Spotlight
Biotechnology
BiotechnologyGeneration of a Prophage-Free Variant of the Fast-Growing Bacterium Vibrio natriegensThe fast-growing marine bacterium Vibrio natriegens represents an emerging model host for molecular biology and biotechnology, featuring a reported doubling time of less than 10 minutes. In many bacterial species, viral DNA (prophage elements) may constitute a considerable fraction of the whole genome and may have detrimental effects on the growth and fitness of...
BiotechnologySecretory Expression Fine-Tuning and Directed Evolution of Diacetylchitobiose Deacetylase by Bacillus subtilisWe successfully achieved efficient secretory production and improved the catalytic efficiency of diacetylchitobiose deacetylase in Bacillus subtilis, and this provides a good foundation for the application of diacetylchitobiose deacetylase in the production of chitosan oligosaccharides and monosaccharides.
Environmental Microbiology
Environmental MicrobiologyCalcium-Mediated Biophysical Binding of Cryptosporidium parvum Oocysts to Surfaces Is Sensitive to Oocyst AgeThe mechanisms by which pathogens bind to surfaces are of interest to a wide variety of scientific communities, as these mechanisms drive infectivity, fate, and transport of the pathogenic organisms. This study begins to reveal the mechanism of direct binding of Cryptosporidium parvum to surfaces containing both carboxylic acid and amine moieties, in an attempt to...
Environmental MicrobiologyNitrate-Utilizing Microorganisms Resistant to Multiple Metals from the Heavily Contaminated Oak Ridge ReservationNitrate contamination is a global issue that affects groundwater quality. In some cases, cocontamination of groundwater with nitrate and mixtures of heavy metals could decrease microbially mediated nitrate removal, thereby increasing the duration of nitrate contamination. Here, we used metal and nitrate concentrations that are present in a contaminated site at the Oak Ridge Reservation to isolate seven metal-resistant strains. All were...
Food Microbiology
Food MicrobiologyHeat and Chemical Treatments Affect the Viability, Morphology, and Physiology of Staphylococcus aureus and Its Subsequent Antibody Labeling for Flow Cytometric AnalysisFCM data indicated that cells conventionally considered to be dead and which would not give rise to CFU in a plate count assay, e.g., cells heated to 80°C, were labeled by antibody staining. This finding suggests that without the inclusion of a live/dead discriminating dye, these cells would be erroneously detected as viable within an FCM assay. Reductions in antibody staining due to physicochemical treatment were strain related,...
Food MicrobiologySynergistic Antimicrobial Activity by Light or Thermal Treatment and Lauric Arginate: Membrane Damage and Oxidative StressThis study highlights an effective antimicrobial processing approach using a novel combination of lauroyl arginate ethyl (LAE) and two different physical treatments, light (UV-A) and mild heat. Both combinations demonstrated synergistic inactivation against a model Gram-negative bacterium or a Gram-positive bacterium or both by a >5-log reduction. Further mechanistic study revealed that oxidative stress is responsible for synergistic...
Food MicrobiologyFacultative Anaerobes Shape Multispecies Biofilms Composed of Meat Processing Surface Bacteria and Escherichia coli O157:H7 or Salmonella enterica Serovar TyphimuriumResults of this study demonstrate that Salmonella enterica serovar Typhimurium and E. coli O157:H7 can integrate into biofilms when cocultured with bacteria from meat plant processing surfaces. However, the degree of biofilm formation for both pathogens was substantially reduced in the presence of...
Geomicrobiology
Geomicrobiology | SpotlightAccumulation and Release of Rare Earth Ions by Spores of Bacillus Species and the Location of These Ions in SporesBiosorption of rare earth ions by growing cells of Bacillus species has been well studied and has attracted attention for possible hydrometallurgy applications. However, the interaction of spores from Bacillus species with rare earth ions has not been well studied. We investigated here the adsorption and/or desorption of two rare earth ions, Tb3+ and Dy3+, by Bacillus spores, the location...
Invertebrate Microbiology
Invertebrate Microbiology | SpotlightCryptophlebia peltastica Nucleopolyhedrovirus Is Highly Infectious to Codling Moth Larvae and CellsThe emergence of codling moth populations resistant to commercially applied isolates of CpGV is posing an imminent threat to organic pome fruit production. Very few CpGV isolates are left that are able to overcome the reported types of resistance, emphasizing the demand for new and highly virulent baculoviruses. Here we report the recently discovered CrpeNPV as highly infectious to all types of resistant codling moth populations with a...
