Editorial
Spotlight
Biotechnology
BiotechnologyProbing the Nanostructure and Arrangement of Bacterial Magnetosomes by Small-Angle X-Ray ScatteringThis study explores lab-based small-angle X-ray scattering (SAXS) as a novel quantitative stand-alone technique to monitor the size, shape, and arrangement of magnetosomes during different stages of particle biogenesis in the model organism Magnetospirillum gryphiswaldense. The SAXS data sets contain volume-averaged, statistically accurate information on both the...
BiotechnologyRole of BGS13 in the Secretory Mechanism of Pichia pastorisThe yeast Pichia pastoris is used as a host system for the expression of recombinant proteins. Many of these products, including antibodies, vaccine antigens, and therapeutic proteins such as insulin, are currently on the market or in late stages of development. However, one major weakness is that sometimes these proteins are not secreted from the yeast cell...
Environmental Microbiology
Environmental Microbiology | SpotlightArcobacter peruensis sp. nov., a Chemolithoheterotroph Isolated from Sulfide- and Organic-Rich Coastal Waters off PeruOur multidisciplinary approach provides new insights into the ecophysiology of a newly isolated environmental Arcobacter species, as well as the physiological flexibility within the Arcobacter genus and sulfide-oxidizing, denitrifying microbial communities within oceanic oxygen minimum zones (OMZs). The chemolithoheterotrophic species Arcobacter peruensis...
Environmental MicrobiologyGenetic Interaction Studies Reveal Superior Performance of Rhizobium tropici CIAT899 on a Range of Diverse East African Common Bean (Phaseolus vulgaris L.) GenotypesThe existence of genotype-by-strain (GL × GR) interaction has implications for the expected stability of performance of legume inoculants and could represent both challenges and opportunities for improvement of nitrogen fixation. We find that significant genotype-by-strain interaction exists in common bean (Phaseolus vulgaris L.) but that the...
Environmental Microbiology | SpotlightGlobal Comparison of the Bacterial Communities of Bilge Water, Boat Surfaces, and External Port WaterInvasive species have been a worldwide problem for many years. However, the potential for microorganisms to become invasive is relatively underexplored. As the tools to study bacterial communities become more affordable, we are able to perform large-scale studies and examine bacterial communities in higher resolution than was previously practical. This study looked at the potential for bacteria to colonize both boat surfaces and bilge...
Environmental MicrobiologyAidB, a Novel Thermostable N-Acylhomoserine Lactonase from the Bacterium Bosea sp.A quorum-sensing system using AHLs as the signal in many bacterial pathogens is a critical virulence regulator and an attractive target for anti-infective drugs. In this work, we identified a novel AHL lactonase, AidB, from a soil bacterial strain, Bosea sp. F3-2. The expression of aidB reduced the production of AHL signals and QS-dependent virulence factors in...
Enzymology and Protein Engineering
Enzymology and Protein EngineeringTrichoderma reesei Dehydrogenase, a Pyrroloquinoline Quinone-Dependent Member of Auxiliary Activity Family 12 of the Carbohydrate-Active Enzymes Database: Functional and Structural CharacterizationPyrroloquinoline quinone (PQQ) is an important cofactor synthesized by prokaryotes and involved in enzymatic alcohol and sugar oxidation. In eukaryotes, the benefit of PQQ as a vitamin has been suggested but never proved. Recently, the first eukaryotic enzyme using PQQ was characterized in the basidiomycete Coprinopsis cinerea, demonstrating that fungi are able to use...
Enzymology and Protein Engineering | SpotlightCrystal Structure of the Catalytic and Cytochrome b Domains in a Eukaryotic Pyrroloquinoline Quinone-Dependent DehydrogenasePyrroloquinoline quinone (PQQ) is known as the “third coenzyme” following nicotinamide and flavin. PQQ-dependent enzymes have previously been found only in prokaryotes, and the existence of a eukaryotic PQQ-dependent enzyme was in doubt. In 2014, we found an enzyme in mushrooms that catalyzes the oxidation of various sugars in a PQQ-dependent manner and that was a PQQ-dependent enzyme found in eukaryotes. This paper presents the X-ray...
Food Microbiology
Food MicrobiologyAn Alkylpyrazine Synthesis Mechanism Involving l-Threonine-3-Dehydrogenase Describes the Production of 2,5-Dimethylpyrazine and 2,3,5-Trimethylpyrazine by Bacillus subtilisDespite alkylpyrazines' contribution to flavor and their commercial value, the synthesis mechanisms of alkylpyrazines by microorganisms remain poorly understood. This study revealed the substrate, intermediates, and related enzymes for the synthesis of 2,5-dimethylpyrazine (2,5-DMP), which differ from the previous reports about the synthesis of 2,3,5,6-tetramethylpyrazine (TTMP). The synthesis mechanism described here can also explain...
