研究者詳細 - 前田　憲成

論文 - 前田　憲成

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Valorization of biodiesel side stream waste glycerol for rhamnolipids production by Pseudomonas aeruginosa RS6 査読有り

Baskaran S.M., Zakaria M.R., Mukhlis Ahmad Sabri A.S., Mohamed M.S., Wasoh H., Toshinari M., Hassan M.A., Banat I.M.

Environmental Pollution 276 2021年05月

記述言語：英語掲載種別：研究論文（学術雑誌）

Biodiesel side stream waste glycerol was identified as a cheap carbon source for rhamnolipids (RLs) production which at the same time could improve the management of waste. The present study aimed to produce RLs by using Pseudomonas aeruginosa RS6 utilizing waste glycerol as a substrate and to evaluate their physico-chemicals properties. Fermentation conditions such as temperature, initial medium pH, waste glycerol concentration, nitrogen sources and concentrations resulted in different compositions of the mono- and di-RLs produced. The maximum RLs production of 2.73 g/L was obtained when P. aeruginosa RS6 was grown in a basal salt medium supplemented with 1% waste glycerol and 0.2 M sodium nitrate at 35 °C and pH 6.5. At optimal fermentation conditions, the emulsification index (E24) values of cooking oil, diesel oil, benzene, olive oil, petroleum, and kerosene were all above E24=50%. The surface tension reduction obtained from 72.13 mN/m to 29.4–30.4 mN/m was better than the surface activity of some chemical-based surfactants. The RLs produced possessed antimicrobial activities against Gram-negative and Gram-positive bacteria with values ranging from 37% to 77% of growth inhibition when 1 mg/mL of RLs was used. Concentrations of RLs below 1500 μg/mL did not induce phytotoxicity effects on the tested seeds (Vigna radiata) compared to the chemical-based- surfactant, SDS. Furthermore, RLs tested on zebrafish (Danio rerio) embryos only exhibited low acute toxicity with an LC50 value of 72.97 μg/mL at 48 h of exposure suggesting a green and eco-biochemical worthy of future applications to replace chemical-based surfactants. Pseudomonas aeruginosa RS6 shows the ability to consume biodiesel side stream waste glycerol for the production of green biochemicals and less-toxic rhamnolipids.

DOI： 10.1016/j.envpol.2021.116742

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Antibacterial chitosan nanofiber thin films with bacitracin zinc salt 査読有り

Kumamoto K., Maeda T., Hayakawa S., Mustapha N.A.B., Wang M.J., Shirosaki Y.

Polymers 13 ( 7 ) 2021年04月

記述言語：英語掲載種別：研究論文（学術雑誌）

Chitosan nanofiber has a highly uniform structure of 20–50 nm in diameter and shows high dispersibility in water due to its submicron size and high surface-to-volume ratio. The stacked nanofibers film is useful for breathability because it has a gap with a size of several tens of nm or more. However, the chemical bonds between the nanofibers cannot be broken during use. In this study, the thin films were obtained by filtration of chitosan nanofibers and 3-glycidoxypropyltri-methoxysilane (GPTMS) mixture. The addition of GPTMS changed the wettability, mechanical property and stability in water of the thin films. Bacitracin zinc salt (BZ) has been used for the localized dermatological medicines and loaded in the films. BZ interacted electrostatically with the thin films matrix and the release of BZ was controlled by the amount of GPTMS. A higher released amount of BZ showed higher antibacterial effects toward S. aureus. The film was also tested their toxicity by L929 fibroblasts. The release of less than 11.9 μg of BZ showed antibacterial effects, but were not toxic for fibroblast cells.

DOI： 10.3390/polym13071104

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Design, synthesis and antibacterial studies of novel cationic amphipathic cyclic undecapeptides and their linear counterparts against virulent bacterial strains 査読有り

Farrag H.N., Maeda T., Kato T.

