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International Journal of Molecular... Aug 2022Herein, a novel laccase gene, , was amplified from and successfully expressed in with a molecular weight of approximately 50 kDa. The purified Melac13220 had no...
Herein, a novel laccase gene, , was amplified from and successfully expressed in with a molecular weight of approximately 50 kDa. The purified Melac13220 had no absorption peak at 610 nm and remained silent within electron paramagnetic resonance spectra, suggesting that Melac13220 belongs to the non-blue laccase group. Both inductively coupled plasma spectroscopy/optical emission spectrometry (ICP-OES) and isothermal titration calorimetry (ITC) indicated that one molecule of Melac13220 can interact with two iron ions. Furthermore, the optimal temperature of Melac13220 was 65 °C. It also showed a high thermolability, and its half-life at 65 °C was 80 min. Melac13220 showed a very good acid environment tolerance; its optimal pH was 1.5. Cu and Co can slightly increase enzyme activity, whereas Fe could increase Melac13220's activity five-fold. Differential scanning calorimetry (DSC) indicated that Fe could also stabilize Melac13220. Unlike most laccases, Melac13220 can efficiently decolorize Congo Red and Indigo Carmine dyes even in the absence of a redox mediator. Thus, the non-blue laccase from shows potential application value and may be valuable for environmental protection, especially in the degradation of dyes at low pH.
Topics: Coloring Agents; Escherichia coli; Hydrogen-Ion Concentration; Indigo Carmine; Laccase; Methylobacterium extorquens; Temperature
PubMed: 36077196
DOI: 10.3390/ijms23179804 -
Genome Biology and Evolution Aug 2022Methylobacterium is a group of methylotrophic microbes associated with soil, fresh water, and particularly the phyllosphere, the aerial part of plants that has been well...
Methylobacterium is a group of methylotrophic microbes associated with soil, fresh water, and particularly the phyllosphere, the aerial part of plants that has been well studied in terms of physiology but whose evolutionary history and taxonomy are unclear. Recent work has suggested that Methylobacterium is much more diverse than thought previously, questioning its status as an ecologically and phylogenetically coherent taxonomic genus. However, taxonomic and evolutionary studies of Methylobacterium have mostly been restricted to model species, often isolated from habitats other than the phyllosphere and have yet to utilize comprehensive phylogenomic methods to examine gene trees, gene content, or synteny. By analyzing 189 Methylobacterium genomes from a wide range of habitats, including the phyllosphere, we inferred a robust phylogenetic tree while explicitly accounting for the impact of horizontal gene transfer (HGT). We showed that Methylobacterium contains four evolutionarily distinct groups of bacteria (namely A, B, C, D), characterized by different genome size, GC content, gene content, and genome architecture, revealing the dynamic nature of Methylobacterium genomes. In addition to recovering 59 described species, we identified 45 candidate species, mostly phyllosphere-associated, stressing the significance of plants as a reservoir of Methylobacterium diversity. We inferred an ancient transition from a free-living lifestyle to association with plant roots in Methylobacteriaceae ancestor, followed by phyllosphere association of three of the major groups (A, B, D), whose early branching in Methylobacterium history has been heavily obscured by HGT. Together, our work lays the foundations for a thorough redefinition of Methylobacterium taxonomy, beginning with the abandonment of Methylorubrum.
Topics: Ecosystem; Methylobacterium; Phylogeny; Plant Leaves; Plants; RNA, Ribosomal, 16S
PubMed: 35906926
DOI: 10.1093/gbe/evac123 -
Microbiology Spectrum Aug 2022The genus includes widespread plant-associated bacteria that are abundant in the plant phyllosphere (leaf surfaces), consume plant-secreted methanol, and can produce...
The genus includes widespread plant-associated bacteria that are abundant in the plant phyllosphere (leaf surfaces), consume plant-secreted methanol, and can produce plant growth-promoting metabolites. However, despite the potential to increase agricultural productivity, their impact on host fitness in the natural environment is relatively poorly understood. Here, we conducted field experiments with three traditionally cultivated rice landraces from northeastern India. We inoculated seedlings with native versus nonnative phyllosphere strains and found significant impacts on plant growth and grain yield. However, these effects were variable. Whereas some isolates were beneficial for their host, others had no impact or were no more beneficial than the bacterial growth medium on its own. Host plant benefits were not consistently associated with colonization and did not have altered phyllosphere microbiome composition, changes in the early expression of plant stress response pathways, or bacterial auxin production. We provide the first demonstration of the benefits of phyllosphere for rice yield under field conditions and highlight the need for further analysis to understand the mechanisms underlying these benefits. Given that the host landrace- relationship was not generalizable, future agricultural applications will require careful testing to identify coevolved host-bacterium pairs that may enhance the productivity of high-value rice varieties. Plants are associated with diverse microbes in nature. Do the microbes increase host plant health, and can they be used for agricultural applications? This is an important question that must be answered in the field rather than in the laboratory or greenhouse. We tested the effects of native, leaf-inhabiting bacteria (genus ) on traditionally cultivated rice varieties in a crop field. We found that inoculation with some bacteria increased rice grain production substantially while a nonnative bacterium reduced plant health. Overall, the effect of bacterial inoculation varied across pairs of rice varieties and their native bacteria. Thus, knowledge of evolved associations between specific bacteria hosted by specific rice varieties is necessary to develop ways to increase the yield of traditional rice landraces and preserve these important sources of cultural and genetic diversity.
