Spotlight
Minireview
MinireviewFructophilic Lactic Acid Bacteria, a Unique Group of Fructose-Fermenting MicrobesFructophilic lactic acid bacteria (FLAB) are a recently discovered group, consisting of a few Fructobacillus and Lactobacillus species. Because of their unique characteristics, including poor growth on glucose and preference of oxygen, they are regarded as “unconventional” lactic acid bacteria (LAB...
Biodegradation
Biodegradationiac Gene Expression in the Indole-3-Acetic Acid-Degrading Soil Bacterium Enterobacter soli LF7Bacterial iac genes code for the enzymatic conversion of the plant hormone indole-3-acetic acid (IAA) to catechol. Here, we demonstrate that the iac genes of soil bacterium Enterobacter soli LF7 enable growth on IAA by coarrangement and coexpression with a set of pca and cat genes that code for complete conversion of catechol to...
BiodegradationAn Amidase Gene, ipaH, Is Responsible for the Initial Step in the Iprodione Degradation Pathway of Paenarthrobacter sp. Strain YJN-5Iprodione is a widely used dicarboxamide fungicide, and its residue has been frequently detected in the environment. The U.S. Environmental Protection Agency has classified iprodione as moderately toxic to small animals and a probable carcinogen to humans. Bacterial degradation of iprodione has been widely investigated. Previous studies demonstrate that hydrolysis of its N-1 amide bond is the initial step in the typical bacterial...
Biotechnology
BiotechnologySingle-Homology-Arm Linear DNA Recombination by the Nonhomologous End Joining Pathway as a Novel and Simple Gene Inactivation Method: a Proof-of-Concept Study in Dietzia sp. Strain DQ12-45-1bMany nonmodel Gram-positive bacteria lack efficient genetic manipulation systems, but they express genes encoding Ku and LigD. The NHEJ pathway in Dietzia sp. DQ12-45-1b was evaluated and was used to successfully knock out 11 genes in the genome. Since bioinformatic studies revealed that the putative genes encoding Ku and LigD ubiquitously exist in phylogenetically diverse bacteria and archaea, the single-homology-arm linear...
BiotechnologyFunctional Genetic Elements for Controlling Gene Expression in Cupriavidus necator H16This report provides tools for robust and predictable control of gene expression in the model lithoautotroph C. necator H16. To address a current need, we designed, built, and tested promoters and RBSs for controlling gene expression in C. necator H16. To answer a question on how existing and newly...
BiotechnologyLessons in Membrane Engineering for Octanoic Acid Production from Environmental Escherichia coli IsolatesThe production of bulk fuels and chemicals in a bio-based fermentation process requires high product titers. This is often difficult to achieve, because many of the target molecules damage the membrane of the microbial cell factory. Engineering the composition of the membrane in order to decrease its vulnerability to this damage has proven to be an effective strategy for improving bioproduction, but additional strategies and engineering...
Biotechnology | SpotlightMicrobial Cell Factories à la Carte: Elimination of Global Regulators Cra and ArcA Generates Metabolic Backgrounds Suitable for the Synthesis of Bioproducts in Escherichia coliAlthough the effects of many global regulators, especially ArcA and Cra, have been studied in Escherichia coli, the metabolic changes caused by the absence of global regulators have been observed to differ between strains. This scenario complicates the identification of the individual effects of the regulators, which is essential for the design of metabolic...
BiotechnologyAlcohol Acetyltransferase Eat1 Is Located in Yeast MitochondriaEthyl acetate is a common bulk chemical that is currently produced from petrochemical sources. Several Eat1-containing yeast strains naturally produce large amounts of ethyl acetate and are potential cell factories for the production of bio-based ethyl acetate. Rational design of the underlying metabolic pathways may result in improved production strains, but it requires fundamental knowledge on the function of Eat1. A key feature is...
Environmental Microbiology
Environmental MicrobiologyIsolation of Previously Uncultured Slow-Growing Bacteria by Using a Simple Modification in the Preparation of Agar MediaMost microbial species inhabiting natural environments have not yet been isolated. One of the serious issues preventing their isolation is intrinsically slow and/or poor growth. Moreover, these slow and/or poor growers are likely to be highly sensitive to environmental stresses, especially oxidative stress. We reported previously that interaction between agar and phosphate during autoclave sterilization generates hydrogen peroxide,...