Scientia Pharmaceutica 89 ( 1 ) 1 - 11 2021年03月

記述言語：英語掲載種別：研究論文（学術雑誌）

Bacteria have acquired resistance against almost all antibiotics because of the misuse of antibacterial agents and long periods of treatment. Antimicrobial peptides (AMPs) are one of the most encouraging candidates to solve this problem, as they possess high prokaryotic selectivity, and affect the bacteria by a unique mode of action. Novel cyclic undecapeptides (QNRNFYFNRNQ and QNRNFHFNRNQ) and their linear counterparts were investigated for their antibacterial activity against virulent strains. The minimal inhibitory concentration (MIC) values showed that tyrosine and histidine AMPs have promising antibacterial activity against virulent bacteria. The MIC values against the P. aeruginosa PA14, E. coli O157:H7 CR3, S. aureus 209P, and B. subtilis ATCC 6633 bacterial strains were evaluated for the cyclic peptide containing tyrosine, and their values were 6.25, 12.5, 12.5, and 12.5 µM, respectively. Meanwhile, for the linear form, they were 9.3, 12.5, 12.5, and 12.5 µM, respectively. The cyclic-peptide–containing histidines’ MIC values were 6.25, 3.1, 6.25, and 3.1 µM, respectively. Meanwhile, for the linear form, they were 3.1, 3.1, 3.1, and 6.25 µM, respectively. The antibacterial activities of the new AMPs were compared with that of gentamicin sulfate, and showed relatively higher potencies. Time-inhibition studies demonstrated the rapid antibacterial effects of the novel AMPs, which were more likely to be concentration-dependent, rather than time-dependent. At double the MIC concentration, all of the tested peptides exhibited relatively stable antibacterial effects up to 24 h, especially the peptides containing tyrosine, which showed an improved antibacterial effect.

DOI： 10.3390/scipharm89010010

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Enrichment of waste sewage sludge for enhancing methane production from cellulose 査読有り

Zhu Q., Dai L., Wang Y., Tan F., Chen C., He M., Maeda T.

Bioresource Technology 321 2021年02月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Low ability of waste sewage sludge to degrade cellulose is observed due to its less cellulolytic bacteria content. The enrichment of sewage sludge in the absence or presence of carboxymethylcellulose (CMC) was conducted to improve anaerobic digestion (AD) of cellulose in this study. Compared to initial sewage sludge (IS), enriched sludge without CMC addition (ES) displayed 69.81% higher CH yield and about 1.7-fold greater anaerobic biodegradation of cellulose. In particular, bacterial and archaeal diversities in samples inoculated with ES were significantly altered, with Ruminiclostridium and Methanobacterium as the predominant genera. Enriched sludge with CMC addition (ESC) displayed enhanced methane production at initial cellulose fermentation but showed no distinct difference compared with the control after incubation 24 days. These findings suggest that enrichment of waste sewage sludge without CMC addition is more beneficial for promoting AD of cellulose, providing a novel insight for efficient energy utilization of lignocellulosic wastes. 4

DOI： 10.1016/j.biortech.2020.124497

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Survivability of Alcaligenaceae and Chromatiaceae as palm oil mill effluent pollution bioindicators under fluctuations of temperature, pH and total suspended solid 査読有り

Mohamad-Zainal N.S.L., Ramli N., Zolkefli N., Mustapha N.A., Hassan M.A., Maeda T.

Journal of Bioscience and Bioengineering 2021年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Alcaligenaceae and Chromatiaceae were previously reported as the specific pollution bioindicators in the receiving river water contaminated by palm oil mill effluent (POME) final discharge. Considering the inevitable sensitivity of bacteria under environmental stresses, it is crucial to assess the survivability of both bacteria in the fluctuated environmental factors, proving their credibility as POME pollution bioindicators in the environment. In this study, the survivability of Alcaligenaceae and Chromatiaceae from facultative pond, algae (aerobic) pond and final discharge were evaluated under varying sets of temperature (25–40°C), pH (pH 7–9) and low/high total suspended solid (TSS) contents of POME collected during low/high crop seasons of oil palm, respectively. Following treatment, the viability status and compositions of the bacterial community were assessed using flow cytometry-based assay and high-throughput Illumina MiSeq, respectively, in correlation with the changes of physicochemical properties. The changes in temperature, pH and TSS indeed changed the physicochemical properties of POME. The functionality of bacterial cells was also shifted where the viable cells and high nucleic acid contents reduced at elevated levels of temperature and pH but increased at high TSS content. Interestingly, the Alcaligenaceae and Chromatiaceae continuously detected in the samples which accounted for more than 0.5% of relative abundance, with a positive correlation with biological oxygen demand (BOD5) concentration. Therefore, either Alcaligenaceae or Chromatiaceae or both could be regarded as the reliable and specific bacterial indicators to indicate the pollution in river water due to POME final discharge despite the fluctuations in temperature, pH and TSS.

