Dickeya colocasiae sp. nov. isolated from wetland taro, Colocasia esculentum

Bacterial pathogens identified as Dickeya sp. have recently been associated with a corm rot of wetland taro on Oahu, Hawaii, but the species designation of these strains was unclear. A Gram-negative, pectinolytic bacterial strain PL65T isolated from an infected taro corm was subjected to polyphasic analysis to determine its genomic and phenotypic characteristics. Multi-locus sequence analyses (MLSA) based on five housekeeping genes (dnaA, gapA, gyrB, atpD, and purA) revealed that Dickeya zeae and D. oryzae, were the closest relatives. Phylogenetic analysis based on 463 core gene sequences clearly showed two potentially new species within Dickeya oryzae. In silico DNA-DNA hybridization value of strain PL65T with 12 Type strains of Dickeya species was <68%. Average nucleotide identity (ANI) analysis revealed that PL65T was at the margin of the species delineation cut-off values with a 96% ANI value. The metabolic profile of strain PL65T using BIOLOG differentiated it from the type strains of all other known species of Dickeya. Based on the results of genome-to-genome comparisons and phenotypic data presented in this report, we propose establishment of a new species, Dickeya colocasiae sp. nov. with strain PL65T as the type strain (ICMP 24361T).

Lelliottia Rebaudianalis Sp. Nov. Isolated From Wild Stevia Rebaudiana Bertoni

A Gram-stain-negative, aerobic, chemoheterotrophic bacterium, characterized with rod shape and mobility, designated as LST-1T, was isolated from wild Stevia rebaudiana Bertoni and subjected to polyphasic taxonomic analysis. The LST-1T strain grew optimally at 37 °C and pH 6.0–7.0 in the presence of 0.5 % (w/v) NaCl. Phylogenetic sequence analysis based on 16S rDNA from LST-1 indicated that it is close to Lelliottia jeotgali (99.85%), Lelliottia nimipressuralis (98.82%), and Lelliottia amnigena (98.54%). Multi-locus sequence typing analysis of concatenated partial recA, atpD, and infB was performed to improve resolution, and clear distinctions between the closest related type strains were exhibited. Meanwhile, the results from average nucleotide identify analyses and DNA–DNA hybridization with four species (16S rDNA similarity > 98.65%) were less than 90% and 40% respectively, verifying the distinct characteristics from other species of Lelliottia, The cellular fatty acid profile of the strain consisted of C16:0, Summed Feature3, and Summed Feature8 (may be 16:1 w6c/16:1 w7c and 18:1 w6c) as major components. The major polar lipids included phosphatidylethanolamine, phosphatidylglycerol, aminophospholipid, three non-characteristic phospholipids, and a non-characteristic lipid. The genome of LST-1T is 4,611,055 bp, with a DNA G + C content of 55.02%. Combination of several phenotypic, chemotaxonomic, and genomic characteristics proved that the LST-1T strain does represent a novel genus, for which the name Lelliottia sp. LST-1 was proposed. The type strain is LST-1T (= CGMCC 1.19175T = JCM 34938T).

Functional Characterization of Transporters for L-Aspartate in Bacillus licheniformis

Amino acid efflux and influx transport systems play vital roles in industrial microorganisms’ cell growth and metabolism. However, although biochemically characterized, most of them remain unknown at the molecular level in Bacillus licheniformis. In this study, three proteins, namely, YdgF, YvbW, and YveA, were predicted to be involved in the active transport of L-aspartate (L-Asp). This was verified by manipulating their encoding genes. When growing in the minimal medium with L-Asp as the only carbon and nitrogen source, the growth of strains lacking proteins YdgF, YvbW, and YveA was significantly inhibited compared with the wild-type strains, while supplementing the expression of the corresponding proteins in the single-gene knockout strains could alleviate the inhibition. Upon overexpression, the recombinant proteins mediated the accumulation of L-aspartate to varying degrees. Compared with the wild-type strains, the single knockout strains of the three protein genes exhibited reduced absorption of L-aspartate. In addition, this study focused on the effects of these three proteins on the absorption of β-alanine, L-glutamate, D-serine, D-alanine, and glycine.

