研究者詳細 - 前田　憲成

論文 - 前田　憲成

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Effect of Photo Irradiation on the Anaerobic Digestion of Waste Sewage Sludge-Reduced Methane and Hydrogen Sulfide Productions 招待有り査読有り国際誌

Toya S., Iriguchi S., Yamaguchi K., Maeda T.

Fermentation 9 ( 11 ) 2023年11月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Since a large amount of sewage sludge (WSS) is generated daily, exploring effective methods for utilizing WSS is necessary. Although a photo-fermentation system sometimes alters the characteristics of microbial functions, there have been no attempts to perform photo-fermentation using WSS, which is regularly treated via dark fermentation. In this study, the effect of photo-fermentation (photo-irradiation) on anaerobic digestion using WSS was revealed. Photo-irradiation during the anaerobic digestion of WSS significantly reduced the amount of methane and hydrogen sulfide. Methane production was also reduced 5.6-fold at 13 days under light conditions, whereas hydrogen sulfide was consumed almost completely at 6 days. However, it was shown that the activity of sulfate-reducing bacteria in WSS under light treatment increased. Photo-irradiation also stimulated the growth of green sulfur bacteria and induced anoxygenic photosynthesis, via which process the fermented samples turned green in a manner that was correlated with their consumption of hydrogen sulfide. The production of organic acids was lowered in the samples that were irradiated using light. Finally, dark/light switching fermentation was only able to reduce hydrogen sulfide while methane production remained the same. The amounts of methane and hydrogen sulfide were 35 mmol/g VS, and they were undetected at 58 days in photo-irradiated samples compared to the control samples that produced 37 mmol/g VS of methane and 15 ppm/g VS of hydrogen sulfide.

DOI： 10.3390/fermentation9110943

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Quorum quenching of autoinducer 2 increases methane production in anaerobic digestion of waste activated sludge 査読有り国際誌

Sarah Sabidi, Yuki Hoshiko, Toshinari Maeda

Applied Microbiology and Biotechnology ( Springer ) 106 ( 12 ) 4763 - 4774 2022年06月

Evaluating greenhouse gas reduction in Seremban, Malaysia: A pilot study on biogas production from organic municipal solid waste 査読有り国際誌

Samsuri I.A., Yusoff M.Z.M., Hassan M.A., Sharaai A.H., Ramli N., Ahmad Farid M.A., Abd Hamid M.A., Maeda T.

Energy for Sustainable Development 86 2025年06月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

The growing population causes municipal solid waste (MSW) buildup, which is a major problem. National MSW output in Malaysia is estimated at 1.17 kg per capita. This issue is crucial since 29 Malaysian landfills produce 200 thousand tons of MSW per month, releasing greenhouse gasses (GHGs). Anaerobic digestion (AD) may convert MSW into biogas to lower its organic content for landfill disposal. The AD system aims to produce biogas from domestic organic waste to create a circular economy. This study also surveyed Seremban, Malaysia, inhabitants on MSW composition and disposal. The organic fraction of MSW was subjected to the pilot-scale 500 L AD reactor, resulting in a daily average biogas production of 92–262 L, where a significant proportion of the biogas constituent, ranging from 60 to 70 %, is CH<inf>4</inf>. Biogas production was shown to be enhanced by an increase in feedstock, as seen by a greater daily intake of 5 kg. SimaPro was then used to quantify the resulting GHGs emissions from the AD process. The results indicated a value of 0.215 kgCO<inf>2</inf> equivalent for every 5 kg food waste that underwent processing. The proposed AD system exhibits a remarkable 80 % improvement in GHG emission reduction per kg of food waste processed, in comparison to existing methods. A thorough familiarity with organic waste's make-up and disposal patterns is necessary for its effective implementation. Statistics revealed that only 35.45 % of Seremban residents disposed of MSW daily, and that waste segregation rates were below 50 %. As a percentage of MSW, organic waste account for 55 %, or 0.35 kg/person/day. With a daily capacity of 20 kg for processing food waste, the proposed AD system is highly dependent on a constant organic waste supply. Instead of continuing to be inept at waste management, this effort offered an alternative. MSW poses significant environmental concerns, but the proposed pilot-scale AD system shows promise in addressing these issues and encouraging sustainable habits in local communities. At the very least, this could result in a reduction in MSW sent to landfills and GHG emissions for residents of Seremban.

