Spotlight
Minireview
Minireview | SpotlightDeterminants of Phage Host Range in Staphylococcus SpeciesBacteria in the genus Staphylococcus are important targets for phage therapy due to their prevalence as pathogens and increasing antibiotic resistance. Here we review Staphylococcus outer surface features and specific phage resistance mechanisms that define the host range, the set of strains that an individual phage can potentially infect.
Biodegradation
BiodegradationMicrobial Community Analysis Provides Insights into the Effects of Tetrahydrofuran on 1,4-Dioxane BiodegradationWidespread in groundwater and carcinogenic to humans, 1,4-dioxane (dioxane) is attracting significant attention in recent years. Advanced oxidation processes can effectively remove dioxane but require high energy consumption and operation costs. Biological removal of dioxane is of particular interest due to the ability of some bacteria to mineralize dioxane at a low energy cost. Although dioxane is generally considered recalcitrant to...
Biotechnology
BiotechnologyMapping the Neutralizing Epitopes of Enterotoxigenic Escherichia coli K88 (F4) Fimbrial Adhesin and Major Subunit FaeGEnterotoxigenic Escherichia coli (ETEC) strains producing K88ac fimbriae and enterotoxins are a major cause of porcine neonatal diarrhea and postweaning diarrhea in the United States. Currently, there is no vaccine to induce broadly protective antiadhesin and antitoxin immunity against ETEC-associated diarrhea. To develop a broadly effective ETEC vaccine, we need to...
Environmental Microbiology
Environmental MicrobiologyMicrocin PDI Inhibits Antibiotic-Resistant Strains of Escherichia coli and Shigella through a Mechanism of Membrane Disruption and Protection by Homotrimer Self-ImmunityMicrocins represent potential alternatives to conventional antibiotics for human and veterinary medicine. For them to be applied in this manner, however, we need to better understand their spectrum of activity, how these proteins interact with susceptible cells, and how producer cells are protected against the antimicrobial properties of the microcins. For microcin PDI (MccPDI), we report that the spectrum of activity likely includes...
Environmental Microbiology | SpotlightLanI-Mediated Lantibiotic Immunity in Bacillus subtilis: Functional AnalysisThe two lantibiotics nisin and subtilin are produced by Lactococcus lactis and Bacillus subtilis, respectively. Both peptides have strong antimicrobial activity against Gram-positive bacteria, and therefore, appropriate protection mechanisms are required for the producing strains. To prevent...
Environmental MicrobiologySensitive and Specific Whole-Cell Biosensor for Arsenic DetectionArsenic poisoning is a severe public health issue. Rapid and simple methods for the sensitive and specific monitoring of arsenic concentration in drinking water are needed. In this study, we designed an arsenic WCB with a positive feedback amplifier. It is highly sensitive and able to detect arsenic below the WHO limit level. In addition, it also significantly improves the specificity of the biosensor toward arsenic, giving a signal...
Environmental MicrobiologyBiofilm-Constructing Variants of Paraburkholderia phytofirmans PsJN Outcompete the Wild-Type Form in Free-Living and Static Conditions but Not In PlantaParaburkholderia phytofirmans strain PsJN is a well-studied plant-associated bacterium known to induce resistance against biotic and abiotic stresses. In this work, we described the spontaneous appearance of mucoid variants in PsJN from static cultures. We showed that the conversion from the wild-type (WT) form to variants (V) correlates with an overproduction of EPS...
Environmental MicrobiologyComparative Metagenomics Reveals Enhanced Nutrient Cycling Potential after 2 Years of Biochar Amendment in a Tropical OxisolThe incorporation of biochar into soil is a promising management strategy for sustainable agriculture owing to its potential to sequester carbon and improve soil fertility. Expanding the addition of biochar to large-scale agriculture hinges on its lasting beneficial effects on the microbial community. However, there exists a significant knowledge gap regarding the specific role that biochar plays in altering the key biological soil...
Enzymology and Protein Engineering
Enzymology and Protein Engineering | SpotlightEfficient Synthesis of Methyl 3-Acetoxypropionate by a Newly Identified Baeyer-Villiger MonooxygenaseBVMOs are emerging as a green alternative to traditional oxidants in the BV oxidation of ketones. Although many BVMOs are discovered and used in organic synthesis, few are really applied in industry, especially in the case of aliphatic ketones. Herein, a highly soluble and relatively stable monooxygenase from Rhodococcus pyridinivorans (BVMORp) was...
Enzymology and Protein EngineeringConserved Pyridoxal 5'-Phosphate-Binding Protein YggS Impacts Amino Acid Metabolism through Pyridoxine 5'-Phosphate in Escherichia coliRecent studies showed that deletion or mutation of members of the YggS protein family causes pleiotropic effects in many organisms. Little is known about the causes, mechanisms, and consequences of these diverse phenotypes. It was previously shown that yggS mutations in E. coli result in the accumulation of PNP and some metabolites in the Ile/Val biosynthetic...
Enzymology and Protein Engineering6-Hydroxypseudooxynicotine Dehydrogenase Delivers Electrons to Electron Transfer Flavoprotein during Nicotine Degradation by Agrobacterium tumefaciens S33Nicotine has been studied as a model for toxic N-heterocyclic aromatic compounds. Microorganisms can catabolize nicotine via various pathways and conserve energy from its oxidation. Although several oxidoreductases have been characterized to participate in nicotine degradation, the electron transfer involved in these processes is poorly understood. In this study, we found that 6-hydroxypseudooxynicotine dehydrogenase, a key...
