Reducing residual chlortetracycline in wastewater using a whole-cell biocatalyst.

Antibiotic contamination has become an increasingly important environmental problem as a potentially hazardous emergent and recalcitrant pollutant that poses threats to human health. In this study, manganese peroxidase displayed on the outer membrane of Escherichia coli as a whole-cell biocatalyst (E. coli MnP) was expected to degrade antibiotics. The manganese peroxidase activity of the whole-cell biocatalyst was 13.88 ± 0.25 U/L. The typical tetracycline antibiotic chlortetracycline was used to analyze the degradation process. Chlortetracycline at 50 mg/L was effectively transformed via the whole-cell biocatalyst within 18 h. After six repeated batch reactions, the whole-cell biocatalyst retained 87.2 % of the initial activity and retained over 87.46 % of the initial enzyme activity after storage at 25°C for 40 days. Chlortetracycline could be effectively removed from pharmaceutical and livestock wastewater by the whole-cell biocatalyst. Thus, efficient whole-cell biocatalysts are effective alternatives for degrading recalcitrant antibiotics and have potential applications in treating environmental antibiotic contamination.

Progress in ultrasmall ferrite nanoparticles enhanced T1 magnetic resonance angiography.

Contrast-enhanced magnetic resonance angiography (CE-MRA) plays a critical role in diagnosing and monitoring various vascular diseases. Achieving high-sensitivity detection of vascular abnormalities in CE-MRA depends on the properties of contrast agents. In contrast to clinically used gadolinium-based contrast agents (GBCAs), the new generation of ultrasmall ferrite nanoparticles-based contrast agents have high relaxivity, long blood circulation time, easy surface functionalization, and high biocompatibility, hence showing promising prospects in CE-MRA. This review aims to comprehensively summarize the advancements in ultrasmall ferrite nanoparticles-enhanced MRA for detecting vascular diseases. Additionally, this review also discusses the future clinical translational potential of ultrasmall ferrite nanoparticles-based contrast agents for vascular imaging. By investigating the current status of research and clinical applications, this review attempts to outline the progress, challenges, and future directions of using ultrasmall ferrite nanoparticles to drive the field of CE-MRA into a new frontier of accuracy and diagnostic efficacy.

Rapamycin inhibits corneal inflammatory response and neovascularization in a mouse model of corneal alkali burn.

Alkali burn-induced corneal injury often causes inflammation and neovascularization and leads to compromised vision. We previously reported that rapamycin ameliorated corneal injury after alkali burns by methylation modification. In this study, we aimed to investigate the rapamycin-medicated mechanism against corneal inflammation and neovascularization. Our data showed that alkali burn could induce a range of different inflammatory response, including a stark upregulation of pro-inflammatory factor expression and an increase in the infiltration of myeloperoxidase- and F4/80-positive cells from the corneal limbus to the central stroma. Rapamycin effectively downregulated the mRNA expression levels of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1ß), toll-like receptor 4 (TLR4), nucleotide binding oligomerization domain-like receptors (NLR) family pyrin domain-containing 3 (NLRP3), and Caspase-1, and suppressed the infiltration of neutrophils and macrophages. Inflammation-related angiogenesis mediated by matrix metalloproteinase-2 (MMP-2) and rapamycin restrained this process by inhibiting the TNF-α upregulation in burned corneas of mice. Rapamycin also restrained corneal alkali burn-induced inflammation by regulating HIF-1α/VEGF-mediated angiogenesis and the serum cytokines TNF-α, IL-6, Interferon-gamma (IFN-γ) and granulocyte-macrophage colony-stimulating factor (GM-CSF). The findings of this study indicated rapamycin may reduce inflammation-associated infiltration of inflammatory cells, shape the expression of cytokines, and balance the regulation of MMP-2 and HIF-1α-mediated inflammation and angiogenesis by suppressing mTOR activation in corneal wound healing induced by an alkali injury. It offered novel insights relevant for a potent drug for treating corneal alkali burn.

Reducing cadmium accumulation in shrimp using Escherichia coli with surface-displayed peptide.

