Poly(U)-specific endoribonuclease ENDOU promotes translation of human CHOP mRNA by releasing uORF element-mediated inhibition.

Upstream open reading frames (uORFs) are known to negatively affect translation of the downstream ORF. The regulatory proteins involved in relieving this inhibition are however poorly characterized. In response to cellular stress, eIF2α phosphorylation leads to an inhibition of global protein synthesis, while translation of specific factors such as CHOP is induced. We analyzed a 105-nt inhibitory uORF in the transcript of human CHOP (huORFchop ) and found that overexpression of the zebrafish or human ENDOU poly(U)-endoribonuclease (Endouc or ENDOU-1, respectively) increases CHOP mRNA translation also in the absence of stress. We also found that Endouc/ENDOU-1 binds and cleaves the huORFchop transcript at position 80G-81U, which induces CHOP translation independently of phosphorylated eIF2α. However, both ENDOU and phospho-eIF2α are nonetheless required for maximal translation of CHOP mRNA. Increased levels of ENDOU shift a huORFchop reporter as well as endogenous CHOP transcripts from the monosome to polysome fraction, indicating an increase in translation. Furthermore, we found that the uncapped truncated huORFchop -69-105-nt transcript contains an internal ribosome entry site (IRES), facilitating translation of the cleaved transcript. Therefore, we propose a model where ENDOU-mediated transcript cleavage positively regulates CHOP translation resulting in increased CHOP protein levels upon stress. Specifically, CHOP transcript cleavage changes the configuration of huORFchop thereby releasing its inhibition and allowing the stalled ribosomes to resume translation of the downstream ORF.

Translation initiation factor eIF4G1 modulates assembly of the polypeptide exit tunnel region in yeast ribosome biogenesis.

eIF4G is an important eukaryotic translation initiation factor. In this study, eIF4G1, one of the eIF4G isoforms, was shown to directly participate in biogenesis of the large (60S) ribosomal subunit in Saccharomyces cerevisiae cells. Mutation of eIF4G1 decreased the amount 60S ribosomal subunits significantly. The C-terminal fragment of eIF4G1 could complement the function in 60S biogenesis. Analyses of its purified complex with mass spectrometry indicated that eIF4G1 associated with the pre-60S form directly. Strong genetic and direct protein-protein interactions were observed between eIF4G1 and Ssf1 protein. Upon deletion of eIF4G1, Ssf1, Rrp15, Rrp14 and Mak16 were abnormally retained on the pre-60S complex. This purturbed the loading of Arx1 and eL31 at the polypeptide exit tunnel (PET) site and the transition to a Nog2 complex. Our data indicate that eIF4G1 is important in facilitating PET maturation and 27S processing correctly. This article has an associated First Person interview with the first author of the paper.

Mutations of ribosomal protein genes induce overexpression of catalase in Saccharomyces cerevisiae.

Ribosome assembly defects result in ribosomopathies, primarily caused by inadequate protein synthesis and induced oxidative stress. This study aimed to investigate the link between deleting one ribosomal protein gene (RPG) paralog and oxidative stress response. Our results indicated that RPG mutants exhibited higher oxidant sensitivity than the wild type (WT). The concentrations of H2O2 were increased in the RPG mutants. Catalase and superoxide dismutase (SOD) activities were generally higher at the stationary phase, with catalase showing particularly elevated activity in the RPG mutants. While both catalase genes, CTT1 and CTA1, consistently exhibited higher transcription in RPG mutants, Ctt1 primarily contributed to the increased catalase activity. Stress-response transcription factors Msn2, Msn4, and Hog1 played a role in regulating these processes. Previous studies have demonstrated that H2O2 can cleave 25S rRNA via the Fenton reaction, enhancing ribosomes' ability to translate mRNAs associated with oxidative stress-related genes. The cleavage of 25S rRNA was consistently more pronounced, and the translation efficiency of CTT1 and CTA1 mRNAs was altered in RPG mutants. Our results provide evidence that the mutations in RPGs increase H2O2 levels in vivo and elevate catalase expression through both transcriptional and translational controls.