Methods
MethodsA Vibrating Mesh Nebulizer as an Alternative to the Collison Three-Jet Nebulizer for Infectious Disease AerobiologyRespiratory infection by pathogens via aerosol remains a major concern for both natural disease transmission as well as intentional release of biological weapons. Critical to understanding the disease course and pathogenesis of inhaled pathogens are studies in animal models conducted under tightly controlled experimental settings, including the inhaled dose. The route of administration, particle size, and dose can affect disease...
Microbial Ecology
Microbial EcologyCompetition between Escherichia coli Populations with and without Plasmids Carrying a Gene Encoding Extended-Spectrum Beta-Lactamase in the Broiler Chicken GutBacteria that produce extended-spectrum beta-lactamases are resistant to an important class of antimicrobials in human and veterinary medicine. Reduction in antibiotic use is expected to decrease the prevalence of resistance. However, resistance genes often lie on plasmids which can be copied and transferred to other bacteria by conjugation, so in vitro resistance was observed to increase in the absence of antimicrobials. We...
Microbial EcologyA Global Survey of Mycobacterial Diversity in SoilMycobacteria are common inhabitants of soil, and while most members of this bacterial group are innocuous, some mycobacteria can cause environmentally acquired infections of humans and other animals. Human infections from nontuberculous mycobacteria (NTM) are increasingly prevalent worldwide, and some areas appear to be “hotspots” for NTM disease. While exposure to soil is frequently implicated as an important mode of NTM transmission,...
Plant Microbiology
Plant Microbiology | SpotlightInfection Rates and Alkaloid Patterns of Different Grass Species with Systemic Epichloë EndophytesSevere problems of livestock intoxication from Epichloë-infected forage grasses have been reported from New Zealand, Australia, and the United States, but much less frequently from Europe, and particularly not from Germany. Nevertheless, it is important to monitor infection rates and alkaloids of grasses with Epichloë fungi to estimate possible intoxication risks. Most studies focus on agricultural grass species like...
Public and Environmental Health Microbiology
Public and Environmental Health MicrobiologyEffective Surveillance Using Multilocus Variable-Number Tandem-Repeat Analysis and Whole-Genome Sequencing for Enterohemorrhagic Escherichia coli O157Intensive surveillance for enterohemorrhagic Escherichia coli (EHEC) serogroup O157 is important to detect outbreaks and to prevent the spread of the bacterium. Recent advances in sequencing technology made molecular surveillance using whole-genome sequence (WGS) realistic. To develop rapid, high-throughput, and cost-effective typing methods for real-time surveillance...
Public and Environmental Health Microbiology | SpotlightK2 Capsule Depolymerase Is Highly Stable, Is Refractory to Resistance, and Protects Larvae and Mice from Acinetobacter baumannii SepsisAcinetobacter baumannii is an important nosocomial pathogen resistant to many, and sometimes all, antibiotics. The A. baumannii K2 capsular type has been associated with elevated antibiotic resistance. The capsular depolymerase characterized here fits the new trend of alternative antibacterial...
Public and Environmental Health MicrobiologyVibrio parahaemolyticus in the Chesapeake Bay: Operational In Situ Prediction and Forecast Models Can Benefit from Inclusion of Lagged Water Quality MeasurementsVibrio parahaemolyticus is one of the leading causes of seafood-borne illness in the United States and across the globe. Exposure often occurs from the consumption of raw shellfish. Despite public health concerns, there have been only sporadic efforts to develop environmental prediction and forecast models for the bacterium preharvest. This analysis used commonly...
Public and Environmental Health MicrobiologyBiocide Resistance and Transmission of Clostridium difficile Spores Spiked onto Clinical Surfaces from an American Health Care FacilityClostridium difficile is a health care-acquired organism and the causative agent of antibiotic-associated diarrhea. Its spores are implicated in fecal to oral transmission from contaminated surfaces in the health care environment due to their adherent nature. Contaminated surfaces are cleaned using high-strength chemicals to remove and kill the spores; however,...
Public and Environmental Health Microbiology | SpotlightMicrobial Dynamics of Biosand Filters and Contributions of the Microbial Food Web to Effective Treatment of Wastewater-Impacted Water SourcesAlthough microbial activities are known to contribute to the effectiveness of biosand filtration for drinking water treatment, we have a limited understanding of what microbial groups are most effectively removed, colonize the sand, or make it through the filter. This study tracked the microbial communities in the influent, sand, and effluent of lab-scale, intermittently operated biosand filters over 8 weeks. These results represent the...
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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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Dr. Harold L. Drake, Editor in Chief