DOI： 10.1016/j.esd.2025.101718

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Genomic insights into pigmented Serratia marcescens strains isolated from patients in northeast Mexico 査読有り国際誌

Sánchez-Pérez M., Andrade A., Flores-Maldonado O., de Anda-Mora K., García-Contreras R., Maeda T., Becerril-García M.A., Tavares-Carreón F.

Microbial Pathogenesis 203 2025年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

Serratia marcescens (SM) is an opportunistic pathogen associated with outbreaks in immunocompromised hosts. While SM is commonly isolated from clinical and environmental sources, prodigiosin production is typically associated with environmental strains rather than clinical isolates. Here, we report the genome sequences of three pigmented SM clinical isolates —HU1848, HU2225, and HU2228— and examine their genomic and phenotypic characteristics. Phylogenetic analysis using 1103 finished public SM genomes revealed that these isolates cluster more closely with environmental SM strains than with those typically associated with clinical settings. Notably, despite their environmental-like genomic background, these isolates harbor multiple virulence genes implicated in colonization and resistance to fertilizers, as well as antimicrobial resistance genes for chloramphenicol, fosfomycin, and tetracycline. MIC determination showed susceptibility to aminoglycosides and fluoroquinolones. Additionally, we observed that the phenolic compound methyl gallate modulates pigment production and motility. The absence of AHL biosynthetic genes in these pigmented strains challenges previous associations between quorum sensing and prodigiosin biosynthesis. These findings suggest that certain SM strains with environmental-like genetic features can persist in clinical settings, underscoring the need to further investigate their potential role in nosocomial infections.

DOI： 10.1016/j.micpath.2025.107456

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Novel insights into indigenous phenol-degrading bacteria from palm oil mill effluent and their potential mechanisms for efficient phenol degradation 査読有り国際誌

Sabri I., Ng K.X., Ku Mohammad Soffi N., Mohd Yusoff M.Z., Nor Muhammad N.A., Ho L.S., Maeda T., Ramli N.

Environmental Technology and Innovation 37 2025年02月

記述言語：英語掲載種別：研究論文（学術雑誌）

Phenol is a toxic pollutant with mutagenic, carcinogenic, and teratogenic properties, necessitating its removal from phenol-contaminated environments. Biodegradation presents a viable solution, with microbial sources commonly found in phenol-contaminated environments, including palm oil mill effluent (POME). However, the indigenous bacteria capable of efficiently metabolizing phenol from POME remain unidentified, with limited knowledge of their composition, potential functions, and mechanisms of phenol degradation. The ability of the phenol-acclimatized mixed culture (PBMC) derived from POME to metabolize phenol was assessed by evaluating its bacterial composition using 16S rRNA amplicon sequencing, followed by predictions of its potential mechanisms. Subsequently, the phenol degradation capability was evaluated through batch cultivations with phenol as the sole carbon source. This was then compared with an isolated phenol degrader from POME, identified as Acinetobacter sp. AL9, whose genetic makeup was revealed through whole-genome sequencing. Well-known phenol degraders thrived in the PBMC, including Acinetobacter (16.75 %), Pseudomonas (10.48 %), and Flavobacterium (10.35 %). This community degraded phenol through seven different pathways, primarily catalyzed by protocatechuate 3,4-dioxygenase via the protocatechuate degradation II (ortho-cleavage pathway). The presence of catechol 1,2-dioxygenase and catechol 2,3-dioxygenase also signified the involvement of catechol ortho-cleavage, and catechol degradation I and II (meta-cleavage) pathways, respectively. The PBMC completely degraded 300 mg/L of phenol more rapidly within 16 hours compared to the isolated Acinetobacter sp. AL9, which took 40 hours. This aligns with AL9’s phenol metabolism, which relies solely on the complete catechol ortho-cleavage pathway. This finding highlights the potential for harnessing the indigenous bacterial mixed culture from POME for efficient phenol bioremediation.

DOI： 10.1016/j.eti.2024.103983

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Microbial Population Dynamics of the Low-strength Partial Nitritation System and Its Correlation of Nitrifiers to the Model-predicted Biomass 査読有り国際誌

Pham T.Y., Maeda T., Sun M., Terashima M., Goel R., Yasui H.