Functional Characterization and Structural Modeling of a Novel Glycine Oxidase from Variovorax paradoxus Iso1.

The N-acyl-d-amino acid amidohydrolase (N-d-AAase) of Variovorax paradoxus Iso1 can enantioselectively catalyze the zinc-assisted deacetylation of N-acyl-d-amino acids to yield consistent d-amino acids. A putative FAD-binding glycine/d-amino acid oxidase was located immediately upstream of the N-d-AAase gene. The gene encoding this protein was cloned into Escherichia coli BL21 (DE3)pLysS and overexpressed at 25°C for 6 h with 0.5 mM isopropyl ß-d-1-thiogalactopyranoside induction. After purification, the tag-free recombinant protein was obtained. The enzyme could metabolize glycine, sarcosine, and d-alanine, but not l-amino acids or bulky d-amino acids. Protein modeling further supported these results, demonstrating that glycine, sarcosine, and d-alanine could fit into the pocket of the enzyme's activation site, while l-alanine and d-threonine were out of position. Therefore, this protein was proposed as a glycine oxidase, and we designated it VpGO. Interestingly, VpGO showed low sequence similarity to other well-characterized glycine oxidases. We found that VpGO and N-d-AAase were expressed on the same mRNA and could be transcriptionally induced by various N-acetyl-d-amino acids. Western blotting and zymography showed that both proteins had similar expression patterns in response to different types of inducers. Thus, we have identified a novel glycine oxidase that is co-regulated with N-d-AAase in an operon, and metabolizes N-acyl-d-amino acids in the metabolically versatile V. paradoxus Iso1. IMPORTANCE The Gram-negative bacterium Variovorax paradoxus has numerous metabolic capabilities, including the association with important catabolic processes and the promotion of plant growth. We had previously identified and characterized an N-acyl-d-amino-acid amidohydrolase (N-d-AAase) gene from the strain of V. paradoxus Iso1. The aim of this study was to isolate and characterize (both in vitro and in vivo) another potential gene found in the promoter region of this N-d-AAase gene. The protein was identified as a glycine oxidase, and the gene existed in an operon with N-d-AAase. The structural basis for its FAD-binding potential and substrate stereo-specificity were also elucidated. This study first reported a novel glycine oxidase from V. paradoxus. We believe that our study makes a significant contribution to the literature, because this enzyme has great potential for use as an industrial catalysis, as a biosensor, and in agricultural biotechnology.

High-dose copper activates p53-independent apoptosis through the induction of nucleolar stress in human cell lines.

Copper is an essential micronutrient involved in many redox reactions in human cells. However, a high concentration of copper, intake from the environment or abnormal accumulation within cells because of genetic mutation, leads to cell toxicity. This is attributable to oxidative damage, altered gene expression, and functional impairment of the mitochondria. Copper stress also alters the morphology of the nucleolus, but the process has not been fully elucidated. In this study, cells were treated with copper sulfate at 3-9 ppm and examined if a high dose of copper would block ribosome biogenesis. With the incorrect distribution of nucleolar proteins nucleophosmin and fibrillarin to the nucleoplasm, ribosomal RNA (rRNA) processing was impaired; 34S rRNA from an abnormal A2 cut increased, and downstream pre-rRNAs decreased. The under-accumulation of 60S subunits was detected using sucrose gradients. From transcriptome analysis, ribosome synthesis-related genes were misregulated. Blockage in ribosome synthesis under copper-treatment induced nucleolar stress and triggered p53-independent apoptosis pathways. Thus, nucleolar stress is one cause of cell death under copper exposure.

Elp1 facilitates RAD51-mediated homologous recombination repair via translational regulation.