Food MicrobiologyImplications of Mobile Genetic Elements for Salmonella enterica Single-Nucleotide Polymorphism Subtyping and Source Tracking InvestigationsDespite increasingly routine use of WGS and SNP subtyping in outbreak and source tracking investigations, whether and how MGEs affect SNP subtyping has not been thoroughly investigated. Besides chromosomal MGEs, plasmids are frequently entangled in draft genome assemblies and yet to be assessed for their impact on SNP subtyping. This study provides evidence-based guidance on the treatment of MGEs in SNP analysis for Salmonella...
Genetics and Molecular Biology
Genetics and Molecular Biology | SpotlightTranscription Factor Atf1 Regulates Expression of Cellulase and Xylanase Genes during Solid-State Fermentation of AscomycetesThe transition to a more environmentally friendly economy encourages studies involving the high-value-added utilization of lignocellulosic biomass. Solid-state fermentation (SSF), that simulates the natural habitat of soil microorganisms, is used for a variety of applications such as biomass biorefinery. Prior to the current study, our understanding of genome-wide gene expression and of the regulation of gene expression of...
Genetics and Molecular BiologyPhenylacetyl Coenzyme A, Not Phenylacetic Acid, Attenuates CepIR-Regulated Virulence in Burkholderia cenocepaciaThe opportunistic pathogen Burkholderia cenocepacia uses a chemical signal process called quorum sensing (QS) to produce virulence factors. In B. cenocepacia, QS relies on the presence of the transcriptional regulator CepR which, upon binding QS signal molecules, activates virulence. In this work,...
Genetics and Molecular Biology | SpotlightA Single Transcription Factor (PDD1) Determines Development and Yield of Winter Mushroom (Flammulina velutipes)Mushrooms are sources of food and medicine and provide abundant nutrients and bioactive compounds. However, most of the edible mushrooms cannot be cultivated commercially due to the limited understanding of basidioma development. From winter mushroom (Flammulina velutipes; also known as Enokitake), one of the most commonly cultivated mushrooms, we identified a novel...
Genetics and Molecular BiologyConjugative Transfer of IncP-9 Catabolic Plasmids Requires a Previously Uncharacterized Gene, mpfK, Whose Homologs Are Conserved in Various MPFT-Type PlasmidsIncP-9 plasmids are important mobile genetic elements for the degradation of various aromatic hydrocarbons. Elucidation of conjugative transfer of such plasmids is expected to greatly contribute to our understanding of its role in the bioremediation of polluted environments. The present study mainly focused on the conjugation system of NAH7, a well-studied and naphthalene-catabolic IncP-9 plasmid. Our analysis showed that the NAH7...
Microbial Ecology
Microbial EcologyTripartite Symbiosis of an Anaerobic Scuticociliate with Two Hydrogenosome-Associated Endosymbionts, a Holospora-Related Alphaproteobacterium and a Methanogenic ArchaeonTripartite symbioses between anaerobic ciliated protists and their intracellular archaeal and bacterial symbionts are not uncommon, but most reports have been based mainly on microscopic observations. Deeper insights into the function, ecology, and evolution of these fascinating symbioses involving partners from all three domains of life have been hampered by the difficulties of culturing anaerobic ciliates in the laboratory and the...
Microbial EcologyLocal Adaptation of Bacterial Symbionts within a Geographic Mosaic of Antibiotic CoevolutionRecently, coevolutionary theory in macroorganisms has been advanced by the geographic mosaic theory of coevolution (GMC), which considers how geography and local adaptation shape coevolutionary dynamics. Here, we test GMC in an ancient symbiosis in which the ant Apterostigma dentigerum cultivates fungi in an agricultural system analogous to human farming. The cultivars are parasitized by the fungus Escovopsis. The ants...
Microbial EcologyEscherichia coli B2 Phylogenetic Subgroups in the Infant Gut Microbiota: Predominance of Uropathogenic Lineages in Swedish Infants and Enteropathogenic Lineages in Pakistani InfantsThe intestinal microbiota is an important reservoir for bacteria that cause extraintestinal infections. Escherichia coli is found ubiquitously in the gut microbiota, and it also causes urinary tract infections, infantile septicemia, and meningitis. Urinary tract infections are usually caused by E. coli...
