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Ecotoxicology and Environmental Safety Jan 2024Silver nanoparticles (AgNPs) are widely used in daily life and industry because of their excellent antibacterial properties. AgNPs can exist in wastewater in various...
Silver nanoparticles (AgNPs) are widely used in daily life and industry because of their excellent antibacterial properties. AgNPs can exist in wastewater in various forms, such as Ag, AgSO, AgCO, AgS, AgO, and AgCl. To assess the potential environmental risk of AgNPs and various forms of Ag, their toxic effects were investigated using the common denitrifier species Pseudomonas stutzeri (P. stutzeri). The inhibitory effect of AgNPs and various forms of Ag on P. stutzeri growth and its denitrification performance occurred in a concentration-dependent manner. The denitrification efficiency of P. stutzeri decreased from 95%∼97% to 89∼95%, 74∼95%, and 56∼85% under low, medium, and high exposure doses, respectively, of AgNPs and various forms of Ag. The changes in cell membrane morphology and increases in lactate dehydrogenase (LDH) release indicated that AgNPs and various forms of Ag damaged the cell membrane of P. stutzeri. Oxidative stress caused by excessive accumulation of reactive oxygen species (ROS) increased superoxide dismutase (SOD) and catalase (CAT) activities and decreased glutathione (GSH) levels. Overall, this study will help elucidate the impact of AgNPs and their transformation products on nitrogen removal efficiency in wastewater biological treatment systems.
Topics: Silver; Pseudomonas stutzeri; Metal Nanoparticles; Denitrification; Wastewater; Nitrogen; Antioxidants
PubMed: 38056119
DOI: 10.1016/j.ecoenv.2023.115785 -
IScience Oct 2023Emergence of new SARS-CoV-2 VOCs jeopardize global vaccine and herd immunity safeguards. VOCs interactions with host microbiota might affect clinical course and outcome....
Emergence of new SARS-CoV-2 VOCs jeopardize global vaccine and herd immunity safeguards. VOCs interactions with host microbiota might affect clinical course and outcome. This longitudinal investigation involving Pre-VOC and VOCs (Delta & Omicron) holo-transcriptome based nasopharyngeal microbiome at taxonomic levels followed by metabolic pathway analysis and integrative host-microbiome interaction. VOCs showed enrichment of with dominance of . Interestingly with superiority of and , were highlights of Delta VOC rather than Omicron. Common species comprising the core microbiome across all variants, reiterated the significance of in Delta, and its association with metabolic pathways enhancing inflammation in patients. Microbe-host gene correlation network revealed , , and modulating immune pathways, which might augment clinical severity in Delta. Importantly, opportunistic species of , , , and were abundant in Delta-mortality. The study establishes a functional association between elevated nasal pathobionts and dysregulated host response, particularly for Delta.
PubMed: 37701571
DOI: 10.1016/j.isci.2023.107779 -
Microorganisms Jun 2024Enhanced denitrification has been reported under weak electric fields. However, it is difficult to investigate the mechanism of enhanced denitrification due to the...
Enhanced denitrification has been reported under weak electric fields. However, it is difficult to investigate the mechanism of enhanced denitrification due to the complex interspecific interactions of mixed-culture systems. In this study, , capable of denitrification under anaerobic conditions, was selected for treating low COD/N (2.0, ratio between concentration of chemical oxygen demand and NO-N) artificial wastewater under constant external voltages of 0.2, 0.4, and 0.6 V. The results revealed that exhibited the highest efficiency in nitrate reduction at 0.2 V. Moreover, the maximum nitrate removal rate was 15.96 mg/(L·h) among the closed-circuit groups, 19.39% higher than that under the open-circuit group. Additionally, a notable reduction in nitrite accumulation was observed under weak electric fields. Enzyme activity analysis showed that the nitrate reductase activities were significantly increased among the closed-circuit groups, while nitrite reductase activities were inhibited. Transcriptomic analysis indicated that amino acid metabolism, carbohydrate metabolism, and energy metabolism were increased, enhancing the resistance of to environmental stress and the efficiency of carbon source utilization for denitrification. The current study examined the impacts of weak electric fields on enzyme activities and microbial metabolic pathways and offers valuable insights into the mechanism by which denitrification is enhanced by weak electric fields.