BACKGROUND: RAD51-dependent homologous recombination (HR) is one of the most important pathways for repairing DNA double-strand breaks (DSBs), and its regulation is crucial to maintain genome integrity. Elp1 gene encodes IKAP/ELP1, a core subunit of the Elongator complex, which has been implicated in translational regulation. However, how ELP1 contributes to genome maintenance is unclear. METHODS: To investigate the function of Elp1, Elp1-deficient mouse embryonic fibroblasts (MEFs) were generated. Metaphase chromosome spreading, immunofluorescence, and comet assays were used to access chromosome abnormalities and DSB formation. Functional roles of Elp1 in MEFs were evaluated by cell viability, colony forming capacity, and apoptosis assays. HR-dependent DNA repair was assessed by reporter assay, immunofluorescence, and western blot. Polysome profiling was used to evaluate translational efficiency. Differentially expressed proteins and signaling pathways were identified using a label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics approach. RESULTS: Here, we report that Elp1 depletion enhanced genomic instability, manifested as chromosome breakage and genotoxic stress-induced genomic DNA fragmentation upon ionizing radiation (IR) exposure. Elp1-deficient cells were hypersensitive to DNA damage and exhibited impaired cell proliferation and defective HR repair. Moreover, Elp1 depletion reduced the formation of IR-induced RAD51 foci and decreased RAD51 protein levels. Polysome profiling analysis revealed that ELP1 regulated RAD51 expression by promoting its translation in response to DNA damage. Notably, the requirement for ELP1 in DSB repair could be partially rescued in Elp1-deficient cells by reintroducing RAD51, suggesting that Elp1-mediated HR-directed repair of DSBs is RAD51-dependent. Finally, using proteome analyses, we identified several proteins involved in cancer pathways and DNA damage responses as being differentially expressed upon Elp1 depletion. CONCLUSIONS: Our study uncovered a molecular mechanism underlying Elp1-mediated regulation of HR activity and provides a novel link between translational regulation and genome stability.

Differences in anti-inflammatory properties of water soluble and insoluble bioactive polysaccharides in lipopolysaccharide-stimulated RAW264.7 macrophages.

ß-Linked polysaccharides including ß-glucans are well known to be important functional ingredients, and are known to possess immunomodulatory and anti-tumor activities. This study aimed to investigate the anti-inflammatory properties and participating receptor of water soluble and insoluble bioactive polysaccharides from Grifola frondosa (GFP, non-digestible water soluble polysaccharides), Laminaria digitata (laminarin, a water soluble ß-glucan) and Saccharomyces cerevisiae (zymosan, a water insoluble ß-glucan) in lipopolysaccharide (LPS)-stimulated parental and Dectin-1 highly expressing RAW264.7 macrophages. Results showed that GFP and laminarin significantly inhibited nitric oxide and prostaglandin E2 production, but only the GFP with high molecular weight exhibited strong inhibition on pro-inflammatory cytokine (TNF-α and IL-6) secretion in a concentration-dependent manner. The activation of NF-κB was also significantly down-regulated by GFP treatment as compared with cells treated with LPS alone. Although GFP and laminarin were able to bind to ß-glucan receptor Dectin-1, there was no relationship between the inhibitory potency and the content of ß-glucans in GFP, and these inhibitory effects were not affected by the expression level of Dectin-1 in macrophage cells. In contrast, zymosan significantly intensified LPS-induced inflammatory responses through Dectin-1. In conclusion, these results suggest that the inhibitory effects of water soluble polysaccharides on LPS-induced pro-inflammatory mediator production in murine macrophages may not involve ß-glucan receptor Dectin-1.

Use Microfluidic Chips to Study the Phototaxis of Lung Cancer Cells.