Journal of Water and Environment Technology ( 公益社団法人日本水環境学会 ) 23 ( 2 ) 94 - 106 2025年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Using a lab-scale activated sludge system equipped with an external selector for suppressing nitrite oxidising organism (NOO), the microbial population dynamics were investigated during about 400 days of the continuous operation. In the varied selector operations and excess sludge withdrawal, the nitrification, partial nitritation, and nitrification loss followed by the recovery of partial nitritation consecutively took place. The DNA analysis with the high-throughput sequencing revealed that only Nitrosomonas spp. retained during the nitritation-nitrification and only Nitrospira spp. could grow in nitrification, respectively. Proteobacteria was the most predominant heterotroph in the main aeration tank, whilst Bacteroidota was abundant in the external selector in association with the reduced microbial diversities. In the external selector, due to the high nitrite and ammonium, the ammonium oxidising organism’s (AOO) inherent enzyme genes (Amo and Hao) per total microbial gene copies were as low as about 50% of that in the main aeration tank. The dynamically calculated AOO and NOO concentrations using the IWA-ASMl-based model could be linearly correlated to both relative abundances in the activated sludge. The correlations suggested that the DNA analysis could be potentially utilised as an alternative tool to estimate the nitrifier biomass of activated sludge instead of performing kinetic modelling.

DOI： 10.2965/jwet.24-136

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Effect of Biochar Addition in Two Different Phases of the Co-Composting of Green Waste and Food Waste: An Analysis of the Process, Product Quality and Microbial Community 査読有り国際誌

Oviedo-Ocaña E.R., Soto-Paz J., Parra-Orobio B.A., Zafra G., Maeda T., Galezo-Suárez A.C., Diaz-Larotta J.T., Sanchez-Torres V.

Waste and Biomass Valorization 2025年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Green waste (GW) contains lignocellulosic substances that are resistant to degradation and prolong the composting process. Different strategies have been used to improve GW composting, including adding co-substrates and additives like food waste (FW) and biochar (Bc). FW offers advantages such as its constant availability in MSW streams, its high content of readily degradable organic matter, and its contribution of essential nutrients like nitrogen and potassium. On the other hand, Bc is incorporated at the beginning of the process. However, the effect of its addition in the phase of greatest biological activity has not been studied. This article compares the effect on the process, product quality, and the compost microbial community of adding 2% Bc in two different phases of the co-composting GW with food waste (FW). Two treatments were evaluated using the same mixture of substrates (wet/ weight) (i.e., 48%GW + 35%FW + 13%Sawdust + 2% Phosphate Rock + 2%Bc), but Bc was added in the mesophilic phase for T1 and the thermophilic phase for T2. With the addition of Bc at the mesophilic phase, higher temperatures were reached in the thermophilic phase, with a maximum temperature of 52.5 °C for T1 and 47.7 °C for T2. T1 final product had higher nutrient content (i.e., 28.30% TOC, 1.91% TN, and 4.69% TP in T1 compared to 15.80% TOC, 1.14% TN, and 4.29% TP in T2) and achieved a higher fertility index. Streptomyces and Nonomuraea were more abundant in T1 than T2, while Rhizobium, Roseiflexus, and Chloroflexus were significantly more abundant in T2 than in T1. These results suggest that T1 presents a microbial community that is more robust in degrading complex organic materials. This article demonstrated increased biological activity, lignocellulosic degradation, and nutrient content in the product when biochar is added from the beginning of the process.

DOI： 10.1007/s12649-024-02878-6

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Whole genome sequencing of methicillin-resistant Staphylococcus aureus clinical isolates from Terengganu, Malaysia, indicates the predominance of the EMRSA-15 (ST22-SCCmec IV) clone 査読有り国際誌

Che Hamzah A.M., Chew C.H., Al-Trad E.I., Puah S.M., Chua K.H., Nor N.I., Ismail S., Maeda T., Palittapongarnpim P., Yeo C.C.