DOI： 10.1016/j.jbiosc.2021.04.014

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Preparation of bioactive and antibacterial PMMA-based bone cement by modification with quaternary ammonium and alkoxysilane 査読有り

Wang H., Maeda T., Miyazaki T.

Journal of Biomaterials Applications 2021年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Bone cement based on poly(methyl methacrylate) (PMMA) powder and methyl methacrylate (MMA) liquid is a very popular biomaterial used for the fixation of artificial joints. However, there is a risk of this cement loosening from bone because of a lack of bone-bonding bioactivity. Apatite formation in the body environment is a prerequisite for cement bioactivity. Additionally, suppression of infection during implantation is required for bone cements to be successfully introduced into the human body. In this study, we modified PMMA cement with γ-methacryloxypropyltrimetoxysilane and calcium acetate to introduce bioactive properties and 2-(tert-butylamino)ethyl methacrylate (TBAEMA) to provide antibacterial properties. The long-term antibacterial activity is attributed to the copolymerization of TBAEMA and MMA. As the TBAEMA content increased, the setting time increased and the compressive strength decreased. After soaking in simulated body fluid, an apatite layer was detected within 7 days, irrespective of the TBAEMA content. The cement showed better antibacterial activity against Gram-negative E. Coli than Gram-positive bacteria; however, of the Gram-positive bacteria investigated, B. subtilis was more susceptible than S. aureus.

DOI： 10.1177/08853282211004413

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Antibacterial properties of phenothiazine derivatives against multidrug-resistant Acinetobacter baumannii strains 査読有り

Aguilar-Vega L., López-Jácome L.E., Franco B., Muñoz-Carranza S., Vargas-Maya N., Franco-Cendejas R., Hernández-Durán M., Otero-Zúñiga M., Campo-Beleño C., Jiménez-Cortés J.G., Martínez-Vázquez M., Rodríguez-Zavala J.S., Maeda T., Zurabian R., García-Contreras R.

Journal of Applied Microbiology 2021年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Aim: As options to treat recalcitrant bacterial infections which are increasingly limited due to multidrug-resistant strains, searching for new, effective antibacterial compounds is necessary. One strategy is to generate treatment alternatives by drug repurposing. Methods and Results: In this work, phenotypic microarrays were used for the screening of miscellaneous compounds against the growth and biofilm formation of Acinetobacter baumannii, an important emergent multidrug-resistant opportunistic pathogen. The results showed that the phenothiazine derivatives, such as promethazine, trifluoperazine, thioridazine, and chlorpromazine, inhibited the growth of antibiotic-sensitive and multidrug-resistant strains (showing minimal inhibitory concentrations ranging from 0·05 to 0·6 g l−1 and minimal bactericidal concentrations ranging from 0·1 to 2·5 g l−1). All phenothiazine derivatives were active against biofilm cells (with minimal biofilm eradication concentrations ranging from 0·5 to >3 g l−1). Chlorpromazine promoted reactive oxigen species (ROS) production, and cell membrane and DNA damage. Chlorpromazine showed synergy with antibiotics such as ceftazidime, meropenem, and colistin and was an effective treatment for experimentally infected Galleria mellonella when combined with ceftazidime. Conclusions: It was demonstrated that phenothiazine derivatives, especially chlorpromazine, are drugs with attractive antibacterial properties against nosocomial MDR strains of A. baumannii, by generating ROS and cell membrane and DNA damage. Significance and Impact of the Study: The present study indicates that repurposing phenothiazine derivatives for treating recalcitrant infections by A. baumannii could be promising.