Food Microbiology
Food MicrobiologyHigh Prevalence of Fluoroquinolone-Resistant Campylobacter Bacteria in Sheep and Increased Campylobacter Counts in the Bile and Gallbladders of Sheep Medicated with Tetracycline in FeedCampylobacter is a major cause of foodborne illness in humans, and antibiotic-resistant Campylobacter is considered a serious threat to public health in the United States and worldwide. As a foodborne pathogen, Campylobacter commonly exists in the intestinal tract of ruminant animals, such as sheep and cattle. Results from this study reveal the predominant genotypes and high prevalence of tetracycline (TET)...
Food Microbiology | SpotlightInfluence of Plant Species, Tissue Type, and Temperature on the Capacity of Shiga-Toxigenic Escherichia coli To Colonize, Grow, and Be Internalized by PlantsFresh produce is an important vehicle for STEC transmission, and experimental evidence shows that STEC can colonize plants as secondary hosts, but differences in the capacity to colonize occur between different plant species and tissues. Therefore, an understanding of the impact that these plant factors have on the ability of STEC to grow and establish is required for food safety considerations and risk assessment. Here, we determined...
Food MicrobiologyComposition and Origin of the Fermentation Microbiota of Mahewu, a Zimbabwean Fermented Cereal BeverageThis study provides insight into the composition and origin of the microbiota of mahewu and the composition of millet malt microbiota. Fermentation microbiota are often hypothesized to be derived from the environment, but the evidence remains inconclusive. Our findings confirm that millet malt is the major source of mahewu microbiota. By complementing culture methods with high-throughput sequencing of 16S rRNA amplicons and strain-...
Genetics and Molecular Biology
Genetics and Molecular BiologyNext Generation of Tn7-Based Single-Copy Insertion Elements for Use in Multi- and Pan-Drug-Resistant Strains of Acinetobacter baumanniiAcinetobacter baumannii is a high-priority pathogen for which research on mechanisms of resistance and virulence is a critical need. Commonly used antibiotic selection markers are not suitable for use in MDR and XDR isolates of A. baumannii due to the high antibiotic resistance of these isolates,...
Genetics and Molecular BiologyDevelopment of a CRISPR/Cas9 System for Methylococcus capsulatus In Vivo Gene EditingIn this study, we targeted the development and evaluation of broad-host-range CRISPR/Cas9 gene-editing tools in order to enhance the genetic-engineering capabilities of an industrially relevant methanotrophic biocatalyst. The CRISPR/Cas9 system developed in this study expands the genetic tools available to define molecular mechanisms in methanotrophic bacteria and has the potential to foster advances in the generation of novel...
Methods
MethodsMultilocus Sequence Analysis, a Rapid and Accurate Tool for Taxonomic Classification, Evolutionary Relationship Determination, and Population Biology Studies of the Genus ShewanellaThe MLSA scheme based on six housekeeping genes (HKGs) (gyrA, gyrB, infB, recN, rpoA, and topA) is well established as a reliable tool for taxonomic, evolutionary, and population diversity analyses of the genus Shewanella in this study. The standard MLSA method allows researchers to make rapid, economical, and precise identification of Shewanella strains. The robust...
Microbial Ecology
Microbial Ecology | SpotlightRapid and Stable Microbial Community Assembly in the Headwaters of a Third-Order StreamHeadwater streams are critical introduction points of microbial diversity for larger connecting rivers and play key roles in the establishment of taxa that partake in in-stream nutrient cycling. We examined the microbial community composition of a first- through third-order stream using fine-scale temporal and spatial regimes. Our results show that the bacterioplankton community develops rapidly and predictably from the headwater...
Physiology
PhysiologyPhototrophic Lactate Utilization by Rhodopseudomonas palustris Is Stimulated by Coutilization with Additional SubstratesBacterial carbon source utilization is frequently assessed using cultures provided single carbon sources. However, the utilization of carbon mixtures by bacteria (i.e., mixed-substrate utilization) is of both fundamental and practical importance; it is central to bacterial physiology and ecology, and it influences the utility of bacteria as biotechnology. Here we investigated mixed-substrate utilization by the model organism...
Plant Microbiology
![Insights into the Phylogeny, Nodule Function, and Biogeographic Distribution of Microsymbionts Nodulating the Orphan Kersting’s Groundnut [<em>Macrotyloma geocarpum</em> (Harms) Marechal & Baudet] in African Soils](https://aem.asm.org/sites/default/files/styles/thumbnail/public/externals/5872e975e8c74c66b6b9ddd9fbe3dd44.jpg?itok=N1HOkkO_)
Plant MicrobiologyInsights into the Phylogeny, Nodule Function, and Biogeographic Distribution of Microsymbionts Nodulating the Orphan Kersting’s Groundnut [Macrotyloma geocarpum (Harms) Marechal & Baudet] in African SoilsRhizobia play important roles in agroecosystems, where they contribute to improving overall soil health through their symbiotic relationship with legumes. This study explored the microsymbionts nodulating Kersting’s groundnut, a neglected orphan legume. The results revealed the presence of different bradyrhizobial populations with high N2-fixing efficiencies as the dominant symbionts of this legume across diverse...
Public and Environmental Health Microbiology
Public and Environmental Health MicrobiologySpecific Environmental Temperature and Relative Humidity Conditions and Grafting Affect the Persistence and Dissemination of Salmonella enterica subsp. enterica Serotype Typhimurium in Tomato Plant TissuesTomatoes are one of the most widely produced vegetables around the world; however, fresh tomatoes have been connected to multiple wide-scale salmonellosis outbreaks over the past decades. Salmonella is commonly found in the environment and can persist in hostile conditions for several weeks before being internalized into plant tissues, where it is protected from conventional sanitation methods. In addition to biotic factors (...
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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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