Scientific Reports 14 ( 1 ) 2024年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

Despite the importance of methicillin-resistant Staphylococcus aureus (MRSA) as a priority nosocomial pathogen, the genome sequences of Malaysian MRSA isolates are currently limited to a small pool of samples. Here, we present the genome sequence analyses of 88 clinical MRSA isolates obtained from the main tertiary hospital in Terengganu, Malaysia in 2016–2020, to obtain in-depth insights into their characteristics. The EMRSA-15 (ST22-SCCmec IV) clone of the clonal complex 22 (CC22) lineage was predominant with a total of 61 (69.3%) isolates. Earlier reports from other Malaysian hospitals indicated the predominance of the ST239 clone, but only two (2.3%) isolates were identified in this study. Two Indian-origin clones, the Bengal Bay clone ST772-SCCmec V (n = 2) and ST672 (n = 10) were also detected, with most of the ST672 isolates obtained in 2020 (n = 7). Two new STs were found, with one isolate each, and were designated ST7879 and ST7883. From the core genome phylogenetic tree, the HSNZ MRSA isolates could be grouped into seven clades. Antimicrobial phenotype-genotype concordance was high (> 95%), indicating the accuracy of WGS in predicting most resistances. Majority of the MRSA isolates were found to harbor more than 10 virulence genes, demonstrating their pathogenic nature.

DOI： 10.1038/s41598-024-54182-x

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Transplant of gut microbiota ameliorates metabolic and heart disorders in rats fed with a hypercaloric diet by modulating microbial metabolism and diversity 査読有り国際誌

Peña-Ocaña B.A., Silva-Flores M., Shotaro T., García-Gálvez L., Hernández-Esquivel L., Robledo-Cadena D.X., Barrera-Oviedo D., Pérez-Torres I., Tostado-Islas O., Maeda T., Rodríguez-Zavala J.S., Marín-Hernández Á., García-Contreras R., Jasso-Chávez R.

Biomedicine and Pharmacotherapy 181 2024年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

Metabolic syndrome (MS) is a cluster of metabolic disorders which have a tight correlation with dysbiosis of gut microbiota (GM) that have to be treated to avoid higher risks for health. In this work, probiotics obtained from healthy cultured GM were provided to rats with metabolic syndrome (MSR) as therapy in treating MS through the correction of dysbiosis. MSR showed obesity, high blood pressure, abnormal blood chemistry parameters and high heart rate respect to control rats (CNTR). Cultivated GM from feces of MSR in media favoring anaerobic species, showed dysbiosis as judged by differences in the 16S rRNA metabarcoding analysis and by affected intermediary metabolism (methane and SCFA production, nutrients consumption and enzyme activities) compared to CNTR. The metabarcoding analysis of cultured healthy GM identified 211 species, which were further transplanted alive in MSR once a week for 9 weeks. Thereafter, in transplanted MSR the excess of Clostridium and Lactobacillus diminished, while Prevotella, Eubacterium, Faecalibacterium and methanogens, among others increased, leading to the recovery of the microbial metabolic capacity. The presence of butyric acid-producing bacteria in the transplanted GM correlated with increased levels of anti-inflammatory cytokines. Therefore, transplanted MSR recovered the normal levels of weight, blood glucose, triglycerides and cholesterol as well as the heart function. Data suggested that the great diversity of species contained in the GM transplanted restored the microbial metabolism, consuming excessive nutrients and secondary metabolites produced by MS. The use of cultivated GM as probiotics may be a safer alternative for the treatment of different diseases.

DOI： 10.1016/j.biopha.2024.117667

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Novel Insights into Cr(VI)-Induced Rhamnolipid Production and Gene Expression in Pseudomonas aeruginosa RW9 for Potential Bioremediation 査読有り国際誌

Arisah F.M., Ramli N., Ariffin H., Maeda T., Farid M.A.A., Yusoff M.Z.M.