DOI： 10.1111/jam.15109

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Diluted Luria-Bertani medium vs. sewage sludge as growth media: comparison of community structure and diversity in the culturable bacteria 査読有り

Yamamoto K., Toya S., Sabidi S., Hoshiko Y., Maeda T.

Applied Microbiology and Biotechnology 2021年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Because colony formation is essential to seek bacterial functions by the direct observation of phenotype, the diversification of colony formation for culturable bacteria is a big challenge in the research field of Environmental Biotechnology. In this study, the biodiversity of cultivable bacteria (colony or liquid culture) was compared by using Luria-Bertani (LB) medium and waste sewage sludge (WSS) under different dilutions and temperatures. When WSS was used as a bacterial source, whereas the highest number of colonies was found at the concentration of WSS (5%), a particular concentration of LB (10%) or WSS (1%) as a growth medium showed the best number of the operational taxonomic units (OTUs) of colonies. The results of bacterial community structure indicated that there are 1, 8, and 12 bacterial genera found uniquely in the agar plates of LB, 10% LB, and 5% WSS. By contrast, when palm oil mill effluent sludge was used as a bacterial source, the effect of dilution was different with WSS. When comparing the biodiversity between colonies and liquid culture, a high OTU value was observed in the colonies on the plate. In addition, 30°C showed the highest number of colonies in LB, 10% LB, and 5% WSS whereas the best OTUs were observed at 37°C for LB and 10% LB, and at 25°C for 5% WSS. This study demonstrates the diversification of cultivable bacteria through the number of OTUs in diluted LB medium and WSS, which is beneficial to isolate a unique bacterial strain. Key points • Impacts of diluted LB medium and WSS for colony formation were determined. • Difference of concentration of LB and WSS made different effects on colony formation. • Temperature change affected on diluted LB and WSS as media.

DOI： 10.1007/s00253-021-11248-4

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Iron limitation by transferrin promotes simultaneous cheating of pyoverdine and exoprotease in Pseudomonas aeruginosa 査読有り

Tostado-Islas O., Mendoza-Ortiz A., Ramírez-García G., Cabrera-Takane I.D., Loarca D., Pérez-González C., Jasso-Chávez R., Jiménez-Cortés J.G., Hoshiko Y., Maeda T., Cazares A., García-Contreras R.

ISME Journal 2021年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Pseudomonas aeruginosa is a primary bacterial model to study cooperative behaviors because it yields exoproducts such as siderophores and exoproteases that act as public goods and can be exploited by selfish nonproducers behaving as social cheaters. Iron-limited growth medium, mainly casamino acids medium supplemented with transferrin, is typically used to isolate and study nonproducer mutants of the siderophore pyoverdine. However, using a protein as the iron chelator could inadvertently select mutants unable to produce exoproteases, since these enzymes can degrade the transferrin to facilitate iron release. Here we investigated the evolutionary dynamics of pyoverdine and exoprotease production in media in which iron was limited by using either transferrin or a cation chelating resin. We show that concomitant loss of pyoverdine and exoprotease production readily develops in media containing transferrin, whereas only pyoverdine loss emerges in medium treated with the resin. Characterization of exoprotease- and pyoverdine-less mutants revealed loss in motility, different mutations, and large genome deletions (13–33 kb) including Quorum Sensing (lasR, rsal, and lasI) and flagellar genes. Our work shows that using transferrin as an iron chelator imposes simultaneous selective pressure for the loss of pyoverdine and exoprotease production. The unintended effect of transferrin uncovered by our experiments can help to inform the design of similar studies.