Oxidative ornithine metabolism supports non-inflammatory C. difficile colonization

The enteric pathogen Clostridioides difficile (Cd) is responsible for a toxin-mediated infection that causes more than 200,000 recorded hospitalizations and 13,000 deaths in the United States every year1. However, Cd can colonize the gut in the absence of disease symptoms. Prevalence of asymptomatic colonization by toxigenic Cd in healthy populations is high; asymptomatic carriers are at increased risk of infection compared to noncolonized individuals and may be a reservoir for transmission of Cd infection2,3. Elucidating the molecular mechanisms by which Cd persists in the absence of disease is necessary for understanding pathogenesis and developing refined therapeutic strategies. Here, we show with gut microbiome metatranscriptomic analysis that mice recalcitrant to Cd infection and inflammation exhibit increased community-wide expression of arginine and ornithine metabolic pathways. To query Cd metabolism specifically, we leverage RNA sequencing in gnotobiotic mice infected with two wild-type strains (630 and R20291) and isogenic toxin-deficient mutants of these strains to differentiate inflammation-dependent versus -independent transcriptional states. A single operon encoding oxidative ornithine degradation is consistently upregulated across non-toxigenic Cd strains. Combining untargeted and targeted metabolomics with bacterial and host genetics, we demonstrate that both diet- and host-derived sources of ornithine provide a competitive advantage to Cd, suggesting a mechanism for Cd persistence within a non-inflammatory, healthy gut.

Peptoniphilus Colimassiliensis sp. nov. and Peptoniphilus Urinimassiliensis sp. nov., Two New Species Isolated From Humans

Strains Marseille-P3761 and Marseille-P3195 are representatives of two bacterial species isolated from human specimens. Strain Marseille-P3761 was isolated from the stool of a healthy volunteer, while strain Marseille-P3915 was cultivated from the urine of a kidney transplant recipient. Both strains are anaerobic Gram-positive cocci bacteria. Both are catalase-negative and oxidase-negative and grow optimally at 37°C in anaerobic conditions. They also metabolize carbohydrates such as galactose, glucose, fructose, and glycerol. The major fatty acids were hexadecanoic acid for both strains, Marseille-P3761 (38%) and Marseille-P3195 (31%). The highest DNA-DNA hybridization values of Marseille-P3761 and Marseille-P3195 strains when compared to their closest phylogenetic relatives were 52.3% and 56.4%, respectively. The morphological, biochemical, phenotypic and genomic characteristics strongly support that these strains are new members of the Peptoniphilus genus. Thus, we suggest that strains Marseille-P3761 (CSUR P3761 = CCUG71569) and Marseille-P3195 (CSUR P3195 = DSM 103468) are the type strains of two new Peptoniphilus species, for which we propose the names Peptoniphilus colimassiliensis sp. nov. and Peptoniphilus urinimassiliensis sp. nov., respectively.

Micromonospora humida sp. nov., exhibiting antimicrobial potential, isolated from riverside soil

An actinobacterial strain designated MMS20-R1-14T was isolated from a riverside soil sample. Colonies on agar plates were orange to strong orange brown in colour, which later became black. The cells grew at 10–40 °C (optimum, 37 °C), pH 5.0–11.0 (pH 8.0) and in the presence of 0–4 % NaCl (1 %). The 16S rRNA gene sequence of strain MMS20-R1-14T showed highest similarities to Micromonospora wenchangensis CCTCC AA 2012002T (99.51 %) and Micromonospora rifamycinica AM105T (99.37 %). The orthoANI values between strain MMS20-R1-14T and the two type strains were 95.72 and 90.99 %, and the digital DNA–DNA hybridization values were 63.6 and 40.8 %, respectively, thus confirming the distinction of strain MMS20-R1-14T from its mostly related species. The DNA G+C content of strain MMS20-R1-14T was 72.9 mol%. The strain contained meso-diaminopimelic acid as the major cell-wall amino acid, and the characteristic whole-cell sugars were arabinose, xylose, glucose, ribose and rhamnose. The main cellular fatty acids were C18 : 1 ω9c, iso-C15 : 0 and iso-C16 : 0, the diagnostic polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine, and the predominant menaquinones were MK-10(H4) and MK-10(H6), all of which were consistent with those of Micromonospora . Strain MMS20-R1-14T showed antimicrobial activity against a range of bacterial and yeast species. The genome of the strain was found to contain 33 potential biosynthetic gene clusters for secondary metabolites, thus showing a high potential as a producer of bioactive compounds. On the basis of these phenotypic, genotypic and chemotaxonomic data, strain MMS20-R1-14T merits recognition as representing a novel species of the genus Micromonospora , for which the name Micromonospora humida sp. nov. (type strain=MMS20 R1-14T=KCTC 49541T=JCM 34494T) is proposed.

