Spotlight
Biodegradation
BiodegradationBiodegradation of the Allelopathic Chemical Pterostilbene by a Sphingobium sp. Strain from the Peanut RhizospherePterostilbene, an analog of resveratrol, is a stilbene allelochemical produced by plants to inhibit microbial infection. As a potent antioxidant, pterostilbene acts more effectively than resveratrol as an antifungal agent. Bacterial degradation of this plant natural product would affect the allelopathic efficacy and fate of pterostilbene and thus its ecological role. This study explores the isolation and abundance of bacteria that...
BiodegradationAn Extracytoplasmic Function Sigma Factor Controls Cellulose Utilization by Regulating the Expression of an Outer Membrane Protein in Cytophaga hutchinsoniiThe common cellulolytic bacterium Cytophaga hutchinsonii uses a unique but poorly understood strategy in order to make use of cellulose. Throughout the process of cellulosic biomass breakdown, outer membrane proteins are thought to play key roles; this is evidenced by CHU_1276, which is required for the utilization of cellulose. However, the regulatory mechanism of...
Biotechnology
BiotechnologyHomoethanol Production from Glycerol and Gluconate Using Recombinant Klebsiella oxytoca StrainsGluconate is a biomass-derived degradation product, and glycerol can be obtained as a biodiesel byproduct. Compared to glucose, using them as the sole substrate is accompanied by the production of by-products. Our study shows that through pathway engineering and adoption of a fed-batch culture system, high-yield homoethanol production that usually can be achieved by using glucose as the substrate is achievable using gluconate and...
Biotechnologyl-Rhamnose Metabolism in Clostridium beijerinckii Strain DSM 6423A prerequisite for a successful biobased economy is the efficient conversion of biomass resources into useful products, such as biofuels and bulk and specialty chemicals. In contrast to other industrial microorganisms, natural solvent-producing clostridia utilize a wide range of sugars, including C5, C6, and deoxy-sugars, for production of long-chain alcohols (butanol and 2,3-butanediol), isopropanol, acetone, ...
BiotechnologyExtremely Thermoacidophilic Metallosphaera Species Mediate Mobilization and Oxidation of Vanadium and Molybdenum OxidesIn order to effectively leverage extremely thermoacidophilic archaea for the microbially based solubilization of solid-phase metal substrates (e.g., sulfides and oxides), understanding the mechanisms by which these archaea solubilize metals is important. Physiological analysis of Metallosphaera species growth in the presence of molybdenum and vanadium oxides revealed an indirect mode of metal mobilization, catalyzed by iron...
Environmental Microbiology
Environmental MicrobiologyBacillus velezensis Wall Teichoic Acids Are Required for Biofilm Formation and Root ColonizationBacillus velezensis is a Gram-positive plant-beneficial bacterium which is widely used in agriculture. Additionally, Bacillus spp. are some of the model organisms used in the study of biofilms, and as such, the molecular networks and regulation systems of biofilm formation are well characterized....
Environmental MicrobiologyNiche Differentiation among Three Closely Related Competibacteraceae Clades at a Full-Scale Activated Sludge Wastewater Treatment Plant and Putative Linkages to Process PerformanceMembers of the Competibacter lineage are relevant in biotechnology as glycogen-accumulating organisms (GAOs). Here, we document the presence of three Competibacteraceae clades in a full-scale activated sludge wastewater treatment plant and their linkage to specific operational conditions. We find evidence for niche differentiation among the three clades with temporal variability in clade dominance that correlates with...
Environmental Microbiology | SpotlightBiogeochemical Regimes in Shallow Aquifers Reflect the Metabolic Coupling of the Elements Nitrogen, Sulfur, and CarbonGroundwater is a key resource for drinking water production and irrigation. The interplay between geological setting, hydrochemistry, carbon storage, and groundwater microbiome ecosystem functioning is crucial for our understanding of these important ecosystem services. We targeted the encoded and expressed metabolic potential of groundwater microbiomes along an aquifer transect that diversifies in terms of hydrochemistry and land use....
Environmental MicrobiologyMolecular Identification of Enteroviruses from Cattle and Goat Feces and Environment in ThailandPossible new EV-E and EV-G genotypes were identified for EVs detected in this study. The EV-E viruses were also successfully isolated from MDBK cells. The goat EV sequence analysis suggested the presence of an ovine/caprine-specific EV group that is different from EV-G of porcine origin. The significance of our research is that it identifies and characterizes possible novel EVs, thereby indicating that enteroviruses in animals are...
Enzymology and Protein Engineering
Enzymology and Protein Engineering | SpotlightActivity and Thermostability of GH5 Endoglucanase Chimeras from Mesophilic and Thermophilic ParentsThermal stability is an essential property of enzymes in many industrial biotechnological applications, as high temperatures improve bioreactor throughput. Many protein engineering approaches, such as rational design and directed evolution, have been employed to improve the thermal properties of mesophilic enzymes. Structure-based recombination has also been used to fuse TIM barrel fragments, and even fragments from unrelated folds, to...