Cell migration is an important process involved in wound healing, tissue development, and so on. Many studies have been conducted to explore how certain chemicals and electric fields induce cell movements in specific directions, which are phenomena termed chemotaxis and electrotaxis, respectively. However, phototaxis, the directional migration of cells or organisms toward or away from light, is rarely investigated due to the difficulty of generating a precise and controllable light gradient. In this study, we designed and fabricated a microfluidic chip for simultaneously culturing cells and generating a blue light gradient for guiding cell migration. A concentration gradient was first established inside this chip, and by illuminating it with a blue light-emitting diode (LED), a blue light gradient was generated underneath. Cell migration in response to this light stimulus was observed. It was found that lung cancer cells migrated to the dark side of the gradient, and the intracellular reactive oxygen species (ROS) was proportional to the intensity of the blue light.

Puf6 and Loc1 Are the Dedicated Chaperones of Ribosomal Protein Rpl43 in Saccharomyces cerevisiae.

Ribosomal proteins are highly expressed, and the quality of ribosomal proteins must be rigorously controlled to build up a functional ribosome. Rpl43, ribosomal protein large subunit 43, is located nearby the E-site of ribosomes. In our previous study, we found that Puf6, Loc1, and Rpl43 form a trimeric complex in Saccharomyces cerevisiae. Rpl43 protein levels are under-accumulated in the absence of PUF6 or LOC1. However, why the loss of Puf6 or Loc1 decreased the protein levels of Rpl43 remained unclear. In the present study, we further dissected the connections among these three proteins and found that the processing defects of pre-ribosomal RNA in puf6Δ and loc1Δ are similar to those of the mutant with depletion of Rpl43. The stability of newly synthesized Rpl43 protein decreased slightly in puf6Δ and significantly in loc1Δ. We also found that Puf6 and Loc1 could interact with nascent Rpl43 co-translationally via the N-terminus of Rpl43. While the association and dissociation of Rpl43 with karyopherins did not depend on Puf6 and Loc1, Puf6 and Loc1 interacted with nascent Rpl43 in collaboration. While the N-terminus of Puf6 contained nuclear localization signals for transport, the PUF (Pumilio) domain was essential to interaction with Loc1, Rpl43, and 60S subunits. The C-terminus of Loc1 is more important for interaction with Puf6 and Rpl43. In this study, we found that Puf6 and Loc1 are the dedicated chaperones of ribosomal protein Rpl43 and also analyzed the potential interaction domains among the three proteins. Correct formation of the Puf6, Loc1, and Rpl43 ternary complex is required to properly proceed to the next step in 60S biogenesis.

Bcp1 Is the Nuclear Chaperone of Rpl23 in Saccharomyces cerevisiae.

Eukaryotic ribosomes are composed of rRNAs and ribosomal proteins. Ribosomal proteins are translated in the cytoplasm and imported into the nucleus for assembly with the rRNAs. It has been shown that chaperones or karyopherins responsible for import can maintain the stability of ribosomal proteins by neutralizing unfavorable positive charges and thus facilitate their transports. Among 79 ribosomal proteins in yeast, only a few are identified with specific chaperones. Besides the classic role in maintaining protein stability, chaperones have additional roles in transport, chaperoning the assembly site, and dissociation of ribosomal proteins from karyopherins. Bcp1 has been shown to be necessary for the export of Mss4, a phosphatidylinositol 4-phosphate 5-kinase, and required for ribosome biogenesis. However, its specific function in ribosome biogenesis has not been described. Here, we show that Bcp1 dissociates Rpl23 from the karyopherins and associates with Rpl23 afterward. Loss of Bcp1 causes instability of Rpl23 and deficiency of 60S subunits. In summary, Bcp1 is a novel 60S biogenesis factor via chaperoning Rpl23 in the nucleus.

Defining the pathway of cytoplasmic maturation of the 60S ribosomal subunit.