Paenibacillus tianjinensis sp. nov., isolated from corridor air

A Gram-stain-positive, facultatively anaerobic, non-motile, endospore-forming and rod-shaped bacterium, occurring singly or in pairs, designated TB2019T, was isolated from environmental monitoring samples of corridor air collected at the Tianjin Institute for Drug Control, Tianjin Province (PR China). The isolate was able to grow at 15–40 °C (optimum growth at 37 °C), pH 6.0–8.0 (pH 7.0) and in the presence of 0–2% (w/v) NaCl (0% NaCl). Comparison of 16S rRNA gene sequences indicated that TB2019T was most closely related to Paenibacillus typhae CGMCC 1.11012T (98.63%), Paenibacillus albidus Q4-3T (98.19%), Paenibacillus borealis DSM 13188T (97.55%), Paenibacillus helianthi P26ET (97.33%) and Paenibacillus odorifer DSM 15391T (97.19%). The digital DNA–DNA hybridization and the average nucleotide identity values between TB2019T and the five type strains mentioned above ranged from 20.7 to 25.0% and 75.2 to 81.3%, respectively, and the genomic DNA G+C content was 49.52 mol%. The diagnostic cell-wall sugar was ribose, and the diagnostic amino acid was meso-diaminopimelic acid. The polar lipids of TB2019T included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unidentified aminophospholipids and one unidentified phospholipid. MK-7 was the predominant menaquinone, and anteiso-C15:0 (30.6%) was the major fatty acid. Based on the polyphasic taxonomic data, strain TB2019T represents a novel species of the genus Paenibacillus , for which the name Paenibacillus tianjinensis sp. nov. is proposed. The type strain is TB2019T (=CICC 25065T=JCM 34610T).

Echinocandins and their Activity against Aspergillus terreus Species Complex: A Novel Agar Screening Method

We evaluated the newly proposed agar-screening method for echinocandin susceptibility testing of 144 Aspergillus section Terrei isolates in comparison with Etest®. Both methods defined the isolates to be wild type strains for anidulafungin and micafungin, with Etest® minimal effective concentrations (MECs) being ≤0.004 mg/L. For caspofungin, the novel agar-screening method identified 37 isolates to be caspofungin non-wild type based on their fluffy colony appearance on caspofungin agar. Etest® MECs for caspofungin for these isolates scattered widely from 0.002 to 0.750 mg/L, showing only partial accordance between the two methods.

The mating type transcription factor MAT1-1-1 from the fungal human pathogen Aspergillus fumigatus: synthesis, purification, and crystallization of the DNA binding domain.

Mating type (MAT) loci are the most important and significant regulators of sexual reproduction and development in ascomycetous fungi. Usually, they encode two transcription factors (TFs), named MAT1-1-1 or MAT1-2-1. Mating-type strains carry only one of the two TF genes, which control expression of pheromone and pheromone receptor genes, involved in the cell-cell recognition process. The present work presents the crystallization for the alpha1 (α1) domain of MAT1-1-1 from the human pathogenic fungus Aspergillus fumigatus (AfMAT1-1-1). Crystals were obtained for the complex between a polypeptide containing the α1 domain and DNA carrying the AfMAT1-1-1 recognition sequence. A streak seeding technique was applied to improve native crystal quality, resulting in diffraction data to 3.2 Å resolution. Further, highly redundant data sets were collected from the crystals of selenomethionine-substituted AfMAT1-1-1 with a maximum resolution of 3.2 Å. This is the first report of structural studies on the α1 domain MAT regulator involved in the mating of ascomycetes.

A natural bacterial strain Bacillus pumilus 16: Identification and antibiotic resistance evaluation

Microbial biopreparations are actively used to prevent, diagnose, and treat infectious, allergic, tumor, and autoimmune diseases in humans and animals; to stimulate the growth and development of plant crops. Natural bacterial strains with valuable technical properties are a vital biological resource for developing new biopreparations and rotating already known microbial preparations in the world market. This study describes a new natural strain B. pumilus 16, which was isolated from the rhizosphere of Cichorium. The strain was identified using morphological and physiological parameters, biochemical tests, and primers Pum-f. and Pum-r. Antibiotic sensitivity and antagonistic activity against Escherichia coli were determined by diffusion of discs and delayed antagonism methods, respectively. The new natural strain (like type strains) fermented arabinose, cellobiose, mannitol, mannose, salicin, sucrose, and trehalose, and gave a positive reaction to arginine dihydrolase, ONPG, Voges-Proskauer test. It also gave a negative reaction to inositol, raffinose, sorbitol, methyl-D-glucoside, inulin, and lecithinase. B. pumilus 16, unlike the test strains, was capable of fermenting citrate. Strain B. pumilus 16 was highly sensitive to cephalexin (37.9&plusmn;0.7 mm) and enrofloxacin (25.7&plusmn;8.9 mm); sensitive to ole-andomycin (17.1&plusmn;1.9 mm), benzylpenicillin (18.5&plusmn;1.2 mm), and monomycin (16.0&plusmn;0.6 mm); resist-ant to oxacillin. By the agar blocks method (7.3&plusmn;1.5 mm), a more pronounced antagonism of the new strain against E. coli was recorded than by the method of agar wells (5.3&plusmn;0.6 mm). Due to the level of antagonistic activity, B. pumilus 16 was more effective than the type strains (two of which did not show an antagonistic effect). On the basis of this, the new strain can be recommended for inclusion in the bacterial preparation composition for the national economy.