Cadmium (Cd) is a hazardous metal that can accumulate in aquatic organisms and endanger human health via the food chain. In this study, genetic engineering was used to display a peptide with Cd-binding potential on the surface of Escherichia coli cells. This whole-cell adsorbent exhibited high affinity for Cd ions (Cd2+) in the solution. The Cd2+ adsorption capacity of the whole-cell adsorbent was three-fold that of the control cells in a 20 µM Cd2+ solution, and 97.2% ± 2.38% of the Cd2+ was removed. The whole-cell adsorbent was fed to shrimp (Neocaridina denticulata), and the surface-engineered E. coli successfully colonized the shrimp intestine, which showed significantly less Cd accumulation than the group not fed surface-engineered E. coli. The whole-cell adsorbent evidently protected shrimp from the toxicity of Cd2+ by adsorbing it. Moreover, the whole-cell adsorbent mitigated the changes in microbial community structure in the shrimp gut caused by the exposure of Cd2+. These findings suggest that this strategy is effective for controlling the contamination of Cd2+ in shrimp.

Human supplementation with Pediococcus acidilactici GR-1 decreases heavy metals levels through modifying the gut microbiota and metabolome.

Exposure to heavy metals (HMs) is a threat to human health. Although probiotics can detoxify HMs in animals, their effectiveness and mechanism of action in humans have not been studied well. Therefore, we conducted this randomized, double-blind, controlled trial on 152 occupational workers from the metal industry, an at-risk human population, to explore the effectiveness of probiotic yogurt in reducing HM levels. Participants were randomly assigned to two groups: one consumed probiotic yogurt containing the HM-resistant strain Pediococcus acidilactici GR-1 and the other consumed conventional yogurt for 12 weeks. Analysis of metal contents in the blood revealed that the consumption of probiotic yogurt resulted in a higher and faster decrease in copper (34.45%) and nickel (38.34%) levels in the blood than the consumption of conventional yogurt (16.41% and 27.57%, respectively). Metagenomic and metabolomic studies identified a close correlation between gut microbiota (GM) and host metabolism. Significantly enriched members of Blautia and Bifidobacterium correlated positively with the antioxidant capacities of GM and host. Further murine experiments confirmed the essential role of GM and protective effect of GR-1 on the antioxidative role of the intestine against copper. Thus, the use of probiotic yogurt may be an effective and affordable approach for combating toxic metal exposure through the protection of indigenous GM in humans.ClinicalTrials.gov identifier: ChiCTR2100053222.

miR-188-3p-targeted regulation of ATG7 affects cell autophagy in patients with nonobstructive azoospermia.

BACKGROUND: Nonobstructive azoospermia (NOA) is one of the most difficult forms of male infertility to treat, and its pathogenesis is still unclear. miRNAs can regulate autophagy by affecting their target gene expression. Our previous study found that miR-188-3p expression in NOA patients was low. There are potential binding sites between the autophagy gene ATG7 and miR-188-3p. This study aimed to verify the binding site between miR-188-3p and ATG7 and whether miR-188-3p affects autophagy and participates in NOA by regulating ATG7 to influence the autophagy marker genes LC3 and Beclin-1. METHODS: Testicular tissue from 16 NOA patients and 16 patients with normal spermatogenesis and 5 cases in each group of pathological sections were collected. High-throughput sequencing was performed to detect mRNA expression differences. Quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, immunohistochemical staining and immunofluorescence were used to detect protein localization and expression. Autophagosome changes were detected by electron microscopy. The targeting relationship between miR-188-3p and ATG7 was confirmed by a luciferase assay. RESULTS: ATG7 protein was localized in the cytoplasm of spermatogenic cells at all levels, and the ATG7 gene (p = 0.019) and protein (p = 0.000) were more highly expressed in the NOA group. ATG7 expression after overexpression/inhibition of miR-188-3p was significantly lower (p = 0.029)/higher (p = 0.021) than in the control group. After overexpression of miR-188-3p, the ATG7 3'UTR-WT luciferase activity was impeded (p = 0.004), while the ATG7 3'UTR-MUT luciferase activity showed no significant difference (p = 0.46). LC3 (p = 0.023) and Beclin-1 (p = 0.041) expression in the NOA group was significantly higher. LC3 and Beclin-1 gene expression after miR-188-3p overexpression/inhibition was significantly lower (p = 0.010 and 0.024, respectively) and higher (p = 0.024 and 0.049, respectively). LC3 punctate aggregation in the cytoplasm decreased after overexpression of miR-188-3p, while the LC3 punctate aggregation in the miR-188-3p inhibitor group was higher. The number of autophagosomes in the miR-188-3p mimic group was lower than the number of autophagosomes in the mimic NC group. CONCLUSIONS: LC3 and Beclin-1 were more highly expressed in NOA testes and negatively correlated with the expression of miR-188-3p, suggesting that miR-188-3p may be involved in the process of autophagy in NOA. miR-188-3p may regulate its target gene ATG7 to participate in autophagy anDual luciferase experiment d affect the development of NOA.