Journal of Microbiology and Biotechnology 34 ( 9 ) 1877 - 1889 2024年09月

記述言語：英語掲載種別：研究論文（学術雑誌）

Rhamnolipid (RL) is renowned for its efficacy in bioremediating several types of organic and metal contaminants. Nevertheless, there has been a scarcity of studies specifically examining the relationship between this substance and metals, especially in terms of their impact on RL formation and the underlying interaction processes. This study addresses this gap by investigating the RL mechanism in Cr (VI) remediation and evaluating its effect on RL production in Pseudomonas aeruginosa RW9. In this study, P. aeruginosa RW9 was grown in the presence of 10 mg l-1 Cr (VI). We monitored RL yield, congeners distribution, and their ratios, as well as the transcriptional expression of the RL-encoded genes: rhlA, rhlB, and rhlC. Our results revealed that RL effectively reduced Cr (VI) to Cr (III), with RL yield increasing threefold, although with a slight delay in synthesis compared to control cells. Furthermore, Cr (VI) exposure induced the transcriptional expression of the targeted genes, leading to a significant increase in di-RL production. The findings confirm that Cr (VI) significantly impacts RL production, altering its structural compositions and enhancing the transcriptional expression of RL-encoded genes in P. aeruginosa RW9. This study represents a novel exploration of Cr (VI)'s influence on RL production, providing valuable insights into the biochemical pathways involved and supporting the potential of RL in Cr (VI) bioremediation.

DOI： 10.4014/jmb.2406.06034

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Antibacterial mechanism of Pseudomonas aeruginosa UKMP14T rhamnolipids against multidrug resistant Acinetobacter baumannii 査読有り国際誌

Firdose A., Maeda T., Sukri M.A.M., Yasin N.H.M., Sabturani N., Aqma W.S.

Microbial Pathogenesis 193 2024年08月

記述言語：英語掲載種別：研究論文（学術雑誌）

Rhamnolipids, a major category of glycolipid biosurfactant, have recently gained enormous attention in medical field because of their relevance as effective antibacterial agents against a wide variety of pathogenic bacteria. Our previous studies have shown that rhamnolipids from an environmental isolate of Pseudomonas aeruginosa UKMP14T possess antibacterial, anti-adhesive and anti-biofilm activity against multidrug-resistant ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter sp.) pathogens. However, the mechanism of their antibacterial action remains unclear. Thus, this study aimed to elucidate the mechanism of the antibacterial action of P. aeruginosa UKMP14T rhamnolipids by studying the changes in cells of one of the ESKAPE pathogens, Acinetobacter baumannii, which is the most difficult strain to kill. Results revealed that rhamnolipid treatment rendered A. baumannii cells more hydrophobic as evaluated through contact angle measurements. It also induced the release of cellular proteins measuring 510 μg/mL at a rhamnolipid concentration of 1000 μg/mL. In addition, rhamnolipids were found to be bactericidal in their action as they could permeate the inner membranes, leading to a leak-out of nucleotides. More than 50 % of the cells were found to be killed upon 1000 μg/mL rhamnolipid treatment as observed through fluorescence microscopy. Other cellular changes such as irregular shape and size, membrane perturbations, clumping, shrinkage and physical damage were clearly visible in SEM, FESEM and laser micrographs. Furthermore, rhamnolipid treatment inhibited the levels of acyl-homoserine lactones (AHLs) in A. baumannii, which are vital for their biofilm formation and virulence. The obtained results indicate that P. aeruginosa UKMP14T rhamnolipids target outer and inner bacterial membranes through permeation, including physical damage to the cells, leading to cell leakage. Furthermore, AHL inhibition appears to be the mechanism behind their anti-biofilm action. All these observations can be correlated to rhamnolipids’ antibacterial effect against A. baumannii.

DOI： 10.1016/j.micpath.2024.106743

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An innovative temperature control strategy to improve optically pure L-lactic acid production from food waste 査読有り国際誌

Wang X., Sun H., Narita J.y., Ma X., Gao M., Maeda T., Wang Q.

Process Biochemistry 141 112 - 117 2024年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

Fermentation of food waste to lactic acid (LA) is a strategy for resource recovery. However, the poor yield and optical activity (OA) of L-lactic acid (L-LA) are major bottlenecks for such efforts. This study focuses on enhancing L-LA yield and optical purity from the food waste without sterilization and inoculation at pilot-scale. First, the effects of temperature on LA production were explored. A higher LA yield but lower purity was obtained under mesophilic conditions, whereas the opposite results were represented at high temperature. On the basis of these findings, a novel two-stage temperature regulation strategy was developed that combined the benefits of both temperature conditions. This strategy not only ensured a L-LA yield of 0.371 g/g volatile solid, but also achieved a high optical purity of 98.0%. The underlying mechanism is that high temperature could enrich L-lactic acid bacteria (LAB) and inhibit LAB producing both L- and D-LA. Overall, this innovative strategy may be well-suited for generating optically pure L-LA from food waste fermentation.

