-Component Signaling System Involved in Bacterial Competition and Biofilm Morphology.

Bacteria use two-component signaling systems to adapt and respond to their competitors and changing environments. For instance, competitor bacteria may produce antibiotics and other bioactive metabolites and sequester nutrients. To survive, some species of bacteria escape competition through antibiotic production, biofilm formation, or motility. Specialized metabolite production and biofilm formation are relatively well understood for bacterial species in isolation. How bacteria control these functions when competitors are present is not well studied. To address fundamental questions relating to the competitive mechanisms of different species, we have developed a model system using two species of soil bacteria, Bacillus subtilis and Streptomyces sp. strain Mg1. Using this model, we previously found that linearmycins produced by Streptomyces sp. strain Mg1 cause lysis of B. subtilis cells and degradation of colony matrix. We identified strains of B. subtilis with mutations in the two-component signaling system yfiJK operon that confer dual phenotypes of specific linearmycin resistance and biofilm morphology. We determined that expression of the ATP-binding cassette (ABC) transporter yfiLMN operon, particularly yfiM and yfiN, is necessary for biofilm morphology. Using transposon mutagenesis, we identified genes that are required for YfiLMN-mediated biofilm morphology, including several chaperones. Using transcriptional fusions, we found that YfiJ signaling is activated by linearmycins and other polyene metabolites. Finally, using a truncated YfiJ, we show that YfiJ requires its transmembrane domain to activate downstream signaling. Taken together, these results suggest coordinated dual antibiotic resistance and biofilm morphology by a single multifunctional ABC transporter promotes competitive fitness of B. subtilisIMPORTANCE DNA sequencing approaches have revealed hitherto unexplored diversity of bacterial species in a wide variety of environments that includes the gastrointestinal tract of animals and the rhizosphere of plants. Interactions between different species in bacterial communities have impacts on our health and industry. However, many approaches currently used to study whole bacterial communities do not resolve mechanistic details of interspecies interactions, including how bacteria sense and respond to their competitors. Using a competition model, we have uncovered dual functions for a previously uncharacterized two-component signaling system involved in specific antibiotic resistance and biofilm morphology. Insights gleaned from signaling within interspecies interaction models build a more complete understanding of gene functions important for bacterial communities and will enhance community-level analytical approaches.

Metabolic engineering of Serratia marcescens MG1 for enhanced production of (3R)-acetoin.

BackgroundOptically pure acetoin (AC) is an important platform chemical which has been widely used to synthesize novel optically active α-hydroxyketone derivatives and liquid crystal composites.ResultsIn this study, slaC and gldA encoding meso-2,3-butanediol dehydrogenase (meso-2,3-BDH) and glycerol dehydrogenase (GDH), respectively, in S. marcescens MG1 were knocked out to block the conversion from AC to 2,3-butanediol (2,3-BD). The resulting strain MG14 was found to produce a large amount of optically pure (3R)-AC with a little 2,3-BD, indicating that another enzyme responsible for 2,3-BD formation except meso-2,3-BDH and GDH existed in the strain MG1. Furthermore, SlaR protein, a transcriptional activator of AC cluster, was overexpressed using P C promoter in the strain MG14, leading to enhancement of the (3R)-AC yield by 29.91%. The recombinant strain with overexpression of SlaR, designated as S. marcescens MG15, was used to perform medium optimization for improving (3R)-AC production.ConclusionUnder the optimized conditions, 39.91 ± 1.35 g/l (3R)-AC was produced by strain MG15 with the productivity of 1.11 g/l h and the conversion rate of 80.13%.

First Record of Potentially Pathogenic Amoeba Vermamoeba vermiformis (Lobosea: Gymnamoebia) Isolated from a Freshwater of Dokdo Island in the East Sea, Korea

Vermamoeba vermiformis is a very important free-living amoeba for human health in association with Legionnaires’ disease and keratitis. This interesting amoeba was firstly isolated from a freshwater of Dokdo (island), which was historically used for drinking water. Trophozoites and cyst forms of V. vermiformis strain MG1 are very similar to previous reported species. Trophozoites of V. vermiformis strain MG1 showed cylindrical shape with prominent anterior hyaline region. The average ratio of length and width was about 6.5. Typically, cysts of the strain MG1 showed a spherical or slightly ovoidal shape with smooth wall, and lacked cyst pores. Some cysts had crenulatewalled ectocyst, which was separated from endocyst wall. Further, 18S rRNA gene sequence of V. vermiformis strain MG1 showed very high similarity to other V. vermiformis species (99.4%-99.9% identity). Molecular phylogenetic analysis based on 18S rRNA gene sequences clearly confirmed that the isolate was one strain of V. vermiformis with maximum bootstrap value (maximum likelihood: 100%) and Bayesian posterior probability of 1. Thus, the freshwater of Dokdo in Korea could harbor potentially pathogenic amoeba that may cause diseases in humans.

Recently published Streptomyces genome sequences.

Recently published Streptomyces genome sequences.

De Novo Assembly of the Streptomyces sp. Strain Mg1 Genome Using PacBio Single-Molecule Sequencing

We report a draft genome assembly of Streptomyces sp. strain Mg1, a competitive soil isolate with multiple secondary metabolite gene clusters.

Decolorizing Activity of Malachite Green and Its Mechanisms Involved in Dye Biodegradation by Achromobacter xylosoxidans MG1

An Achromobacter xylosoxidans MG1 strainisolated from the effluent treatment plant of a textile and dyeing factory from Yunnan Province in China was found capable of decolorizing the malachite green dye at a high efficacy. Strain MG1 reduced 86% malachite green at the concentration of 2,000 mg/l within 1 h, representing a greater ability for decolorizing and a higher tolerance of this compound than all previously reported bacteria. Color removal was optimal at pH 6 and 38°C. Further experimental evidences demonstrated that both cytoplasmic and extracellular biodegradation contributed to the decolorization of malachite green. Nested PCR was employed to identify the candidate genes responsible for malachite green decolorization, and we identified a cytoplasmic triphenylmethane reductase gene with 100% amino acid similarity to the corresponding gene in Citrobacter sp. strain. In contrast to our expectation, the addition of metyrapone had little effect on the cytoplasmic biodegradation, suggesting that cytochrome P450 was not involved in the high-performance reduction. The extracellular biodegradation was likely attributable to the secretion of extracellular proteases and some heat-resistant compounds.

Foliar fungal endophytes from two species of the mangrove Rhizophora

Endophytic fungi were isolated from leaves of Rhizophora apiculata Bl. and Rhizophora mucronata Lamk., two typical mangrove plants growing in the Pichavaram mangrove of Tamil Nadu, Southern India. Three hundred leaf segments from each plant species were sampled during dry and rainy months. More endophytes could be isolated during the rainy months than during the dry period. Hyphomycetes and sterile forms were more prevalent than ascomycetes or coelomycetes. Sporormiella minima, Acremonium sp. strain MG1 and a sterile fungus (MG90) were isolated from both plants irrespective of the season. Some endophytes were common to both plants, although a few appeared to be host specific. This is the first report on fungal endophytes in leaves of mangrove plants in India.Key words: endophytic fungi, Rhizophora apiculata, Rhizophora mucronata, mangrove, leaves.