Microbial EcologySuccession of Microbial Decomposers Is Determined by Litter Type, but Site Conditions Drive Decomposition RatesAnthropogenic disturbance may cause shifts in vegetation and alter the litter input. We studied the decomposition of different litter types under soil conditions of a nutrient-rich grassland and nutrient-poor forest to identify factors responsible for changes in the community structure and succession of microbial decomposers. This will help to predict the consequences of induced changes on the abundance and activity of microbial...
Physiology
PhysiologyComplex Oxidation of Apocytochromes c during Bacterial Cytochrome c MaturationDsbA is a powerful oxidase that functions in the bacterial periplasm to introduce disulfide bonds in many proteins, including apocytochromes c. It has been well established that although DsbA is not essential, it plays a primary role in cytochrome c maturation, based on studies in bacteria hosting several cyts c. Here, with cyt c-rich S....
PhysiologyAmino Acid and Sugar Catabolism in the Marine Bacterium Phaeobacter inhibens DSM 17395 from an Energetic ViewpointHeterotrophic members of the bacterioplankton serve the marine ecosystem by transforming organic matter, an activity that is governed by the bacterial growth efficiencies (BGEs) obtained under given environmental conditions. In marine ecology, the concept of BGE refers to the carbon assimilation efficiency within natural communities. The marine bacterium studied here, ...
Plant Microbiology
Plant MicrobiologyAn Alkane Sulfonate Monooxygenase Is Required for Symbiotic Nitrogen Fixation by Bradyrhizobium diazoefficiens (syn. Bradyrhizobium japonicum) USDA110TRhizobia form symbiotic associations with legumes that lead to the formation of nitrogen-fixing nodules. Sulfur-containing molecules play a crucial role in nitrogen fixation; thus, the rhizobia inside nodules require large amounts of sulfur. Rhizobia can assimilate both inorganic (sulfate) and organic (sulfonates) sources of sulfur. However, very little is known about rhizobial sulfur metabolism during symbiosis. In this report, we show...
Plant MicrobiologyMultiple Introductions of Tomato Pathogen Clavibacter michiganensis subsp. michiganensis into Iran as Revealed by a Global-Scale Phylogeographic AnalysisClavibacter michiganensis subsp. michiganensis, the causal agent of tomato bacterial canker disease, is one of the economically important pathogens of solanaceous crops (e.g., eggplant, pepper, and tomato) around the world. The disease occurs in many countries, with a particular importance in regions characterized by high precipitation and humid environmental...
Public and Environmental Health Microbiology
Public and Environmental Health MicrobiologyCampylobacter jejuni Strains Associated with Wild Birds and Those Causing Human Disease in Six High-Use Recreational Waterways in New ZealandIn 2016, there was a large-scale waterborne outbreak of campylobacteriosis in New Zealand, which was estimated to have affected over 5,000 people. This highlighted the need for a greater understanding of the sources of contamination of both surface and groundwater and risks associated with exposure to both drinking and recreational water. This study reports the prevalence and population structure of...
Public and Environmental Health MicrobiologyEnvironmental Surveillance Can Dynamically Track Ecological Changes in EnterovirusesIn this study, we showed that environmental enterovirus surveillance can be used to monitor the propagation of nonpolio enteroviruses in addition to poliovirus detection. Since epidemiological studies of virus transmission based on the past were performed using specimens from humans, there were limitations to research design, such as specimen collection for implementation on a large-scale target population. However, environmental...
Public and Environmental Health MicrobiologyMetagenomic Signatures of Gut Infections Caused by Different Escherichia coli PathotypesE. coli infectious diarrhea is an important contributor to child mortality worldwide. However, diagnosing and thus treating E. coli infections remain challenging due to technical and other reasons associated with the limitations of the traditional culture-based techniques and the requirement to...
Public and Environmental Health MicrobiologyImpact of Chlorine and Chloramine on the Detection and Quantification of Legionella pneumophila and Mycobacterium SpeciesThe primary purpose of tap water disinfection is to control the presence of microbes. This study evaluated the role of disinfectant choice on the presence at the tap of L. pneumophila, its Sg1 serogroup, and three species of mycobacteria in tap water samples collected at points of human exposure at locations across the United States. The study demonstrates that...
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Applied and Environmental Microbiology® (AEM) publishes study results that make significant contributions to applied microbial research, basic microbial ecology research, and genetic and molecular investigations of microbial topics of practical value.
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