DOI： 10.1038/s41396-021-00938-6

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下水汚泥の嫌気消化促進のための微生物相互作用の理解招待有り査読有り

前田憲成

生物工学会誌 ( 公益社団法人日本生物工学会 ) 99 ( 12 ) 621 - 622 2021年01月

A Novel Archaeal Lineage in Boiling Hot Springs around Oyasukyo Gorge (Akita, Japan) 査読有り

Asamatsu Katsuhiro, Yoshitake Kai, Saito Makoto, Prasitwuttisak Wipoo, Ishibashi Jun-ichiro, Tsutsumi Akihi, Mustapha Nurul Asyifah, Maeda Toshinari, Yanagawa Katsunori

Ｍｉｃｒｏｂｅｓ　ａｎｄ　ｅｎｖｉｒｏｎｍｅｎｔｓ ( 日本微生物生態学会 / 日本土壌微生物学会 / Taiwan Society of Microbial Ecology / 植物微生物研究会 / 極限環境微生物学会 ) 36 ( 4 ) 2021年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

<p>A novel deep-branching archaeal lineage was discovered at high-temperature hot springs around Oyasukyo Gorge in Akita Prefecture, Japan. Actively boiling hot spring water contained >1×10<sup>4</sup> microbes mL<sup>–1</sup>. The microbial community composition assessed by analyzing 16S rRNA gene amplicons revealed that the dominant bacterial phyla were <i>Proteobacteria</i> and <i>Aquificae</i> (>50% of the microbial composition) in samples collected in 2016 and 2019, respectively. Approximately 10% of the reads obtained in both years were not assigned to any taxonomy. The more detailed phylogenetic positions of the unassigned sequences identified using a clone library and phylogenetic tree showed that they formed a clade that was independent, distantly related to known phyla, and had low similarity (<82%) to all other sequences in available databases. The present results suggest that this novel archaeal phylum-level lineage thrives in boiling hot springs in Japan.</p>

DOI： 10.1264/jsme2.ME21048

その他リンク： https://ci.nii.ac.jp/naid/130008120278

Microbial community dynamics and electricity generation in MFCs inoculated with POME sludges and pure electrogenic culture 査読有り

Albarracin-Arias J.A., Yu C.P., Maeda T., Valdivieso Quintero W., Sanchez-Torres V.

International Journal of Hydrogen Energy 2021年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Palm Oil Mill Effluent (POME) requires treatment before disposal due to its high organic matter content. In this study, the electrical performance and wastewater treatment efficiency were evaluated for Microbial Fuel Cells (MFC) treating unsterile POME with chemical oxygen demand (COD) from 200 to 10 000 mg/L. Since the inoculum type is a key factor in MFC performance, three types of sludge (methanogenic sludge (MS), facultative sludge (FS), and dry sludge (DS), obtained from the current POME treatment ponds were evaluated as inoculum. Dry sludge (DS) developed a maximum power output of 3.30 W/m3 by oxidizing 71% out of the COD provided by POME (1000 mg/L). Also, raw POME microbiota contributed to an enrichment of the community in DS inoculum along with the operation, in which Geobacter was the predominant genus reaching a current generation of 247 mA/m2 and a power density of 2.36 W/m3. Conversely, pure electrogenic (Shewanella sp.) inoculation led to a diversification process, resulting in a lower current generation of 52 mA/m2 and a power density of 0.10 W/m3. Consequently, microbial community dynamics revealed that MFC inoculation tends to a microbial equilibrium wherein generation of high current density was achieved by gradual microbial enrichment rather than external electrogenic invasion.

DOI： 10.1016/j.ijhydene.2021.08.218

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Engineering anaerobic digestion via optimizing microbial community: effects of bactericidal agents, quorum sensing inhibitors, and inorganic materials 招待有り査読有り

Maeda T., Sabidi S., Sanchez-Torres V., Hoshiko Y., Toya S.