PubMed: 38930600
DOI: 10.3390/microorganisms12061218 -
Enrichment of native plastic-associated biofilm communities to enhance polyester degrading activity.Environmental Microbiology Dec 2023Plastic pollution is an increasing worldwide problem urgently requiring a solution. While recycling rates are increasing globally, only 9% of all plastic waste has been...
Plastic pollution is an increasing worldwide problem urgently requiring a solution. While recycling rates are increasing globally, only 9% of all plastic waste has been recycled, and with the cost and limited downstream uses of recycled plastic, an alternative is needed. Here, we found that expanded polystyrene (EPS) promoted high levels of bacterial biofilm formation and sought out environmental EPS waste to characterize these native communities. We demonstrated that the EPS attached communities had limited plastic degrading activity. We then performed a long-term enrichment experiment where we placed a robust selection pressure on these communities by limiting carbon availability such that the waste plastic was the only carbon source. Seven of the resulting enriched bacterial communities had increased plastic degrading activity compared to the starting bacterial communities. Pseudomonas stutzeri was predominantly identified in six of the seven enriched communities as the strongest polyester degrader. Sequencing of one isolate of P. stutzeri revealed two putative polyesterases and one putative MHETase. This indicates that waste plastic-associated biofilms are a source for bacteria that have plastic-degrading potential, and that this potential can be unlocked through selective pressure and further in vitro enrichment experiments, resulting in biodegradative communities that are better than nature.
Topics: Polyesters; Bacteria; Polystyrenes; Biofilms; Carbon
PubMed: 37515381
DOI: 10.1111/1462-2920.16466 -
Molecules (Basel, Switzerland) Jul 2023Various host systems have been employed to increase the yield of recombinant proteins. However, some recombinant proteins were successfully produced at high yields but...
Various host systems have been employed to increase the yield of recombinant proteins. However, some recombinant proteins were successfully produced at high yields but with no functional activities. To achieve both high protein yield and high activities, molecular biological strategies have been continuously developed. This work describes the effect of signal peptide (SP) and co-expression of molecular chaperones on the production of active recombinant protein in . Extracellular enzymes from , including β-1,4-xylanase, β-1,4-glucanase, and β-mannanase constructed with and without their signal peptides and intracellular enzymes from ST201, including benzoylformate decarboxylase (BFDC), benzaldehyde dehydrogenase (BADH), and d-phenylglycine aminotransferase (d-PhgAT) were cloned and overexpressed in BL21(DE3). Co-expression of molecular chaperones with all enzymes studied was also investigated. Yields of β-1,4-xylanase (Xyn), β-1,4-glucanase (Cel), and β-mannanase (Man), when constructed without their N-terminal signal peptides, increased 1112.61-, 1.75-, and 1.12-fold, respectively, compared to those of spXyn, spCel, and spMan, when constructed with their signal peptides. For the natural intracellular enzymes, the chaperones, GroEL-GroES complex, increased yields of active BFDC, BADH, and d-PhgAT, up to 1.31-, 4.94- and 37.93-fold, respectively, and also increased yields of Man and Xyn up to 1.53- and 3.46-fold, respectively, while other chaperones including DnaK-DnaJ-GrpE and Trigger factor (Tf) showed variable effects with these enzymes. This study successfully cloned and overexpressed extracellular and intracellular enzymes in BL21(DE3). When the signal peptide regions of the secretory enzymes were removed, yields of active enzymes were higher than those with intact signal peptides. In addition, a higher yield of active enzymes was obtained, in general, when these enzymes were co-expressed with appropriate chaperones. Therefore, can produce cytoplasmic and secretory enzymes effectively if only the enzyme coding sequence without its signal peptide is used and appropriate chaperones are co-expressed to assist in correct folding.
Topics: Humans; Escherichia coli; beta-Mannosidase; Molecular Chaperones; Escherichia coli Proteins; Recombinant Proteins
PubMed: 37513466
DOI: 10.3390/molecules28145594 -
Foods (Basel, Switzerland) Sep 2023The fermented liquid sector is developing all over the world due to its contribution to health. Our study has contributed to the debate about whether industrially...