DOI： 10.1016/j.procbio.2024.02.011

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Improved complete genome sequence of Bdellovibrio bacteriovorus 109J, a widely studied laboratory strain of predatory bacteria 査読有り

Hoshiko Y., Okuno M., Yamamoto T., Maeda T., Ogura Y.

Microbiology Resource Announcements 13 ( 6 ) 2024年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

The complete genome sequence of Bdellovibrio bacteriovorus 109J, a well-studied laboratory strain of predatory bacteria, first determined in 2014. Here we report an improved complete genome sequence of B. bacteriovorus 109J, incorporating 16 assembly and 87 nucleotide corrections. This revised genome will be helpful to studies on the predatory bacteria.

DOI： 10.1128/mra.01296-23

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Rhamnolipids production by Pseudomonas aeruginosa RW9 using palm oil mill effluent sludge oil as a carbon source 査読有り国際誌

Mohd Asmadi N.A.N., Zee K.M., Baskaran S.M., Ariffin H., Wasoh H., Maeda T., Hassan M.A., Zakaria M.R.

Biocatalysis and Agricultural Biotechnology 57 2024年04月

記述言語：英語掲載種別：研究論文（学術雑誌）

The production of biosurfactants has garnered considerable attention in recent years due to their unique properties, which include the ability to enhance oil solubility in water, reduce surface tension, and exhibit low environmental toxicity. In this study, we investigated the production of biosurfactants by Pseudomonas aeruginosa RW9, using a renewable and non-food competitive, palm oil mill effluent (POME) sludge oil as a carbon source. Various carbon and nitrogen sources were introduced into the mineral salt medium to optimize biosurfactant production. The results demonstrated that P. aeruginosa RW9 successfully generated 1.57 g/L of rhamnolipids (RLs) biosurfactant. Liquid chromatography-mass spectrometry (LC-MS) analysis confirmed the presence of mono-RLs and di-RLs congeners. Furthermore, the RLs produced from POME sludge oil exhibited a significant reduction in surface tension, reaching 28.55 mN/m, and demonstrated efficient emulsification of diesel, with an emulsion index of up to 56.6 %. This research underscores the promising potential of using POME sludge oil as a sustainable substrate for RLs production. This approach not only adds value to a vastly available resource but also contributes to the production of environmentally friendly biochemicals.

DOI： 10.1016/j.bcab.2024.103069

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Identification of skin bacterial profiles of early deceased bodies and the rto post-mortem interval 査読有り国際誌

Chong C.K., Emamjomeh M., Joseph N., Siew S.F., Maeda T., Mustapha N.A., Hoshiko Y., Muthanna A., Amin-Nordin S.

Tropical Biomedicine 41 ( 1 ) 109 - 117 2024年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Post-mortem microbiology (PMM) is an important tool in identifying possible causes of sudden unexpected death, as an infectious cause is highly suspected. However, contamination is a major problem in microbiology, and this has increased the difficulty determining the true pathogen that contributes to death in post-mortem cases. Skin commensals are common contaminants in blood cultures. This study was conducted to investigate the skin flora on early deceased bodies and observe the bacteria detected at different post-mortem intervals (PMIs). As blood is usually drawn from the neck and femoral sites for PMM examination, the two body sites were chosen as the sampling sites. Skin swab samples from the neck and femoral (n=80) of each early deceased body were collected by sterile cotton swabs. DNA was extracted from the swabs and then subjected to high-throughput 16S rRNA sequencing by using the Illumina MiSeq platform. Staphylococcus was found to be the most dominant genus in both neck and femoral sites. LEfSe results showed that Cutibacterium is significantly different at the neck site while Corynebacterium is more abundant at femoral site. There are significant differences at genus level between PMI<5H and PMI>5H at both neck and femoral sites. The findings of the present study may act as a reference for microbiologists and forensic pathologists when mixed growth or contamination occurs in post-mortem blood cultures.