Environmental Microbiology | SpotlightAssessment of Rumen Microbiota from a Large Dairy Cattle Cohort Reveals the Pan and Core Bacteriomes Contributing to Varied PhenotypesThis study revealed the rumen bacteriome from a large dairy cattle cohort (n = 334) raised under the same management and showed the linkages among the rumen core and pan bacteriomes, rumen short-chain fatty acids, and milk production phenotypes. The findings from this study suggest that the pan rumen bacteriome, together with the core bacteriome, potentially contributes to variations in host milk production traits. Fundamental...
Environmental MicrobiologyAlgicidal Activity of Novel Marine Bacterium Paracoccus sp. Strain Y42 against a Harmful Algal-Bloom-Causing Dinoflagellate, Prorocentrum donghaienseP. donghaiense is one of the most common dinoflagellate species that form harmful algal blooms, which frequently cause serious ecological pollution and pose health hazards to humans and other animals. Screening for bacteria with high algicidal activity against P. donghaiense and studying their...
Environmental Microbiology | SpotlightResponse of Secondary Metabolism of Hypogean Actinobacterial Genera to Chemical and Biological StimuliMicrobial secondary metabolites are an important source of biologically active and therapeutically relevant small molecules. However, much of this active molecular diversity is challenging to access due to low production levels or difficulty in discerning secondary metabolites within complex microbial extracts prior to isolation. Here, we demonstrate that ecological stimuli increase secondary metabolite production in phylogenetically...
Environmental Microbiology“Candidatus Nitrosotenuis aquarius,” an Ammonia-Oxidizing Archaeon from a Freshwater Aquarium BiofilterNitrification is a critical process for preventing ammonia toxicity in engineered biofilter environments. This work describes the cultivation and complete genome sequence of a novel AOA representative enriched from a freshwater aquarium biofilter. In addition, despite the common belief in the aquarium industry that AOB mediate ammonia oxidation, the present study suggests an in situ role for “Ca. Nitrosotenuis aquarius...
Environmental MicrobiologyOuter Membrane Iron Uptake Pathways in the Model Cyanobacterium Synechocystis sp. Strain PCC 6803Cyanobacteria are globally important primary producers and contribute about 25% of global CO2 fixation. Low Fe bioavailability in surface waters is thought to limit the primary productivity in as much as 40% of the global ocean. The Fe acquisition strategies that cyanobacteria have evolved to overcome Fe deficiency remain poorly characterized. We experimentally characterized the key players and the cooperative work mode of...
Enzymology and Protein Engineering
Enzymology and Protein EngineeringA Novel β-Glucuronidase from Talaromyces pinophilus Li-93 Precisely Hydrolyzes Glycyrrhizin into Glycyrrhetinic Acid 3-O-Mono-β-d-GlucuronideCompared to chemical methods, the biotransformation of glycyrrhizin (GL) into glycyrrhetinic acid 3-O-mono-β-d-glucuronide (GAMG), which has a higher sweetness and stronger pharmacological activity than those of GL, via catalysis by β-glucuronidase is an environmentally friendly approach due to the mild reaction conditions and the high yield of GAMG. However, currently available GUSs...
Enzymology and Protein EngineeringIn Vivo Titration of Folate Pathway EnzymesE. coli can survive in drought and flooding conditions and can tolerate large changes in osmolality. However, the cell processes that limit bacterial growth under high osmotic stress conditions are not known. In this study, the dose of four different enzymes in E. coli was decreased by using...
Evolutionary and Genomic Microbiology
Evolutionary and Genomic MicrobiologyMultiple Optimal Phenotypes Overcome Redox and Glycolytic Intermediate Metabolite Imbalances in Escherichia coli pgi Knockout EvolutionsA mechanistic understanding of how microbes are able to overcome the loss of a gene through regulatory and metabolic changes is not well understood. Eight independent adaptive laboratory evolution (ALE) experiments with pgi knockout strains resulted in eight phenotypically distinct endpoints that were able to overcome the gene loss. Utilizing multi-omics analysis, the coordinated mechanisms from genome to metabolome that lead...
Food Microbiology
Food Microbiology | SpotlightA Consensus Ochratoxin A Biosynthetic Pathway: Insights from the Genome Sequence of Aspergillus ochraceus and a Comparative Genomic AnalysisOchratoxin A (OTA) is a significant mycotoxin that contaminates cereal products, coffee, grapes, wine, cheese, and meat. OTA is nephrotoxic, carcinogenic, teratogenic, and immunotoxic. OTA contamination is a serious threat to food safety, endangers human health, and can cause huge economic losses. At present, >20 species of the genera Aspergillus and...