Reducing residual antibiotic levels in animal feces using intestinal Escherichia coli with surface-displayed erythromycin esterase.

Antibiotics are widely used in livestock and poultry industries, which results in large quantities of antibiotic residues in manure that influences subsequent treatments. In this study, an Escherichia coli strain was engineered to display erythromycin esterase on its cell surface. The engineered strain (E. coli ereA) efficiently degraded erythromycin by opening the macrocyclic 14-membered lactone ring in solution. Erythromycin (50 mg/L) was completely degraded in a solution by E. coli ereA (1 × 109 CFU/mL) within 24 h. E. coli ereA retained over 86.7 % of the initial enzyme activity after 40 days of storage at 25 °C, and 78.5 % of the initial activity after seven repeated batch reactions in solution at 25 °C. Mice were fed with E. coli ereA and real-time quantitative PCR data showed that E. coli ereA colonized in the mice large intestine. The mice group fed E. coli ereA exhibited 83.13 % decrease in erythromycin levels in their feces compared with the mice group not fed E. coli ereA. E. coli ereA eliminated antibiotics from the source preventing its release into the environment. The surface-engineered strain therefore is an effective alternative agent for treating recalcitrant antibiotics, and has the potential to be applied in livestock and poultry industries.

Hg2+-binding peptide decreases mercury ion accumulation in fish through a cell surface display system.

Mercury is a potentially toxic trace metal that poses threats to aquatic life and to humans. In this study, a mercury-binding peptide was displayed on the surface of Escherichia coli cells using an N-terminal region ice nucleation protein anchor. The surface-engineered E. coli facilitated selective adsorption of mercury ions (Hg2+) from a solution containing various metal ions. The Hg2+ adsorption capacity of the surface-engineered cell was four-fold higher than that of the original E. coli cells. Approximately 95% of Hg2+ was removed from solution by these whole-cell sorbents. The transformed strains were fed to Carassius auratus, so that the bacteria could colonize fish intestine. Engineered bacteria-fed C. auratus showed significantly less (51.1%) accumulation of total mercury when compared with the group that had not been fed engineered bacteria. The surface-engineered E. coli effectively protected fish against the toxicity of Hg2+ in aquatic environments by adsorbing more Hg2+. Furthermore, the surface-engineered E. coli mitigated microbial diversity changes in the intestine caused by Hg2+ exposure, thereby protecting the intestinal microbial community. This strategy is a novel approach for controlling Hg2+ contamination in fish.

Reducing methylmercury accumulation in fish using Escherichia coli with surface-displayed methylmercury-binding peptides.

Seafood consumption is widely considered as the primary route for human exposure to the neurotoxin methylmercury (MeHg) that is produced by certain anaerobic microorganisms and can bioaccumulate to high concentration levels in natural aquatic food webs. In this study, a novel methylmercury-binding peptide with seven amino acids was displayed on the cell surfaces of Escherichia coli strain W-1, which was isolated from fish feces and fused with ice nucleation protein. These cells exhibited high affinity and selectivity toward methylmercury. They efficiently removed more than 96% of 12 µM methylmercury, and accumulation of methylmercury in the engineered strain was four times higher than that in the wild type. Transmission electron microscopy confirmed methylmercury accumulation on cell membranes. Carassius auratus was fed by engineered bacteria, which showed a decrease in methylmercury concentration in muscles of about 36.3 ± 0.7%; whereas an increase in methylmercury concentration was observed in the feces (36.7 ± 0.8%) in comparison to the control group. The engineered strain in the gut captured methylmercury and prevented it's absorption by muscles, while some bacteria with methylmercury were excreted in the feces. The surface-engineered E. coli effectively protected fish from methylmercury contamination.

A Comprehensive Review on the Biological and Pharmacological Activities of Rhodanine Based Compounds for Research and Development of Drugs.