The fermented liquid sector is developing all over the world due to its contribution to health. Our study has contributed to the debate about whether industrially manufactured fermented liquids live up to their claims by analyzing pathogens and beneficial bacteria using a 16S rRNA sequencing technique called metagenomic analysis. , , , , , and were the most abundant bacterial genera observed as potential probiotics. , , and , which have plant-growth-promoting traits, were also detected. The fact that we encounter biocontroller bacteria that promote plant growth demonstrates that these organisms are widely used in foods and emphasizes the necessity of evaluating them in terms of public health. Their potential applications in agriculture may pose a danger to food hygiene and human health in the long term, so our data suggest that this should be evaluated.
PubMed: 37835192
DOI: 10.3390/foods12193538 -
Scientific Reports Jan 2024There has recently been an explosion of studies implicating the human microbiome in playing a critical role in many disease and wellness states. The etiology of abnormal... (Observational Study)
Observational Study
There has recently been an explosion of studies implicating the human microbiome in playing a critical role in many disease and wellness states. The etiology of abnormal semen analysis (SA) parameters is not identified in 30% of cases; investigations involving the semen microbiome may bridge this gap. Here, we explore the relationship between the semen microbiome and alterations of sperm parameters. We recruited men presenting for fertility evaluation or vasectomy consultation with proven biological paternity. SA and next generation sequencing was performed. Differential abundance testing using Analysis of composition of Microbiota with Bias Correction (ANCOM-BC) was performed along with canonical correlational analysis for microbial community profiling. Men with abnormal (N = 27) sperm motility showed a higher abundance of Lactobacillus iners compared to those with normal (N = 46) sperm motility (mean proportion 9.4% versus 2.6%, p = 0.046). This relationship persisted on canonical correlational analysis (r = 0.392, p = 0.011). Men with abnormal sperm concentration (N = 20) showed a higher abundance of Pseudomonas stutzeri (2.1% versus 1.0%, p = 0.024) and Pseudomonas fluorescens (0.9% versus 0.7%, p = 0.010), but a lower abundance of Pseudomonas putida (0.5% versus 0.8%, p = 0.020), compared to those with normal sperm concentration (N = 53). Major limitations are related to study design (cross-sectional, observational). Our results suggest that a small group of microorganisms may play a critical role in observed perturbations of SA parameters. Some of these microbes, most notably Lactobacillus iners, have been described extensively within other, fertility-related, contexts, whereas for others, this is the first report where they have potentially been implicated. Advances in our understanding of the semen microbiome may contribute to potentially new therapeutic avenues for correcting impairments in sperm parameters and improving male fertility.
Topics: Humans; Male; Cross-Sectional Studies; Fertility; Infertility, Male; Lactobacillus; Semen; Semen Analysis; Sperm Count; Sperm Motility; Spermatozoa
PubMed: 38212576
DOI: 10.1038/s41598-024-51686-4 -
Heliyon Apr 2024Overuse of sulfonamides in aquaculture and agriculture leads to residual drugs that cause serious pollution of the environment. However, the residues of sulfonamides in...
Overuse of sulfonamides in aquaculture and agriculture leads to residual drugs that cause serious pollution of the environment. However, the residues of sulfonamides in the environment are not unique, and the existing microbial degradation technology has a relatively low degradation rate of sulfonamides. Therefore, in this study, a strain (DLY-21) with the ability to degrade four common SAs was screened and isolated from aerobic compost. Under optimal conditions, the DLY-21 strain degraded four sulfonamides simultaneously within 48 h, and the degradation rates were all over 90%, with the average degradation rates of SAs being sulfoxide (SDM) ≈ sulfachloropyridazine (SCP) > sulfa quinoxaline (SQ) > sulfadiazine (SQ). In addition, the main compounds of the strain DLY-21-degrading SAs were identified by LC-MS analysis. On this basis, four detailed reaction pathways for SA degradation were deduced. This is the first report of the use of a strain to degrade four sulfonamide antibiotics (SQ, SDM, SCP, and SM1), which can improve the removal efficiency of sulfonamide antibiotic pollutants and thus ameliorate environmental pollution. The results showed that DLY-21 had a good degradation effect on four SAs (SQ, SDM, SCP, and SM1).