In eukaryotic cells the final maturation of ribosomes occurs in the cytoplasm, where trans-acting factors are removed and critical ribosomal proteins are added for functionality. Here, we have carried out a comprehensive analysis of cytoplasmic maturation, ordering the known steps into a coherent pathway. Maturation is initiated by the ATPase Drg1. Downstream, assembly of the ribosome stalk is essential for the release of Tif6. The stalk recruits GTPases during translation. Because the GTPase Efl1, which is required for the release of Tif6, resembles the translation elongation factor eEF2, we suggest that assembly of the stalk recruits Efl1, triggering a step in 60S biogenesis that mimics aspects of translocation. Efl1 could thereby provide a mechanism to functionally check the nascent subunit. Finally, the release of Tif6 is a prerequisite for the release of the nuclear export adaptor Nmd3. Establishing this pathway provides an important conceptual framework for understanding ribosome maturation.

The Roles of Puf6 and Loc1 in 60S Biogenesis Are Interdependent, and Both Are Required for Efficient Accommodation of Rpl43.

Puf6 and Loc1 have two important functional roles in the cells, asymmetric mRNA distribution and ribosome biogenesis. Puf6 and Loc1 are localized predominantly in the nucleolus. They bind ASH1 mRNA, repress its translation, and facilitate the transport to the daughter cells. Asymmetric mRNA distribution is important for cell differentiation. Besides their roles in mRNA localization, Puf6 and Loc1 have been shown to be involved in 60S biogenesis. In puf6Δ or loc1Δ cells, pre-rRNA processing and 60S export are impaired and 60S subunits are underaccumulated. The functional studies of Puf6 and Loc1 have been focused on ASH1 mRNA pathway, but their roles in 60S biogenesis are still not clear. In this study, we found that Puf6 and Loc1 interact directly with each other and both proteins interact with the ribosomal protein Rpl43 (L43e). Notably, the roles of Puf6 and Loc1 in 60S biogenesis are interdependent, and both are required for efficient accommodation of Rpl43. Loc1 is further required to maintain the protein level of Rpl43. Additionally, the recruitment of Rpl43 is required for the release of Puf6 and Loc1. We propose that Puf6 and Loc1 facilitate Rpl43 loading and are sequentially released from 60S after incorporation of Rpl43 into ribosomes in yeast.

Enrichment of two isoflavone aglycones in black soymilk by Rhizopus oligosporus NTU 5 in a plastic composite support bioreactor.

BACKGROUND: A plastic composite support (PCS) bioreactor was implemented to evaluate the effects on isoflavone deglycosylation in black soymilk fermented by Rhizopus oligosporus NTU 5. RESULTS: Evaluation for the optimal PCS for mycelia immobilisation was conducted, which led to the significant results that the most mycelium weight (0.237 g per PCS, P < 0.05) is held by an S-type PCS; therefore, it was selected for black soymilk fermentation. It was found that the PCS fermentation system without pH control exhibits better efficiency of isoflavone bioconversion (daidzin to daidzein, and genistin to genistein) than the one with pH control at pH 6.5. As for the long-run fermentation, those without pH control indeed accelerate the isoflavone bioconversion by continuously releasing ß-glucosidase into soymilk. Deglycosylation can be completed in 8 to 24 h and sustained for at least 34 days as 26 batches. The non-pH-control fermentation system also exhibits the highest total phenolic content (ranged from 0.147 to 0.340 mg GAE mL(-1) sample) when compared to the pH-controlled and suspended ones. Meanwhile, the black soymilk from the 22nd batch with 8 h fermentation demonstrated the highest DPPH radical scavenging effect (54.7%). CONCLUSION: A repeated-batch PCS fermentation system was established to accelerate the deglycosylation rate of isoflavone in black soymilk. © 2015 Society of Chemical Industry.

Exploring the multifaceted impact of lanthanides on physiological pathways in human breast cancer cells.