Topics: Agriculture; Edible Grain; Methylobacterium; Oryza; Plant Leaves
PubMed: 35856668
DOI: 10.1128/spectrum.00810-22 -
Dental and Medical Problems 2022Wearing masks has become an essential safety measure during the coronavirus 2019 (COVID-19) pandemic. Especially clinicians in dental clinics should focus on infection...
BACKGROUND
Wearing masks has become an essential safety measure during the coronavirus 2019 (COVID-19) pandemic. Especially clinicians in dental clinics should focus on infection control. However, there is currently no data regarding the frequency of replacement of the masks used in hospitals. Hence, it is necessary for dental clinic staff, who deal with many patients in an aerosol-producing environment, to have precise mask-wearing guidelines.
OBJECTIVES
The aim of this study was to evaluate the contamination on the inner surface of the masks used by clinicians in dental clinics and provide basic data to describe hospital infection control guidelines in greater detail.
MATERIAL AND METHODS
For Study I,12 participants were recruited. The experiment was conducted indoors. After wearing the mask, the temperature and the humidity inside the mask were measured at the set time points (immediately after wearing the mask, and 10 min, 30 min, 1 h, 2 h, and 4 h after wearing the mask). During the experiment, talking was not allowed. For Study II, 23 clinicians from dental clinics were recruited. After wearing the mask, the temperature, the humidity and the number of colony-forming units (CFU) inside the mask were measured at the set time points. Finally, 15 samples were selected for the study based on a survey. Bacterial identification was conducted using the 16S rDNA sequencing.
RESULTS
The temperature and the humidity inside the mask increased significantly relative to room temperature and room humidity, respectively. Bacteria were found in all the masks worn for more than 10 min and the CFU values increased with the mask-wearing time. Bacteria belonging to the genera Staphylococcus, Bacillus and Roseomonas were detected in the used mask.
CONCLUSIONS
A mask should not be worn for more than 2 h; however, the frequency of mask replacement can vary, depending on the number of patients encountered and the working environment.
Topics: Bacteria; COVID-19; Dental Clinics; Humans; Pandemics
PubMed: 35761755
DOI: 10.17219/dmp/143544 -
Clinical and Translational Medicine Apr 2022
Topics: Dermatitis, Atopic; Humans; Skin; Staphylococcus aureus
PubMed: 35452188
DOI: 10.1002/ctm2.828 -
Bioresource Technology May 2022In the context of algal wastewater bioremediation, this study has identified a novel consortium formed by the bacterium Methylobacterium oryzae and the microalga...
In the context of algal wastewater bioremediation, this study has identified a novel consortium formed by the bacterium Methylobacterium oryzae and the microalga Chlamydomonas reinhardtii that greatly increase biomass generation (1.22 g L·d), inorganic nitrogen removal (>99%), and hydrogen production (33 mL·L) when incubated in media containing ethanol and methanol. The key metabolic aspect of this relationship relied on the bacterial oxidation of ethanol to acetate, which supported heterotrophic algal growth. However, in the bacterial monocultures the acetate accumulation inhibited bacterial growth. Moreover, in the absence of methanol, ethanol was an unsuitable carbon source and its incomplete oxidation to acetaldehyde had a toxic effect on both the alga and the bacterium. In cocultures, both alcohols were used as carbon sources by the bacteria, the inhibitory effects were overcome and both microorganisms mutually benefited. Potential biotechnological applications in wastewater treatment, biomass generation and hydrogen production are discussed.
Topics: Acetates; Biomass; Carbon; Chlamydomonas; Denitrification; Ethanol; Hydrogen; Methanol; Methylobacterium; Nitrogen
PubMed: 35364237
DOI: 10.1016/j.biortech.2022.127088 -
Frontiers in Microbiology 2022Pink-pigmented facultative methylotrophs have long been studied for their ability to grow on reduced single-carbon (C) compounds. The C groups that support...