PubMed: 38601639
DOI: 10.1016/j.heliyon.2024.e29123 -
EFSA Journal. European Food Safety... Jul 2023The qualified presumption of safety (QPS) approach was developed to provide a regularly updated generic pre-evaluation of the safety of microorganisms, intended for use...
Update of the list of qualified presumption of safety (QPS) recommended microbiological agents intentionally added to food or feed as notified to EFSA 18: Suitability of taxonomic units notified to EFSA until March 2023.
The qualified presumption of safety (QPS) approach was developed to provide a regularly updated generic pre-evaluation of the safety of microorganisms, intended for use in the food or feed chains, to support the work of EFSA's Scientific Panels. The QPS approach is based on an assessment of published data for each agent, with respect to its taxonomic identity, the body of relevant knowledge and safety concerns. Safety concerns identified for a taxonomic unit (TU) are, where possible, confirmed at the species/strain or product level and reflected by 'qualifications'. In the period covered by this Statement, no new information was found that would change the status of previously recommended QPS TUs. Of 38 microorganisms notified to EFSA between October 2022 and March 2023 (inclusive) (28 as feed additives, 5 as food enzymes, food additives and flavourings, 5 as novel foods), 34 were not evaluated because: 8 were filamentous fungi, 4 were and 2 were (taxonomic units that are excluded from the QPS evaluation) and 20 were taxonomic units (TUs) that already have a QPS status. Three of the other four TUs notified within this period were evaluated for the first time for a possible QPS status: , (former ) and . Microorganism strain DSM 11798 has also been notified in 2015 and as its taxonomic unit is notified as a strain not a species, it is not suitable for the QPS approach. and are not recommended for the QPS status due to a limited body of knowledge of its use in the food and feed chains. is not recommended for inclusion in the QPS list based on safety concerns and limited information about the exposure of animals and humans through the food and feed chains.
PubMed: 37434788
DOI: 10.2903/j.efsa.2023.8092 -
Journal of Advanced Research Dec 2023Transcription of biological nitrogen fixation (nif) genes is activated by the NifA protein which recognizes specific activating sequences upstream of σ-dependent nif...
INTRODUCTION
Transcription of biological nitrogen fixation (nif) genes is activated by the NifA protein which recognizes specific activating sequences upstream of σ-dependent nif promoters. The large quantities of nitrogenase which can make up 20% of the total proteins in the cell indicates high transcription activating efficiency of NifA and high transcription level of nifHDK nitrogenase genes.
OBJECTIVES
Development of an efficient gene transcription activating strategy in bacteria based on positive transcription regulatory proteins and their regulating DNA sequences.
METHODS
We designed a highly efficient gene transcription activating strategy in which the nifA gene was placed directly downstream of its regulating sequences. The NifA protein binds its regulating sequences and stimulates transcription of itself and downstream genes. Overexpressed NifA causes transcription activation by positive reinforcement.
RESULTS
When this gene transcription activating strategy was used to overexpress NifA in Pseudomonas stutzeri DSM4166 containing the nif gene cluster, the nitrogenase activity was increased by 368 folds which was 16 times higher than that obtained by nifA driven by the strongest endogenous constitutive promoter. When this strategy was used to activate transcription of exogenous biosynthetic genes for the plant auxin indole-3-acetic acid and the antitumor alkaloid pigment prodigiosin in DSM4166, both of them resulted in better performance than the strongest endogenous constitutive promoter and the highest reported productions in heterologous hosts to date. Finally, we demonstrated the universality of this strategy using the positive transcriptional regulator of the psp operon, PspF, in E. coli and the pathway-specific positive transcription regulator of the polyene antibiotic salinomycin biosynthesis, SlnR, in Streptomyces albus.
CONCLUSION
Many positive transcription regulatory proteins and their regulating DNA sequences have been identified in bacteria. The gene transcription activating strategy developed in this study will have broad applications in molecular biology and biotechnology.
PubMed: 38123018
DOI: 10.1016/j.jare.2023.12.015