Lanthanum (La) and cerium (Ce), rare earth elements with physical properties similar to calcium (Ca), are generally considered non-toxic when used appropriately. However, their ions possess anti-tumor capabilities. This investigation explores the potential applications and mechanisms of LaCl3 or CeCl3 treatment in triple-negative breast cancer (TNBC) cell lines. TNBC, characterized by the absence of estrogen receptor (ERα), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) expression, is prone to early metastasis and resistant to hormone therapy. Our results demonstrate that La/Ce treatment reduces cell growth, and when combined with cisplatin, it synergistically inhibits cell growth and the PI3K/AKT pathway. La and Ce induce oxidative stress by disrupting mitochondrial function, leading to protein oxidation. Additionally, they interfere with protein homeostasis and induce nucleolar stress. Furthermore, disturbance in F-actin web formation impairs cell migration. This study delves into the mechanism by which calcium-like elements La and Ce inhibit breast cancer cell growth, shedding light on their interference in mitochondrial function, protein homeostasis, and cytoskeleton assembly.

Using microfluidic and conventional platforms to evaluate the effects of lanthanides on spheroid formation.

Metastasis contributes to the increased mortality rate of cancer, but the intricate mechanisms remain unclear. Cancer cells from a primary tumor invade nearby tissues and access the lymphatic or circulatory system. If these cells manage to survive and extravasate from the vasculature into distant tissues and ultimately adapt to survive, they will proliferate and facilitate malignant tumor formation. Traditional two-dimensional (2D) cell cultures offer a rapid and convenient method for validating the efficacy of anticancer drugs within a reasonable cost range, but their utility is limited because of tumors' high heterogeneity in vivo and spatial complexities. Three-dimensional (3D) cell cultures that mimic the physiological conditions of cancer cells in vivo have gained considerable interest. In these cultures, cells assemble into spheroids through gravity, magnetic forces, or their low-adhesion to the plates. Although these approaches address some of the limitations of 2D cultures, they often require a considerable amount of time and cost. Therefore, this study aims to enhance the effectiveness of 3D culture techniques by using microfluidic systems to provide a high-throughput and sensitive pipeline for drug screening. Using these systems, we studied the effects of lanthanide elements, which have garnered interest in cancer treatment, on spheroid formation and cell spreading. Our findings suggest that these elements alter the compactness of cell spheroids and decrease cell mobility.

Dual protection by Bcp1 and Rkm1 ensures incorporation of uL14 into pre-60S ribosomal subunits.

Eukaryotic ribosomal proteins contain extended regions essential for translation coordination. Dedicated chaperones stabilize the associated ribosomal proteins. We identified Bcp1 as the chaperone of uL14 in Saccharomyces cerevisiae. Rkm1, the lysine methyltransferase of uL14, forms a ternary complex with Bcp1 and uL14 to protect uL14. Rkm1 is transported with uL14 by importins to the nucleus, and Bcp1 disassembles Rkm1 and importin from uL14 simultaneously in a RanGTP-independent manner. Molecular docking, guided by crosslinking mass spectrometry and validated by a low-resolution cryo-EM map, reveals the correlation between Bcp1, Rkm1, and uL14, demonstrating the protection model. In addition, the ternary complex also serves as a surveillance point, whereas incorrect uL14 is retained on Rkm1 and prevented from loading to the pre-60S ribosomal subunits. This study reveals the molecular mechanism of how uL14 is protected and quality checked by serial steps to ensure its safe delivery from the cytoplasm until its incorporation into the 60S ribosomal subunit.

Gallium maltolate shows synergism with cisplatin and activates nucleolar stress and ferroptosis in human breast carcinoma cells.