Enzymology and Protein EngineeringStructure-Based Engineering of Amidase from Pantoea sp. for Efficient 2-Chloronicotinic Acid BiosynthesisIn recent years, the demand for 2-chloronicotinic acid has been greatly increased. To date, several chemical methods have been used for the synthesis of 2-chloronicotinic acid, but all include tedious steps and/or drastic reaction conditions, resulting in both economic and environmental issues. It is requisite to develop an efficient and green synthesis route. We recently screened Pa-Ami and demonstrated its potential for...
Enzymology and Protein EngineeringpH-Dependent Relationship between Catalytic Activity and Hydrogen Peroxide Production Shown via Characterization of a Lytic Polysaccharide Monooxygenase from Gloeophyllum trabeumLytic polysaccharide monooxygenases promote enzymatic depolymerization of lignocellulosic materials by microorganisms due to their ability to oxidatively cleave recalcitrant polysaccharides. The properties of these copper-dependent enzymes are currently of high scientific and industrial interest. We describe a previously uncharacterized fungal LPMO and show how reductants, which are needed to prime the LPMO by reducing Cu(II) to Cu(I)...
Genetics and Molecular Biology
Genetics and Molecular BiologyGlycosyltransferase-Mediated Biofilm Matrix Dynamics and Virulence of Streptococcus mutansTooth decay, a costly and painful disease affecting the vast majority of people worldwide, is caused by the bacterium Streptococcus mutans. The bacteria utilize dietary sugars to build and strengthen biofilms, trapping acids onto the tooth’s surface and causing demineralization and decay of teeth. As knowledge of our body’s microbiomes increases, the need for...
Genetics and Molecular Biology | SpotlightLysPBC2, a Novel Endolysin Harboring a Bacillus cereus Spore Binding DomainBacteriophages produce highly evolved lytic enzymes, called endolysins, to lyse peptidoglycan and release their progeny from bacterial cells. Due to their potent lytic activity and specificity, the use of endolysins has gained increasing attention as a natural alternative to antibiotics. Since most endolysins from Gram-positive-bacterium-infecting phages have a modular structure, understanding the function of each domain is crucial to...
Genetics and Molecular BiologyExperimental Evolution of Escherichia coli K-12 in the Presence of Proton Motive Force (PMF) Uncoupler Carbonyl Cyanide m-Chlorophenylhydrazone Selects for Mutations Affecting PMF-Driven Drug Efflux PumpsThe genetic responses of bacteria to depletion of proton motive force (PMF), and their effects on drug resistance, are poorly understood. PMF drives export of many antibiotics, but the energy cost may decrease fitness when antibiotics are absent. Our evolution experiment reveals genetic mechanisms of adaptation to the PMF uncoupler CCCP, including selection for increased CCCP efflux but also against the expression of PMF-driven pumps...
Invertebrate Microbiology
Invertebrate Microbiology | SpotlightContrasting Patterns of Virus Protection and Functional Incompatibility Genes in Two Conspecific Wolbachia Strains from Drosophila pandoraWolbachia strains are common endosymbionts in insects, with multiple strains often coexisting in the same species. The coexistence of multiple strains is poorly understood but may rely on Wolbachia organisms having diverse phenotypic effects on their hosts. As Wolbachia is increasingly being developed as a tool to control disease transmission and suppress pest populations, it is important to understand the...
Methods
MethodsTowards Quantitative Microbiome Community Profiling Using Internal StandardsHigh-throughput-sequencing-based marine microbiome profiling is rapidly expanding and changing how we study the oceans. Although powerful, the technique is not fully quantitative; it provides taxon counts only in relative abundances. In order to address this issue, we present a method to quantitatively estimate microbial abundances per unit volume of seawater filtered by spiking known amounts of internal DNA standards into each sample....
Public and Environmental Health Microbiology
Public and Environmental Health Microbiology | SpotlightSurvival of Escherichia coli in Manure-Amended Soils Is Affected by Spatiotemporal, Agricultural, and Weather Factors in the Mid-Atlantic United StatesCurrent language in the Food Safety Modernization Act Produce Safety Rule states no objection to a 90- or 120-day interval between application of untreated BSAAO and harvest of crops to minimize transfer of pathogens to produce intended for human consumption with the intent to limit potential cases of foodborne illness. This regional multiple season, multiple location field trial determined survival durations of...
Public and Environmental Health MicrobiologyCampylobacter coli Clade 3 Isolates Induce Rapid Cell Death In VitroCampylobacter coli is a common zoonotic cause of gastroenteritis in humans worldwide. The majority of infections are caused by C. coli clade 1 isolates, whereas infections due to clade 2 and 3 isolates are rare. Whether this depends on a low prevalence of clade 2 and 3 isolates in reservoirs...
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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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