DOI： 10.47665/tb.41.1.013

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CO<sub>2</sub> Sequestration by Thermophilic Enriched Methanogens in Activated Sludge for Methane Production 査読有り

Koya Masahiro, Koyakumaru Saki, Maeda Toshinari

環境バイオテクノロジー学会誌 ( NPO法人環境バイオテクノロジー学会 ) 24 ( 1 ) 97 - 103 2024年01月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

<p>In this study, we examined the anaerobic incubation of waste-activated sludge (WAS) under thermophilic conditions. First, we reconfirmed CO<sub>2</sub> sequestration using WAS without any enrichment process at different temperatures under mixed gases (CO<sub>2</sub>:H<sub>2</sub> = 1:4). We observed that the methanogens, which were previously enriched at 37°C, displayed strong CO<sub>2</sub> sequestration at an early incubation time. Although CO<sub>2</sub> sequestration at 60°C showed the largest impact after 6 days, no methane production was observed at each thermophilic condition within 4 days. Therefore, we enriched methanogens using a novel WAS protocol for 10 days under nitrogen gas under thermophilic conditions. These methanogens displayed better CO<sub>2</sub> sequestration than the original strain at 37°C. Moreover, methane production by the thermophilic methanogens was due to the hydrogenotrophic pathway rather than the acetoclastic one because low methanogenic activity from acetate was observed. Microbial community structure analysis showed that the <i>Methanothermobacter</i> genus belonging to hydrogenotrophic methanogens was predominant among the thermophilic enriched methanogens at 60°C. Taken together, the thermophilic methanogens can be a useful tool to sequestrate CO<sub>2</sub> efficiently.</p>

DOI： 10.50963/jenvbio.24.1_97

Pseudomonas aeruginosa-mediated cr(VI) bioremediation: mechanistic insights and future directions 査読有り国際誌

Mat Arisah F., Ramli N., Ariffin H., Maeda T., Ahmad Farid M.A., Yusoff M.Z.M.

Bioremediation Journal 2024年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Contamination of hexavalent chromium (Cr(VI)) is a major environmental issue since it has the ability to cause cancer and genetic mutations. Bioremediation techniques using Pseudomonas aeruginosa have emerged as potential methods to tackle this problem. This study offers a thorough examination of the underlying mechanisms and potential future paths in the process of P. aeruginosa-mediated Cr(VI) remediation. Herein, the strategies used by P. aeruginosa were examined for the removal of Cr(VI) via processes such as biosorption, intracellular reduction, and extracellular metabolism. In addition, the function of extracellular polymeric substances (EPS) in capturing and isolating Cr(VI) was studied and the possibility of using genetic engineering techniques to improve P. aeruginosa’s ability to remove Cr(VI) from the environment was explored. In addition, we investigate the difficulties related to the use of P. aeruginosa for Cr(VI) bioremediation, such as environmental conditions and the presence of other microorganisms, and suggest potential areas for further study. These include the development of bioremediation strategies using consortia of microorganisms and the incorporation of nanomaterials to improve the removal of Cr(VI). This study seeks to enhance the development of sustainable solutions for remediating Cr(VI) by integrating existing information and identifying future research directions, with a focus on employing P. aeruginosa.

DOI： 10.1080/10889868.2024.2420071

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Assessing microbial biodiversity in oil palm seedlings using oil palm waste compost mixed media 査読有り国際誌

Salamat S.S., Yusoff M.Z.M., Hassan M.A., Zainudin M.H.M., Shirai Y., Mohd Hanif A.H., Norizan M.S., Arisah F.M., Farid M.A.A., Maeda T., Mat Isa M.N., Abu Bakar M.F.