Applied Microbiology and Biotechnology 2021年01月

担当区分：筆頭著者記述言語：英語掲載種別：記事・総説・解説・論説等（学術雑誌）

Abstract: Anaerobic digestion of sewage sludge (SS) is one of the effective ways to reduce the waste generated from human life activities. To date, there are many reports to improve or repress methane production during the anaerobic digestion of SS. In the anaerobic digestion process, many microorganisms work positively or negatively, and as a result of their microbe-to-microbe interaction and regulation, methane production increases or decreases. In other words, understanding the complex control mechanism among the microorganisms and identifying the strains that are key to increase or decrease methane production are important for promoting the advanced production of bioenergy and beneficial compounds. In this mini-review, the literature on methane production in anaerobic digestion has been summarized based on the results of antibiotic addition, quorum sensing control, and inorganic substance addition. By optimizing the activity of microbial groups in SS, methane or acetate can be highly produced. Key points: • Bactericidal agents such as an antibiotic alter microbial community for enhanced CH4production. • Bacterial interaction via quorum sensing is one of the key points for biofilm and methane production. • Anaerobic digestion can be altered in the presence of several inorganic materials.

DOI： 10.1007/s00253-021-11536-z

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Effect of Aso limonite on anaerobic digestion of waste sewage sludge 査読有り

Mustapha N.A., Toya S., Maeda T.

AMB Express 10 ( 1 ) 2020年12月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2020, The Author(s). The effect of Aso volcanic limonite was explored in anaerobic digestion using waste sewage sludge (WSS). In this study, methane and hydrogen sulfide were remarkably inhibited when Aso limonite was mixed with WSS as well as a significant reduction of ammonia. Although pH was lowered after adding Aso limonite, methane was still inhibited in neutralized pH condition at 7.0. Hydrolysis stage was not influenced by Aso limonite as supported by the result that a high protease activity was still detected in the presence of the material. However, acidogenesis stage was affected by Aso limonite as indicated by the different productions of organic acids. Acetic acid, was accumulated in the presence of Aso limonite due to the inhibition of methane production, except in the highest concentration of Aso limonite which the production of acetate may be inhibited. Besides, the production of propionate and butyrate reduced in accordance to the increased concentration of Aso limonite. In addition, Archaeal activity (methanogens) in WSS with Aso limonite was low in agreement with the low methane production. Thus, these results indicate that Aso limonite influences the acidogenesis and methanogenesis processes, by which the productions of methane and ammonia were inhibited. On the other hand, in the contactless of Aso limonite during the anaerobic digestion of WSS (Aso limonite was placed in the area of headspace in the vial), Aso limonite had the adsorptive ability for hydrogen sulfide from WSS, but not for methane. This contactless system of Aso limonite may be a practical means to remove hydrogen sulfide without inhibiting methane production as an important bioenergy source.

DOI： 10.1186/s13568-020-01010-w

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A review of current and emerging approaches for water pollution monitoring 査読有り

Zolkefli N., Sharuddin S.S., Yusoff M.Z.M., Hassan M.A., Maeda T., Ramli N.

Water (Switzerland) 12 ( 12 ) 1 - 30 2020年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. The aquatic ecosystem is continuously threatened by the infiltration and discharge of anthropogenic wastewaters. This issue requires the unending improvement of monitoring systems to become more comprehensive and specific to targeted pollutants. This review intended to elucidate the overall aspects explored by researchers in developing better water pollution monitoring tools in recent years. The discussion is encircled around three main elements that have been extensively used as the basis for the development of monitoring methods, namely the dissolved compounds, bacterial indicator, and nucleic acids. The latest technologies applied in wastewater and surface water mapped from these key players were reviewed and categorized into physicochemical and compound characterizations, biomonitoring, and molecular approaches in taxonomical and functional analyses. Overall, researchers are continuously rallying to enhance the detection of causal source for water pollution through either conventional or mostly advanced approaches focusing on spectrometry, high-throughput sequencing, and flow cytometry technology among others. From this review’s perspective, each pollution evaluation technology has its own advantages and it would be beneficial for several aspects of pollutants assessments to be combined and established as a complementary package for better aquatic environmental management in the long run.

DOI： 10.3390/w12123417

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Effect of calcium acetate content on apatite-forming ability and mechanical property of pmma bone cement modified with quaternary ammonium 査読有り

Wang H., Maeda T., Miyazaki T.