At present, diseases resulting from various reasons have been causing deadly fears to humans and previously incogitable losses to health. Meanwhile, the patient compliance has been weakening because of drug resistance and serious drug adverse effects. There is therefore an urgent need for the development of novel structural agents. Rhodanine derivatives have exhibited wide biological activities, as well as significant industrial applications, which suggests that rhodanine heterocycle represents a key structural motif in heterocyclic chemistry and occupies a prominent position in drug discovery. Here, we review some deadly defects of clinical medicines to the therapy of diseases and important advances on rhodanine derivatives in drug researches (e.g. as anti-diabetic, anti-viral, antiinflammatory, anti-microbial, anti-tumor agents and inhibitors for Alzheimer Disease), indicating that rhodanine heterocycle could be used as a significant pharmacophore to develop novel pharmacological active molecules. It is believed that the review is of importance for new ideas in the development of and rational designs of rhodanine-based drugs.

[Phylogenetic and genetic heterogeneity of 23 Acidithiobacillus strains isolated from different geographical locations].

Objective: To study the phylogenetic and genetic heterogeneity of 23 Acidithiobacillus strains from various geographical locations, as well as the relationship between the DNA fingerprinting classification and geographical origin of Acidithiobacillus. Methods: Partial 16S-23S rRNA gene intergenic spacer (ITS) was used to construct corresponding phylogenetic trees based on the sequence homology. rus gene amplification and rep-PCR assay with two different primers (BOXAIR and ERIC) were performed to analyze genetic heterogeneity of Acidithiobacillus strains from diverse environment. Results: Acidithiobacillus revealed a great genetic heterogeneity. The whole isolates were classified into five groups by ITS sequence analysis. This result was similar with that obtained by rep-PCR. Acidithiobacillus ferrooxidans strains were always divided into two groups of phylogenetic and BOXAIR fingerprinting cluster analysis. However, these were clustered one group in the ERIC dendrogram. Genotypic analysis of the rus gene suggested that different iron oxidation pathways have been evolved in these closely related bacteria. Taken together, the iron oxidation pathway of Acidithiobacillus and phylogenetic groups have no obvious correlation. ITS gene has been proven very useful in distinguishing closely related species or subspecies of Acidithiobacillus, to BOXAIR-PCR, which has been recommended as reliable tool for genetic heterogeneity analysis of Acidithiobacillus.

[Phylogenetic and diversity analysis of Acidithiobacillus spp. based on 16S rRNA and RubisCO genes homologues].

Objective: The purpose of the study was to reveal geographic region-related Acidithiobacillus spp. distribution and allopatric speciation. Phylogenetic and diversity analysis was done to expand our knowledge on microbial phylogeography, diversity-maintaining mechanisms and molecular biogeography. Methods: We amplified 16S rRNA gene and RubisCO genes to construct corresponding phylogenetic trees based on the sequence homology and analyzed genetic diversity of Acidithiobacillus spp.. Results: Thirty-five strains were isolated from three different regions in China (Yunnan, Hubei, Xinjiang). The whole isolates were classified into five groups. Four strains were identified as A. ferrivorans, six as A. ferridurans, YNTR4-15 Leptspirillum ferrooxidans and HBDY3-31 as Leptospirillum ferrodiazotrophum. The remaining strains were identified as A. ferrooxidans. Analysis of cbbL and cbbM genes sequences of representative 26 strains indicated that cbbL gene of 19 were two copies (cbbL1 and cbbL2) and 7 possessed only cbbL1. cbbM gene was single copy. In nucleotide-based trees, cbbL1 gene sequences of strains were separated into three sequence types, and the cbbL2 was similar to cbbL1 with three types. Codon bias of RubisCO genes was not obvious in Acidithiobacillus spp.. Conclusion: Strains isolated from three different regions in China indicated a great genetic diversity in Acidithiobacillus spp. and their 16S rRNA/RubisCO genes sequence was of significant difference. Phylogenetic tree based on 16S rRNA genes and RubisCO genes was different in Acidithiobacillus spp..

Studies on the microwave extraction of the yellow pigment from Rabdosia serra (Maxim.) Hara.

A new method of microwave extraction was used to extract the yellow pigment from Rabdosia serra (Maxim.) Hara. The extraction processes were investigated and the optimal conditions were determined as follows: raw material is 2. 0000 g dry powder, the extraction agent is 95% alcohol, the ratio of raw material to extraction agent is 1:60 (g:ml) , microwave power is 464 W, extraction time is 350 s, extraction times is 3. Under the optimal conditions, extraction rate is 90.6%, productive rate is 12.7%, colority E (1%, 330 nm) is 53.3 and pH value of the extractive is 6.0. Compared with solvent extraction, microwave extraction reduces extraction time from 6 h to 350 s and increases extraction rate from 90.4% to 90.6%.