International Journal of Recycling of Organic Waste in Agriculture 13 ( Special Issue ) 2024年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Purpose: The oil palm nursery plays a pivotal role in ensuring optimal replanting materials for sustained productivity. However, conventional practices that rely exclusively on inorganic fertilizers can degrade soil over time, highlighting the need to reassess planting materials. This study examines the impact of incorporating compost into soil media on oil palm seedling development in primary nurseries. Method: The study compared microbial biodiversity in soil media with compost amendments by employing DNA sequencing to assess microbial communities. The analysis focused on bacterial species richness and the prevalence of key phyla, including Proteobacteria, Actinobacteria, Acidobacteria, and others. Results: The compost-amended media (T2) demonstrated significantly higher microbial biodiversity, with 60,769 sequences compared to 45,741 sequences in media containing only soil and inorganic fertilizer (T1). This compost-enriched media notably increased bacterial species richness, particularly benefiting nutrient-cycling bacteria such as Proteobacteria and Actinobacteria. While Acidobacteria showed sensitivity to compost, other phyla like Firmicutes, Planctomycetes, and Chloroflexi remained stable under the nutrient dynamics of elevated organic content. Streptomyces, known for its metabolic versatility, dominated across all media compositions. The co-occurrence of Bacteroidetes and Acidobacteria in compost-treated soils suggested pH stability that supports plant growth and ecosystem resilience. Conclusion: Integrating compost into nursery media significantly enhances microbial biodiversity and dynamics, particularly favoring beneficial nutrient-cycling bacteria. This suggests that compost amendments can serve as a viable pathway for improving oil palm nursery practices, promoting sustainable soil management, and ensuring long-term productivity.

DOI： 10.57647/ijrowa-m2gt-yd26

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Impact of antibiotics on methane produced from cellulose 査読有り国際誌

Zhu Q., Maeda T., Chen C., Wang Y., Tan F., Hu G., He M.

Journal of Renewable and Sustainable Energy 15 ( 6 ) 2023年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

Enhancing production of methane from cellulose is of utmost importance to improve the fermentation efficiency of lignocellulosic biomass. Antibiotics have demonstrated their ability to stimulate anaerobic digestion (AD) by influencing micro-organism activity. However, there has been limited research on the specific effect of antibiotics on cellulose AD. In this study, we investigated the impact of three antibiotics—tetracycline (TC), cephalexin (CLX), and azithromycin (AZM)—on cellulose AD when inoculated with waste sewage sludge. The results revealed that the presence of AZM and TC led to significantly higher methane yields, with increases of 51.94% and 34.96%, respectively, during a 20-day AD period. In contrast, the presence of CLX resulted in a 23.95% lower methane yield compared to the control. Furthermore, detailed analyses indicated that AZM had a positive influence on cellulose AD at all stages, including methanogenesis, acidogenesis/acetogenesis, and hydrolysis. On the other hand, TC primarily promoted AD during the methanogenesis stage. These findings collectively offer valuable guidance for efficiently transforming the energy potential of lignocellulosic wastes.

DOI： 10.1063/5.0175655

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Insights into bacterial community metatranscriptome and metabolome in river water influenced by palm oil mill effluent final discharge 査読有り国際誌

Sharuddin S.S., Ramli N., Yusoff M.Z.M., Muhammad N.A.N., Ho L.S., Maeda T.

Journal of applied microbiology 134 ( 10 ) 2023年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

AIMS: This study aimed to investigate the effect of palm oil mill effluent (POME) final discharge on the active bacterial composition, gene expression, and metabolite profiles in the receiving rivers to establish a foundation for identifying potential biomarkers for monitoring POME pollution in rivers. METHODS AND RESULTS: The POME final discharge, upstream (unpolluted by POME), and downstream (effluent receiving point) parts of the rivers from two sites were physicochemically characterized. The taxonomic and gene profiles were then evaluated using de novo metatranscriptomics, while the metabolites were detected using qualitative metabolomics. A similar bacterial community structure in the POME final discharge samples from both sites was recorded, but their composition varied. Redundancy analysis showed that several families, particularly Comamonadaceae and Burkholderiaceae [Pr(>F) = 0.028], were positively correlated with biochemical oxygen demand (BOD5) and chemical oxygen demand (COD). The results also showed significant enrichment of genes regulating various metabolisms in the POME-receiving rivers, with methane, carbon fixation pathway, and amino acids among the predominant metabolisms identified (FDR < 0.05, PostFC > 4, and PPDE > 0.95). This was further validated through qualitative metabolomics, whereby amino acids were detected as the predominant metabolites. CONCLUSIONS: The results suggest that genes regulating amino acid metabolism have significant potential for developing effective biomonitoring and bioremediation strategies in river water influenced by POME final discharge, fostering a sustainable palm oil industry.

DOI： 10.1093/jambio/lxad219

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