Materials 13 ( 21 ) 1 - 8 2020年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

© MDPI AG. All rights reserved. Polymethyl methacrylate (PMMA)-based bone cement is a popular biomaterial used for fixation of artificial joints. A next-generation bone cement having bone-bonding ability, i.e., bioactivity and antibacterial property is desired. We previously revealed that PMMA cement added with 2-(tert-butylamino)ethyl methacrylate, γ-methacryloxypropyltrimethoxysilane and calcium acetate showed in vitro bioactivity and antibacterial activity. This cement contains calcium acetate at 20% of the powder component. Lower content of the calcium acetate is preferable, because the release of a lot of calcium salt may degrade mechanical properties in the body environment. In the present study, we investigate the effects of calcium acetate content on the setting property and mechanical strength of the cement and apatite formation in simulated body fluid (SBF). The setting time increased and the compressive strength decreased with an increase in calcium acetate content. Although the compressive strength decreased after immersion in SBF for 7 d, all the cements still satisfied the requirements of ISO5833. Apatite was formed in SBF within 7 d on the samples where the calcium acetate content was 5% or more. Therefore, it was found that PMMA cement having antibacterial properties and bioactivity can be obtained even if the amount of the calcium acetate is reduced to 5%.

DOI： 10.3390/ma13214998

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Mechanism of carbon partitioning towards starch and triacylglycerol in Chlorella vulgaris under nitrogen stress through whole-transcriptome analysis 査読有り

Nordin N., Yusof N., Maeda T., Mustapha N.A., Mohd Yusoff M.Z., Raja Khairuddin R.F.

Biomass and Bioenergy 138 2020年07月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2020 Elsevier Ltd This study aims to elucidate the mechanism of carbon partitioning towards starch and triacylglycerol (TAG) under nitrogen stress. Whole-transcriptome analysis was performed using RNA sequencing before being validated with qRT-PCR. The strain, Chlorella vulgaris UPSI-JRM01, exhibited a two-stage response to nitrogen stress: i) carbohydrate accumulation, plastid protein degradation and amino acid biosynthesis; and ii) lipid accumulation, carbohydrate degradation and DNA damage. In the first stage, the genes responsible for plastid protein degradation (CD4A), amino acid biosynthesis (arg, GLSN, AHCY, win1), carbon fixation (RuBisCO, GapC, fba, TK) and starch synthesis (SS, SBE2) were upregulated. In the second stage, the upregulation of genes responsible for starch degradation (SP), glycolysis (PFO, PK, ACS), fatty acid biosynthesis (FabH, accD) and TAG accumulation (DGAT2) were observed. By contrast, the components of photosystem I (PsbD, PsbC, PsbB), photosystem II (PsaA), cytochrome b6/f (PetA, PetG) and F-type ATPase (beta, alpha) were downregulated. The results suggested that nitrogen stress triggered high starch accumulation before the carbon was partitioned towards triacylglycerol (TAG) for long-term energy storage by two different pathways: chloroplastic TAG synthesis and glycerolipid metabolism. The starch build-up functions served as a rapid response to nitrogen stress, whereas subsequent lipid accumulation benefited the long-term storage of energy. This research provides in-depth understanding of the metabolic changes triggered by nitrogen stress.

DOI： 10.1016/j.biombioe.2020.105600

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Microalgae-bacteria interaction in palm oil mill effluent treatment 査読有り

Mohd Udaiyappan A.F., Hasan H.A., Takriff M.S., Abdullah S.R.S., Maeda T., Mustapha N.A., Mohd Yasin N.H., Nazashida Mohd Hakimi N.I.