Pink-pigmented facultative methylotrophs have long been studied for their ability to grow on reduced single-carbon (C) compounds. The C groups that support methylotrophic growth may come from a variety of sources. Here, we describe a group of strains that can engage in methoxydotrophy: they can metabolize the methoxy groups from several aromatic compounds that are commonly the product of lignin depolymerization. Furthermore, these organisms can utilize the full aromatic ring as a growth substrate, a phenotype that has rarely been described in . We demonstrated growth on -hydroxybenzoate, protocatechuate, vanillate, and ferulate in laboratory culture conditions. We also used comparative genomics to explore the evolutionary history of this trait, finding that the capacity for aromatic catabolism is likely ancestral to two clades of , but has also been acquired horizontally by closely related organisms. In addition, we surveyed the published metagenome data to find that the most abundant group of aromatic-degrading in the environment is likely the group related to , and they are especially common in soil and root environments. The demethoxylation of lignin-derived aromatic monomers in aerobic environments releases formaldehyde, a metabolite that is a potent cellular toxin but that is also a growth substrate for methylotrophs. We found that, whereas some known lignin-degrading organisms excrete formaldehyde as a byproduct during growth on vanillate, do not. This observation is especially relevant to our understanding of the ecology and the bioengineering of lignin degradation.
PubMed: 35359736
DOI: 10.3389/fmicb.2022.849573 -
Oxygen diffusion pathways in mutated forms of a LOV photoreceptor from : A molecular dynamics study.Biomolecular Concepts Mar 20224511 from is a photoreceptor of the light, oxygen voltage (LOV) family, binding flavin mononucleotide (FMN) as a chromophore. It exhibits the prototypical LOV...
4511 from is a photoreceptor of the light, oxygen voltage (LOV) family, binding flavin mononucleotide (FMN) as a chromophore. It exhibits the prototypical LOV photocycle, with the reversible formation of an FMN-Cys71 adduct via fast decay of the FMN triplet state. 4511 has high potential as a photosensitiser for singlet oxygen (SO) upon mutation of C71. 4511-C71S shows a triplet lifetime ( ) of several hundreds of microseconds, ensuring efficient energy transfer to dioxygen to form SO. In this work, we have explored the potential diffusion pathways for dioxygen within 4511 using molecular dynamics (MD) simulations. The structural model of wild-type (wt) 4511 showed a dimeric structure stabilised by a strong leucine zipper at the two C-terminal helical ends. We then introduced the C71S mutation and analysed transient and persistent oxygen channels. MD simulations indicate that the chromophore binding site is highly accessible to dioxygen. Mutations that might favour SO generation were designed based on their position with respect to FMN and the oxygen channels. In particular, the C71S-Y61T and C71S-Y61S variants showed an increased diffusion and persistence of oxygen molecules inside the binding cavity.
Topics: Flavin Mononucleotide; Methylobacterium; Molecular Dynamics Simulation; Oxygen
PubMed: 35334189
DOI: 10.1515/bmc-2022-0013 -
BMJ Case Reports Mar 2022Hepatic abscesses can rarely cause pericardial disease by erosion into the pericardial space and present with haemodynamic instability due cardiac tamponade. While rare,...
Hepatic abscesses can rarely cause pericardial disease by erosion into the pericardial space and present with haemodynamic instability due cardiac tamponade. While rare, these dramatic presentations are more often due to amoebic abscesses than bacterial abscesses. Importantly, a cause must be found for any cryptogenic hepatic abscess regardless of presentation, as there is a high association with underlying malignancy. We report a previously healthy man in his 30s who presented with cardiac tamponade from perforation of a pyogenic hepatic abscess into the pericardium in the absence of bacteremia and biliary disease. One year later, he was found to have diffusely metastatic hepatoid carcinoma.
Topics: Adenocarcinoma; Cardiac Tamponade; Humans; Liver Abscess, Pyogenic; Male; Methylobacteriaceae
PubMed: 35304358
DOI: 10.1136/bcr-2022-248947 -
Microorganisms Jan 2022Total and diazotrophic bacteria were assessed in the rhizosphere soils of native and encroaching legumes growing in the Succulent Karoo Biome (SKB), South Africa. These...
Total and diazotrophic bacteria were assessed in the rhizosphere soils of native and encroaching legumes growing in the Succulent Karoo Biome (SKB), South Africa. These were , , , and , of Fabaceae family near Springbok (Northern Cape Province) and neighboring refugia of the Fynbos biome for for comparison purposes. Metabarcoding approach using 16S rRNA gene revealed (26.7%) (23.6%) and (10%), while the gene revealed (70.3%) and (29.5%) of the total sequences recovered as the dominant phyla. Some of the diazotrophs measured were assigned to families; (39%) and (24.4%) (all legumes), (7.9%), (4.6%) and (3%) (, , ) (4.2%; ), (4%; , ), (3.1%; ), and (2.7%; ) of the total sequences recovered. These families have the potential to fix the atmospheric nitrogen. While some diazotrophs were specific or shared across several legumes, a member of species was common in all rhizosphere soils considered. had statistically significantly higher Alpha and distinct Beta-diversity values, than other legumes, supporting its influence on soil microbes. Overall, this work showed diverse bacteria that support plant life in harsh environments such as the SKB, and shows how they are influenced by legumes.
PubMed: 35208671
DOI: 10.3390/microorganisms10020216