PURPOSE: Breast cancer is the most common cancer in women. Triple-negative breast cancer (TNBC) is an aggressive disease with poor outcomes. TNBC lacks effective targeted treatments, and the development of drug resistance limits the effectiveness of chemotherapy. It is crucial to identify new drugs that can enhance the efficacy of traditional chemotherapy to reduce drug resistance and side effects. METHODS: TNBC cell lines, MDA-MB-231 and Hs 578T, and a normal cell line, MCF-10 A, were included in this study. The cells were treated with gallium maltolate (GaM), and their transcriptome was analyzed. Ferroptosis and nucleolar stress markers were detected by qPCR, western blotting, fluorescence microscopy, and flow cytometry. The impairment of ribosome synthesis was evaluated by northern blotting and sucrose gradients. RESULTS: GaM triggered cell death via apoptosis and ferroptosis. In addition, GaM impaired translation and activated nucleolar stress. Cisplatin (DDP) is a chemotherapeutic agent for advanced breast cancer. While single treatment with GaM or DDP at low concentrations did not impact cell growth, co-administration enhanced cell death in TNBC but not in normal breast cells. The enhancement of ferroptosis and nucleolar stress could be observed in TNBC cell lines after co-treatment. CONCLUSIONS: These results suggest that GaM synergizes with cisplatin via activation of nucleolar stress and ferroptosis in human breast carcinoma cells. GaM is marginally toxic to normal cells but impairs the growth of TNBC cell lines. Thus, GaM has the potential to be used as a therapeutic agent against TNBC.

The dedicated chaperones of eL43, Puf6 and Loc1 can also bind RPL43 mRNA and regulate the production of this ribosomal protein.

The level of ribosome biogenesis is highly associated with cell growth rate. Because many ribosomal proteins have extraribosomal functions, overexpression or insufficient supply of these proteins may impair cellular growth. Therefore, the supply of ribosomal proteins is tightly controlled in response to rRNA syntheses and environmental stimuli. In our previous study, two RNA-binding proteins, Puf6 and Loc1, were identified as dedicated chaperones of the ribosomal protein eL43, with which they associate to maintain its protein level and proper loading. In this study, we demonstrate that Puf6 and Loc1 interact with RPL43 mRNA. Notably, Puf6 and Loc1 usually function as a dimeric complex to bind other mRNAs; however, in this instance, the individual proteins, but not the complex form, can bind RPL43 mRNA. Thus, Puf6 or Loc1 could bind RPL43 mRNA in loc1Δ or puf6Δ, respectively. The binding of Puf6 or Loc1 caused negative effects for eL43 production: decreased RNA stability and translation of RPL43A/B mRNA. The present results suggest that these dedicated chaperones control the protein levels of eL43 from the standpoint of stability and through regulating its production.

Antimicrobial and Anticorrosion Activity of a Novel Composite Biocide against Mixed Bacterial Strains in Taiwanese Marine Environments.

Taiwan is an island with a humid subtropical climate. The relatively warm seawater results in biofouling of the surfaces of marine facilities. Biocide application is a common practice for combating and eliminating adhesive fouling. However, a single type of biocide may have limited antimicrobial effects due to the relatively high microbial diversity in marine environments. Therefore, applying a mixture of various biocides may be necessary. In this study, the antimicrobial and anticorrosion properties of a newly designed composite biocide, namely a combination of thymol and benzyldimethyldodecylammonium chloride, were investigated by applying the biocide to 304 stainless steel substrates immersed in inocula containing bacterial strains from Tamsui and Zuoying harbors. The ability of 3TB and 5TB treatments to prevent sessile cells and biofilm formation on the 304 stainless steel coupon surface was determined through scanning electron microscopy investigation. In addition, confocal laser scanning microscopy indicated that the 5TB treatment achieved a greater bactericidal effect in both the Tamsui and Zuoying inocula. Moreover, electrochemical impedance spectroscopy revealed that the diameter of the Nyquist semicircle was almost completely unaffected by Tamsui or Zuoying under the 5TB treatment. Through these assessments of antimicrobial activity and corrosion resistance, 5TB treatment was demonstrated to have superior bactericidal activity against mixed strains in both southern and northern Taiwanese marine environments.

Correction: Lin. et al. Effects of Substrate-Coating Materials on the Wound-Healing Process. Materials 2019, 12, 2775.

The authors wish to make the following correction to this paper [...].