Journal of Water Process Engineering 35 2020年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2020 Elsevier Ltd Palm oil mill effluent (POME) contains a substantial amount of nutrients and a significant amount of indigenous microorganisms that consume the nutrients for their growth. In this study, we demonstrated that cultivation of microalgae in POME was able to reduce its carbon and nutrient contents. Three native microalgae isolates, namely, Coelastrella sp. UKM4, Chlamydomonas sp. UKM6 and Scenedesmus sp. UKM9, were cultured in sterilized and unsterilized anaerobic POME to evaluate the microalgae-bacteria interactions for phycoremediation of POME. The results showed higher COD removal in unsterilized POME than in sterilized POME due to microalgae-bacteria consortia interaction. Of the three microalgae isolates, the interaction of Scenedesmus sp. UKM9 with bacteria showed the highest COD and PO43− removal percentages. For NH4+ removal, all three isolates showed removal of more than 80 % in both sterilized and unsterilized POME. Quantitative real-time polymerase chain reaction analysis showed that the quantities of bacteria were constant after the treatment, while the quantities of microalgae changed. Metagenomics analysis showed that the community of bacteria shifted after microalgae cultivation in POME, with Actinobacteria, Bacteroidetes, Planctomycetes and Proteobacteria being the major phyla.

DOI： 10.1016/j.jwpe.2020.101203

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Characterization of gallium resistance induced in a Pseudomonas aeruginosa cystic fibrosis isolate 査読有り

Tovar-García A., Angarita-Zapata V., Cazares A., Jasso-Chávez R., Belmont-Díaz J., Sanchez-Torres V., López-Jacome L.E., Coria-Jiménez R., Maeda T., García-Contreras R.

Archives of Microbiology 202 ( 3 ) 617 - 622 2020年04月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. The repurposing of gallium nitrate as an antibacterial, a drug used previously for the treatment of hypercalcemia, is a plausible alternative to combat infections by Pseudomonas aeruginosa, since it has antipseudomonal properties in vitro and in vivo in animal models and in human lung infections. Furthermore, gallium nitrate tolerance in clinical isolates is very rare. Nevertheless, studies on the reference strains PA14 and PAO1 show that resistance against gallium nitrate is achieved by decreasing gallium intracellular levels by increasing the production of pyocyanin. In this work, we induced resistance in a cystic fibrosis P. aeruginosa isolate and explored its resistance mechanisms. This isolated strain, INP-58M, was not a pyocyanin producer, and its pyoverdine levels remained unchanged upon gallium addition. However, it showed higher activities of NADPH-producing enzymes and the antioxidant enzyme SOD when gallium was added, which suggests a better antioxidant response. Remarkably, gallium intracellular levels in the resistant isolate were higher than those of the parental strain at 20 h but lower after 24 h of culture, suggesting that this strain is capable of gallium efflux.

DOI： 10.1007/s00203-019-01777-y

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Biochar enhanced the nitrifying and denitrifying bacterial communities during the composting of poultry manure and rice straw 査読有り

Zainudin M.H., Mustapha N.A., Maeda T., Ramli N., Sakai K., Hassan M.

Waste Management 106 240 - 249 2020年04月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2020 Elsevier Ltd Biochar has proven to be a feasible additive for mitigating nitrogen loss during the composting process. This study aims to evaluate the influence of biochar addition on bacterial community and physicochemical properties changes, including ammonium (NH4+), nitrite (NO2−) and nitrate (NO3−) contents during the composting of poultry manure. The composting was carried out by adding 20% (w/w) of biochar into the mixture of poultry manure and rice straw with a ratio of 2:1, and the same treatment without biochar was prepared as a control. The finished product of control compost recorded the high contents of NO2− and NO3− (366 mg/kg and 600 mg/kg) with reduced the total NH4+ content to 10 mg/kg. Meanwhile, biochar compost recorded a higher amount of total NH4+ content (110 mg/kg) with low NO2− and NO3− (161 mg/kg and 137 mg/kg) content in the final composting material. The principal component analysis showed that the dynamics of dominant genera related to Halomonas, Pusillimonas, and Pseudofulvimonas, all of which were known as nitrifying and denitrifying bacteria, was significantly correlated with the dynamic of NO2− and NO3− content throughout the composting process. The genera related to Pusillimonas, and Pseudofulvimonas appeared as the dominant communities as the NO2− and NO3− increased. In contrast, as the NO2− and NO3− concentration decreased, the Halomonas genus were notably enriched in biochar compost. This study revealed the bacterial community shifts corresponded with the change of physicochemical properties, which provides essential information for a better understanding of monitoring and improving the composting process.

DOI： 10.1016/j.wasman.2020.03.029

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