Food MicrobiologyDynamics and Biodiversity of Bacterial and Yeast Communities during Fermentation of Cocoa BeansIn spite of the limited effectiveness of the considered inoculated starter strains, this study provides new information on the microbial development of box and heap cocoa fermentations, under inoculated and noninoculated conditions, as we coupled yeast/bacterial amplicon-based sequencing data with microbial metabolite detection. The information so far available suggests that microbial communities have played an important role in the...
Food MicrobiologyGrowth-Inhibitory Effect of d-Tryptophan on Vibrio spp. in Shucked and Live OystersOysters are the primary transmission vehicles for human Vibrio infections. Raw oyster consumption is frequently associated with gastroenteritis. The current postharvest methods, such as high-pressure processing, used to control Vibrio spp. in fresh oysters are still insufficient because of limited...
Food MicrobiologyA Diverse Range of Human Gut Bacteria Have the Potential To Metabolize the Dietary Component Gallic AcidDespite the increasing wealth of sequencing data, the health contributions of many bacteria found in the human gut microbiota have yet to be elucidated. This study applies a novel experimental approach to predict the ability of gut microbes to carry out a specific metabolic activity, i.e., gallate metabolism. The study showed that, while gallate-decarboxylating bacteria represented 47% of the bacterial genera detected previously in the...
Genetics and Molecular Biology
Genetics and Molecular BiologyVibrio fischeri Biofilm Formation Prevented by a Trio of RegulatorsBacterial biofilms promote attachment to a variety of surfaces and protect the constituent bacteria from environmental stresses, including antimicrobials. Understanding the mechanisms by which biofilms form will promote our ability to resolve them when they occur in the context of an infection. In this study, we found that Vibrio fischeri tightly controls biofilm...
Genetics and Molecular BiologyErgot Alkaloid Synthesis Capacity of Penicillium camembertiThe presence of ergot alkaloid synthesis genes in the genome of Penicillium camemberti is significant, because the fungus is widely consumed in Brie and Camembert cheeses. Our results show that, although the fungus has several functional genes from the ergot alkaloid pathway, it produces only an early pathway intermediate in culture and does not produce ergot...
Plant Microbiology
Plant MicrobiologyDiversity of Bacterial Microbiota of Coastal Halophyte Limonium sinense and Amelioration of Salinity Stress Damage by Symbiotic Plant Growth-Promoting Actinobacterium Glutamicibacter halophytocola KLBMP 5180Halophytes are important coastal plants often used for the remediation of saline coastal soils. Limonium sinense is well known for its medical properties and phytoremediation of saline soils. However, excessive exploitation and utilization have made the wild resource endangered. The use of endophytic and rhizosphere bacteria may be one of the suitable ways to solve...
Public and Environmental Health Microbiology
Public and Environmental Health MicrobiologyAntimicrobial Susceptibility Testing and Tentative Epidemiological Cutoff Values for Five Bacillus Species Relevant for Use as Animal Feed Additives or for Plant ProtectionWhen commercializing bacterial strains, like Bacillus spp., for feed applications or plant bioprotection, it is required that the strains are free of acquired antimicrobial resistance genes that could potentially spread to pathogenic bacteria, thereby adding to the pool of resistance genes that may cause treatment failures in humans or animals. Conversely, if...
Public and Environmental Health MicrobiologyAlterations of Salmonella enterica Serovar Typhimurium Antibiotic Resistance under Environmental PressureAntibiotic resistance is attributed to the misuse or overuse of antibiotics in agriculture, and antibiotic resistance genes can also be transferred to bacteria under environmental stress. In this study, we report a unidirectional alteration in antibiotic resistance from susceptibility to increased resistance. Highly sensitive Salmonella enterica serovar Typhimurium...
Public and Environmental Health Microbiology | SpotlightRole of DNA Repair and Protective Components in Bacillus subtilis Spore Resistance to Inactivation by 400-nm-Wavelength Blue LightEffective methods of spore inactivation would be of considerable interest in the health care and medical products industries, particularly if the decontamination method effectively killed spores while remaining benign to both humans and sensitive equipment. Intense blue light radiation is one such treatment that has drawn significant interest. In this work, all known spore-protective features, as well as universal and spore-specific DNA...
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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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